NITROGEN-UTILIZATION OF GROWING-FINISHING BARBADOS BLACKBELLY LAMBS

Twelve 6-8 months old male Barbados Blackbelly lambs were used in a 4 x 4 latin square experiment with three replicates to study the utilization of diets made from local byproducts and containing 64, 93, 125 or 143 g crude protein/kg d.m.Both dry-matter (mean 750-1 g/day) and digestible-energy (mean 6-2 MJ DE/day) intakes, and their digestibility coefficients increased, though not significantly, with increasing dietary protein concentration. However, nitrogen digestibility, urinary-nitrogen output and nitrogen retention all increased significantly (P<0-01) with increasing dietary protein concentration.Metabolic faecal nitrogen and endogenous urinary nitrogen derived from the intercept of significant regressions of nitrogen intake against urine and faecal nitrogen outputs were 5-07 g/kg dry matter eaten and 3-46 g/day (0-35 kg W0.75) respectively. The diets had a mean biological value of 73-6. The digestible crude protein requirements for maintenance were (g/day) 29-0, 38-4 and 26-6 when estimated from nitrogen retention, factorially and from liveweight performance respectively. © 1979, Cambridge University Press. All rights reserved.