Purpose for an Early Acclimatization of Broiler Chickens under Production Conditions in Venezuela

Abstract

Intensive production of broiler chickens is efficient in Venezuela. However, in the finishing period, high heat-related mortality causes serious economic losses. The early-acclimatization technique, successfully tested in station, consists in exposing five-day-old chicks to a high temperature (35-38°C) for 24 h. Two experiments were carried out to confirm these results at the production level. In experiment 1, 35,200 Ross chicks were tested in two chicken houses. In chicken house A, they were acclimatized at 35 ± 2°C, and in chicken house NA, they were maintained at 31 ± 2°C. The 24-hour period excepted, farming conditions were kept the same. In experiment 2, out of 12,650 Ross chicks from a single house, 970 (A chicks) were marked on the right leg and acclimatized at 38 ± 1°C using two circles, and 970 (NA chicks or control) were marked on the left leg and kept inside two circles at 31 ± 1°C. At six days of age the circles were removed to let marked chicks mix with the others. In both experiments early acclimatization induced similar results to those obtained in station: a body temperature drop of about 0.20°C and a decrease in mortality in the finishing period. In experiment 2, the final live weight of A chickens increased by 94 g compared to that of NAs. The protocol of experiment 2 was found more adapted than that of experiment 1 in this type of field trial.