Losses and dry matter recovery of Pioneiro grass ( Pennisetum purpureum ) and maize silages in mixtures

Forages ensiled with high moisture content produce increased quantities of effluents, losing highly digestible nutrients (McDonald 1981). The silage making process usually involves gaseous and effluent losses, which are related to the moisture content of the plants used for forage conservation. The additions of material with high dry matter content and material to improve the fermentation pattern have been strategies to reduce these effluent losses. Whole maize plants and maize grain, because of their physical and fermentative characteristics, are possible materials to reduce the losses in the process (Anaya-Ortega et al. 2009). This study aimed to evaluate the effects of the addition of whole plant maize and maize grain to Pioneiro grass at ensiling as a way to reduce dry matter (DM) losses.


Introduction
Forages ensiled with high moisture content produce increased quantities of effluents, losing highly digestible nutrients (McDonald 1981).The silage making process usually involves gaseous and effluent losses, which are related to the moisture content of the plants used for forage conservation.The additions of material with high dry matter content and material to improve the fermentation pattern have been strategies to reduce these effluent losses.Whole maize plants and maize grain, because of their physical and fermentative characteristics, are possible materials to reduce the losses in the process (Anaya-Ortega et al. 2009).This study aimed to evaluate the effects of the addition of whole plant maize and maize grain to Pioneiro grass at ensiling as a way to reduce dry matter (DM) losses.

Methods
The research was carried out at the Federal University of Paraná, Palotina Campus, Palotina, PR, Brazil.Pioneiro grass (Pennisetum purpureum) and maize were chopped to 20 mm segments and placed into PVC experimental silos with 600 kg of fresh mass/m 3 .The silos were provided with upper Bunsen valves for the escape of gases and bottom valves to drain effluents.A completely randomized design was used, with 4 treatments and 8 replicates.The treatments involved 4 types of silage mixtures: Pioneiro grass 100%; Pioneiro grass 90% + ___________ Correspondence: Américo F. Garcez Neto, Universidade Federal do Paraná (UFPR), Laboratório de Nutrição Animal, Campus Palotina, Palotina CEP 85950-000, PR, Brazil.Email: americo.garcez@ufpr.brwhole plant maize 10%; Pioneiro grass 98% + maize grain 2%; and whole plant maize 100%.The quantities of whole plant maize and maize grain added to the treatments were calculated on a fresh mass basis.
Statistical analysis was performed using the GLM procedure and test of multiple comparison of means (SNK) at 5% level of significance by the SAS software (version 9.0).

Results and Discussion
Table 1 presents the average percentages of DM at ensiling, ensiled DM lost as gases (GL) and effluents (EL) and dry matter recovery (DMR).Silage type had a significant effect (P<0.05) on GL and DMR.The whole plant maize silage (M) and Pioneiro grass silage with maize grain (PMG) had lower GL and, although differences were not significant, no EL.The large GLs of Pioneiro grass silage (P) and Pioneiro grass silage with whole plant maize (PWPM) are likely due to lower carbohydrate and higher moisture contents of the ensiled material.As with most tropical grasses, for Pioneiro to reach a DM content comparable with the maize plant, it would need to grow for a longer periodbut the increase would be at the expense of forage/silage quality.Although the effluent losses were not significant with the different DM contents, Pioneiro grass silage had the lowest DMR, which, however, could be considerably improved by adding maize grain.

Conclusion
High DM losses from Pioneiro silage alone are a concern in ensiling this material.Addition of maize to Pioneiro grass when ensiling offers an excellent strategy to reduce gaseous losses and improve dry matter recovery.Mixing Pioneiro grass with whole plant maize when ensiling seems an ineffective way to reduce losses and savings might not justify the extra effort involved.