Nitrogen retention and nutrient digestibility in sheep given a basal diet of sorghum hay supplemented with protein of varying degradability

A metabolic study was conducted in 4x4 Latin square design involving four cross bred (Fl, Kaghani x Rambouillet) wethers and four diets. The wethers were kept in individual metabolic crates and fed a basal diet of sorghum hay ad libitum. The basal diet was supplemented with 150 g/d untreated mustard seed cake (UMSC), 150 g/d formaldehyde treated mustard seed cake (TMSC), 211 g/d cottonseed cake (CSC) or 211 g/d wheat bran (WB) + 9.3 g/d urea. All the supplements were fed on iso-nitrogenous basis (8 g N/d/wether). Each period consisted ten days adaptation followed by five days of data collection. In sacco protein degradabilities (12 h) of UMSC, TMSC, CSC and WB were 83.99, 8.96, 80.46 and 88.75%, respectively and the differences were statistically significant (P 0.05). Hay dry matter intake was maximum (P 0.05) in wethers receiving TMSC supplement. The differences in hay dry matter intake among the wethers receiving UMSC,CSC and WB supplements were non significant. Total dry matter intake remained the highest (P 0.05) on TMSC (784.10 g/d) and was minimum (P 0.05) on UMSC (700.88 g/d). Total dry matter intake on diets containing CSC and WB were intermediate and recorded as 761.27 and 768.48 g/d, respectively. In vivo digestibilities of dry matter, organic matter and acid detergent fiber were not affected by diets. However, nitrogen digestibility was maximum (P 0.05) in wethers receiving WB supplement. Nitrogen retention as g/d or percent of total N intake was maximum (P 0.05) in wethers on the diet containing WB and remained lower (P 0.05) and did not differ among the other three diets. Nitrogen retention was 4.48, 4.72, 4.63 and 6.93 g/d in wethers receiving diets A, B, C and D, respectively. Formaldehyde treatment of mustard seed cake did not affect nitrogen retention in the wethers.