The effect of short-term fasting on performance traits and rectal temperature of broilers during the summer season.

1. The present study was conducted to determine if detrimental effects of high temperature on broiler performance could be overcome by short-term fasting and to examine the effect of food withdrawal on the responses of two commercial strains (S1 and S2). 2. An experimental design was used with three feeding groups and two strains. Birds in the control (C) group were fed ad libitum during the experimental period (0 to 6 weeks), while feed was withdrawn in the other groups between 10:00 and 16:00 h during weeks 5 and 6 (F1) or week 6 (F2), respectively. After standard brooding for the first 3 weeks temperature and humidity varied according to outside climate between 4 and 6 weeks of age. 3. Feeding strategy significantly affected body weight at week 6 (BW6) and daily weight gain during week 6 (DWG5-6). F2 gave the best results in BW6 and DWG5-6. Strain effect was significant on DWG4-5 and DWG5-6; S1 had higher DWG4-5 and S2 gained more at the last stage. S1C broilers had greater BW6 than S2C but the S2 strain gave a better response to short-term fasting compared with S1 and this resulted in significant strain by feeding interaction effect on BW6 and DWG5-6. 4. It was shown that short-term fasting was an effective method for controlling rectal temperature (RT) of broilers at 5 and 6 weeks of age. 5. Total food consumption (FCO-6), food conversion ratio (FCRO-6), mortality, and carcase characteristics were not affected by short-term fasting in the experimental conditions. 6. In conclusion, it can be recommended that broiler producers may practise 6 h of fasting during the hot period of the day without any adverse effect on slaughter weight and FCR when the birds are close to the average slaughter weight and a heat wave is expected. Strain differences in RT measurements also indicate the importance of choosing strains to be used in hot and warm climate conditions with attention to the thermoregulation ability of broilers.