Acute and chronic hormone and metabolite changes in lambs fed the beta-agonist, cimaterol.
The objective of this study was to determine if acute and chronic changes in circulating metabolic hormone and metabolite concentrations are associated with beta-agonist-induced nutrient repartitioning in young growing lambs. Two groups of 12 Dorset and Dorset-Finn cross ram lambs weighing 36 or 33 kg live weight were assigned to 3- or 6-week treatment intervals, respectively, to achieve similar slaughter weights. Six lambs within each treatment interval were fed ad libitum a complete mixed high-concentrate diet containing either 0 or 10 ppm cimaterol. During the first 12 hr of cimaterol administration plasma somatotropin (ST), thyroxine (T4), and triiodothyronine (T3) concentrations were not altered by treatment, but plasma insulin, glucose, non-esterified fatty acids (NEFA) and glycerol concentrations were elevated 2 hr after ingestion. These acute responses suggest direct stimulation of glycogenolysis and lipolysis by cimaterol, which is characteristic of beta-adrenergic alteration of carbohydrate and lipid metabolism. Chronic administration of cimaterol significantly decreased insulin concentrations by 36% and 52% at 3 and 6 weeks, respectively, while glucose concentrations remained unchanged. Serum IGF-I concentrations were not significantly altered by cimaterol. T4 levels were reduced 22.1% after 3 weeks of cimaterol treatment. Although plasma NEFA concentrations were chronically elevated 56% to 65% in lambs fed cimaterol, plasma glycerol concentrations remained at baseline levels. The relative changes in plasma NEFA and glycerol concentrations are consistent with a decreased rate of lipogenesis, rather than an increase in lipolysis.
Department of Animal Science, Cornell University, Ithaca, NY.
R M
RM
O'Connor
W R
WR
Butler
K D
KD
Finnerty
D E
DE
Hogue
D H
DH
Beermann
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D050260:Carbohydrate Metabolism; D004983:Ethanolamines / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005990:Glycerol / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D006728:Hormones / Q000097:blood*; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D016014:Linear Models; D050356:Lipid Metabolism; D008297:Male; D012756:Sheep / Q000378:metabolism*; D013963:Thyroid Hormones / Q000097:blood
D000318:Adrenergic beta-Agonists; D001786:Blood Glucose; D004983:Ethanolamines; D005230:Fatty Acids, Nonesterified; D006728:Hormones; D007328:Insulin; D013963:Thyroid Hormones; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D005990:Glycerol; C047411:cimaterol