A Preliminary Study of Egg Production and Heat Tolerance in a New Breed of Fowl (Leghorn x Bedouin)'

ABSTRACT Physiological responses to high (40-45 ° C.) ambient temperatures were studied in acclimatized chronically cannulated laying Leghorn x Bedouin fowl. Normal values for body temperature (TB), respiratory rate (R.R.) and acid base parameters were determined in hens exposed to ambient temperatures (TA) of 25 ° C. Mean value for TB was 40.49 ° C. and R. R. ranged 11-26 breaths per min. Arterial pH, carbon dioxide partial pressure (PaC02) and plasma bicarbonate ion concentrations [HC03~] were: 7.549, 23.87 mm. Hg and 20.56 m M / L, respectively. Egg production studies under outdoor conditions, during 100 days, were carried out on 30 week old pullets. The rate of lay was 80.5%, and mean egg weight was 54.89 gms. The total egg output was 44.2 gm./hen day. This value was found to be about 44 % higher than that calculated for laying Sinai Bedouin fowl. During long term exposure (8-10 hrs.) to high TAs (37-45 ° C.) TB increased within a range 2.1 ° C. higher than normal. Panting was indicated by an increased R.R., to 238-293 breaths per min., accompanied by synchronous gular fluttering. The thermal panting was accompanied by a slight decrease in PaC02 to values of 19.15-21.44 mm. Hg which was compensated for by a lowering of bicarbonate ion concentration to 17.11-18.86 mM/L. Arterial pH was regulated close to normal level i.e. 7.562 at 42 ° C. and 7.571 at 45 ° C. TA. The results suggest that the Leghorn x Bedouin offspring are well adapted to extreme dry heat conditions and are highly efficient in their egg production, as compared to their Bedouin parents