Effect of repetitive acute cold exposures during the last phase of broiler embryogenesis on cold resistance through the life span

Abstract

The time just before hatch is critical, because the embryo shifts toward internal and external pipping. This study aimed to determine the beneficial effect of repeated acute reductions of the incubation temperature during the last phase of broiler embryogenesis on posthatch cold tolerance and on the development of ascites syndrome. Fertile eggs were incubated at 37.8 degrees C and 56% RH. At 18 and 19 d of incubation, 3 treatments were conducted, comprising 2 or 3 exposures to 15 degrees C for 30 or 60 min each. During these cold exposures, egg temperature was measured by infrared thermography to determine sensible heat loss from the eggs. At hatch, BW and body temperature were measured. At 3 and 14 d of age, chicks were challenged by cold exposure to 10 degrees C for 3 h. From 14 d of age onward, three-quarters of the chicks were raised under ascites-inducing conditions (AIC) and the others were raised under regular conditions. The sensible heat loss from the eggs was 512 +/- 66 cal and 718 +/- 126 cal for 30 and 60 min of cold exposure, respectively. No effect of treatment on hatchability was observed, but body temperature and BW were greater to significantly greater in the treated chicks. Cold challenges at 3 and 14 d of age revealed a relative thermoregulatory advantage of embryos exposed to cold for 60 min. Under AIC, fewer treated chickens than controls developed ascites. At 38 d of age, BW and relative breast muscle weight were numerically to significantly greater in the treated chicks than in the control chicks when both were raised under regular conditions, whereas no differences were observed among the chicks raised under AIC. Repeated brief acute cold exposures during the last phase of embryogenesis appeared to improve the ability of growing broilers to withstand low ambient temperatures during their life span. Moreover, chickens treated during embryogenesis improved their performance under regular growth conditions.

Endocrinology of thermoregulation in birds in a changing climate

“…For example, chickens that are exposed to a short cold challenge exactly during the HPT and HPA axis development in the egg are better heat-producers after hatching and later in life while in contrast, chickens exposed to similar short-duration d heat challenges prenatally cope better in higher ambient temperatures later in life (Kamanli et al, 2015;Loyau et al, 2015;Morita et al, 2016;Piestun et al, 2009;Piestun et al, 2008a;Piestun et al, 2008b;Piestun et al, 2015;Shinder et al, 2009;Yahav et al, 2004). For non-domesticated species, Nord & Nilsson (2011) and DuRant et al (2011), found that blue tits and wood ducks (Aix sponsa) that were incubated in cold temperature throughout the incubation period had higher metabolic rate close to independence, which was interpreted in the same wayi.e.…”

Thermal stimulation of Ross®-lineage embryos on a commercial scale

“…Organs involved in thermoregulation (hypothalamus, thyroid, and pituitary gland) develop during growth phase, but their final maturation occurs in the last days of incubation and shortly after hatching (FLORES et al, 2013 Different temperatures during incubation may have different effects on broiler weight after hatching, and may affect the final slaughter weight (TONA et al, 2004;WILLEMSEN et al, 2008); these variations may also increase tolerance to environmental temperature challenges (MORAES et al, 2003;COLLIN et al, 2007), alter post-natal growth (COLLIN et al, 2005;HALEVY et al, 2006), and resulted in improved performance on site at 38 days of age (SHINDER et al, 2009). These long-term adaptations occur after application of periodic thermal manipulation during the last phase of maturation, when embryos are most responsive to "training" (TZSCHENTKE & HALLE, 2009).…”

Technology and Poultry Welfare

“…On the other hand, infrared image technology appears to be suitable to provide modelling tools to calculate optimal air velocity rate for good thermoregulation and growth rate [76], as well as for establishing incubation programs that may improve the ability of broilers to cope with heat stress and reduce the incidence of other health issues later in life [79]. …”

“…Studies conducted by Shinder et al [79] using IRTI during the final phase of incubation showed that body weight and body temperature were significantly higher in chicks that were exposed to short periods of cold stress during incubation (days 18 and 19) and had 13% to 18% lower incidence of ascites in comparison to control birds. On the other hand, Naas et al [80] used IRTI technology to estimate heat exchange between broilers and their environment at pre-slaughter.…”