Effect of ambient temperature on the body temperature and growth of Aigamo ducklings

The present study was undertaken to investigate the body temperature, growth, mortality and feed utilization of Aigamo ducklings as related to ambient temperature. The effects on plasma concentrations of triiodothyronine ( T sub3 ) , thyroxine ( T sub4 ) and corticostrone ( CTC ) were also examined. Fifty Aigamo ducklings were allocated to 5 different ambient temperature treatments ( 15, 20, 25, 30 and 37 deg C ) from hatching to 28 d of age. The mortality rate showed the lowest value ( 8 % ) at 30 deg C, while it increased in lower and higher ambient temperatures. The body temperature of the ducklings at 2 d of age revealed about 41 deg C in the 20-37 deg C treatments, whereas it significantly decreased in the 15 deg C treatment. The body temperature of the ducklings at 8 d of age reached to 42 deg C in all the treatments expect for the 30 deg C one, which was similar to the body temperature of adults. The body weight during the first 6 d of age in the 30 deg C treatment was significantly heavier than those in other treatments ( P<0.05 ) . Furthermore, the body weight at 28 d of age was more in the order of37, 30, 25, 15 and 20 deg C. The feed intake of the ducklings tended to decrease, but the feed conversion ratio ( feed/gain ratio ) was more likely to increase as the ambient temperature increased . Plasma concentrations of T sub3 and T sub4 tended to decrease as the ambient temperature increased, however there were no differences in plasma concentration of CTC among treatments ( P>0.05 ) . The weights of thyroid glands per body weight were not different between 15 and 20 deg C), but they tended to be larger than those at 25, 30 and 37 deg C. Adrenal glands were likely to be smaller at 30 deg C, and then liver showed the smallest value ( P<0.05 ) . It was concluded that the body temperature of the ducklings at 8 d of age reached to 42 deg C in the all treatments expect for the 30 deg C one, which was similar to the body temperature of adults. In addition, it seems to be beneficial for growth of Aigamo ducklings that the animals were kept at about 30 deg C from hatching to 6 d of ag e, and at about 20 deg C thereafter.