Effects of early feed restriction programs on production performance and hormone level in plasma of broiler chickens

Abstract

Age, duration and intensity of feed restriction of broiler chickens were studied by L9(34) orthogonal experiment. Broiler production performance and meat color were measured to evaluate the effects of feed restriction and explore the superior FR program. A total of 250 1-day-old Ross 308 chicks were selected and randomly allocated to ten groups, including one feed ad libitum (AL) group and nine feed restriction (FR) groups; each group had 5 pens with 5 chickens each. Broilers (T5D7I90), feed-restricted to 90% from day 5 to day 11, had the highest body weight (BW), carcass weight, eviscerated weight, leg muscle weight and breast muscle weight, as well as muscle ratio. While broilers (T5D14I70), feed-restricted to 70% from day 5 to day 18, had the lowest. Triiodothyronine (T3) and growth hormone (GH) decreased while thyroxine (T4) and the ratio of T4/T3 increased in FR broilers. Feed conversion ratio, abdominal fat ratio, whole eviscerated weight ratio and lightness (L*) and yellow/blue (b*) value of leg muscle color increased in FR broilers (P> 0.05). T5D14I70 had the lowest red/green (a*) color value of leg muscle and the highest L* and b* color values of breast muscle (P> 0.05). FR groups except T10D14I90 had lower a* color value of breast muscle than AL. FR program of T5D7I90 resulted in superior production performance and higher capability of meat production. Broilers feedrestricted T5D14I70 were stunted with the lowest muscle growth capability and deteriorated in the breast muscle color. FR improved leg muscle color and increased broiler byproduct production. Lower T3 and GH concentration and higher T4/T3 ratio in plasma were related with the increased feed conversion rate and fat deposition in FR broilers; however, they had no relation with meat production and growth rate.