Effect of maturity stage and processing on chemical composition, in vitro gas production and preference of Panicum maximum and Pennisetum purpureum

Abstract

The trials arranged in 2 x 2 x 2 factorial completely randomized design to evaluated the selection preference of Guinea grass (Panicum maximum) and Elephant grass (Pennisetum purpureum ) of four and eight weeks regrowth served either fresh green chop or pelleted using 12 intact Muturu calves in a 15 min cafeteria. The diets were served to animals either individual or in group. The CP content of the grasses ranged from 105 to 133 g/kg DM with pelleted Panicum at 8 weeks old having the highest CP. Pelleted grasses of 4 week old had the lowest (P<0.05) NDF in the trial. Panicum pelleted at 4 weeks old recorded the highest (P < 0.05) sequential in vitro gas volume of 5.25 ml/200g while the volume of gas produced by pelleted grasses was higher (P < 0.01) than the fresh grasses. Pennisetum pelleted at 8 weeks old had the highest (P<0.05) ME of 6.18 MJ/kg DM. Age at harvest influenced preference as forages harvested at 4 weeks old had higher intake. Group feeding also influenced forage preference. Correlation analysis showed that DM, SCFA, and ash contents have poor (P> 0.01) capacity to preference of forages. Forage preference considered in terms of intake rate indicated that growing calves preferred fresh P. maximum 4 week old to the other samples used in this study. It is concluded that in order to optimize DM intake farmers should consider the type of grasses and their age at harvest particularly for Muturu. Pelleting improves acceptability of forages when rejected by animal as fresh forage form due to advanced age.

Keyword: pelleting; muturu calves; panicum; pennisetum; age at harvest