R.S. KALMBACHER¹, F.G. MARTIN² and A.E. KRETSCHMER, Jr³

¹University of Florida, Range Cattle Research and Education Centre, Ona,
²Gainesville, and
³Ft Pierce Research and Education Centre, Ft Pierce, USA

Abstract

Paspalum atratum cv. Suerte, a leafy, perennial bunchgrass rapidly established from seed and adapted to moist soils, was grazed during 2 years by 3.3, 6.6 and 10 yearling steers/ha at Ona, Florida in a replicated trial. In an unreplicated ranch trial, 80 heifers grazed 16.3 ha of Suerte. Steers grazed for 140 d (each year) at 10 steers/ha; 168 d (each year) at 6.6 steers/ha; and 168 (1993) and 224 d (1994) at 3.3 steers/ha. There was an interaction between year, month and stocking rate for average daily gain (ADG) over common 140-d grazing seasons. Variation in rainfall between years and changes in rainfall and nutritive value of Suerte within year influenced ADG. Over both years, ADG averaged 0.71, 0.55 and 0.49 kg/d for 3.3, 6.6 and 10 steers/ha, respectively. On the ranch, heifer ADG was 0.60 kg/d over 119 d with 4.9 heifers/ha. Two-year average liveweight gains were 460, 610 and 680 kg/ha at 3.3, 6.6 and 10 steers/ha, respectively. Suerte presentation yields declined linearly from 2870 kg/ha in April to 670 kg/ha in August with 10 steers/ha. Presentation yields with 3.3 steers/ha increased linearly from 2050 kg/ha in April to 6940 kg/ha in August. There was no difference in presentation yield over months with 6.6 steers/ha (2720 kg/ha). Crude protein (CP) and in vitro organic matter digestibility (IVOMD) of Suerte were not affected by stocking rate, but CP concentration (range 76–142 g/kg) changed quadratically over months, while IVOMD (range 58–68%) declined linearly. Suerte plant density (13.5 plants/ m²) was not affected by stocking rate or year. Under Florida conditions, Suerte should be stocked at 6 yearlings/ha, which will result in about 0.6 kg/d ADG over a 168-d season. Suerte may have potential as a valuable grass for growing young cattle in the humid tropics.