<b>Thermal conditioning during the first week on performance, heart morphology and carcass yield of broilers submitted to heat stress</b> - doi: 10.4025/actascianimsci.v35i3.18707

Abstract

<p class="aTitulodoArtigo">This study aimed to assess the influence of thermal conditioning during the first week, and to verify the effect of this, upon the heat challenge by the end of the productive period on performance, heart morphology and carcass yield. A total of 980 Ross male broiler chicks randomly assigned according to a completely randomized design with 4 treatment and 8 replications totaling 32 experimental units. The treatments consisted of different temperature ranges in the first week of life: thermal comfort temperature, temperature below the comfort zone, temperature above the comfort zone and thermal oscillation. At 35 days of age four replicates of each treatment were submitted or not to heat stress in last week's rearing (27 and 32°C). Animals submitted to thermal conditioning in the first week of life showed no adaptation to heat capable of increasing production and carcass characteristics when submitted to chronic heat stress during the final rearing period. Metabolic disorders such as ascites syndrome and sudden death syndrome can occur in both broilers reared above the temperature of thermal comfort in the first week, as those submitted to heat stress from 35 days of age, considering the heart morphometric analysis performed on these birds.</p> <p class="apalavrachave"> </p><br /

Períodos de estresse térmico durante o crescimento afetam negativamente o desempenho e o rendimento de carcaça de frango de corte

“…According to Fernandes et al (2013), broilers need to keep the internal body temperature at relatively constant levels in environments where temperature conditions are variable, through physiological mechanisms represented by compensation. These adjustments are done at the expense of production from these animals that instead of employing the nutrients for the synthesis use them to generate or dissipate heat.…”

Effects of supplementation of betaine hydrochloride on physiological performances of broilers exposed to thermal stress

“…In the PC and NC groups, the respiration rate dipped after day 28 and at day 35, the difference between the dietary groups was insignificant. In the Bet 1.3 group, respiration showed an increasing trend during days 21-35, and in the Bet 2.0 group the respiration rate was on a downward trend during days [28][29][30][31][32][33][34][35]. Panting occurred in all groups during the day, when both ambient temperature and RH were on the higher side.…”

“…Betaine supplementation reportedly helps in reducing body temperature to some extent. 27,28 A lower rectal temperature in the NC group up to day 28 may be explained by a retarded metabolic rate in that group caused by suboptimal levels of dietary methionine and energy. This also helps in explaining the retarded growth rate in this group.…”

Ameliorative effects of betaine and ascorbic acid administration to broiler chickens during the hot-dry season in Zaria: A review

“…Metabolic disorders such as ascites and sudden death syndromes may occur in broilers reared above the temperature of thermal comfort in the first week of life of the birds (Fernandes et al, 2013). Broiler chickens subjected to heat stress show elevated corticosterone levels and lower levels of thyroid hormones (Mahmoud et al, 2014).…”

“…Broiler chickens exhibit different behavior in response to daily variations in the thermal environment. Wingspreading and beak-opening are some important adaptations to thermal environments (Fernandes et al, 2013). Since adaptation of animal (including birds) to their thermal environment requires regulation of body temperature, measurement of that adaptation through the energy the animal expends, provides an indicator of the extent and energy cost of adaptation (Nienaber et al, 2009).…”