Manipulation of Incubation Temperatures to Increase Cold Resistance of Broilers:Influence on Embryo Development, Organ Weights, Hormones and Body Composition

Abstract

Eighteen hundred eggs obtained from Ross broiler breeders at 32 and 48 wk age were randomly assigned to two incubation treatments: T1 eggs were incubated at 37.6℃ throughout, while for T2 eggs the incubation temperature was reduced 1℃ for 6 h daily at embryonic ages (EA) 10 to 18. Embryo and organ weights and body composition were measured at EA 14, 19 and day of hatch (DOH). Hatchability and hatching duration, as well as serum triiodothyronine (T 3 ), thyroxin (T 4 ), and triglycerides were measured at DOH. T1 eggs contained less water than T2 eggs at EA 18. Hatchability was lower and the incubation period was 4.2 h longer for T2 than T1 chicks. On DOH for older breeders chick weights and serum T 3 levels were higher for T2 than T1; however, those from younger breeders were similar at both incubation temperatures. These results may show a beneficial effect of T2 treatment in older breeders. Incubation temperature did not affect triglycerides levels. On DOH, higher body lipids content of T2 than T1 chicks may contribute to their resistance to cold post hatch.

Yumurtadan Yeni Çıkmış Broiler Civcivlerde Döngüsel Yüksek İnkübasyon (Kuluçka) Sıcaklıklarının Vücut ve Organ Ağırlıkları, Tiroit Hormonları ve HSP70 Gen Ekspresyonu Üzerine Etkileri

“…Inconsistent with our finding, Yalcin and Siegel [24] reported that heart weight of chicks exposed to higher temperature during embryonic ages from days 10 to 18 of incubation was higher than control numerically. The findings of Leksrisompong et al [23] and Yalcin et al [25] concerning heart weight of chicks exposed to higher temperature are in agreement to our result. The lower heart weight in chicks exposed to higher incubation temperatures compared to control group may be explained by low rate of cell division in heart of embryos.…”

Effect of prenatal temperature conditioning of laying hen embryos: Hatching, live performance and response to heat and cold stress during laying period

“…Such an increase in T 3 concentration, but no change in T 4 concentration, demonstrated that LOW-Inc chicks produced T 4 at a sufficient rate for peripheral deiodination. This result was in agreement with other studies, who reported an increased T 3 level in cold exposed chickens (Kühn et al, 1984;Collin et al, 2003;Yalçın et al, 2012a). This increase in T 3 level may suggest the potential for acquiring tolerance to cold exposure later in life.…”

“…Our results also showed that there was no negative effect of higher or lower temperatures from day 10 to 18 of incubation on hatching performance and hatch weight of laying chicks. Similar to previous studies with broiler (Yalçın et al, 2008a(Yalçın et al, , 2012a and layer embryos (Molenaar et al, 2010;Walstra et al, 2010) incubation period was shortened with cyclic higher temperatures but lengthened with lower temperatures. The results also showed that although laying chicks had different incubation durations due to their incubation temperature, they hatched after reaching a similar chick weight.…”

“…In respect to improving thermoregulation, short periods 1 or 2°C changes in incubation temperature did not influence hatching efficiency of broilers in previous studies (Yahav et al, 2004a,b;Tona et al, 2008;Yalçın et al, 2008aYalçın et al, , 2012a. Similarly, Walstra et al (2010) reported that 4 h of exposure to 40°C from 14 to 18 d of incubation had no effect on hatchability and weight of laying chicks.…”

Monitoring the hatch time of individual chicken embryos

“…The T egg around 37.8°C is usually used as the temperature set point for proper embryo development or as reference to compare effects of distinct embryo temperature profiles (Lourens et al, 2005;Leksrisompong et al, 2009;Molenaar et al, 2011). Similarly, standard incubation temperature is approximately 37.5 to 37.8°C (Tzschentke, 2007(Tzschentke, , 2008Willemsen et al, 2011;Yalcin et al, 2012).…”