THE EFFECT OF BETA-HYDROXY-BETA-METHYLBUTYRATE ON GROWTH, MORTALITY, AND CARCASS QUALITIES OF BROILER-CHICKENS

Experiments were conducted to determine whether the leucine catabolite beta-hydroxy-beta-methylbutyrate (HMB) could influence protein metabo lism in broilers. In Experiment 1, HMB was fed at either .01 or .05% o f the diet. Beta-Hydroxy-beta-methylbutyrate did not improve feed conv ersion or BW gain; however, broilers fed HMB at .01% in a diet formula ted to meet NRC (1984) recommendations had no mortality (P <.03) from 0 to 21 d of age. In Experiment 2, HMB fed at .003, .01, .03, and .09% of the diet had no significant affect on growth or carcass yield of t he broilers when compared with control-fed broilers. In Experiment 3, HMB fed at .001, .003, and .01% of the diet had no effect on broiler g rowth. In Experiment 4, HMB was fed at .01% of the diet in combination with an antibiotic and coccidiostat (GP). Use of GP increased (P < .0 1) BW, feed conversion, and carcass yield when compared with the contr ol broilers. In Experiment 5, HMB was fed at .1% of the diet, and effe cts of sex and GP were examined. Beta-Hydroxy-beta-methylbutyrate decr eased (P < .01) mortality by 72% in the male broilers. In a combined a nalysis, HMB fed at .01% of the diet (Experiments 1, 2, and 3) increas ed breast yield (P <.05) and reduced mortality by 56% (P <.04) from 0 to 21 d of age. In a combined analysis, HMB fed at .003% of the diet ( Experiments 2 and 3) increased 42-d BW (P < .02) and hot (P < .04) and chilled (P < .05) carcass yields. In conclusion, across all HMB dosag es mortality of male broilers was decreased from 6.37 to 4.39% (-31%, P < 04) by feeding HMB, with the pattern of death suggesting that HMB decreased the incidence of sudden death syndrome in these broilers.