Early feed restriction in chicks: effect of age, duration, and sex.

Several regimens of feed restriction, calculated to support the maintenance of body weight without any allowance for growth, were applied beginning at the ages of 3 to 11 days for periods of 3 to 7 days using male and female broilers. In males, the 7-day feed restriction treatment resulted in improved feed efficiency on an age basis, or on a body weight basis after body weight had reached .7 to 1 kg. Feed restriction also resulted in a reduction in the amount of abdominal fat at the age of 54 to 59 days without any concomitant reduction in body weight. Within the range tested, 3 to 11 days of age, the initiation of the 7-day restriction treatment did not affect response. Similar responses were obtained in females, but with little benefit in feed efficiency when compared with ad libitum-fed birds on a body-weight basis. Also in females, reduction in 56-day body weight and loss of benefits derived from improved feed efficiency and reduced carcass fat could be avoided if the period of restriction was kept at 3 to 5 days.