Evaluation of growth, hormonal, and hematological responses of neonatal chickens to reduced temperature brooding.
A series of experiments was conducted to examine the response of neonatal, male broiler chicks to brooding at a reduced temperature. In Trials 1 and 2, chicks brooded at 26.7 C generally had lower body weights and higher serum corticosterone levels during the first week after hatch than those brooded at 32.2 C. However, significant differences in body weight were observed only on Day 6 in Trial 1 and on Days 1 and 5 in Trial 2. Serum corticosterone levels, likewise, were not significantly different on all days in Trials 1 and 2. These hormone levels were statistically different on Days 1 and 5 in Trial 1 and on Days 1 and 3 in Trial 2. Brooding neonates at 26.7 C for 3 days in Trials 3 and 4 resulted in consistently lower body weights and gain and higher serum corticosterone, thyroxine, total protein, albumin, and globulin. Serum growth hormone levels in chicks brooded at 26.7 C were initially depressed the first day but were elevated on the 2 subsequent days, compared with chicks brooded at 32.2 C. Considering the physiological importance of corticosterone and thyroxine in the adaptation of chickens to cold environmental temperatures, it would be useful to evaluate the genetic variation associated with the responsiveness of these hormones in a randombred population and to improve tolerance of neonatal chickens to reduced temperature brooding through selection.
D000818:Animals; D000831:Animals, Newborn; D001798:Blood Proteins / Q000378:metabolism*; D001835:Body Weight; D002645:Chickens / Q000097:blood / Q000254:growth & development / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D006728:Hormones / Q000097:blood*; D008297:Male; D012709:Serum Albumin / Q000378:metabolism; D012712:Serum Globulins / Q000378:metabolism; D013696:Temperature; D013974:Thyroxine / Q000097:blood
D001798:Blood Proteins; D006728:Hormones; D012709:Serum Albumin; D012712:Serum Globulins; D013006:Growth Hormone; D013974:Thyroxine; D003345:Corticosterone