Thermoregulatory Responses of Chicks (Gallus domesticus) to Low Ambient Temperatures at an Early Age

Abstract

The potential to induce improved thermotolerance in broiler chickens is of great importance. Thermal conditioning is one of the management tools used to improve thermotolerance, enabling broilers to cope with extreme environmental conditions. This study investigated the effects of exposing chicks to low ambient temperature (T(a)) on-chick body (T(b)), surface (T(s)) temperatures and total sensible heat loss (SHL) by convection and radiation from the body and from 2 main radiative organs, the face and the legs. At 3, 4, or at both 3 and 4 d of age, chicks were exposed to 5 degrees C for 1.5 h a day (to avoid mortality) or to 10 or 15 degrees C for 3 h a day. In general, in all treatments, the results during exposure to cold differed significantly from the control. A second cold exposure (on d 4 after a first exposure on d 3) clearly enhanced the chicks' ability to maintain on-chick body surface temperatures during exposure to 15 degrees C and to recover much faster from cold exposure. A dramatic decline in average surface temperature was observed during the first 15 min of chicks' exposure to the various low ambient temperatures in all ages, reaching the lowest values in the 5 degrees C treated chicks. The face responded immediately to cold exposure by significantly increasing its SHL to a level that then remained relatively steady (15 degrees C) or declined moderately with time (10 and 5 degrees C). In the legs, however, a significant and continuous decline in SHL was exhibited in all ages. The dynamics of SHL from the legs differed from that from the face, suggesting that the legs are a major organ for vasomotor responses, whereas the face is a more conservative vasoregulatory organ. It is concluded that repetitive exposure to cold may enhance thermotolerance, and that this is partially related to the vasomotor responses. This is the first report quantifying the differentiation between the legs as a responsive vasomotor organ and the face as a conservative vasomotor one.

Factors Associated with Cumulative First-Week Mortality in Broiler Chicks

“…As a result, eggs from old breeders hatch earlier [20], and therefore, the risk of chick dehydration increases with breeder age. Dehydration of chicks at an early age may result in increased FWM [22,23]. Another possible hypothesis is that chicks from old breeders have low chick quality and viability and a worse healing navel, increasing the probability of suffering diverse pathologies and infections of the yolk sac, which might increase FWM [1,22].…”

Dampak Pemberian Tepung Bawah Putih Terhadap Profil Lipid Liver Dan Plasma Darah Puyuh Yang Mengalami Cekaman Panas

“…Sisi lain, cekaman panas juga meningkatkan resiko mutasi DNA dan denaturasi protein tubuh (enzim, reseptor, transporter sel, hormon). Mutasi DNA dan denaturasi protein dipicu oleh meningkatnya produksi radikal bebas (Shinder et al, 2007;Tao et al, 2013;Slimen et al, 2016;Mushawwir dkk., 2019) melalui proses oksidasi reduksi mitokondria (stress sellular), dan atau cekaman langsung dalam bentuk radiasi panas lingkungan ke tubuh ternak puyuh. Kondisi tersebut berdampak luas terhadap metabolisme, khususnya produksi energi di bagian matriks dalam mitokondria.…”

Uma perspectiva comportamental da termorregulação de emas (Rhea americana)

“…A presença de penas na superfície corporal é uma das principais características das aves, sendo de fundamental importância quando as aves estão expostas à baixa temperatura ambiental. Assim, essas áreas cobertas com penas, onde a atividade vasomotora é mínima, podem ser vistas como vasorregulatórias conservadoras, auxiliando na conservação do calor corporal (Richards 1971;Shinder et al 2007). As penas nas aves têm um papel fundamental no equilíbrio térmico entre o organismo e o ambiente, acarretando peculiaridades na regulação do equilíbrio térmico.…”