The effects of naked neck genotypes, ambient temperature, and feeding status and their interactions on body temperature and performance of broilers

The effect of ambient temperature (AT) and feeding status on body temperature (BT) were investigated in broilers of the three naked neck genotypes (Na/ Na, Na, na, and na/na). From 29 to 49 d of age, chicks were reared in a temperature-controlled chamber, where AT alternated daily between 24 and 32 C. At Day 47, all birds were deprived of feed for 12 h at 32 C, followed by 12 h of ad libitum intake at 24 C, then 12 h of ad libitum intake at 32 C, and finally feed deprivation for 12 h at 24 C. Body temperature was measured at the end of each of these 12-h periods. Body weight, feed consumption, feather coverage, and breast yield were determined. The Na/na and Na/Na birds had 20 and 40% less feather mass than the na/na birds. The three genotypes had similar BW at Day 49, but the naked neck birds had a higher breast: yield. At high AT, BT was positively associated with feather mass of the three naked neck genotypes. The highest BT was exhibited by the fully feathered birds, and the lowest by the homozygous naked neck birds. The feeding status also affected BT of all birds, but to a larger extent in the normally feathered than in the naked neck birds. It appears that the lower negative effects of high AT on growth rate and meat yield in naked neck broilers can be attributed to their lower BT. Thus, it is suggested that measuring BT of broilers can be used as an indicator of the level of stress imposed on them by high AT.