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 metabolism in broilers. In Experiment 1, HMB was fed at either.01 or.05% of the diet. beta-Hydroxy-beta-methylbutyrate did not improve feed conversion or BW gain; however, broilers fed HMB at 0.01% in a diet formulated to meet NRC (1984) recommendations had no mortality (P .03) from 0 to 21 d of age. In Experiment 2, HMB fed at 0.003, 0.01, 0.03, and 0.09% of the diet had no significant affect on growth or carcass yield of the broilers when compared with control-fed broilers. In Experiment 3, HMB fed at 0.001, 0.003, and 0.01% of the diet had no effect on broiler growth. In Experiment 4, HMB was fed at.01% of the diet in combination with an antibiotic and coccidiostat (GP). Use of GP increased (P .01) BW, feed conversion, and carcass yield when compared with the control broilers. In Experiment 5, HMB was fed at.1% of the diet, and effects of sex and GP were examined. beta-Hydroxy-beta-methylbutyrate decreased (P 0.01) mortality by 72% in the male broilers. In a combined analysis, HMB fed at 0.01% of the diet (Experiments 1, 2, and 3) increased breast yield (P 0.05) and reduced mortality by 56% (P .04) from 0 to 21 d of age. In a combined analysis, HMB fed at 0.003% of the diet (Experiments 2 and 3) increased 42-d BW (P 0.02) and hot (P 0.04) and chilled (P 0.05) carcass yields. In conclusion, across all HMB dosages mortality of male broilers was decreased from 6.37 to 4.39% (-31%, P 0.04) by feeding HMB, with the pattern of death suggesting that HMB decreased the incidence of sudden death syndrome in these broilers