Effect of heat stress on some productive and physiological traits in chicken [electronic resource].

Includes reference

This work was conducted at the poultry farm of the Faculty of Agriculture "Norta Project" Menofiya University, Shebin EI-Kom The aim of the investigation was to study the effect of heat stress on some physiological traits and consequently productive pertormance of two strains of chicken at 8 weeks post hatch. A total number of 276 birds were divided into two comparable groups. The first was exposed to the natural ambient temperature (control) (2930co) and relative humidity of 55%, whereas, the second was exposed to heat stress (35- 37co) for six hours, 1 time weekly. Climatic chamber was used for adjustment of temperature and humidity of 65%. The treatments were continued up to 32 weeks. The chicks were fed adlibitum, a starter ration (with crude protein 22.17 % and 2920 kcal/kg. M.E) and a layer ration (with crude protein 18.09% and 2790 kcal/kg. M.E). The most important results could be summarized as follows: 1. Body weight of either Norta or Fayoumi of control group were higher than that of treated group. 2. Growth rate was higher in Fayoumi than in Norta chickens during 4-20 weeks of age. 3. Age at sexual maturity was earlier in Norta than Fayoumi chickens in control group but the reverse in treated group where Norta was the latest age at sexual maturity among treated groups. 4. Average body weight at sexual maturity in Norta chickens was heavier than that of Fayoumi when exposed to heat stress. 5. Average egg weight at sexual maturity was higher in the group treated when compared with control one. 6. Average egg number in the first three months of production increased in control group than that produced in treated group in Norta and Fayoumi layers. 7. Average respiratory rate in Norta pullets was higher in treated group than control group at all ages. 8. Average body temperature in Norta pullets was increased in treated group than control one. 9. Effect of heat stress on antibody production: The present results indicated that females had higher antibody titers against SRBCs than males at 14-d post-immunization in Norta and Fayoumi chickens before exposed to heat stress. The differences between sex were significant. However, in Fayoumi chickens, before exposure to heat stress, the antibody level was increased than Norta chickens after injection of SRBCs. While after exposure to heat stress the most of antibody level against SRBC s was reduced in treated group than the control group in Norta and Fayoumi chickens while male had higher antibody level than females in Norta and Fayoumi.

Summary in arabic.

1