Fractionation of carbohydrate and protein content of some forage feeds of ruminants for nutritive evaluation.

AIM To evaluate some forage feeds of ruminants in terms of their carbohydrate (CHO) and protein fractions using Cornell Net Carbohydrate and Protein System (CNCPS). MATERIALS AND METHODS Eleven ruminant feeds (six green fodders - maize, oat, sorghum, bajra, cowpea, berseem and five range herbages - para grass, guinea grass, hedge lucerne, setaria grass and hybrid napier) were selected for this study. Each feed was chemically analyzed for proximate principles (dry matter, crude protein [CP], ether extract, organic matter and ash), fiber fractions (neutral detergent fiber, acid detergent fiber, acid detergent lignin, cellulose and hemicellulose), primary CHO fractions (CHO, non-structural CHO, structural CHO and starch) and primary protein fractions (neutral detergent insoluble CP, acid detergent insoluble CP, non-protein nitrogen and soluble protein). The results were fitted to the equations of CNCPS to arrive at various CHO (CA - fast degrading, CB1 - intermediate degrading, CB2 - slow degrading and CC - non-degrading or unavailable) and protein (PA - instantaneously degrading, PB1 - fast degrading, PB2 - intermediate degrading, PB3 - slow degrading and PC - non-degrading or unavailable) fractions of test feeds. RESULTS Among green fodders, cowpea and berseem had higher CA content while except hedge lucerne all range herbages had lower CA values. CB1 content of all feeds was low but similar. All feeds except cowpea, berseem, and hedge lucerne contained higher CB2 values. Oat among green fodders and hybrid napier among range herbages had lower CC fraction. Feeds such as bajra, cowpea, berseem and the setaria grass contained lower PA fraction. All green fodders had higher PB1 content except maize and cowpea while all range herbages had lower PB1 values except hedge lucerne. Para grass and hybrid napier contained exceptionally low PB2 fraction among all feeds. Low PC contents were reported in oat and berseem fodders. CONCLUSION Based on our findings, it was concluded that feeds with similar CP and CHO content varied significantly with respect to their CHO and protein fractions. Due to lower CC fraction, oat and hybrid napier were superior feeds in terms of CHO supply to ruminants. Similarly, among all feeds oat and berseem had a lower PC fraction, thus were considered good sources of protein for ruminants.