Physiological and Behavioral Responses of Young Chicks to High Ambient Temperature

Abstract

Birds reduce their food intake by the exposure to high ambient temperature (HT) which ultimately affects their productivity. However, physiological and behavioral responses of young chicks of different ages to HT have not yet been investigated. In this study, we examined the effects of HT (40℃, 4-h) in 3-, 5-, 7-, 14-and 21-d old chicks. There were no significant differences in food intake between heat exposed and control chicks up to 7-d old, while clear suppressions of food intake were observed in 14-and 21-d old heat exposed chicks. Body weights were not affected in all age groups; however, rectal temperature was significantly increased in almost all ages. We examined blood metabolites of 7-, 14-and 21-d old chicks and found that plasma glucose concentration gradually increased in 14-to 21-d old heat exposed chicks. Conversely, triacylglycerol age-dependently decreased during exposure to HT. No significant changes were detected in plasma total protein, uric acid and calcium investigated in 7-, 14-and 21-d old heat exposed chicks compared to control groups. However, plasma glutamic-oxalacetic transaminase showed a significant interaction between HT and age, implying that liver and/or heart was damaged by HT with aging. These results indicate that HT (40℃; 4-h) suppresses food intake in young chicks of 14-or 21-d old age which reflects in some of their plasma metabolic concentrations.

Changes in free amino acid concentrations in the blood, brain and muscle of heat-exposed chicks

“…Food (Commercial starter diet (metabolisable energy: 12.77 MJ/kg and protein: 24%; food ingredients: grain 61% (mainly maize), defatted meal 25% (soybean meal and maize gluten meal), fish meal 9%, rice bran 1% and others 4%; AX; Toyohashi Feed and Mills Co. Ltd., Aichi, Japan)) and water were available ad libitum. On the basis of our previous experiment, 14-or 21-d-old chicks were more responsive to HT in terms of food intake than neonatal chicks (Chowdhury et al, 2012b). Thus, in the present study, we used 14-d-old chicks to examine the effect of HT (35°C) in comparison with that of a control thermoneutral temperature (CT; 30°C).…”

“…Behavioural, physiological and molecular adjustments occur when chickens are exposed to heat stress (Etches et al, 1995). In our previous report, it was shown that young chicks, when exposed to HT, reduced their food intake and that the expression of a food intake-regulating hypothalamic neuropeptide mRNA increased (Chowdhury et al, 2012b). Balnave and Oliva (1991) showed that the absorption of arginine, an essential amino acid in chickens, decreased significantly during HT.…”

“…In general, high ambient temperature (HT) may induce stress to birds and interfere with the maintenance of homeothermic body temperature as they lack sweat glands and have relatively high body temperatures (around 41.5°C), relying on evaporative cooling (panting) to keep them cool (Marder and Arad, 1989). The exposure of birds to HT can lead to an increase in deep body temperature (rectal temperature) (Yahav and Hurwitz, 1996;Chowdhury et al, 2012aChowdhury et al, , 2012b. When the heat increment of the birds exceeds the heat dissipation, HT can cause stress (Soleimani et al, 2010).…”

Performance of chicks subjected to thermal challenge

“…This is attributed to the fact that newborn chicks are poikilothermic, due to their not yet developed thermoregulatory mechanisms (Mujahid, 2010). As a result, chicks are particularly sensitive to thermal environments outside their comfort range (Moura et al, 2008;Mujahid & Furuse, 2009;Chowdhury et al, 2012). Broilers achieve the best performance when reared in thermoneutral conditions.…”

Predicting chick body mass by artificial intelligence-based models

“…Data on the thermal comfort for chicks have been commonly cited in the literature, showing that both heat and cold stress can cause reduced growth rate, body mass loss, and other damage to the health, and expression of anomalous behaviour of chicks during the first three weeks of life (Mujahid & Furuse;2009;Chowdhury et al, 2012). Damages occur because broiler growth rate is sensitive to extreme environmental temperatures (Zhang et al, 2011).…”