Comparative study on the beneficial effects of different darklengthschedules on the incidence of ascites and metabolicparameters in fast growing broiler chickens

Increasing of oxygen consumption in fastgrowingbroiler chickens is associated with the more pronouncedoccurrence of right ventricular hypertrophy and ascites. While,rearing of susceptible chickens in dark condition could reduce themetabolic rate of birds and hence the incidence of ascites.OBJECTIVES: The present study was designed to investigate acomparative study on the influence of different dark-lengthschedules on the incidence of ascites and metabolic parameters infast growing broiler chickens. METHODS:Atotal of 1000 day-old(Pure Sir Broiler Line Arian) chickens were obtained and subjectedto four different lighting programs. Dead birds were autopsied forthe lesions of ascites. Weekly growth performance of chickens wasdetermined and blood samples were taken, on days 7, 12, 21, 28, 35and 42 of age for hormonal analysis. RESULTS: The incidence ofascites was clearly higher in birds subjected to normal lightingprogram compared with those of dark exposed chickens. Controlchickens showed significantly higher body weight compared to thedark exposure group birds at day 21 of age, while it did not differ atdays 28, 35 and 42 of age. Such differences was accompanied withthe lower levels of plasma T3 and T4 concentrations in dark groupchickens than to control chickens at the earlier age (days 12 and 21).CONCLUSIONS: This phenomenon indicated a reduction ofmetabolic rate and oxygen consumption in dark group chickens thathad been led to reducing of ascites incidence. Our data proves thatincreasing dark-length instead of continuous lighting may bebeneficial for rearing of broiler chickens, especially, when the riskof ascites incidence is higher.

کلیدواژه ها:

broiler chickens ، ascites ، dark-length ، T3 ، T4