Restricted feeding and broiler performance: age at initiation and length of restriction

Effects of meal-time feeding and protein restriction on walking ability and some bone and carcass properties in broilers

This experiment was designed to investigate the effects of meal-time feeding and protein restriction on performance, gait score (GS) and carcass and bone traits in broilers. A total of 420 1-day-old chicks were wing banded and randomly distributed into 21 pens with 20 chicks each. At 7 days of age, chicks were weighed and randomly assigned to one of the three treatments: (1) control (C) feed (23.02% crude protein (CP)) was available ad libitum; (2) meal-time feeding (MF); control feed was available from 0100 to 0900 h and from 1500 to 2300 h. Food was withdrawn from 0900 to 1500 h and whole wheat (10 g/bird per day) was dispersed on the floor from 7 to 21 days; and (3) low-protein (LP) diet (19.71% CP) was fed to the chicks from 7 to 21 days. All of the groups were fed ad libitum from 1 to 7 days of age and from 21 to 45 days of age with a standard commercial diet. Individual body weight was measured on days 7, 21 and 45. Feed consumption was measured from 7 to 21 days and from 21 to 45 days. Forty-two chicks were humanly slaughtered and eviscerated for bone evaluation, on days 21 and 45. Also carcass characteristics were determined on day 45. Control group body weight was significantly higher (P < 0.05) at 21 and 45 days of age than the MF and LP groups, which did not differ. Feed intake was reduced by meal-time feeding and LP diet (P < 0.01). Feed efficiency was the best in the MF group during the period of 21 to 45 days of age (P < 0.01). In the control group, shank was significantly longer than that of the LP group and tibia breaking strength was higher than that of the MF group at 21 days (P < 0.05). However, shank width, tibia wet weight and tibia mid-diaphysis ash percentage of the MF group were significantly lower than those of the C and LP groups at 21 days of age (P < 0.05). GS, shank and carcass and tibia bone traits on day 45 were not significant among groups. No compensatory growth and walking ability improvement were observed at 45 days of age for broilers fed with MF and LP between 7 and 21 days of age.

Ascites syndrome and related pathologies in feed restricted broilers raised in a hypobaric chamber

It has been demonstrated that the incidence of ascites can be significantly reduced through feed restriction. This method is thought to have an effect by slowing the growth rate of the birds. Interestingly, when birds are grown in a hypobaric chamber, ascites incidence increases while the overall growth rate of the birds is decreased. Unfortunately, the restriction programs practiced also have a detrimental effect on growth characteristics. An experiment was conducted to determine if the timing and duration of feed restriction can be used to reduce the incidence of ascites for broilers reared under high altitude and local elevation without having a negative impact on growth. A total of 600 commercial broiler males were used. Birds were divided, placing 360 birds in the hypobaric chamber at a simulated 2900 m (9,500 ft) above sea level, and 240 birds were placed at local elevation [390 m (1,300 ft) above sea level]. At each altitude there were four treatments: 1) fully fed controls; 2) feed available for 8 h/d for 6 wk (the duration of the study); 3) feed available for 8 h/d during the first 3 wk, then full feed for the remaining 3 wk; and 4) full feed for the first wk, then 3 wk of 8 h of feed availability, then 2 wk of full feed. Birds and feed were weighed weekly, and mortalities were necropsied to determine the cause of death. At the end of 6 wk, blood samples were taken, and the birds were weighed, necropsied, and scored for ascites, and organ weights were recorded. All feed restriction treatments significantly reduced ascites incidence, when compared with the fully fed controls. Treatment 2 birds were significantly lighter than any other group at both altitudes. The fully fed controls at local elevation were heavier than the fully fed controls at simulated high altitude, as seen in past experiments.