title: Plasma levels of growth hormone and insulin-like growth factor-I and -II from 2 to 6 weeks of age in meat-type chickens selected for 6-week body weight or for feed conversion and reared under high or normal environmental temperature conditions.
abstract: The aim of this study was to compare the effect of high (33 degrees C) and normal (33-20 degrees C) rearing temperature on growth and plasma levels of the somatotrophic hormones of 2 genetic lines of broiler chickens selected for 6-wk body weight (GL-line) or for feed conversion between 3 and 6 wk of age (FC-line) or for feed conversion between 3 and 6 wk of age (FC-line). Blood samples were collected weekly and analysed for growth hormone (GH) and insulin-like growth factors (IGF)-I and -II levels by RIA. The growth-depressing effect of the HT-treatment was more pronounced in the heavier GL-line and in males. A similar age-related pattern for all hormones studied was observed with the highest levels between 2 and 4 wk of age. FC-line chickens and males had consistently higher plasma GH levels than GL-line chickens and females respectively. No consistent effect of rearing temperature on plasma GH levels were observed. At 2 wk of age, HT-treatment resulted in higher plasma IGF-I levels while this was reversed from 3 wk of age onwards. GL-line chickens had significantly higher plasma IGF-I levels at 2, 3 and 4 wk of age. No consistent effect of sex on plasma IGF-I levels could be observed. For the whole period studied, GL-line chickens had significantly higher plasma IGF-II levels than FC-line chickens. No consistent effect of sex or temperature treatment on plasma IGF-II levels was observed.
authors.affiliation: Spelderholt Centre for Poultry Research and Information Services (COVP-DLO), Beekbergen, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Decuypere
authors.forename: F R
authors.initials: FR
authors.lastname: Leenstra
authors.forename: J
authors.initials: J
authors.lastname: Buyse
authors.forename: L M
authors.initials: LM
authors.lastname: Huybrechts
authors.forename: F C
authors.initials: FC
authors.lastname: Buonomo
authors.forename: L R
authors.initials: LR
authors.lastname: Berghman
mesh_terms: D000375:Aging / Q000097:blood; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000097:blood* / Q000254:growth & development; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D006358:Hot Temperature; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008297:Male; D012727:Sex Characteristics; D015430:Weight Gain
chemical_list: D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone