Rectal temperature as an indicator for heat tolerance in chickens

Abstract

High environmental temperature is perhaps the most important inhibiting factor to poultry production in hot regions. The objective of this study was to test adaptive responses of chickens to high ambient temperatures and identify suitable indicators for selection of heat-tolerant individuals. Full-sib or half-sib Anak-40 pullets (n = 55) with similar body weights were raised in a room with a temperature ranging from 24°C to 28°C, and relative humidity of 50% from 61 to 65 days of age. On day 66, the ambient temperature was increased within 60 min to 35 ± 1°C which was defined as the initial of heat stress (0 h). Rectal temperature (RT) was measured on each pullet at 0, 6, 18, 30, 42, 54 and 66 h. After 66 h the ambient temperature was increased within 30 min to 41 ± 1°C and survival time (HSST) as well as lethal rectal temperatures (LRT) were recorded for each individual. The gap between the RT and initial RT was calculated as ΔTn (ΔT6, ΔT18, ΔT30, ΔT42, ΔT54 and ΔT66), and the interval between LRT and initial RT as ΔTT, respectively. A negative correlation was found between HSST and ΔTn as well as ΔTT (rΔ T 18 = -0.28 and rΔ TT = -0.31, respectively, P < 0.05; rΔT30 = -0.36, rΔ T 42 = -0.38, rΔT54 = -0.56, P < 0.01). Importantly, pullets with low ΔT18 showed a longer HSST (256.0 ± 208.4 min) than those with high ΔT18 (HSST = 123.7 ± 78.3 min). This observation suggested that the ΔT18 or early increment of RT under heat stress might be considered as a reliable indicator for evaluation of heat resistance in chickens.

Identification of quantitative trait loci for body temperature, body weight, breast yield, and digestibility in an advanced intercross line of chickens under heat stress

“…A previous study reported a significant correlation between BT and survival in chickens during heat stress [ 31 ], which suggested that selection for BT during heat stress has potential to reduce mortality. In our study, heritabilities were low (0.03–0.11) for BT and higher (0.10–0.11) for absolute BT than that previously estimated for a broiler line i.e.…”

Daily rhythms of cloacal temperature in broiler chickens of different age groups administered with zinc gluconate and probiotic during the hot-dry season

“…Thus, changes in t cloacal during heat stress are used to evaluate the degree of adaptation of broiler chickens to hot‐dry conditions (Chen et al. ), and level of reactive oxygen species (ROS) in broilers (Azad et al. ), generated in excess during heat stress (Lin et al.…”

Cloacal temperature responses of broiler chickens administered with betaine and ascorbic acid during the hot-dry season

“…It indicates the balance between heat loss and heat gain in broiler chickens (Edgar et al 2013). Thus, changes in CT during heat stress may be of value in determining the resistance of broiler chickens to hot-dry conditions (Chen et al 2013). Isidahomen et al (2012) reported that the normal upper limit of body temperature in poultry does not exceed 42.2°C.…”