Abstract

Evaluation of the biological and physiological responses of the local breeds of Saudi Arabia to seasonal variation is not well documented in the literature. Due to the lack of such studies, this work was conducted in an attempt to study the biological and physiological response of two breeds of local layers, Saudi Local (SL) and Naked Neck local (NN) layers to seasonal variation in ambient temperatures and compare them with the single comb white leghorn layers exposed to the same environment. The results of the study indicated a significant breed X period interaction on egg production, egg mass, egg weight, body weight, feed conversion, egg shell thickness, egg specific gravity, livability, and respiration rate. Seasonal variations in temperature had a significant effect on feed consumption, Haugh unit, and body temperature, Naked neck performance was superior during hot weather in egg production, egg mass, feed conversion, egg shell thickness, specific gravity of the egg and respiration rate when compared to the white leghorn and Saudi local birds. Seasonal variation in temperature (periods) had a significant effect on blood PH, PCO 2 , and TCO 2 of the birds in general, while breed effect was evident on Blood PO 2 and HCO 3 of the layers. It is concluded that naked neck birds can perform efficiently in areas where hot climate prevailed as in Saudi Arabia.

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