Protein Requirement Studies by Balance Method and Endogenous Nitrogen Losses in Male Calves

Sixteen male crossbred (Holstein Friesian x Sahiwal) calves above six months of age (68-111 kg body weight) were distributed into 4 groups of 4 each in a factorial RBD. The calves in the respective groups were fed with ration supplying DCP and TDN in the ratio of 100:100, 100:130, 130:100 and 130:l30 percent levels of the existing standards. The average live weight change in calves in groups 1, 2, 3 and 4 were—0.025, 100, 400 and 450 g/day respectively. There was significant (P < 0.01) effect of energy, protein and their interaction on N retention. Loss of N in faeces was 53.25, 55.03, 44.97 and 52.25 percent and in urine it was 46.33, 51.33, 43.51 and 47i49 percent of total N intake in the respective groups. Regression of metabolic body size and live weight gain over CP and DCP intake gave the maintenance requirement (g/kg W^0.75/day) as 15.79 and 7.63. The requirement for one kg live weight gain was estimated as 419 g CP and 268 g DCP.