Effect of chronic growth hormone treatment on responses to epinephrine and thyrotropin-releasing hormone in lactating cows

Bovine growth hormone was administered to four Holstein cows (late lactation) in a Latin square. Treatments were 1) control, subcutaneous injection of placebo, 2) subcutaneous injection of 25 IU growth hormone on alternate days, 3) daily subcutaneous injection of 25 IU growth hormone, and 4) continu...

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Bibliographic Details
Published in:Journal of dairy science 1986-01, Vol.69 (1), p.44-51
Main Authors: McCutcheon, S.N, Bauman, D.E
Format: Article
Language:English
Subjects:
ADRENALINE
Animals
BOVIN LAITIER
Cattle
COWS
DAIRY CATTLE
EPINEFRINA
EPINEPHRINE
Epinephrine - pharmacology
Female
GANADO DE LECHE
Growth Hormone - administration & dosage
Growth Hormone - pharmacology
HORMONAS
HORMONAS PITUITARIAS
HORMONE
HORMONE HYPOPHYSAIRE
HORMONES
Infusions, Parenteral
Injections, Subcutaneous
Kinetics
LACTACION
LACTATION
Lactation - drug effects
PITUITARY HORMONES
Pregnancy
Thyrotropin-Releasing Hormone - pharmacology
VACA
VACHE
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Summary:Bovine growth hormone was administered to four Holstein cows (late lactation) in a Latin square. Treatments were 1) control, subcutaneous injection of placebo, 2) subcutaneous injection of 25 IU growth hormone on alternate days, 3) daily subcutaneous injection of 25 IU growth hormone, and 4) continuous subcutaneous infusion of 25 IU/d growth hormone. Intravenous challenges of epinephrine and thyrotropin-releasing hormone were administered separately on the 1st d after a 12-d interval of growth hormone treatment. Baseline concentrations of nonesterified fatty acids in plasma were not affected by growth hormone treatment. However, release of nonesterified fatty acids to epinephrine challenge was positively related to amount of growth hormone in plasma during treatment and was correlated with milk fat yield and milk energy secretion. Growth hormone release following thyrotropin-releasing hormone was negatively related to amount of growth hormone in plasma during treatment. Release of prolactin to thyrotropin-releasing hormone challenge was not related to average daily dose of exogenous growth hormone. The galactopoeitic action of growth hormone may be partly attributable to its effects on responsiveness of adipose tissue to a lipolytic stimulus but apparently is not associated with changes of pituitary sensitivity to thyrotropin-releasing hormone. Results are consistent with growth hormone functioning as a homeorhetic control of nutrient partitioning.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(86)80368-X