Prediction of feed intake, digestibility and growth rate of sheep fed basal diets of maize stover supplemented with Desmodium intortum hay from dry matter degradability of the diets

Abstract

The in sacco dry matter (DM) degradability of diets based on maize stover harvested at three stages of maturity and supplemented with graded levels of desmodium ( Desmodium intortum cv. Greenleaf) hay were estimated from degradability of the individual feeds and their corresponding DM intake. The estimated DM degradability of the diets was used for prediction of DM intake (DMI), digestible DM intake (DDMI), DM digestibility (DMD) and growth rate of sheep feeding on the diets. The desmodium hay had significantly higher ( P<0.05) DM disappearance than the maize stovers after 4, 8, 16, 24 and 48 h of incubation, as well as higher washing loss ( A), degradation rate ( c value) and effective DM degradability (ED) than the maize stovers. The washing loss was lowest in maize stover harvested at stage III and, as a consequence, the washing loss of the diets showed a significant decrease ( P<0.05) with increasing stage of maturity of the stovers. The DM disappearance after 48 h incubation, washing loss and degradation rate showed a significant increase whereas the insoluble, but potentially degradable, fraction ( B) showed a significant decrease ( P<0.05) with increasing level of supplementation. The DM disappearance after 24 and 48 h of incubation, washing loss, ED and degradation rate showed strong positive correlation whereas the insoluble, but potentially degradable, fraction showed a negative correlation with DMI, DMD, DDMI and growth rate. On the other hand, the DM disappearance after 96 h of incubation, potential degradability and the lag phase showed very low correlation with these parameters. In general, the washing loss, ED and the DM disappearance after 24 and 48 h of incubation were found to be simple and reliable predictors of DMI, DDMI, DMD and growth rate. However, the use of the A, B and c values simultaneously in a multiple regression gave a more precise prediction of feed intake, digestibility and growth rate.