GROWTH OF BROILER-CHICKENS IN RESPONSE TO FEED RESTRICTION REGIMENS TO REDUCE ASCITES

A trial was conducted to investigate the impact of early feed restrict ion on ascites induced by cold temperatures and the subsequent effect on the whole body and breast muscle growth of broilers. Two feed restr iction regimens were tested, consisting of limiting daily feed intake of the birds to 75% of the ME required for normal growth from either 4 to 11 d or from 7 to 14 d. At 21 d, half of the birds were moved to a cold house (17.8 C) to induce ascites. Five birds from each pen were killed for the breast muscle growth, Pectoralis major and Pectoralis m inor, and heart and abdominal fat pad weights at 4, 7, 11, 14, 21, 35, and 49 d of the experiment. Birds in the cold house were heavier and had better feed conversion than birds in the control house at 49 d of age. This could be attributed to the high ambient temperatures (27 to 33 C) in the control house. The ad libitum birds had a significantly g reater percentage of P. major than the feed-restricted birds. Exposure to cold temperatures caused significantly higher percentage of ascite s from 21 to 49 d. Cold temperatures also increased the percentage of total heart and the right ventricle weight relative to total heart wei ght ratio at 35 and 49 d of age, suggesting that the surviving birds w ere more likely to develop ascites. Although catch-up growth was obser ved, the final body weight of feed-restricted birds was not the same a s ad libitum birds. Early feed restriction reduced the incidence of as cites, but at the cost of breast muscle growth.