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Rainer Schultze-Kraft,
Lyle Winks,
Centro Internacional de Agricultura Tropical (CIAT),
Former editor of “Tropical Grasslands”,
Colombia
Australia
Management Committee
Changjun Bai,
Rainer Schultze-Kraft,
Chinese Academy of Tropical Agricultural Sciences
Centro Internacional de Agricultura Tropical (CIAT),
(CATAS),
Colombia
P.R. China
Cacilda B. do Valle,
Robert J. Clements,
Empresa Brasileira de Pesquisa Agropecuária (Embrapa),
Agricultural Consultant,
Brazil
Australia
Lyle Winks,
Asamoah Larbi,
Former editor of “Tropical Grasslands”,
International Institute of Tropical Agriculture (IITA),
Australia
Nigeria
Michael Peters,
Centro Internacional de Agricultura Tropical (CIAT),
Colombia
Editorial Board
Changjun Bai,
Albrecht Glatzle,
Chinese Academy of Tropical Agricultural Sciences
Iniciativa para la Investigación y Transferencia de
(CATAS),
Tecnología Agraria Sostenible (INTTAS),
P.R. China
Paraguay
Caterina Batello,
Orlando Guenni,
Food and Agriculture Organization of the United Nations
Universidad Central de Venezuela (UCV),
(FAO),
Venezuela
Italy
Jean Hanson,
International Livestock Research Institute (ILRI),
Michael Blümmel,
Ethiopia
International Livestock Research Institute (ILRI),
India
Michael David Hare,
Ubon Ratchathani University,
Robert J. Clements,
Agricultural Consultant,
Thailand
Australia
Mario Herrero,
Commonwealth Scientific and Industrial Research
Myles Fisher,
Organisation (CSIRO),
Centro Internacional de Agricultura Tropical (CIAT),
Australia
Colombia
Bruce Pengelly,
University of Miyazaki,
Agricultural Consultant,
Japan
Australia
Peter Horne,
T. Reginald Preston,
Australian Centre for International Agricultural Research
University of Tropical Agriculture Foundation (UTA),
(ACIAR),
Colombia
Australia
Johann Huguenin,
Kenneth Quesenberry,
Centre de Coopération Internationale en Recherche
University of Florida,
Agronomique pour le Développement (CIRAD),
USA
France
Max Shelton,
Muhammad Ibrahim,
University of Queensland,
Centro Agronómico Tropical de Investigación y Enseñanza
Australia
(CATIE),
Costa Rica
Werner Stür,
Australian Centre for International Agricultural Research
Asamoah Larbi,
(ACIAR),
International Institute of Tropical Agriculture (IITA),
Australia
Nigeria
Carlos E. Lascano,
Cacilda B. do Valle,
Universidad Nacional de Colombia - Sede Bogotá,
Empresa Brasileira de Pesquisa Agropecuária (Embrapa),
Colombia
Brazil
Robert Paterson,
Agricultural Consultant,
Spain
Principal Contacts
Rainer Schultze-Kraft
Centro Internacional de Agricultura Tropical (CIAT)
Colombia
Phone: +57 2 4450100 Ext. 3036
Email: r.schultzekraft@cgiar.org
Technical Support
Cristhian David Puerta R.
Centro Internacional de Agricultura Tropical (CIAT)
Colombia
Phone: +57 2 4450100 Ext. 3354
Email: CIAT-TGFT-Journal@cgiar.org
Research Papers
Complementary use of neotropical savanna and grass-legume pastures for early weaning and effects on
50-65
growth and metabolic status of weaners and inter-calving intervals of dams
Raúl R. Vera, Carlos A. Ramírez-Restrepo
66-76
Jonathan R. Garay, Santiago Joaquin Cancino, Pedro Zárate Fortuna, Martín A. Ibarra Hinojosa, Juan C.
Martínez González, Ricardo P. González Dávila, Eugenia G. Cienfuegos Rivas
77-84
( Pennisetum pedicellatum Trin.) in the highlands of Ethiopia
Genet Tilahun, Bimrew Asmare, Yeshambel Mekuriaw
Weeds alter the establishment of Brachiaria brizantha cv. Marandu
85-93
Sidnei R. de Marchi, José R. Bellé, Celso H. Foz, Jucilene Ferri, Dagoberto Martins
Short Communications
A simple method for determining maize silage density on farms
94-99
Ana Maria Krüger, Clóves C. Jobim, Igor Q. de Carvalho, Julienne G. Moro
Book Reviews
100-102
Tropical Grasslands-Forrajes Tropicales (2017) Vol. 5(2):50– 65 50
Research Paper
Complementary use of neotropical savanna and grass-legume
pastures for early weaning and effects on growth and metabolic
status of weaners and inter-calving intervals of dams
Uso complementario de sabana nativa neotropical y pasturas con
asociaciones gramíneas-leguminosas para destete precoz y efectos en el
crecimiento y metabolismo de los terneros y la fertilidad de las vacas
RAÚL R. VERA1,2 AND CARLOS A. RAMÍREZ-RESTREPO1,3
1 Formerly International Center for Tropical Agriculture (CIAT), Cali, Colombia. www.ciat.cgiar.org
2 Departamento de Ciencias Animales, Pontificia Universidad Católica de Chile, Santiago, Chile. www.uc.cl
3 Commonwealth Scientific and Industrial Research Organisation, CSIRO Agriculture, Townsville, QLD, Australia.
Abstract
Extensive, rangeland-based beef production systems that predominate in the neotropical savannas of northern South America are low input-low output beef breeding systems, and their intensification faces major hurdles due to their location, soil, water and topographic constraints. Intensification requires the introduction of improved pastures strategically managed to complement the native savannas, to improve production and to allow opportunities for a wider
range of associated ecosystem services. This study assessed the feasibility of early weaning of beef calves onto small
areas of sown pastures to aid system intensification. Weaning calves at 90 days of age and grazing on Andropgon gayanus, A. gayanus-Pueraria phaseoloides, A. gayanus-Centrosema acutifolium and Brachiaria humidicola-Arachis pintoi sown tropical pastures stocked at 6 animals/ha was compared with conventional weaning on native savanna over 4 consecutive years. The reproductive performance of their Brahman ( Bos indicus) and crossbred [Brahman x San Martinero (native; B. taurus)] dams grazing savanna (0.2 cows/ha) was monitored in comparison with control cow-calf systems, where calves were weaned onto savanna between 240 and 270 days of age. Post-weaning weight gains of early
weaned calves on sown pasture (0.1‒0.2 kg/d) were much lower than those of unweaned animals on savanna (0.31‒0.35
kg/d), but compensatory gains realized after the end of the weaning experiments allowed early weaned calves to reach
weights similar to those of control animals 400 days after the end of the pasture phase. As expected, early weaned cows
achieved higher live weights and had shorter inter-calving intervals than their counterparts. Trade-offs between performance of calves and of cows are discussed, but it is suggested that the strategic use of small areas of sown pastures for early weaned calves may productively complement large areas of native savannas. It is hypothesized that the improved quality, frequency and intensity of management required by these intensified systems may place a burden on
these low-input primary enterprises, which may also challenge the productive and environmental adaptive capacity of
primary resource users.
Keywords : Cattle, extensive systems, intensification, rangelands, sustainability, tropical pastures.
___________
Correspondence: R.R. Vera, Departamento de Ciencias Animales,
Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860,
Santiago de Chile, Chile.
Email: rverai@uc.cl
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 51
Resumen
Los sistemas de producción de carne extensivos basados en pasturas nativas, son frecuentemente considerados
tradicionales y sustentables. Este tipo de sistema en las sabanas del norte de Sur América usa bajos insumos y su productividad también es baja. Su intensificación está limitada frecuentemente por su localización y por características
de suelo, topografía y acceso a agua. La introducción de pasturas tropicales sembradas, usadas en forma estratégica como
complemento de las sabanas, permite intensificar la producción animal y provee oportunidades para mejorar algunos
servicios ecológicos. Durante 4 años consecutivos se experimentó el destete precoz de terneros de carne a los 90 días,
en pasturas sembradas de Andropgon gayanus, A. gayanus-Pueraria phaseoloides, A. gayanus-Centrosema acutifolium
y Brachiaria humidicola-Arachis pintoi. Simultáneamente se registró el desempeño reproductivo de hatos de la raza Brahman ( Bos indicus) y cruzas con San Martinero ( Bos taurus) en pastoreo en sabanas con carga de 0.2 vacas/ha, en comparación con sistemas control caracterizados por destete tradicional a los 240‒270 días de edad. Las ganancias de
peso vivo de los terneros destetados tempranamente fueron bajas en comparación con los animales control, pero se lograron ganancias compensatorias posteriormente, alcanzando pesos vivos a los 400 días después de la fase
experimental sin diferencias significativas (P>0.05) entre ambos grupos de animales. Como se esperaba, las vacas destetadas precozmente lograron mayores pesos y mejor desempeño reproductivo que las del grupo control. Se discute
el compromiso entre desempeño de terneros y de vacas, pero es aparente que áreas pequeñas de pasturas sembradas pueden complementar efectivamente grandes extensiones de sabana para intensificar la producción de hatos de carne.
Se hipotetiza que estos usos complementarios requieren un mejoramiento en la cantidad, calidad y frecuencia de la gestión de dichos recursos. Este tipo de manejo puede ser una oportunidad para mejorar la productividad de los hatos
por parte de los ganaderos, lo que requiere de ellos una mayor capacidad de adaptación y mejoramiento de la producción
concomitante con las actuales necesidades ambientales.
Palabras clave : Ganado bovino, intensificación, pasturas tropicales, sabanas, sistemas extensivos, sostenibilidad.
Introduction
Andean foothills. Overall, cropped areas represent 4.3‒
11.8%, whereas rangelands cover 72‒89% of the Orinoco
The continuous increase in demand for food requires
basin in Colombia (DANE 2016).
intensification of land use systems in the agricultural
This expansion of crops and plantations has taken
sector and achieving a compromise between increases in
place at the expense of native savannas supporting beef
production and ecological conservation constitutes an
cattle ranching. On areas closest to roads in the Plains,
important challenge (Davies et al. 2010; van Vuuren and
beef breeding herds have been replaced by yearlings
Chilibroste 2013). Additionally, climate change may
brought in from the surrounding area for fattening,
further increase the demands on management of resources
interspersed with crops and plantations (Romero-Ruiz et
and the capacity of livestock farmers and their rural
al. 2012; Huertas-Ramírez and Huertas-Herrera 2015).
communities to adapt (Herrero et al. 2017).
The cattle population of the region is estimated at 4.7 M
The watershed of the Orinoco River covers 35 Mha in
head (DANE 2016), largely supported by native savannas
Colombia (33% of the land area) and includes mountains,
that still constitute the main land use in the rest of the area,
foothills and a variety of seasonally flooded and well
mainly dedicated to extensive beef breeding herds
drained
savannas.
The
well
drained
savannas
(Rausch 2013; Huertas-Ramírez and Huertas-Herrera
(“Altillanura”) extend over 13.5 Mha (CONPES 2014),
2015). The latter are low input-low output systems,
35% of which is plain (“Plains”) and 54% is slopes and
frequently constrained by limited access, physiographic
hills (Rippstein et al. 2001). The latter include small
and water limitations, low soil fertility and often shallow
valleys suitable for cropping, surrounded by pronounced
soils that limit intensification (Seré and Vera 1983). On
slopes that have shallow, stony soils. By 2007, 23% of the
the other hand, these savannas are rich in plant and animal
Plains had been converted to crops, sown pastures, palm
biodiversity (Rippstein et al. 2001; Lasso et al. 2011) and
oil plantations (Romero-Ruiz et al. 2012; Rausch 2013)
have varied landscapes and ecosystem services that attract
and a variety of tree plantations and reforested areas
rural tourism highlighted by educational and cultural
amounting to close to 100,000 ha (MADR 2015). Palm oil
values and traditions (Navas Ríos 1999; Molina and
plantations have experienced a significant and ongoing
Triana 2011; Australian Government 2015).
increase in the savannas, and have reached 112,186 ha
Although the real impact of greenhouse gas emissions
(FEDEPALMA 2015), including large areas in the
from cattle on neotropical savannas is still a challenge for
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
52 R. R. Vera and C.A. Ramírez-Restrepo
scientists, it is likely that plant dynamics may mitigate the
et al. 1988; Schlink et al. 1992; Short et al. 1996; Tyler et
demanding effects of climate variability, reflecting the
al. 2012). In the majority of cases, weaners have either
capacity of these plant-animal evolutionary systems to
been raised in feedlots (Arthington et al. 2005) or supple-
adapt to genetic, environmental and management
mented with concentrates or crop by-products on pasture
stressors (O’Neill et al. 2010; Herrero et al. 2015;
(Vendramini et al. 2007; Vendramini and Arthington
Ramírez-Restrepo and Charmley 2015). In this complex
2008). Consequently, Tyler (2012) indicates that the
scenario, primary producers have to contend with low
effect of tropical pastures on the performance of early
seasonal biomass production and nutritive value
weaners should be prioritized in future pastoral research.
(Paladines and Leal 1979; Rippstein et al. 1996; Durmic
Early weaning has rarely been investigated in the
et al. 2017). Together, these factors negatively impact
neotropics (Moore and da Rocha 1983; Betancourt-López
productivity in terms of slow growth and fertility rates
et al. 2012) and, as elsewhere, the practice has generally
that seldom exceed 50%, yielding no more than 3 or 4
been coupled with regular supplementation of cows and
calves weaned over a cow’s lifetime (Kleinheisterkamp
calves with different combinations of concentrates and/or
and Habich 1985; Plessow 1985; Squires and Vera 1992).
other feedstuffs in different settings. However, to the
These traits contrast with the relatively high per-
authors’ knowledge, raising early weaned beef calves
formance reported when Brahman ( Bos indicus) beef
exclusively on sown pastures in the neotropics has not
cows are grazed year-round on well managed tropical
been investigated.
sown pastures (Vera et al. 2002). Nevertheless, expensive
The objectives of this study were to assess the effects
sown pastures are mostly reserved for fattening yearlings
on cow and calf performance of early weaning of beef
and steers (Vera and Seré 1985), and their year-round use
calves onto sown tropical pastures, while their dams were
by the breeding herd may represent an economically
maintained on savanna, in comparison with cow-calf pairs
suboptimal use of an expensive resource. It is possible
grazing native savanna with weaning at the conventional
that strategic and seasonal grazing of improved pastures
age.
by suckling cows to complement native savanna grazing
may significantly increase reproductive indexes (Vera
Materials and Methods
and Seré 1989).
Reproductive rates may be boosted further by early
Experimental design
weaning of calves, a technology that is 50 years old. In
principle, early weaning can be performed at 45 days of
The study was conducted during the late 1980s over 6
age (Rasby 2007) and it is particularly useful in drought
consecutive years at Carimagua Research Station, located
situations and to contend with the negative effects of
87 km northeast of Puerto Gaitán in the Meta Department
climate change (FAO 2013). Cow-calf research in the
on the eastern plains of Colombia (4°36'44.6" N,
savannas of northern Australia has been amply docu-
74°08'42.2" W). Monthly rainfall, ambient temperature
mented in over 100 references and reports summarized by
and their annual variations were recorded during 13
Tyler (2012) and Tyler et al. (2012). Similarly, a large
consecutive years (Table 1).
amount of research was carried out in the USA
Care of animals and experimental procedures were
(Arthington et al. 2005; Vendramini et al. 2006). Much of
performed by accredited Doctors of Veterinary Medicine
this research has addressed the consequences of early
(DVM), including the second author, following national
weaning on the dams’ reproductive performance (Fordyce
husbandry and animal welfare regulations.
Table 1. Monthly average climatic data over 13 years, and annual rainfall recorded during the 1984‒1987 period at Carimagua Research Station, Meta Department, Colombia.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean rainfall 1979‒1991 (mm)
10
25
76
236
292
368
274
260
292
203
116
50
Mean ambient temp 1979‒1991 (ºC)1 26.9
28.0
28.1
27.1
26.2
25.4
25.2
25.7
26.1
26.5
26.9
26.4
Annual rainfall (mm)
1984
94
47
53
213
125
439
179
246
529
351
222
25
1985
0
0
33
196
544
445
327
250
351
266
180
0
1986
36
32
65
221
570
541
462
367
286
214
147
89
1987
n/a
n/a
n/a
n/a
558
528
445
354
275
204
138
82
n/a - records not available.
1Mean monthly temperature for 1984‒1987 not included as there is less than 1 ºC variation between years.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 53
During the first 2 years (Years 1 and 2) exploratory
0.2 cows/ha in large (>200 ha) paddocks managed with
trials were conducted to assess the feasibility of raising
periodic fire following traditional and regional farming
early weaned beef calves on sown pastures alone, and to
practices (Kleinheisterkamp and Habich 1985; Rippstein
monitor the associated health and mortality risks. At the
et al. 2001).
end of the experimental phase of Year 2, the weaners were
In Year 2, the experiment was methodologically
transferred to a savanna paddock and their weight was
similar to Year 1, but 15 calves were weaned at 68 ± 9 kg
monitored until the savanna controls were weaned at the
ILW and 110 ± 8 days of age on 30 May 1985 at the
age of 266 ± 7 days. A further 18 months were required
beginning of the rainy season. They were rotationally
to monitor growth of these weaners on savanna during
grazed on 15 paddocks of AgPp and Ag plus Centrosema
537 days after the early weaning date, and of the
acutifolium cv. Vichada (accession CIAT 5277; AgCa; 6
performance of their dams until the subsequent calving
calves/ha with 7 days grazing, 21 days rest) for 147 days.
event. In the following 2 years (Years 3 and 4), trials
In parallel, 15 similar calves (Control 2) continued to
compared the performance of early weaned calves on a
suckle their dams as part of a large herd grazing native
number of sown tropical pastures with that of normally
savanna, and were weighed at intervals of 21 days during
weaned calves on savanna.
the same period but weaned at 266 ± 7 days of age and
In all cases Brahman and crossbred [Brahman x San
144 ± 20 kg LW. Thereafter, weaned control and early
Martinero (native; B. taurus)] cows and calves were used.
weaned calves were grazed on a native savanna paddock
Calves were born on savanna with a mean live weight
as a single group at 0.25 head/ha for 18 months, and were
(LW) of 22.7 ± 3.4 kg. Body weight of calves during the
weighed about every 120 days.
experimental phase on sown pastures was recorded every
During Year 3, the experiment compared the
7 days. Cows remained on large savanna paddocks as part
performance of groups of 10 weaned calves (68 ± 13 kg
of a large herd and were weighed and rectally palpated at
ILW, 93 ± 4 days of age) rotationally grazing 4 paddocks
~4-monthly intervals to determine if they were pregnant.
(6 calves/ha; 7 days grazing, 21 days rest) each of Ag,
Calving events were recorded daily, but mustering of the
AgPp and AgCa for 123 days during the wet season,
cows was avoided near calving time. Pregnancy rates and
commencing on 25 June 1986 (mid rainy season).
inter-calving intervals were calculated. Approximate date
Year 4 replicated the design of the third year, with the
of conception was back calculated from the calving date.
addition of a Brachiaria humidicola cv. Llanero (syn. B.
Internal and external parasite infestations were controlled
dictyoneura)- Arachis pintoi (BhAp) pasture subjected to
throughout following commercial farming practices.
the same management and sampling practices previously
Mortalities and incidents of ill health were recorded.
described. The experiment began on 23 July 1987. Ten
Cows and calves had free access to fresh water plus a
calves (81 ± 9 kg ILW, 86 ± 5 days of age) were weaned
commercial mineral supplement containing (as-fed):
and placed on each improved pasture, while 10 unweaned
17.5% Na, 26.9% Cl, 8.0% P, 13.7% Ca, 2.0% S, 0.104%
calves grazed on savanna with their dams until weaning
Cu, 0.35% Zn, 0.001% Co and 0.008% I. Supplement
at 319 ± 29 days of age and 155 ± 25 kg live weight.
consumption was recorded every 15 days.
In Year 3 a pilot test of weaning was carried out
Animals, forages and grazing management
starting on 28 July 1986 with one commercial herd at
Carimagua. Forty-six calves born in 2 different savanna
In the first year (Year 1) 10 male calves [112 ± 16 kg
paddocks were weaned at a mean age of 186 ± 62 (range
initial LW (ILW); mean ± standard error of the mean
54‒285) days and LW 131 ± 26 kg, and were transferred
(s.e.m.)] were weaned at 166 ± 10 days old on
to a 1-year-old A. gayanus-Stylosanthes capitata cv.
11 November 1984, coinciding with the end of the rainy
Capica pasture stocked at 3 calves/ha for 99 days until the
season. They were rotationally grazed (6 calves/ha;
end of the rainy season.
7 days grazing, 21 days rest) for 146 days during the dry
season using 4 paddocks of equal size of a 6-year-old
Sample collection and lab analyses
mixture of Andropogon gayanus cv. Carimagua-1 and
commercial Pueraria phaseoloides (AgPp). Fifteen
Pasture. Pre-grazing herbage mass and botanical
cow-calf pairs grazing savanna as part of a larger herd
composition of the introduced pastures were estimated by
served as controls (Control 1) and were monitored at
the BOTANAL method (Tothill 1978; data partially
intervals of ~120 days. Their calves were weaned at
shown). Botanical composition, growth rate and nutritive
280 ± 29 days of age, and the dams were monitored until
value of the savanna have been previously described by
the next calving event. Savanna cows were stocked at
Rivera Sánchez (1988).
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
54 R. R. Vera and C.A. Ramírez-Restrepo
Blood. Jugular blood samples were collected weekly from
shown due to space limitations). Regressions were
each of the calves into two 10 ml BD Vacutainers®
calculated with the GLMSELECT procedure.
(Becton Dickinson, Franklin Lakes, NJ, USA) for
hematology [hematocrit (g/100 ml)], serum enzymes
Results
[aspartate aminotransferase (AST, U/ml) and gamma-
glutamyl transferase (GGT, U/ml)], total protein (g/100
Forages and botanical composition
ml), renal function [urea nitrogen (BUN, mg/100 ml)] and
mineral [P, Ca and Mg (g/100 ml)] analyses. Hematology
Pre-grazing herbage mass in all introduced pastures
and serum biochemistry analyses were performed at the
and across the experimental periods in Years 3 and 4
International Center for Tropical Agriculture, Cali,
always exceeded 2,500 kg DM/ha, except in the Ag
Colombia. Blood enzymes, protein and BUN were
treatment in Year 3 for a brief period during temporary
determined using standard kits (Sigma-Aldrich Corp., St.
flooding of the paddock. Legume percentage in the forage
Louis, MO, USA), N by the micro-Kjeldahl method, P by
on offer was higher for the AgPp (29%) mixture than for
colorimetry and the remaining minerals by atomic
the BhAp (20%) association, with lower amounts
absorption.
(7‒10%) in the AgCa sward. These legume percentages
Feces. Fecal grab samples were individually collected
remained rela-tively stable throughout the experimental
from the rectums of animals at weighing times to
period as shown for Year 3 in Figure 1. The Ag pasture
determine P, Ca, ash and N concentrations, with N
averaged 758 g/kg DM of neutral detergent fiber (NDF)
expressed as percent of fecal organic matter.
and 80 g/kg DM crude protein (CP) during the rainy
season, and 759 and 89 g/kg DM in the dry season,
Statistical analyses
respectively. The AgPp and AgCa pastures had similar
nutritive composition and averaged 756 g NDF and 115 g
Data were analyzed using the Statistical Analysis System,
CP/kg DM and 757 g NDF and 110 g CP/kg DM for the
version 9.4 (SAS Institute, Cary, NC, USA). Results for
rainy and dry seasons, respectively. Similarly, the BhAp
the first 2 years were summarized using descriptive
pasture contained 716 g NDF and 84 g CP/kg DM in the
statistics (means ± s.e.). In Years 3 and 4, calves were
wet season, and 691 g NDF and 21 g CP/kg DM in the dry
balanced for LW and randomly allocated to sown pastures
season.
considering in all cases individual animals as the
experimental unit. Data distribution from all variables
Mortalities
examined (i.e. blood, feces and LW) was reviewed prior
to additional analyses. Repeated-measures of blood, feces
Over the 4 years of the study, 4 deaths out of 95 early
and LW for the same calf were analyzed with the
weaned calves occurred in the AgPp paddocks in Year 3,
GLIMMIX procedure, using a linear mixed model that
which was related to a temporary flooding event. No calf
included the fixed effect of pasture (i.e. sown forages and
mortality of control, suckling calves or their dams was
savanna), and the interaction between pasture and the
recorded in the savanna paddocks.
random effects of year. All interactions were initially
included, and those that were not significant were
Liveweight performance
discarded for the final analysis (Gbur et al. 2012).
Final analyses were preceded by a study of the
Years 1 and 2. Data in Table 2 show the LWs and ages of
covariance structure (Gbur et al. 2012) to adjust the model
calves during Years 1 and 2. Daily LW gains (LWG) of
specification as required. Differences were considered
calves weaned at 166 days of age in Year 1 and grazed on
significant when P≤0.05, and there was tendency to
the AgPp pasture averaged 0.10 ± 0.03 kg/head, whereas
significance if P≤0.10. Denominator degrees of freedom
contemporary suckling calves on savanna gained 0.35 ±
for the test of fixed effects were specified by the
0.19 kg/head. In Year 2, calves weaned at 110 days of age
Kenward-Roger procedure. Multiple comparisons of least
and grazed on AgPp and AgCa pastures gained 0.19 ±
squares means used the Tukey procedure, complemented
0.06 kg/day, and control suckling calves gained 0.60 ±
with graphical interpretation using SAS diffograms (not
0.13 kg/day.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 55
8.,000
a)/h ) 6.,000
a
DM /hMkg D (g 4.,000
erf r (k offfe on 2.,000
o
age onr doeFeF
0.,000
0
20
40
60
80
100
120
140
Experimental days
Experimental days
Grass DM AgPp
Grass DM AgCa
Grass DM Ag
Green DM AgPp
Green DM AgCa
Green DM Ag
Leg DM AgPp
Leg DM AgCa
Figure 1. Forage on offer (kg DM/ha) in 3 Andropogon-based pastures and their respective botanical compositions in Year 3. Grass DM stands for total grass DM on offer in the respective pastures; Green DM is green grass DM; Leg DM is total legume DM. Ag =
Andropogon gayanus; Pp = Pueraria phaseoloides; Ca = Centrosema acutifolium.
Live weights of cows for Years 1 and 2 between
(1985‒1986). Early weaned dams in Year 2 calved at
consecutive calving seasons on savanna are shown in
the end of the dry season, whereas control cows did
Figure 2. Year 1 dams of early weaned calves calved in
so at the end of the following rainy season. Calculated
the late rainy season, while control cows (normally
LWs at conception for the 2 years were 303 ± 43 and 321
weaned) calved at the end of the subsequent dry season
± 45 kg, respectively.
Table 2. Mean (± s.e.) live weights and ages of early weaned Brahman and Brahman cross calves during the exploratory observations in Years 1 and 2.
n
Initial
Final
Year 1
Live weight (kg)
10
112 ± 16
126 ± 18
Age (d)
10
166 ± 10
312 ± 10
Gain (kg/d)
0.10
Year 2
Live weight (kg)
15
69 ± 10
97 ± 13
Age (d)
15
109 ± 8
257 ± 8
Gain (kg/d)
0.19
n - number of animals.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
56 R. R. Vera and C.A. Ramírez-Restrepo
400
380
360
kg))g (tt (kh 340
eighigew w 320
wwoCoC
300
280
260
0
100
200
300
400
500
600
700
Days postpartum
Days postpartum
Early 110
Early 166
Normal 266
Normal 280
Figure 2. Postpartum cows’ live weights in relation to type of weaning. Early and normal refer to weaning treatment, followed by the calves’ ages at weaning. Standard deviations are not shown for clarity, and ranged between 32 and 42 kg, and 24 and 55 kg for early and normal weaning, respectively. Vertical arrows indicate weaning times and ellipses indicate time and spread of calvings.
Years 3 and 4. Consistent with the preliminary observa-
(P<0.0001) in calves on improved forages than in their
tions, calves were weaned at average ages of 93 and 86
suckling counterparts on savanna (Table 3). Differences
days in Years 3 and 4, respectively (Table 3). At the end
in LW productivity amongst sown forages were small
of the 123 days of experimentation, LW was lower
(P>0.05), with the exception of Ag in Year 3 (Table 3).
Table 3. Least squares means (± s.e.) of ages and live weights (LW) of early weaned calves at weaning and their final LW (FLW) after 123 days of experimental grazing on improved pastures (early weaned) and of normally weaned calves off savanna.
Pasture
n
Year 3
Year 4
Age (d)
LW (kg) FLW (kg)
Age (d)
LW (kg) FLW (kg)
Andropogon gayanus
10
92 ± 3
63 ± 15
82a1 ± 4
85 ± 4
77 ± 9
84a ± 4
A. gayanus + Centrosema acutifolium
10
93 ± 5
69 ± 9
91ab ± 3
89 ± 5
77 ± 6
88a ± 4
A. gayanus + Pueraria phaseoloides
10
92 ± 4
72 ± 13
95b ± 4
83 ± 5
89 ± 10
92a ± 4
Brachiaria humidicola + Arachis pintoi
10
n.a.
n.a.
n.a.
86 ± 3
80 ± 7
85a ± 5
Savanna2
10
91 ± 5
74 ± 6
117c ± 3
96 ± 10
89 ± 14
129b ± 5
P
NS
NS
<0.0001
NS
NS
<0.0001
n - number of animals.
n.a. - not applicable.
NS - not significant.
1Within columns values followed by different letters differ significantly (P<0.05).
2Weights and ages of savanna calves were obtained on the same date (± 3 days) as those of the early weaners.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 57
Data on daily LWG (DLWG, g/head) of calves for
pastures (P<0.0001), associated with a temporary increase
each individual grazing period and for each of the 3 Ag-
in the percent legume. Over the same period, relative to
based pastures in 1986 were pooled and regressed on the
calves grazing Ag as monoculture, hematocrit concen-
amount of green grass leaf on offer (GGL; kg DM/ha).
tration was higher (P<0.001) in AgCa and AgPp mixtures
The resulting linear regression equation was: DLWG =
by 31 and 19%, respectively. However, although within
0.702 ± 0.156 GGL – 166.667 ± 98.700; r2 = 0.63, P<0.01.
normal physiological values, a larger hematocrit differ-
ence (58%; P<0.001) was found with the unweaned
Pilot test
calves on savanna (Table 4).
Concentrations of minerals in serum and feces (Table
Despite the very low LWs of some of the early weaned
5) varied considerably between years (P<0.0001). How-
calves, no deaths occurred. Weight gains during the sown
ever, there were small and mostly non-significant
pasture phase averaged 0.18 ± 0.10 kg/day, while the
differences between pastures. There were no effects of
correlation between weaning weight and subsequent
nutritional treatment upon ash or fecal N, on either a DM
weight gain on the sown pasture was not significant (r2 =
or an organic matter basis (Table 5).
0.24, P>0.05).
Cow live weights and reproductive performance
Blood and feces profiles
Early weaned cows were significantly heavier at weaning
Blood data showed that the concentrations of total
than those weaned at normal times (Table 6; P<0.05).
protein, urea nitrogen and the AST and GGT enzymes in
Inter-calving intervals increased significantly (P<0.05)
weaned calves differed significantly (P<0.0001) between
with increasing calf weaning age, but were inversely
years, but there were much smaller differences in
related to cow weight at weaning (P<0.001), with the
concentrations of protein and enzymes amongst the
positive effect of cow weaning weight in reducing inter-
pastures (Table 4). In Year 3, blood urea nitrogen levels
calving interval being greater with older than with
on the AgPp pasture were 8‒10 times those on the other
younger weaning ages (regression equation in Table 6).
Table 4. Least squares means for total blood protein (TBP), hematocrit (HCT), urea nitrogen (BUN) and the body fluid enzymes aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) of early weaned calves grazing sown pastures and unweaned calves grazing savanna in Years 3 and 4.
Pasture
TBP
HCT
BUN
AST
GGT
(g/100 ml)
(g/100 ml)
(g/100 ml)
(IU/ml)
(IU/ml)
Reference values1
6.3–8.9
24–46
6–22
39–79
14–40
Year 3
A. gayanus
5.9 ± 0.14
26.1a ± 1.56 7.4a ± 0.69
76.0 ± 6.00
7.2 ± 7.00
A. gayanus + C. acutifolium
6.2 ± 0.12
34.4b ± 1.38 5.8a ± 0.31
75.0 ± 5.00
7.7 ± 7.30
A. gayanus + P. phaseoloides
6.3 ± 0.13
31.1b ± 1.46 63.5b ± 41
69.0 ± 5.00
3.3 ± 7.40
Savanna
6.8 ± 0.29
41.3c ± 1.47
6.0a ± 0.35 83.0 ± 14.00
42.9± 8.90
Year 4
A. gayanus
6.7 ± 0.53
41.3 ± 1.47 6.6a ± 0.40
80.0 ± 5.00
16.4 ± 8.30
A. gayanus + C. acutifolium
7.6 ± 0.52
n/a
5.9a ± 0.31
82.0 ± 5.00
5.2 ± 8.10
A. gayanus + P. phaseoloides
8.8 ± 0.61
n/a
8.9b ± 0.82
71.0 ± 6.00
1.9 ± 9.35
B. humidicola + A. pintoi
8.0 ± 0.52
n/a
8.8b ± 0.69
84.0 ± 3.00
6.6 ± 8.00
Savanna
6.8 ± 0.20
n/a
7.5b ± 0.81
83.0 ± 8.00
15.0 ± 7.80
Year, Probability
<0.0001
<0.0001
<0.0001
<0.0001
Pasture (year), Probability
= 0.09
<0.001
<0.0001
= 0.09
= 0.25
n/a - not available.
1Aiello and Moses (2016).
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
58 R. R. Vera and C.A. Ramírez-Restrepo
Table 5. Least squares means for blood serum phosphorus and calcium (mg/dl), fecal phosphorus, calcium and ash (% fecal DM, FDM) and fecal nitrogen (% fecal organic matter, FOM) concentrations (means ± s.e.) of early weaned calves grazing sown pastures and un-weaned calves grazing savanna in Years 3 and 4.
Pasture
Serum P
Serum Ca
Fecal P
Fecal Ca
Fecal ash
Fecal N
Year 3
A. gayanus
4.28c1 ± 0.51 8.96 ± 0.23 0.99a ± 0.25 1.24a ± 0.46 13.57a ± 0.93 1.92 ± 0.07
A.gayanus + C. acutifolium
4.17c ± 0.43 8.83 ± 0.21 0.76a ± 0.13 1.03a ± 0.29 12.29a ± 0.85 1.69 ± 0.07
A. gayanus + P. phaseoloides 5.89b ± 0.47 8.75 ± 0.22 0.61a ± 0.08 2.38a ± 1.54 13.08a ± 0.85 1.67 ± 0.07
Savanna
9.78a ± 0.39 10.65 ± 0.24
n/a
n/a
n/a
n/a
Year 4
A. gayanus
4.88a ± 0.44 9.04 ± 0.23 0.64a ± 0.45 0.77a ± 0.84 9.43a ± 1.05 1.79 ± 0.06
A. gayanus + C. acutifolium
5.46a ± 0.42 9.52 ± 0.22 0.61a ± 0.39 0.75a ±0.77 10.58a ± 1.06 1.75 ± 0.05
A. gayanus + P. phaseoloides 5.39a ± 0.49 9.13 ± 0.27 0.32b ± 0.14 0.76a ± 1.07 7.33a ± 1.67 1.87 ± 0.06
B. humidicola + A. pintoi
5.19a ± 0.42 9.71 ± 0.22 0.46b ± 0.25 2.74b ± 5.0 9.20a ± 1.17 1.80 ± 0.06
Savanna
5.93a ± 0.75 10.25 ± 0.30
n/a
n/a
n/a
n/a
Year, Probability
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
Pasture (year), Probability
<0.0001
NS
<0.05
<0.0001
<0.05*
NS
n/a - not analyzed.
NS - not significant.
1Letters compare pasture values within years. Differences were found between pastures in different years, but not within the same year.
Table 6. Reproductive performance and live weight (LW) of cows (n = 45) in relation to age and weight of calves at weaning.
Weaning age (d)
Inter-calving interval (d)1,2
Cow weaning LW (kg)
Calf weaning LW (kg)
110
472d3 (454–491)
339a ± 8
68a ± 4
166
514c (504–557)
308b ± 11
112b ± 5
198
625a (594–656)
304b ± 11
114b ± 5
266
642a (616–669)
306b ± 9
143c ± 4
1Regression equation:
Inter-calving interval (d) = 394 (± 38) + 2.76 (± 0.59) * calf weaning age – 0.00588 (± 0.0019) * calf weaning age * cow weaning LW; adj R2 = 0.45; P<0.001.
2Confidence interval in parentheses.
3Within columns values followed by different letters differ significantly (P<0.05).
Calf compensatory body growth
Table 7. Final live weights (LW) of contemporary calves (n)
weaned early and grazed on various sown pastures for 123
The possible carry-over effects of low calf weaning LW
days and normally weaned calves, following 414 days
were examined by monitoring subsequent performance of
grazing savanna as a single group. Data are least squares means
early weaned calves compared with normally weaned
± s.e.m.
calves, for a total of 414 days after the end of the early
Weaning pasture
n
LW (kg)
weaning experimental period (Table 7). At that time, there
A. gayanus
10
187 ± 19
were no significant (P>0.05) differences in final LW
A. gayanus plus C. acutifolium
10
187 ± 16
between the early weaned and normally weaned calves
A. gayanus plus P. phaseoloides
10
192 ± 13
(Table 7). Over the 414 days of common grazing in
Traditional weaning on savanna
10
205 ± 16
savanna, daily weight gains were inversely related to
Probability
NS
weaning weight, weight gains to weaning, and weight at
end of the experimental phase (r2 = 0.98, P<0.05 in all
n - number of animals.
cases).
NS - not significant.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 59
Discussion
performance of early weaners on limpograss ( Hemarthria
altissima).
The primary objective of this study was to assess the
Casual visual observations showed highly selective
growth of early weaned calves on sown tropical pastures,
grazing on the Ag-based pastures. In earlier studies
while keeping the breeding cows on savanna. A
(Böhnert et al. 1985; 1986), young steers grazing AgPp
secondary objective was to document the effect of early
mixtures selected diets much higher in N than when
weaning (3‒4 months) on inter-calving interval in
grazing Ag as a monoculture but differences in in vitro
breeders compared with traditional rangeland cow-calf
DM digestibility of the diets selected were not significant.
breeding, where calves are weaned at about 9‒10 months
Although some caution is required in extrapolating
old. The low overall mortality rate of calves of 1% over 4
selective grazing behaviors between weaners and 1‒2
consecutive years was a significant finding when
year old steers, the high BUN concentration on the AgPp
compared with commercial, extensive tropical herds that
pasture in Year 3 was likely due to temporary low
normally exhibit death rates of 7‒9% (Kleinheisterkamp
availability of green leaf on Ag and high levels of Pp on
and Habich 1985; Rivera Sánchez 1988). Reduced calf
offer, as Ag leaves were selectively grazed at the start of
mortality would then complement the improved
grazing in each paddock. However, as the availability of
reproductive performance of the breeding cows in terms
Ag leaves rapidly declined, calves were forced to
of reduced inter-calving intervals associated with early
consume the legume. The preliminary, positive relation-
weaning.
ship between green grass on offer on all Ag-based
There has been limited research on management of
pastures and daily LWG points in the same general
early weaners on supplemented tropical pastures
direction.
(Vendramini et al. 2008; Vendramini and Arthington
Overall, this study also showed that none of the early
2008), and even less if unsupplemented. Post-weaning
weaned calves demonstrated a deficiency of total protein,
LW gains by early weaned calves were low and similar
hematocrit, BUN and the sensitive enzyme marker of liver
across the 4 years of experimentation (Tables 2 and 3)
damage, AST (Table 4). However, compared with blood
allowing for the differences between years in age of
reference values, results from all pastures in Years 3 and
calves at weaning. Schottler and Williams (1975)
4 indicated low GGT activity, and high variability
compared the performance of Brahman-Shorthorn
between animals (Table 4). Although the potential
crossbred calves weaned at 4, 5, 6 or 7 months of age on
physiological effects of these values need to be clarified,
a Para grass ( Brachiaria mutica)-Siratro ( Macroptilium
it is reasonable to assume, as demonstrated by Stojević et
atropurpureum) sward for 2 months, followed by a
al. (2005) with healthy dairy cattle, that the observed GGT
buffel
grass
( Cenchrus
ciliaris)-Siratro
pasture.
concentrations reflected a temporary acute situation (i.e.
Regardless of weaning age, LWG ranged between 0.20
circadian changes) associated with age of the calves,
and 0.32 kg/day. Holroyd et al. (1990) weaned calves in
rather than long-term detrimental metabolic effects.
northern Australia at 5 and 8 months of age, and after a
Furthermore, it is unfortunately impossible to define
10-day period of supplementation with good quality
whether the low enzyme concentrations suggested
pasture hay they were transferred to a savanna paddock.
adverse metabolic effects of secondary compounds in the
The LW difference at 8 months between early and late
legumes. Nevertheless, it is worth noting that recent
weaners of 54 kg for males was reduced to 13 kg at the
studies (Ramírez-Restrepo et al. 2016) demonstrated
age of 3.5 years due to compensatory growth in younger
that supplementation of animals with plant-derived
weaned calves, and the research indicated that pasture
compounds increases GGT blood serum values in
quality was probably the limiting factor for better animal
Brahman cattle, which is contrary to the present results.
performance.
Despite differences between pastures and years in
This hypothesis is supported by the observation that
mineral concentrations in serum and feces (Table 4), all
the LW of early weaners (100 days) placed on a higher
values fell within normal ranges (Doornenbal et al. 1988;
quality annual ryegrass ( Lolium rigidum) temperate
Aiello and Moses 2016). The fairly large between-year
pasture did not differ from those of late weaners at 365
differences, and the between-animal variation indicated
days of age (Potter et al. 2004). The close correlation
by the relative magnitude of the standard error terms,
between green leaf and LWG found in the present
question the reliability of single samplings within years
research supports the hypothesis that performance of
and pastures, and by inference, between farming systems
early weaners on pastures may be limited by forage
as frequently carried out in survey studies. Several
quality. In this context, Aguiar et al. (2015) advocated
mineral deficiencies in unsupplemented adult beef cattle
limited creep feeding with soybean meal to improve the
grazing savanna, accompanied by low breeding cow
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
60 R. R. Vera and C.A. Ramírez-Restrepo
LWs, have been reported (Lebdosoekojo et al. 1980).
supported by the literature, would suggest that stress in
Subsequent and detailed analyses by Rivera Sánchez
early weaned beef calves would have been short-term
(1988) in controlled savanna experiments over several
only. Furthermore, and despite the condition of
years showed adequate serum, liver and fecal
generalized under-nutrition, there was no evidence of
concentrations of all minerals in cows, when complete
negative carry-over effects. In fact, by the end of the
mineral mixes were provided. Furthermore, Rivera
observation period, there were no significant differences
Sánchez (1988) found evidence of an interaction of
in the final LWs (Table 7) despite the early advantage of
mineral supplementation with management strategies that
animals allowed to suckle for the normal time, a finding
allowed access to improved grass-dominated pastures by
confirmed by the longer-term on-farm study of Mejía et
the breeding herd.
al. (2009), who weaned female and male calves at
Although fecal N as an indicator of nutrition has
4 months of age on a rotation of B. decumbens,
sometimes been questioned (Hobbs 1987), it is generally
B. humidicola and savanna pastures plus a medium
regarded as appropriate for free-ranging herbivores in the
quality concentrate until reaching 8 months of age.
absence of better, simple indices (Leslie Jr. et al. 2008).
Thereafter these and normally weaned calves (8 months
Similarly, N in feces has been found to be broadly and
old) were raised on the same pastures as above without
linearly related to N intake with a variety of forage diets
supplementation. No significant differences were found
(Nunez-Hernandez et al. 1992). Allden and Jennings
in age at first conception (35 vs. 33.4 months for early and
(1969) proposed that fecal N levels of 1.4‒1.6% in sheep
traditional weaning, respectively). The inter-calving
are indicative of N-limited diets. If these values are
interval of early weaned dams was 141 days shorter than
applicable to calves, data in Table 5 would suggest that
those weaned late. The corresponding males reached
dietary N would not have been the limiting nutritional
slaughter weight (450 kg) with a non-significant
variable. This view accords with that expressed by
difference of 3.2 months and average monthly LWGs of
Lascano (1991), who showed that digestible energy intake
11.5 vs. 10.6 kg for late and early weaners, respectively.
is the most limiting nutrient for yearlings and adult cattle
Under more severe pasture conditions, Holroyd et al.
in neotropical savannas.
(1990) noted that the early weaners (5 months old at
The low calf LWs at the end of the experimental
weaning) grazing savanna in northern Australia were still
periods, coupled with absence of indicators of specific
13 kg lighter than late weaners (8 months old at weaning)
nutritional deficiencies shown by the blood and fecal
at 3.5 years of age.
analyses, are indicative of a general condition of under-
In view of the compensatory growth experienced by
nutrition, a hypothesis supported by the in-depth analyses
the early weaners in the present study, the low LWG
of metabolic profiles of early weaned calves in tropical
recorded on pasture would be acceptable if, as is generally
northeast Argentina. There, Coppo (2003; 2007a; 2007b)
the case, weaners are not sold immediately, but are kept
assessed the stress produced by early weaning at 60 days
as young steers for an additional 12‒18 months. This
of age in crossbred Zebu cattle supplemented with
trade-off between calf LWG and cow reproductive
concentrates, but could not relate it to a large set of blood
performance is an important consideration for farm
parameters and suggested that there was no evidence of
managers who need to balance different forage resources
specific metabolic stresses. Arthington et al. (2005)
and the nutritional needs of stock and prioritize their use.
studied the dynamics of acute-phase proteins in beef
The new ‘crop’ of improved, high-yielding and leafier
calves weaned at 89 days of age onto pasture and fed a
Brachiaria cultivars (Pizarro et al. 2013), together with
supplement, and found them to rise in the first few days
higher quality grasses such as Panicum maximum, may
following separation from the dams, decreasing
help resolve the above issues to some extent, if the
subsequently to normal values. While early weaned
Brachiaria cultivars do not lead to subclinical and clinical
calves were lighter than contemporary suckling calves at
photosensitization (Lima et al. 2012).
120 days of age, and had lower concentrations of BUN,
Notwithstanding few to no weight differences in later
total proteins, triglycerides, P, Mg, Fe and Cu, indicators
life, possible negative effects of low early growth rate on
of stress such as cortisol, aldosterone and AST did not
lifetime beef production of early weaned females through
differ between the 2 groups of calves. The authors
epigenetic effects affecting them and their progeny cannot
concluded that early weaning does not produce clinical
be ignored (Martin et al. 2007; Funston et al. 2012;Wathes
stress in crossbred Zebu calves, despite a general
et al. 2014), although this would probably be a minor
condition of under-nutrition.
concern in extensive systems.
One measure of the sustainability of beef herds is
In our study, early weaned male calves attained
absence of animal stress, and the present results,
weights at 18 months of age similar to those of control
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 61
animals of equivalent ages. Vera (1991) and Vera et al.
they stopped cycling, but they needed to reach weights in
(1993) showed that, despite long periods of sustained
excess of 320 kg to start cycling again. As shown in Table
under-nutrition, heifers and cows could achieve mature
6, only cows, whose calves were weaned at 110 days,
body sizes and inter-calving intervals similar to those of
showed LWs above the purported lower critical weight of
better-fed animals, when given the opportunity to make
320 kg. Inter-calving intervals increased significantly
moderate compensatory gains. In the present study,
with increasing weaning age and were negatively related
weaning calves early removed lactation stress on cows,
to cows’ weights at weaning (P<0.001; footnote of Table
and allowed them to attain plateau weights of 350‒400 kg,
6), whereby the positive effect of cow weaning weight on
confounded with pregnancy, even during the dry season.
inter-calving interval was greater with larger than with
While LWs of this magnitude are seldom observed in
lower weaning ages (Table 5).
traditional savanna-based grazing systems (Rivera
Lastly, early weaning of beef calves and the
Sánchez 1988), weights of Zebu cows above 320 kg do
consequent changes in reproductive performance will
not appear to limit re-conception (Mukasa-Mugerwa
likely lead to significant changes in herd dynamics
1989; Vera et al. 1993). In fact, cows weaned at 166 days
(Turner et al. 2013), whose production, environmental
in the present research conceived after weaning with an
and economic effects remain to be studied. These changes
average weight of 303 ± 43 kg.
would significantly impact management decisions
Early weaning is known to enhance reproductive
(Sullivan et al. 1997). The savannas of the Orinoco
performance of underfed beef cows (Moore and da Rocha
watershed are under transition as represented by: (i)
1983; Holroyd et al. 1990; Schlink et al. 1994; Coppo et
increase in crop and tree plantation areas; (ii) oil
al. 2002; Arthington et al. 2004), an effect shown also in
exploration and extraction; (iii) mining; (iv) growing
Table 6 that demonstrates the trade-offs between weaning
recognition of indigenous rights and lands; (v) and
age and LWs of calves, LWs of their dams and inter-
increasing appreciation of the savanna’s relevance in
calving intervals. Moore and da Rocha (1983)
terms of biodiversity and contribution to greenhouse gas
investigated the effects of 2 levels of nutrition and 5
emissions (Rausch 2013; CONPES 2014). This transition
weaning ages in Zebu Gyr breed cows fed hay of
has been also noted in the Australian savannas (Holmes
B. decumbens in the Brazilian Cerrados and found that,
2010). This implies that extensive beef cattle farming,
irrespective of the cows’ nutritional level, early weaning
even if it continues to represent an important land use
of calves improved cow weights at different stages
system, will need to adapt and intensify to the extent
throughout the reproductive cycle and subsequent
possible. Further, farmers and their communities will
reproductive performance. Weights of cows at weaning
need to modify their decision-making to take into account
were 313 kg and 325 kg on low and high supplementary
the multifunctional traits of these lands. The strategic use
energy treatments, respectively, and the authors suggested
of areas of sown pasture could play an increasingly
that Zebu cows rarely conceive if suckling cows weigh
important role in management of breeding herds.
less than 300 kg. Weights of cows at weaning decreased
linearly from 352 kg, when calves were weaned at 1
Conclusions
month of age, to 294 kg if calves were weaned at 6 months
of age, with LW losses during lactation increasing from
Results from this study suggest that there is considerable
21 to 102 kg for the respective weaning ages (Moore and
scope and flexibility in strategic use of small areas of
da Rocha 1983).
sown pastures for weaners in combination with extensive
Mukasa-Mugerwa (1989) reviewed the literature
savannas to improve productivity of beef breeding herds,
regarding reproduction of Zebu cattle in the tropics, and
if calves are given the opportunity to realize
noted that tropical cattle dependent on natural pastures
compensatory growth. Several authors have commented
most often calve in alternate years, but animals with
on the flexibility, adaptability and sustainability of
access to good quality sown pastures have improved
extensive systems (Davies et al. 2010; Astigarraga and
reproductive performance. For example, Rivera Sánchez
Ingrand 2011), while some of the environmental aspects
(1988) reported inter-calving intervals of 618 days on
have been also described (Ramírez-Restrepo and
well managed savannas over 4 years, whereas Vera et al.
Charmley 2015) or are under scrutiny (Ramírez-Restrepo
(2002) found an average interval of 445 days on well
et al. unpublished data 2017). This study has demon-
managed B. decumbens. Equally large differences have
strated over 4 consecutive years, that early weaning of
been reported by other authors (Arthington et al. 2004).
calves onto a variety of sown tropical pastures is
Hale (cited by Mukasa-Mugerwa 1989) found that, when
technically feasible, resulting in improved LWGs and
the LW of suckling Zebu cows fell from 390 to 320 kg,
reproductive rates in their dams.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
62 R. R. Vera and C.A. Ramírez-Restrepo
Adoption of such early weaning strategies in extensive
Aiello SE; Moses MA. 2016. The Merck Veterinary Manual.
systems, where mating generally extends over 6 or more
11th Edn. Wiley, Hoboken, NJ, USA.
months, would be constrained by the spread of the
Allden WG; Jennings AC. 1969. The summer nutrition of
calvings over an extended period of time. A number of
immature sheep: The nitrogen excretion of grazing sheep in
relation to supplements of available energy and protein in a
weaning events would be needed each year, resulting in
Mediterranean environment. Australian Journal of Agri-
increased labor and management requirements (Sullivan
cultural Research 20:125–140. DOI: 10.1071/ar9690125
et al. 1997). On the other hand, with several batches of
Arthington JD; Lamb GC; Pate FM. 2004. Effects of
early weaned calves dispersed over several months, a
supplement type on growth and pregnancy rate of yearling
smaller area of sown pastures would be needed than if all
Brahman-Crossbred heifers. The Professional Animal
calvings were concentrated into a shorter period of time.
Scientist 20:282–285. DOI: 10.15232/s1080-7446(15)
From a management point of view, seasonal mating to
facilitate early weaning would be desirable, but this
Arthington JD; Spears JW; Miller DC. 2005. The effect of early
would lead to a smaller calf crop in the initial year when
weaning on feedlot performance and measures of stress in
the practice was first implemented. However, increased
beef calves. Journal of Animal Science 83:933–939. DOI:
reproductive rates during the following years due to
Astigarraga L; Ingrand S. 2011. Production flexibility in
improved cow condition and LW, as demonstrated in this
extensive beef farming systems. Ecology and Society
study, would soon compensate for the loss of production
16(1):7. DOI: 10.5751/es-03811-160107
in the implementation year of seasonal mating. A possible
Australian Government. 2015. Our north, our future: White
added benefit would be a reduction in risks, which could
paper on developing northern Australia. Commonwealth of
be posed by climate change. Thus, productive and
Australia, Canberra, Australia. https://goo.gl/Kw6Tho
environmental trade-offs, as suggested above, would need
Betancourt-López L; Pareja-Mejía RI; Conde-Pulgarín A;
better quality and intensity of animal and pasture
Castellanos AF; Moreno-Martínez D. 2012. Manejo
management. Further savanna studies with larger
nutricional de terneros cebú comercial sometidos a
numbers of calves and cows under commercial conditions
amamantamiento restringido y destete precoz en el
piedemonte de Casanare. Revista de Ciencia Animal 5:21–
would confirm these preliminary findings.
Böhnert E; Lascano C; Weniger JH. 1985. Botanical and
Acknowledgments
chemical composition of the diet selected by fistulated steers
under grazing on improved grass-legume pastures in the
This research was financially supported by the
tropical savannas of Colombia. I. Botanical composition of
International Center for Tropical Agriculture (CIAT)’s
forage available and selected. Journal of Animal Breeding
core funding in Colombia. The authors express our
and Genetics 102:385–394. DOI: 10.1111/j.1439-0388.
appreciation to Hernando Ayala, DVM (deceased), who
supervised the first 2 years of the experiment. We further
Böhnert E; Lascano C; Weniger JH. 1986. Botanical and
chemical composition of the diet selected by fistulated steers
acknowledge Obed García Durán, DVM, who confirmed
under grazing on improved grass-legume pastures in the
some of the views and opinions expressed here, and
tropical savannas of Colombia. II. Chemical composition of
facilitated a recent trip by the senior author to the region
forage samples of forage available and selected. Journal of
to verify some of the assertions made in the paper. We
Animal Breeding and Genetics 103:69–79. DOI:
thank staff at CIAT and Carimagua Research Station for
10.1111/j.1439-0388.1986.tb00068.x
their help and technical support with all aspects of this
CONPES. 2014. Política para el desarrollo integral de la
work. Finally, special thanks are extended to the
Orinoquia: Altillanura - Fase 1. Documento 3797. Consejo
Commonwealth Scientific and Industrial Research
Nacional de Política Económica y Social (CONPES),
Organisation (CSIRO) for allowing the time to the second
Departamento Nacional de Planeación (DNP), República de
author to co-write the manuscript.
Colombia, Bogotá, Colombia. https://goo.gl/5IXl2S
Coppo JA. 2003. Early weaning as cause of malnutrition
in
half-bred
Zebu
calves.
Veterinary
Research
References
Communications 27:207–210. DOI: 10.1023/a: 10233925
Aguiar AD; Vendramini JMB; Arthington JD; Sollenberger LE;
Coppo JA. 2007a. Multivariate analysis about causes of growth
Caputti G; Sanchez JMD; Cunha OFR; Silva WL da. 2015.
delay in early weaned calves. Revista de Veterinaria 18:37–
Limited
creep-feeding
supplementation
effects
on
45.
performance of beef cows and calves grazing limpograss
Coppo JA. 2007b. El destete precoz produce estrés en los
pastures. Livestock Science 180:129–133. DOI: 10.1016/
terneros cruza cebú? Revista Electrónica de Veterinaria
REDVET 8(2):020719. https://goo.gl/BWaU5f
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 63
Coppo JA; Coppo NB; Revidatti MA; Capellari A. 2002. Early
Herrero M; Thornton PK; Brendan P; Bogard JR; Remans R;
weaning promotes improvement of blood nutritional
Fritz S; Gerber JS; Nelson G; See L; Waha K; Watson RA;
indicators in half-bred zebu cows. Livestock Research for
West PC; Samberg LH; van de Steeg J; Stephenson E; van
Rural Development 14: Article #42. www.lrrd.org/lrrd14/
Wijk M; Havlík P. 2017. Farming and the geography of
5/copp145.htm (accessed 1 August 2016).
nutrient production for human use: A transdisciplinary
DANE. 2016. 3º Censo Nacional Agropecuario. Tomo 2.
analysis. The Lancet Planet Health 1:e33–42. DOI:
Resultados. Departamento Administrativo Nacional de
Estadística (DANE), Bogotá, Colombia. https://goo.gl/
Hobbs T. 1987. Fecal indices to dietary quality: A critique. The
Journal of Wildlife Management 51:317–320. DOI:
Davies J; Niamir-Fuller MCK; Bauer K. 2010. Extensive
livestock production in transition. The future of sustainable
Holmes J. 2010. The multifunctional transition in Australia's
pastoralism. In: Steinfeld H; Mooney HA; Schneider F;
tropical savannas: The emergence of consumption,
Neville LE, eds. Livestock in a changing landscape. Volume
protection and indigenous values. Geographical Research
1: Drivers, consequences, and responses. Island Press,
48:265–280. DOI: 10.1111/j.1745-5871.2009.00629.x
Washington, DC, USA. p. 285–308.
Holroyd RG; O'Rourke PK; Tyler R; Stephenson HP; Mason
Doornenbal H; Tong AKW; Murray NL. 1988. Reference
GWL; Schroter KL. 1990. Effects of different weaning
values of blood parameters in beef cattle of different ages
strategies on postweaning growth rate, mortality and
and stages of lactation. Canadian Journal of Veterinary
fertility of Bos indicus cross cattle. Australian Journal of
Research 52:99–105. https://goo.gl/5rp7Bz
Experimental Agriculture 30:1–6. DOI: 10.1071/ea9900001
Durmic Z; Ramírez-Restrepo CA; Gardiner C; O’Neill CJ;
Huertas-Ramírez H; Huertas-Herrera A. 2015. Historiografía
Hussein E; Vercoe PE. 2017. Differences in the nutrient
de la ganadería en la Orinoquia. Actas Iberoamericanas de
concentrations, in vitro methanogenic potential and other
Conservación Animal (AICA) 6:300–307. https://goo.gl/
fermentative traits of tropical grasses and legumes for beef
production systems in northern Australia. Journal of the
Kleinheisterkamp I; Habich G. 1985. Colombia. 1. Estudio
Science of Food and Agriculture. Early View (Online
biológico y técnico. In: Vera RR; Seré C, eds. Sistemas de
version of record published before inclusion in an issue).
producción
pecuaria
extensiva.
Brasil,
Colombia,
Venezuela. Informe final del Proyecto ETES 1978–1982.
FAO. 2013. Tackling climate change through livestock: A
Centro Internacional de Agricultura Tropical (CIAT), Cali,
global
assessment
of
emissions
and
mitigation
Colombia. p. 213–278. http://hdl.handle.net/10568/54274
opportunities. Food and Agriculture Organization of the
Lascano C. 1991. Managing the grazing resource for animal
United Nations (FAO), Rome, Italy. https://goo.gl/OiYX3v
production in savannas of tropical America. Tropical
FEDEPALMA. 2015.
Anuario Estadístico 2015: La
Grasslands 25:66–72. https://goo.gl/ow1PLk
agroindustria de la palma de aceite en Colombia y en el
Lasso CA; Rial A; Matallana CL; Ramírez W; Señaris JC;
mundo 2010-2014. Federacion Nacional de Cultivadores de
Díaz-Pulido A; Corzo G; Machado-Allison A, eds. 2011.
Palma de Aceite (FEDEPALMA), Bogotá, Colombia.
Biodiversidad de la cuenca del Orinoco. II. Áreas
prioritarias para la conservación y uso sostenible. Instituto
Fordyce G; Holroyd RG; James TA; Reid DJ. 1988. The effect
de Investigación de Recursos Biológicos Alexander von
of post-weaning growth on the fertility of Brahman cross
Humboldt, Bogotá, Colombia. https://goo.gl/eMq81q
heifers. Proceedings of the Australian Society of Animal
Lebdosoekojo S; Ammerman CB; Raun NS; Gómez J; Littell
Production 17:396.
RC. 1980. Mineral nutrition of beef cattle grazing native
Funston RN; Summers AF; Roberts AJ. 2012. Alpharma Beef
pastures on the Eastern Plains of Colombia. Journal of
Cattle Nutrition Symposium: Implications of nutritional
Animal Science 51:1249–1260. DOI: 10.2527/jas1981.
management for beef cow-calf systems. Journal of Animal
Science 90:2301–2307. DOI: 10.2527/jas.2011-4568
Leslie DM Jr; Bowyer RT; Jenks JA. 2008. Facts from feces:
Gbur EE; Stroup WW; McCarter KS; Durham S; Young LJ;
Nitrogen still measures up as a nutritional index for
Christman M; West M; Kramer M. 2012. Analysis of
mammalian herbivores. Journal of Wildlife Management
generalized linear mixed models in the agricultural and
72:1420–1433. DOI: 10.2193/2007-404
natural resources sciences. American Society of Agronomy
Lima FG; Haraguchi M; Pfister JA; Guimarães VY; Andrade
(ASA), Crop Science Society of America (CSSA), Soil
DDF; Ribeiro CS; Costa GL; Araujo ALL; Fioravanti MCS.
Science Society of America (SSSA), Madison, WI, USA.
2012. Weather and plant age affect the levels of steroidal
DOI: 10.2134/2012.generalized-linear-mixed-models
saponin and Pithomyces chartarum spores in Brachiaria
Herrero M; Wirsenius S; Henderson B; Rigolot C; Thornton P;
grass. International Journal of Poisonous Plant Research
Havlík P; de Boer I; Gerber PJ. 2015. Livestock and the
2:45–53. https://goo.gl/TZrFzx
environment: What have we learned in the past decade?
MADR. 2015. Colombia: Potencial de reforestación comercial
Annual Review of Environment and Resources 40:177–202.
- Diagnóstico. Ministerio de Agricultura y Desarrollo Rural
DOI: 10.1146/annurev-environ-031113-093503
(MADR), Bogotá, Colombia. https://goo.gl/4kwbn2
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
64 R. R. Vera and C.A. Ramírez-Restrepo
Martin JL; Vonnahme KA; Adams DC; Lardy GP; Funston RN.
Ramírez-Restrepo CA; Charmley E. 2015. An integrated
2007. Effects of dam nutrition on growth and reproductive
mitigation potential framework to assist sustainable
performance of heifer calves. Journal of Animal Science
extensive beef production in the tropics. In: Mahanta PK;
85:841–847. DOI: 10.2527/jas.2006-337
Singh JB; Pathak PS, eds. Grasslands: A global research
Mejía RIP; Valencia MJC; Ramos JCR. 2009. Determining the
perspective. Range Management Society of India, Jhansi,
effect of early weaning in beef cattle, on the weight gain in
India. p. 417–436.
males and the age of conception in females. Revista de
Ramírez-Restrepo CA; O’Neill CJ; López-Villalobos N;
Ciencia Animal 2:91–105.
Padmanabha J; Wang JK; McSweeney C. 2016. Effects of
Molina NA; Triana HL. 2011. Panorama de la investigación en
tea seed saponin supplementation on physiological changes
producción animal desde la perspectiva del entorno
associated with blood methane concentration in tropical
socioeconómico y cultural en la región de los Llanos
Brahman cattle. Animal Production Science 56:457–465.
Orientales y el Casanare. Gestión & Sociedad 4:31–44.
Moore CP; da Rocha CMC. 1983. Reproductive performance
Rasby R. 2007. Early weaning beef calves. Veterinary Clinics
of Gyr cows: The effect of weaning age of calves and
of North America: Food Animal Practice 23:29–40. DOI:
postpartum energy intake. Journal of Animal Science
57:807–814. DOI: 10.2527/jas1983.574807x
Rausch JM. 2013. Territorial rule in Colombia and the
Mukasa-Mugerwa E. 1989. A review of reproductive
transformation of the Llanos Orientales. University Press of
performance of female Bos indicus (Zebu) cattle. ILCA
Florida, Gainesville, FL, USA.
Monograph 6. International Livestock Centre for Africa
Rippstein G; Lascano C; Decaëns T. 1996. La production
(ILCA), Addis Ababa, Ethiopia. http://hdl.handle.net/
fourragère dans les savanes d'Amérique du Sud
intertropicale. Fourrages 145:33–52. http://agritrop.cirad.
Navas Ríos CL. 1999. Caracterización socioeducativa,
evaluativa y comparativa de cuatro comunidades en los
Rippstein G; Escobar G; Motta F, eds. 2001. Agroecología y
Llanos
Orientales
de
Colombia.
Masters
Thesis.
biodiversidad de las sabanas en los Llanos Orientales de
Universidad de Antioquia, Medellín, Colombia.
Colombia. Centro Internacional de Agricultura Tropical
Nunez-Hernandez G; Holechek JL; Arthun D; Tembo A;
(CIAT), Cali, Colombia. http://hdl.handle.net/10568/54639
Wallace JD; Galyean ML; Cardenas M; Valdez R. 1992.
Rivera Sánchez B. 1988. Performance of beef cattle herds under
Evaluation of fecal indicators for assessing energy and
different pasture and management systems in the Llanos of
nitrogen status of cattle and goats. Journal of Range
Colombia. Dr. Sc. agr. Thesis. Technische Universität,
Management 45:143–147. DOI: 10.2307/4002772
Berlin, Germany.
O’Neill CJ; Swain DL; Kadarmideen HJ. 2010. Evolutionary
Romero-Ruiz MH; Flantua SGA; Tansey K; Berrio JC. 2012.
process of Bos taurus cattle in favourable versus
Landscape transformation in savannas of northern South
unfavourable environments and its implications for genetic
America: Land use/cover changes since 1987 in the Llanos
selection. Evolutionary Applications 3:422–433. DOI:
Orientales of Colombia. Applied Geography 32:766–776.
10.1111/j.1752-4571.2010.00151.x
DOI: 10.1016/j.apgeog.2011.08.010
Paladines OL; Leal JA. 1979. Manejo y productividad de las
Schlink AC; Jolly PD; McSweeney CS; Houston EM; Hogan
praderas en los Llanos Orientales de Colombia. In: Tergas
JP; Entwistle KW. 1992. Effect of liveweight at weaning
LE; Sánchez PA, eds. Producción de pastos en suelos ácidos
and post-weaning supplementation on return to oestrus in
de los trópicos. Centro Internacional de Agricultura
early weaned Bos indicus cross cows. Proceedings of the
Tropical (CIAT), Cali, Colombia. p. 331–346. http://hdl.
Australian Society of Animal Production 19:428.
Schlink AC; Houston DK; Entwistle KW. 1994. Impact of long
Pizarro EA; Hare MD; Mutimura M; Changjun B. 2013.
term early weaning on the productivity of Bos indicus cows.
Brachiaria hybrids: Potential, forage use and seed yield.
Proceedings of the Australian Society of Animal Production
Tropical Grasslands-Forrajes Tropicales 1:31–35. DOI:
20:330.
Schottler JH; Williams WT. 1975. The effect of early weaning
Plessow C. 1985. Venezuela: Estudio técnico y análisis
of Brahman cross calves on calf growth and reproductive
económico. In: Vera RR; Seré C, eds. Sistemas de
performance of the dam. Australian Journal of Experimental
producción
pecuaria
extensiva:
Brasil,
Colombia,
Agriculture and Animal Husbandry 15:456–459. DOI:
Venezuela. Informe final del Proyecto ETES 1978–1982.
Centro Internacional de Agricultura Tropical (CIAT),
Seré C; Vera R. 1983. Cow-calf systems in the savannas of
Cali, Colombia. p. 337–430. http://hdl.handle.net/10568/
tropical Latin America: A systems diagnosis. In: Dring JC;
Mulholland JR; Maund B, eds. The Fifth World Conference
Pötter BAA; Lobato JFP; Schenkel FS. 2004. Efeitos do manejo
on Animal Production. Japanese Society of Zootechnical
pós-parto de vacas primíparas no desempenho de bezerros
Science, Tokyo, Japan.
de corte até um ano de idade. Revista Brasileira de
Short RE; Grings EE; MacNeil MD; Heitschmidt RK;
Zootecnia 33:426–433. DOI: 10.1590/s1516-3598200
Haferkamp MR; Adams DC. 1996. Effects of time of
weaning, supplement, and sire breed of calf during the fall
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Grass-legume pastures for early weaning in savanna 65
grazing period on cow and calf performance. Journal of
performance of early weaned calves grazing rye - ryegrass
Animal Sciences 74:1701–1710. DOI: 10.2527/1996.
pastures. Crop Science 46:1595–1600. DOI: 10.2135/
Squires VR; Vera RR. 1992. Commercial beef ranching in
Vendramini JMB; Sollenberger LE; Dubeux JCB; Interrante
tropical and semi-arid zones. In: Jarrige R; Béranger C, eds.
SM; Stewart RL; Arthington JD. 2007. Concentrate
Beef cattle production: World Animal Science Series. C:
supplementation effects on the performance of early weaned
Production-System Approach, 5. Elsevier, Amsterdam, The
calves grazing Tifton 85 bermudagrass. Agronomy Journal
Netherlands. p. 437–454.
99:399–404. DOI: 10.2134/agronj2005.0355
Stojević Z; Piršljin, J; Milinković-Tur S; Zdelar-Tunk M;
Vendramini JMB; Sollenberger LE; Dubeux JCB; Interrante
Ljubić BB. 2005. Activities of AST, ALT and GGT in
SM; Stewart RL; Arthington JD. 2008. Sward management
clinically healthy dairy cows during lactation and in the dry
effects on forage component responses in a production
period. Veterinarski Arhiv 75:67–73. https://goo.gl/
system for early weaned calves. Agronomy Journal
100:1781–1786. DOI: 10.2134/agronj2008.0114
Sullivan RM; O'Rourke PK; Neale JA. 1997. A comparison of
Vendramini JMB; Arthington JD. 2008. Effects of
once- and twice-yearly weaning of an extensive herd in
supplementation strategies on performance of early-weaned
northern Australia. 2. Progeny growth and heifer
calves raised on pastures. The Professional Animal Scientist
productivity.
Australian
Journal
of
Experimental
24:445–450. DOI: 10.15232/s1080-7446(15)30880-9
Agriculture 37:287–293. DOI: 10.1071/EA95098
Vera RR. 1991. Growth and conception in continuously
Tothill JC. 1978. Measuring botanical composition of
underfed Brahman heifers. Animal Science 53:45–50. DOI:
grasslands. In: Mannetje L't, ed. Measurement of grassland
vegetation and animal production. Bulletin No. 52.
Vera RR; Seré C. 1985. Evaluation of tropical pasture species
Commonwealth Bureau of Pastures and Field Crops,
with a farming system perspective. Proceedings of the XV
Hurley, Berkshire, UK.
International Grassland Congress, Kyoto, Japan. p. 1187–
Turner BL; Rhoades RD; Tedeschi LO; Hanagriff RD;
1188.
McCuistion KC; Dunn BH. 2013. Analyzing ranch
Vera RR; Seré C. 1989. On farm results with Andropogon
profitability from varying cow sales and heifer replacement
gayanus. In: Toledo JM; Vera RR; Lascano C; Lenné JL,
rates for beef cow-calf production using systems dynamics.
eds. Andropogon gayanus Kunth: A grass for tropical acid
Agricultural Systems 114:6–14. DOI: 10.1016/j.agsy.2012.
soils. Centro Internacional de Agricultura Tropical (CIAT),
Cali, Colombia. p. 323–356. http://hdl.handle.net/10568/
Tyler R. 2012. Weaning management of beef calves - practical
guidelines for northern Australian beef producers. Meat &
Vera RR; Ramírez CA; Ayala H. 1993. Reproduction in
Livestock Australia Ltd, North Sydney, NSW, Australia.
continuously underfed Brahman cows. Animal Science
Tyler R; English B; Sullivan M; Jackson D; Matthews R;
57:193–198. DOI: 10.1017/s0003356100006796
Holmes B; MacDonald N; Oxley T; Leigo S. 2012. Weaner
Vera RR; Ramírez CA; Velásquez N. 2002. Growth
management in northern beef herds. Meat & Livestock
patterns and reproductive performance of grazing
Australia Ltd, North Sydney, NSW, Australia.
cows in a tropical environment. Archivos Latinoameri-
van Vuuren AM; Chilibroste P. 2013. Challenges in the
canos de Producción Animal 10:14–19. https://goo.gl/
nutrition and management of herbivores in the temperate
zone. Animal 7:19–28. DOI: 10.1017/s1751731111001741
Wathes DC; Pollott GE; Johnson KF; Richardson H; Cooke JS.
Vendramini JMB; Sollenberger LE; Dubeux JCB; Interrante
2014. Heifer fertility and carry over consequences for life
SM; Stewart RL; Arthington JD. 2006. Concentrate
time production in dairy and beef cattle. Animal 8:91–104.
supplementation effects on forage characteristics and
DOI: 10.1017/s1751731114000755
(Received for publication 27 October 2016; accepted 30 April 2017; published 31 May 2017)
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Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Tropical Grasslands-Forrajes Tropicales (2017) Vol. 5(2):66– 76 66
Research Paper
Dry matter accumulation and crude protein concentration in
Brachiaria spp. cultivars in the humid tropics of Ecuador
Acumulación de materia seca y concentración de proteína cruda en cultivares
de Brachiaria spp. en el trópico húmedo de Ecuador
JONATHAN R. GARAY1, SANTIAGO JOAQUÍN CANCINO1, PEDRO ZÁRATE FORTUNA1, MARTÍN A.
IBARRA HINOJOSA1, JUAN C. MARTÍNEZ GONZÁLEZ1, RICARDO P. GONZÁLEZ DÁVILA2 AND EUGENIA
G. CIENFUEGOS RIVAS1
1 Universidad Autónoma de Tamaulipas, Facultad de Ingeniería y Ciencias, Ciudad Victoria, Tamaulipas, Mexico.
2 Universidad Tecnológica Equinoccial, Campus Santo Domingo, Investigación y Transferencia de Tecnología, Santo
Domingo de los Tsáchilas, Ecuador. www.ute.edu.ec
Abstract
Climatic conditions throughout the year and age of plants affect both yield and quality of forage grasses. In this research, we evaluated the effects of age of regrowth and seasonal conditions on dry matter accumulation and crude protein concentration in 5 cultivars of Brachiaria spp.: Señal, Xaraés, Marandú, Piatá and Mulato II, harvested at 2, 4, 6, 8 and 10 weeks after a uniformity cut, during the rainy and dry seasons. The variables were: total dry matter (TDM), leaf dry
matter (LDM) and stem dry matter (SDM) yields, leaf area index (LAI), specific leaf area (SLA) and crude protein (CP)
concentration. For TDM yield, in the rainy season there was no significant difference (P>0.05) among cultivars, with
mean DM yield over 10 weeks of 6.34 t/ha; however, during the dry season Xaraés presented a higher (P<0.05) yield
over 10 weeks than other cultivars (5.09 vs. 3.14‒3.89 t/ha). Overall, mean DM yield in the dry season was only 62% of
that in the wet season. In both periods, Señal tended to have the highest SDM yields, while Xaraés had the greatest (P<0.01) LDM yields in the dry season. Mulato II tended to have the highest CP concentrations throughout, especially
in the dry season. This study was conducted in plots with plants only 12 weeks old at commencement. However, it indicated that all cultivars performed well and larger-scale studies of longer duration are warranted to test these cultivars under grazing, especially Mulato II, which showed both high dry matter yield and retention of high protein concentration
throughout the study.
Keywords: Brachiaria decumbens, Brachiaria brizantha, Brachiaria hybrid cv. Mulato II, leaf area index, specific leaf area.
Resumen
En la finca experimental “El Oasis” de la Escuela de Ingeniería Agropecuaria, Universidad Tecnológica Equinoccial,
Campus Santo Domingo, Ecuador, en un suelo Andosol se evaluaron los efectos de la edad de rebrote y la época del año sobre la acumulación de materia seca y la concentración de proteína bruta en 5 cultivares de Brachiaria: Señal ( B. decumbens), Xaraés ( B. brizantha), Marandú ( B. brizantha), Piatá ( B. brizantha) y Mulato II ( Brachiaria híbrido), cosechados a 2, 4, 6, 8 y 10 semanas después de un corte de uniformidad, durante las estaciones lluviosa y seca.
Las variables evaluadas fueron la materia seca (MS) total, MS de hoja y de tallo, el índice de área foliar, el área foliar específica y la concentración de proteína bruta. El rendimiento de MS total a 10 semanas de rebrote (6.34 t/ha en ___________
Correspondence: E. G. Cienfuegos Rivas, Centro Universitario Adolfo
López Mateos, Edificio de Gestión del Conocimiento 4º piso. Cd.
Victoria, CP 87149, Tamaulipas, Mexico.
Email: ecienfue@docentes.uat.edu.mx
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Brachiaria spp. evaluation in Ecuador 67
promedio) en la estación de lluvias no varió entre cultivares (P>0.05) mientras en la estación seca el cv. Xaraés presentó el mayor rendimiento (P<0.05) en comparación con los demás cultivares (5.09 vs. 3.14‒3.89 t/ha). El rendimiento de
MS total en la época seca fue sólo el 62% del obtenido en la época de lluvia. En ambos períodos, el cv. Señal tendió a
tener los rendimientos de MS de tallos más altos, mientras que el cv. Xaraés presentó los mayores rendimientos de MS
de hojas (P<0.01) en la estación seca. El cv. Mulato II tendió a tener las mayores concentraciones de proteína bruta en ambas épocas, especialmente en la seca. Este estudio se realizó en parcelas con plantas de sólo 12 semanas de edad al
inicio. Sin embargo, indicó que todos los cultivares se comportaron satisfactoriamente y estudios a mayor escala y de
mayor duración se justifican para probar estos cultivares bajo pastoreo, especialmente el cv. Mulato II que mostró tanto
un alto rendimiento de MS como una retención de alta concentración de proteína a lo largo del estudio.
Palabras clave: Área foliar específica, Brachiaria decumbens, Brachiaria brizantha, Brachiaria híbrido cv. Mulato II, índice de área foliar.
Introduction
seasonal changes (Fagundes et al. 2005) on the pattern of
growth, quality and chemical composition of pasture
Poor grassland productivity is one of the most important
plants, in order to optimize their use and plan an
limitations in the dual-purpose cattle system in the
appropriate
agronomic
management
strategy
for
Ecuadorian tropics (Avellaneda et al. 2008), because most
grasslands (Avellaneda et al. 2008). Based on the above,
grazing areas are sown with forage species such as
this research aimed to evaluate the effects of plant
Brachiaria humidicola, Brachiaria decumbens and
regrowth age and seasonal conditions on the
Brachiaria brizantha (Vera 2004). These grasses have
accumulation of dry matter and crude protein
limitations in productivity, adaptability and persistence in
concentration in 5 cultivars of Brachiaria spp. in the
these environments; in addition, they are susceptible to
humid tropics of Ecuador.
the spittlebug of pastures caused by Aeneolamia spp.
(Cardona et al. 2006) and foliar fungi such as Rhizoctonia
Materials and Methods
solani, which significantly reduce productivity (Álvarez
et al. 2013). However, new cultivars of the genus
The research was conducted under field conditions from
Brachiaria have been released to the market as options to
December 2011 to November 2012, at the experimental
overcome the problems observed in traditional forages,
farm “El Oasis”, property of the Escuela de Ingeniería
thus providing better fodder options (Pizarro et al. 2013).
Agropecuaria
of
the
Universidad
Tecnológica
In Ecuador, several cultivars of Brachiaria spp. are
Equinoccial,
Campus
Santo
Domingo,
Ecuador
available that have potential for increasing the
(00°13'20' S, 79°15'39'' W; 406 masl). The experimental
productivity of existing grass production systems (Faría
site has a predominantly humid tropical climate, with
Mármol 2006; Miles 2006). Jácome and Suquilanda
annual average temperature of 23.4 °C and annual rainfall
(2014) indicated that cultivars Mulato I and Xaraés are
of 2,600‒3,500 mm with 2 seasons, defined as rainy and
well accepted by farmers because of their high nutritional
dry (SENPLADES 2015). The monthly rainfall and mean
value, adaptation to a range of soils and resistance to or
maximum and minimum temperatures during the
tolerance of pests and diseases (Cardona et al. 2006; Argel
evaluation period are reported in Figure 1.
2008).
In this research 5 Brachiaria cultivars were used:
The productive capacity of forage species can be
Señal ( B. decumbens, considered as the control since
modified by changing various factors, such as: using
it is most widely cultivated in the area); Marandú
different genotypes or cultivars; modifying the
( B. brizantha), Piatá ( B. brizantha), Mulato II ( Brachiaria
agronomic management and age of the plants at harvest;
hybrid) and Xaraés ( B. brizantha); and these were
and by weather conditions throughout the year (Zaragoza
harvested at 5 growth stages (2, 4, 6, 8 and 10 weeks after
et al. 2009; Lara et al. 2010). It is therefore important to
an initial harvest) during the rainy (March‒May) and dry
assess the dynamics of herbage accumulation of
(September‒November) seasons to monitor the rate of
different pasture species and to understand the impact of
DM accumulation over time and assess quality aspects.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
68 J.R. Garay, S. Joaquín, P. Zárate, M.A. Ibarra, J.C. Martínez, R.P. González and E.G. Cienfuegos
35
900
800
30
700
)
C)
25
m
(°
600
m(
20
ure
500
on i
400
at
15
perat
pit
300
ci
em 10
re
T
200
P
5
100
0
0
jan feb mar apr may jun
jul aug sep oct nov dec
Precipitation
Temp. Max.
Temp. Min.
Figure 1. Monthly precipitation and mean maximum and minimum temperatures during 2012 at the Climatological Station of the Universidad Tecnológica Equinoccial, Campus Santo Domingo, Ecuador.
A randomized complete block design in an
season, observations commenced 2 weeks after each
arrangement in divided plots was used, where the large
uniformity cut to measure: accumulation of total (TDM),
plot was the cultivar and the subplots the ages of
leaf (LDM) and stem (SDM) dry matter; plant height
regrowth. On 3 December 2011, seeds of each cultivar
(PH); leaf area index (LAI); specific leaf area (SLA);
were placed in bags (3 seeds/bag) of black polyethylene
and crude protein concentration (CP). During each
with a capacity of approximately 2 kg of soil, to ensure
sampling for the relevant cutting treatment we measured
one plant survived per bag and placed in a greenhouse. At
the height of plants from ground level to ligule of the
6 weeks after seedling emergence (21 January 2012; 7
fully developed leaf and harvested the forage at 15 cm
weeks after sowing), the plants were transplanted to large
above ground level from the relevant 1 m2 subplot
plots of 5 x 5 m (25 m2), leaving an intra-row and inter-
(4 plants). The harvested forage (green matter) was
row spacing of 0.50 m. The useful area within each large
weighed on a precision scale (Model PB3002-S, Mettler
plot was 3 x 3 m, divided into 9 quadrants of 1 m2
Toledo) and 2 subsamples were taken, the first
(subplots), of which 5 subplots were randomly selected to
(approximately 200 g) to define the proportions of leaf
represent each age of regrowth (2, 4, 6, 8 and 10 weeks).
(leaf blade + sheath) and stem after separating these
The soil of the experimental site is of volcanic origin
components. Leaves from this subsample were used for
(Andosol) and a soil sample was taken using a 5-point
leaf area estimation as well. A multifunctional printer
method to 20 cm depth to provide the physicochemical
scanner (HP Photosmart D110) was employed using the
analyses shown in Table 1. All plots were fertilized after
methodology reported by Rincón et al. (2012). The
transplanting with 120 kg N/ha (as urea), 60 kg P/ha (as
second subsample (approximately 1 kg) was used to
Daphos), 70 kg K/ha (as KCl), 60 kg Mg/ha (as
determine CP concentration by the Kjeldahl method (N x
magnesium oxide) and 50 kg S/ha (as ammonium sulfate).
6.25) (AOAC 2000); CP% was determined only for 4, 6
In the sixth week after transplantation the plants
and 8 week cuttings. All samples were dried in a forced-
were 80‒100 cm tall with 45‒65 tillers/plant; senescent
air oven at 65 °C for 48 h to estimate the dry matter (DM)
material was obvious in the lower stratum, so we
concentration and calculate DM yields.
applied an initial uniformity cut on 3 March 2012 to 15
The data were analyzed in time within season by using
cm above ground level. The evaluation during the rainy
PROC GLM of SAS (SAS Institute 2010), in a complete
season then followed. At the end of this period (12 May
randomized block design in an arrangement in divided
2012), the plots were allowed to stand for 15 weeks,
plots. Tukey’s Studentized range tests (P≤0.05) were
when a second uniformity cut was applied on 1 September
performed, when treatments were significantly different
2012. The dry season evaluation then followed. In each
in each season.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
Brachiaria spp. evaluation in Ecuador 69
Table 1. Chemical1 characteristics of the soil used in the experiment2.
pH
OM3
NH4
P
S
Fe
Cu
Zn
Mn
B
K
Ca
Mg
(%)
(mg/kg)
(cmol/kg)
5.9
2.2
41.0
6.5
6.3
42.0
5.6
1.9
2.8
0.3
0.3
8.3
2.9
1Obtained in the Chemistry Laboratory, Universidad Tecnológica Equinoccial, Campus Santo Domingo.
2The analysis to determine the phosphorus concentration in the soil was performed by the method of Olsen modified with a solution of sodium bicarbonate and EDTA adjusted to pH 8.5 with 10N NaOH.
3The organic matter (OM) analysis was performed using the method of Walkley Black, suitable for the conditions of Ecuador.
Results
with the remaining cultivars producing 3.14‒3.89 t
DM/ha. Average accumulation of TDM during the dry
Total dry matter accumulation
season was 62% of that produced in the rainy season.
Accumulation of total dry matter (TDM) followed an
Leaf dry matter accumulation
exponential pattern in both rainy and dry seasons (Table
2). There were no significant differences (P>0.05) in
Leaf dry matter (LDM) yield during the rainy season
TDM accumulation among cultivars of Brachiaria during
varied between cultivars at the various cutting ages but at
the rainy season, with yields ranging from 5.83 to 6.87 t
the tenth week, there were no significant differences in
DM/ha (mean 6.34 t DM/ha) over the 10 week period.
leaf yield between cultivars (P>0.05; Table 3). On the
However, in the dry season differences between cultivars
other hand, during the dry season, significant differences
(P<0.01) were observed in each of the regrowth periods.
(P<0.05) in leaf yield between cultivars at all ages of
While there was little consistency in which cultivars were
regrowth were observed. Towards the end of the dry
superior within particular cutting frequencies, cultivar
season (8 and 10 week cuttings) Xaraés produced more
Xaraés accumulated the greatest amount of TDM during
leaf (P<0.05) than most other cultivars. Dry season leaf
the later part of the dry season and produced the highest
yield at the 10 week cutting varied from 4.28 t DM/ha
DM yield during the dry season period (5.09 t DM/ha),
(Xaraés) to 2.50 t DM/ha (Marandú) (P<0.001).
Table 2. Total dry matter yields at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒November) seasons in humid tropical conditions of Ecuador.
Cultivar
Total dry matter (t/ha)
Rainy season
Dry season
Age of regrowth (weeks)
Age of regrowth (weeks)
2
4
6
8
10
2
4
6
8
10
Señal
0.24
0.96
2.96
4.02
6.87
0.16
0.39
0.75
1.98
3.69
Marandú
0.24
0.85
2.54
4.00
5.83
0.23
0.42
0.73
1.59
3.14
Mulato II
0.29
1.31
2.66
4.33
6.57
0.13
0.28
0.64
1.95
3.76
Piatá
0.28
1.13
2.36
4.36
6.14
0.13
0.41
0.91
1.93
3.89
Xaraés
0.32
1.28
3.16
4.49
6.27
0.13
0.41
0.87
2.49
5.09
Mean
0.27
1.11
2.73
4.24
6.34
0.16
0.38
0.78
1.99
3.92
LSD1
0.09
0.29
1.05
1.59
2.38
0.04
0.1
0.19
0.54
1.09
LS2
0.058
<0.001
0.177
0.812
0.686
<0.001
0.005
0.004
0.003
0.001
1Least Significant Difference (Tukey P≤0.05).
2Level of significance.
Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)
70 J.R. Garay, S. Joaquín, P. Zárate, M.A. Ibarra, J.C. Martínez, R.P. González and E.G. Cienfuegos
Table 3. Leaf dry matter yields at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒November) seasons in humid tropical conditions of Ecuador.
Cultivar
Leaf dry matter (t/ha)
Rainy season
Dry season
Age of regrowth (weeks)
Age of regrowth (weeks)
2
4
6
8
10
2
4
6
8
10
Señal
0.21
0.75
1.71
1.85
3.13
0.16
0.35
0.66
1.55
2.76
Marandú
0.24
0.79
1.76
2.49
3.46
0.23
0.42
0.72
1.48
2.50
Mulato II
0.29
1.26
1.90
2.66
3.85
0.13
0.28
0.63
1.88
3.19
Piatá
0.28
0.97
1.60
2.60
3.21
0.13
0.41
0.88
1.66
3.02
Xaraés
0.32
1.20
2.45
3.50
4.18
0.13
0.41
0.87
2.34
4.28
Mean
0.27
1.00
1.88
2.62
3.57
0.16
0.37
0.75
1.78
3.15
LSD1
0.08
0.24
0.76
0.93
1.17
0.04
0.10
0.19
0.52
1.01
LS2
0.017
<0.001
0.029
0.002
0.072
<0.001
0.004
0.002
0.001
0.001
1Least Significant Difference (Tukey P≤0.05).
2Level of significance.
Stem dry matter accumulation
respectively), while Marandú and Mulato II had the least
(0.64 and 0.57 t DM/ha) (P<0.001).
As for leaf production, stem dry matter (SDM)
accumulation during the rainy season varied between
Plant height
cultivars from the second to the sixth week (P<0.01). At
the 8 and 10 week cuts cultivars Señal and Piatá tended to
During the rainy season plant height of the different
have the highest stem yields and Xaraés the lowest but
cultivars varied but by the eighth and tenth weeks Señal
differences were not significant (P>0.05; Table 4). During
was shorter than all other cultivars (P<0.001; Table 5).
the dry season, SDM accumulation followed an expo-
During the dry season Piatá, Señal and Xaraés progres-
nential pattern, with greatest stem production between the
sively showed superiority in height over the other
8 and 10 week cuts. At the 10 week cut, cultivars Señal
cultivars and by the tenth week Piatá and Xaraés were
and Piatá had the highest SDM (0.93 and 0.87 t DM/ha,
taller than all others (P<0.01).
Table 4. Stem dry matter yields at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒November) seasons in humid tropical conditions of Ecuador.
Cultivar
Stem dry matter (t/ha)
Rainy season
Dry season
Age of regrowth (weeks)
Age of regrowth (weeks)
2
4
6
8
10
2
4
6
8
10
Señal
0.03
0.20
1.22
1.69
2.81
-
0.04
0.09
0.41
0.93
Marandú
-
0.06
0.78
1.39
1.95
-
-
0.02
0.11
0.64
Mulato II
-
0.05
0.76
1.43
2.09
-
-
0.01
0.08
0.57
Piatá
