The Upper Critical Ambient Temperature in Neonatal Chicks

Abstract

Heat production, dry matter, and water loss in the body and yolk sac of neonatal broiler chicks were measured during 24 h exposure to constant temperatures from 30.8 to 38.8 C. Average initial body and yolk sac weights were 41.6 and 4.4 g, respectively. Chicks housed at 30.8 C lost 3.5 g/day and chicks housed at 38.8 C lost 5.7 g/day of total body weight. Between 30.8 and 35.1 C, weight loss of the yolk sac was 1.9 g/day. At 38.8 C, weight loss of the yolk sac was 1.4 g/day. Weight lost from the yolk sac consisted of equal amount of dry matter and water. Water loss from the remainder of the chick's body (the total body without yolk sac) increased from 1.8 to 4.4 g as environmental temperature was raised from 30.8 to 38.8 C. This increase occurred mainly above about 35 C. Chick heat production increased with ambient temperature. Heat production as determined per subsequent 3-h period decreased with increasing duration of exposure from 34.6 to 28.2 kJ/kg per hour (1 kJ = .239 kcal) at 30.8 C and from 44.1 to 35.5 kJ/kg per hour at 38.8 C. The upper critical temperature was derived from regression of heat production on temperature. Results showed that this critical temperature was between 36 and 37 C.

Effect of Environmental Temperature During the First Week of Brooding Period on Broiler Chick Body Weight, Viscera and Bone Development

“…The water and feed consumption data for the three environmental temperatures were analyzed by comparing the regression lines identical according to Graybill (1961). Van der Hel et al (1991) (Van der Hel et al, 1992). In this trial, we also observed that chicks reared at low ambient temperature ate less feed and their body weight was significantly lower when compared to birds kept at 25°C.…”

Thermal comfort zones for starter meat-type quails

“…These results are consistent with those obtained by Van der Hel et al (1991), who observed that the exposure of day-old Table 3 -Body weight gain at day 7, feed intake (FI), weight gain (WG), feed efficiency (FI), and livability (LIV) of one-to seven-d-old quails and black-globe temperature and humidity index (BGTHI) as a function of thermal environments. The quails maintained in the SC (30 ºC) and MC (33 ºC) environments had higher feed intake compared to those housed in TC (36 ºC).…”

Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to the welfare of animals during transport

“…Temperatures of 20-35ºC accompanied by relative humidities (RH) of 50-65% and durations of exposure from 3-12 hours were employed. Metabolic heat productions ranged from 7.8±0.3 to 8.7±0.9 Wkg -1 in close agreement with previously published values (van der Hel et al 1991;Tanaka and Xin 1997a). On the basis of minimal change in body temperature and minimal alterations in basal metabolic rate, hydration state, electrolyte balance, body weight loss and plasma metabolite concentrations an optimal temperaturehumidity range of 24.5-25.0ºC and 63-70% RH for the transport of chicks at commercial stocking density was identified.…”

“…Some previous studies have attempted to define thermoneutral or optimal environments for neonatal chicks on the basis of metabolic heat production and body temperature responses (Misson 1976;Henken et al 1989;Gates et al 1989;van der Hel et al 1991). Generally these studies did not measure other indicators of homeostatic effort which might better define the physiological impact of the thermal micro-environment.…”

“…Whilst commercial breeders and producers have long recognized the necessity to maintain an appropriate thermal environment for chicks in transit (Tamlyn and Starr 1987;Laughlin 1989;Van der Hel and Henken 1990;Qureshi 1991;van der Hel et al 1991) the conditions employed have been largely defined by empirical means and have been based upon minimization of mortality rates during and following transport and efficient productivity during the subsequent rapid growth phase. In current practice the recommended temperature for chick transport is 24-26ºC (Ross Breeders 1996;Meijerhof 1997;Weeks and Nicol 2000), although only the Ross Breeders paper (1996) includes a recommendation for controlled humidity (75% at 24ºC).…”