Pulsatile infusion of growth hormone-releasing factor depresses growth of young broiler chickens.
This study was conducted to determine the effects of programmed intravenous infusion of growth hormone-releasing factor (GRF) on the growth and metabolism of young broiler chickens (4-7 weeks of age). Twelve 4-week-old chickens, fitted with jugular catheters, were randomly assigned to three treatment groups (four birds/group): pulsed infusion of saline [SAL-P] at 3 hr intervals, pulsed infusion of GRF1-44 (5 micrograms/kg at 3 hr intervals)[GRF-P], or continuous infusion of GRF (40 micrograms/kg-day)[GRF-C]. The GRF-P treatment depressed (P < 0.05) average daily gain by 32%, average daily feed consumption by 24%, and final body weight by 17% when compared with the SAL-P group. Pulsatile infusion of GRF (GRF-P) reduced (P < 0.05) abdominal fat weight by 39% and body fat content by 28% when compared to the SAL-P group. Plasma GH levels were elevated (P < 0.05) 2.1-fold in the GRF-P group at 15 min-post-infusion, while GH levels in the GRF-C group were maintained about 70% higher than those in the SAL-P group. Plasma levels of insulin-like growth factor-I (IGF-I) were consistently lower in the GRF-P group at all ages. There were no significant differences in plasma levels of triiodothyronine (T3), thyroxine (T4), insulin, or glucose among treatment groups. This study shows that pulsatile infusion of GRF, designed to enhance plasma GH levels, does not improve growth rate, feed efficiency, or body composition of young broiler chickens.
Moellers
R F
RF
Department of Animal Science and Agricultural Biochemistry, College of Agricultural Sciences, University of Delaware, Newark 19717-1303.
Cogburn
L A
LA
D000273:Adipose Tissue / Q000033:anatomy & histology / Q000187:drug effects; D000818:Animals; D001823:Body Composition; D002645:Chickens / Q000097:blood / Q000254:growth & development*; D004435:Eating / Q000187:drug effects; D006128:Growth / Q000187:drug effects*; D013006:Growth Hormone / Q000097:blood; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage*; D007262:Infusions, Intravenous; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D011897:Random Allocation; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015430:Weight Gain / Q000187:drug effects
D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D013974:Thyroxine