STUDIES ON PROTEIN REQUIREMENTS OF STEERS

II* — NITROGEN BALANCE STUDIES WITH THREE BREEDS OF CATTLE MAINTAINED ON ALL-ROUGHAGE SUPPLEMENTED DIETS

Résumé

Comparative studies lasting between 59 - 63 days were carried out using the N-balance method to investigate the effect of groundnut cake supplementation on N-metabolism and digestible crude protein (DCP)requirements of three breeds of steers maintained on all-roughage rations of hay and fresh dry of Cynodon rulenfuensis var robustus The results indicated that N intake (/day) Increased ed appreciably with supplementation. The percentage Increases li the intake were 16.4.40.0 and 18.0 for the White Fulani, crossbred and German Brown Steer respectively. Apparent digestibility coefficients for N also increased by 10%0.6.8% and 7.1% for these steers respectively. Faucal nitrogen output (/day) Increased slightly with supplementation with all breedy of steen, while urinary nitrogen loss decreased with the White Fulani, increased with the German Brown and showed no difference with the crossbreed. Absorbed nitrogen (g/day), N-balance (g/day) und N-retention (%) all increased with supplementations Mean values for both metabolic f al ultrogen (MEN) (N/kgDM consumed und endogenous urinary nitrogen (EUN) (/day/wkg 0.75) decreased with supplementation while the mean Hological value (BV) (197) Increased. The values were 2.4 6N/kg DM consumed, 0.11/dm/wg 0.75 and 75.87 respectively. Digestible crude protein requirements (DCP) decreed with supplementation in all the breeds of steen. The values were 1.06, 0.38 and 0.81 (0.75 + 0.20)/day/wkg 0.75) by the N-balance methods and 1.08, 0.51 und 1.20 (0.93 = 0.21) 2DCP/day/wkg 0.75 by the Nuctoriul methody. The DCP requirements therefore range from 0.75 - 0.93 /day/weg 0.75 for these breeds of steers, While there were decreases of approximately 13.14%. 1.99 and 6.4% In the mean DM Intake.