title: Influence of protein nutrition on the response of growing lambs to exogenous bovine growth hormone.
abstract: Interactions between protein supply and the anabolic response to exogenous bovine (b) GH have been examined in two experiments using 28-35 kg lambs sustained entirely by intragastric infusion of volatile fatty acids (700 kJ/kg W 0.75 per day) into the rumen and the casein (600 mg (low protein; LP) or 1200 mg (high protein; HP)/kg W 0.75 per day) into the abomasum. Sheep received continuous i.v. infusions of bGH for 6 days in experiment 1 and for 18 days in experiment 2. Nitrogen balances were determined daily throughout both experiments and blood samples, from indwelling catheters, were assayed for GH, insulin-like growth factor-I (IGF-I), insulin and glucose. Infusion of bGH increased plasma GH concentration by five- to sixfold in all animals. There was an increase in N retention in both HP and LP animals over the first 2-3 days of GH administration. HP animals sustained higher N retentions (31%; P less than 0.05) throughout the GH administration but LP animals did not. In contrast, plasma IGF-I concentrations increased progressively over the first 72 to 96 h of GH administration in all sheep and thereafter remained significantly (P less than 0.05) elevated until termination of the GH infusion. In lambs which received both HP and LP infusion in experiment 1 the increase in IGF-I and LP infusions in experiment 1 the increase in IGF-I concentration by day 6 of GH administration was significantly (P less than 0.05) greater when they received the higher protein intake.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Rowett Research Institute, Bucksburn, Aberdeen.
authors.forename: J C
authors.initials: JC
authors.lastname: MacRae
authors.forename: L A
authors.initials: LA
authors.lastname: Bruce
authors.forename: F D
authors.initials: FD
authors.lastname: Hovell
authors.forename: I C
authors.initials: IC
authors.lastname: Hart
authors.forename: J
authors.initials: J
authors.lastname: Inkster
authors.forename: A
authors.initials: A
authors.lastname: Walker
authors.forename: T
authors.initials: T
authors.lastname: Atkinson
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002364:Caseins / Q000008:administration & dosage; D002417:Cattle; D004044:Dietary Proteins / Q000378:metabolism*; D004334:Drug Administration Schedule; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D012756:Sheep / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D002364:Caseins; D004044:Dietary Proteins; D007328:Insulin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D009584:Nitrogen