Eggshell temperature manipulations during incubation and in ovo injection of thyroxine are associated with a decreased incidence of cold-induced ascites in broiler chickens.

A hypothesis was tested that eggshell temperature manipulations during incubation and in ovo injection of thyroxine (T4) would help their progeny chicks to better survive the ascites-inducing condition during the growing period. In experiment 1, a total of 4,800 hatching eggs was randomly arranged in a 2 × 4 factorial design (8 replicates of 75 eggs per treatment), in which the eggs were incubated at a constant eggshell temperature (EST) of 37.8°C throughout the incubation period (CON) or were exposed to 15°C for one h on d 11, 13, 15, and 17 of incubation (EST manipulations; ESTM), and 4 treatment groups of 3 control groups (no injection; INJN, needle pricked; INJP, and sterilized distilled water injection; INJW) and one T4 treatment group (injected with sterilized distilled water containing 65 ng of T4; INJT4). In experiment 2, 240 one-day-old male broiler chicks from 2 temperature conditions and injection (INJN and INJT4) treatment groups were reared for 42 d in a completely randomized design with a 2 × 2 factorial arrangement. To induce ascites, all chicks were exposed to a 15°C room temperature from 14 d onwards. Results from experiment 1 showed that second-grade chicks and yolk sac weight were decreased, and body weight at hatch was increased in the ESTM and INJT4 groups. Also, final body weight was increased in the ESTM group. Ascites mortality rate was decreased in the ESTM and INJT4 groups. In the ESTM and INJT4 groups, the red blood cell (RBC) and the packed cell volume (PCV) count were decreased. In conclusion, the results showed that the ESTM and INJT4 treatments during incubation were associated with improved chick quality, productive performance of broilers, and a decreased incidence of cold-induced ascites in broiler chickens.

Periodical low eggshell temperatures during incubation and post hatch dietary arginine supplementation: Effects on performance and cold tolerance acquisition in broilers.

An experiment was conducted to evaluate the effects of a periodically low eggshell temperature exposure during incubation and dietary supplementation of arginine on performance, ascites incidence, and cold tolerance acquisition in broilers. A total of 2,400 hatching eggs were randomly assigned to 2 treatment groups (16 replicates of 75 eggs per treatment). The eggs were incubated at a constant eggshell temperature (EST) of 37.8ºC throughout the incubation period (CON) or were periodically exposed to 15°C for one hour on days 11, 13, 15, and 17 of incubation and the EST was measured (periodical low EST; PLE). After hatching, 240 one-day-old male broiler chicks from both treatment groups were reared for 42 d with or without dietary arginine supplementation in a completely randomized design with a 2 × 2 factorial arrangement. In order to induce ascites, all chicks were exposed to a 15°C room temperature from 14 d onwards. Results showed that second grade chicks and yolk sac weight were decreased, and final body weight was increased in the PLE group. Ascites mortality rate was decreased only in the PLE group and dietary arginine supplementation had no apparent effect. In the PLE group, the packed cell volume (PCV) percentage and red blood cell (RBC) count were decreased. In conclusion, the results showed that the PLE treatment during incubation was associated with improved hatchability, chick quality, and productive performance of broilers and decreased ascites incidence during post hatch cold exposure. Dietary arginine supplementation had no beneficial effects in cold exposed broilers.