Abstract: The purpose of this experiment was to investigate the effects of dietary beta-hydroxy-beta-methyl-butyrate calcium (HMB-Ca) on growth performance, slaughter trait and blood hormones in broiler chickens. Six hundred day-old Arbor Acres (AA) chickens were randomly divided into five groups with six replicates of twenty chickens and fed different levels of HMB-Ca ( 0 (control group) ,0.05%,0.1%,0.15% and 0.2%) in the diet respectively. The experiment lasted 42 d. Growth performance including average daily weight gain (ADG), average daily feed intake (ADFI), feed to gain ratio (F/G) during 1 to 21 d, 22 to 42 d, 1 to 42 d, slaughter trait at 42 d and serum hormones at the age of 21,42 d were determined. The results showed that, compared with the control, there were no significant differences on ADG,ADFI and F/G by adding different levels of HMB-Ca during the experiment (P＞0.05), and dietary 0.1% HMB-Ca ameliorated the F/G in 22 to 42 d and 1 to 42 d; chicks fed 0.1% HMB-Ca diet had significant increased breast muscle rate (P＞0.05), and also had the trend of increasing leg muscle rate; At 42 d of age ,chicks in the groups of HMB-Ca adding level above 0.05% had significant higher serum insulin level compared to the controls (P＞0.05), and those in 0.1% HMB-Ca group was the highest. Serum GH level was higher in lower (0.05%) HMB-Ca level group than those in higher (0.15%, 0.2%) HMB-Ca levels(P<0.05). In conclusion, appropriate dietary HMB-Ca could enhance the breast muscle rate and serum insulin level, and it seemed that the 0.1% inclusion level was recommended in production.

Key words: broiler chickens; HMB-Ca; growth performance; slaughter trait; serum hormones