Nutritive value of maize residues in comparison with Eragrostis curvula hay as feed for sheep

Abstract

The nutritive value of maize residues containing a low, medium and high in vitro dry matter digestibility (IVDMD) was compared with that of Eragrostis curvula hay. Both forages were milled through a 6 mm sieve and supplemented with nitrogen (2% urea), phosphorus (1% dicalcium phosphate), sulphur (0.1% flowers of sulphur) and sodium chloride (commercial salt, ad libitum). The diets were fed ad libitum on an individual basis to lambs (30 kg) (12 lambs per treatment) in a growth and digestion trial, repeated during 2 different years. The results showed that lambs fed on maize residues with a comparable, and in some cases an even higher IVDMD than E. curvula hay, had a significantly ( P < 0.05) lower live weight increase than lambs fed on E. curvula hay. This was accompanied by a lower digestible dry matter intake (DDMI) due to a lower dry matter intake (DMI) of maize residues. This may be related to a lower weight of dry rumen contents per kilogram of carcass weight and a lower weight of dry rumen contents per volume of rumen contents found for lambs fed on maize residues. Furthermore, lambs fed on maize residues with a comparable and even higher IVDMD, also showed a lower nitrogen retention. Regression analysis indicated that IVDMD of maize residues correlated highly significantly ( P < 0.01) with the live weight change ( r = 0.949 and 0.966), DDMI ( r = 0.921) and DMI ( r = 0.905), showing that the nutritive value of maize residues can be estimated by its IVDMD.