Breeding and genetics - Components of feed efficiency in broiler breeding stock: The use of fasted body temperature as an indicator trait for feed conversion in broiler chickens

Five trials were conducted to evaluate the usefulness of body temperature (BT) measured under conditions of mild handling stress as an indicator trait for feed conversion ratio (FCR) in broilers. The trials used males from 4 lines of broilers (a randombred control population and 3 heavy broiler lines). Birds were reared to approximately 6 wk of age and then selected for FCR testing based upon BW and conformation. At the start of the FCR test, birds were fasted for periods lasting from 18 to 48 h, and their BT were measured, which was followed immediately by initiation of an FCR test lasting I wk. The correlation between FCR and BT was significant in only 2 of the 5 trials. Differences between good and poor converters were generally attributed to greater gains of BW on similar amounts of feed intake. The results of the current trials indicate gain on test is the primary factor affecting FCR and that BT is not a reliable predictor of FCR.