Influence of ambient temperature on true digestibility of protein and amino acids of rapeseed and soybean meals in broilers.

The effect of high ambient temperature (32 versus 21 C) between 4 and 6 wk of age on true digestibility of protein (TDP), amino acids (TDAA), and AME value of rapeseed and soybean meals was investigated in broilers. At 6 wk of age, 96 male and female birds were deprived of feed for 24 h and then force-fed with moistened diet (approximately 90 g). Excreta were collected during the two subsequent 24-h periods after force-feeding. The results of this experiment showed that the ambient temperature had no effect on AME values of the raw materials tested for both sexes of broilers. However, high ambient temperature significantly decreased (P < .001) AMEn values of the two rapeseed meals, which could be related to the nitrogen balance. Moreover, TDP and TDAA of two rapeseed and soybean meals tested in this experiment were decreased as the ambient temperature increased from 21 to 32 C. A 12% reduction in TDP value was observed with the rapeseed meals, whereas the diminution was only 5% with the soybean meal. Sex had no effect on TDP of the raw materials tested. However, for TDAA values, female birds appeared to be more sensitive to high ambient temperature than male chickens when fed rapeseed meals.