A chrono-physiological management protocol in form of simultaneous shifting of both lighting-cycle and feeding-time can enhance the production performance of heat-stressed goat kids

Abstract

In a journey exploring the influence of two external zeitgebers and their interaction on the biophysiological and productive performance of goat kids exposed to heat stress, 15 healthy Aardi male kids (6 months of age and 22.56±1.13 kg) individually housed in climatic chambers were allocated into three groups (5 kids/group). Kids in the first group (the control group, C) were placed under a normal light:dark (12L:12D) cycle and fed in the morning. Kids in the second group (T1) were fed in the morning but placed under a reversed 12D:12L cycle. Kids in the third group (T2) were placed under a reversed 12D:12L cycle and fed in the evening. During the experimental period (~5 weeks), kids were exposed to a hot condition (as manifest by the temperature-humidity index) using a biometeorologically simulated environment with a daily ambient temperature cycle of 25°C to 45°C, and multiple data (i.e., meteorology, biophysiology, and performance) were obtained. Reversing the lighting cycle alone (T1) and/or the simultaneous shifting of both the lighting cycle and feeding time protocol (T2) under hot climatic conditions had no influence on body rectal and skin temperatures as well as plasma concentrations of albumin and glucose. Kids in both treatments showed (p < 0.05) higher coat temperature and respiratory rate as well as plasma concentrations of triacylglycerol compared to the C group kids. Moreover, it was clearly evident that kids in T2 had (p < 0.05) reduced kids DFI, increased (p < 0.05) their ADG, which subsequently had been reflected on having (p < 0.05) better FCR compared to kids in other groups. Collectively, this would suggest that using such chrono-physiological management protocol had desynchronized the heat load emerging from the combined effects of both thermal stress and post-prandial metabolism. Compared to other protocols, our findings point out that simultaneous shifting of both lighting cycle and feeding time protocol might be suitable in enhancing the production performance of growing heat-stressed goats.