Effect of acute heat stress on the physiological parameters of broiler breeder roosters-A study under controlled thermal stress

Heat stress has got deleterious effects on the production potential and reproductive efficiency of breeder birds. Main objective of this experiment was to understand the effect of acute heat stress on the physiological and reproductive performance of broiler breeder roosters. High temperature group (HT) was exposed to 37ºC and RH 70-75% (>THI=90) for 6 hours (10.00 AM to 4.00 PM) in a psychrometric chamber and the control group (C) was maintained at (THI<80; temperature 30ºC, RH 50-55%) for 10 days. Various parameters including body weight, feed intake, water intake, body temperature, serum quality parameters, hematological values and semen quality parameters were analyzed following standard procedures. A reduction in feed intake of HT birds (P<0.05) was noted resulting in loss of body weight (-5.50g) against control (+330.40g). In HT group, water intake and water to feed intake ratio had shown an increase (P<0.05) from day 1-10 in comparison to control group. Serum cholesterol (+8.4% increase) and AST levels (+9.7%) were also increased in HT group (P<0.05) by 10^th day. Along with rise in rectal temperature, an elevation of surface body temperature (P<0.05) on comb, neck and foot was also noted. Significantly high Hb, PCV and H:L ratio were observed in HT in comparison to control after heat exposure. On semen quality analysis, reduction in volume, motility, mass activity, percentage live spermatozoa in HT group were observed (P<0.05). In conclusion, acute heat stress may lead to serious physiological as well as reproductive damage in broiler roosters.