Comparison of the effects of several feed restriction periods to control ascites on performance, carcass characteristics and hematological indices of broiler chickens

ABSTRACT

This experiment was conducted to evaluate the effect of some feed restriction regimes on the performance, carcass characteristics and hematological values of broiler chickens. A number of 480 one-day-old Cobb broilers were distributed into 24 floor pens and reared for 42 days. A basal diet was formulated according to the NRC (1994) recommendations for starter (1-11 d), grower (12-28 d) and finisher (29-42 d) periods. The restricted birds were fed 8 h per day from 7 to 21 (R7-21d), 14 to 28 d (R14-28d) or from 21 to 35d (R21-35d), while the control birds were fed ad libitum. Birds and feed were weekly weighed, and dead birds were submitted to necropsy to determine the cause of death. At the end of experiment, blood samples were taken from 3 birds per pen, birds were weighed, and organ weights were recorded. All birds in the feed restriction treatments had lower body weight gain and feed intake than those fed ad libitum. Feed conversion ratio (FCR) was better in birds under R7-21d as compared to the control group (p 0.05). R7-21d and R14-28d birds presented lower general mortality and death due to ascites as compared to ad libitum-fed broilers. The birds under R21-35d and R14-28d treatments had lower breast weight and abdominal fat weight as compared to control birds, respectively (p 0.05). A similar trend was observed for the percentage of the mentioned cuts. The right/total ventricular weight ratio (RV/TV) was significantly lower both in R7-21d and R14-28d treatments as compared to the control group. Blood constituents, such as glucose, cholesterol, and lactate dehydrogenase were also significantly altered by feeding regimes (p 0.05). The results of present study showed that R7-21d reduced ascites incidence, but had no significant effect on growth performance.