Manipulação térmica embrionária em frangos de corte

Abstract

This experiment aimed to elucidate the effect of thermal manipulation in broiler embryos (TME) on the potential of these birds to withstand thermal stress at marketing age. In the first experimental phase 3072 eggs from Cobb® broiler breeders of 48 weeks old were used. The eggs were subjected to different kinds of temperature on two hatcher machines: 36.5°C and 60% RH (control group) and 37.5°C, 6h continuously per day from embryonic day 18 to 20 (hatcher machine with TME). It was elucidated the TME effect on the hatching performance, weight of chickens, cloacal temperature and yolk sac/chick weight ratio. The experiment was completely randomized design into two thermal treatments realized on hatcher machines. In the second experimental phase were evaluated the effects of different temperatures established in the incubation on the performance parameters and cloacal temperature of one to 28-d old broilers. The experimental design was the same of the first phase. The different thermal manipulations realized in the embryonic period did not affected parameters analyzed in these phases. In the third experimental phase were evaluated the effects of different temperatures established in the incubation period on performance parameters and cloacal temperature of broilers submitted or not to thermal stress from 28th to 40th day of age. Broilers were distributed into a completely randomized experimental design in a factorial arrangement 2x2. In this phase there was no interaction between treatments, but broilers reared in thermoneutral environment showed best results for performance parameters than broilers reared in heat stress environment. It was concluded that thermal manipulation during the portion of embryogenesis did not result in best adaptability of broiler chickens in heat stress environment.