Cardiovascular and metabolic responses during growth hormone treatment of lactating sheep.
Pituitary-derived bovine growth hormone (bGH) was administered to six lactating Friesland ewes for 7 d. There was no consistent galactopoietic response, with changes in milk yield varying from 0 to 33% during treatment compared with the pretreatment period. The major effect of bGH on the concentration of milk constituents was to increase fat by 14.2% (P less than 0.05). Treatment resulted in significant increases in arterial plasma concentrations of growth hormone, insulin-like growth factor I and glucose, with decreases in the plasma arterial concentrations of acetate and certain amino acids. There was a marked reduction in haematocrit and in haemoglobin concentration which took at least 3 d to recover. The arterio-venous difference across the mammary gland decreased for O2 during treatment and the veno-arterial difference for CO2 decreased after treatment. Mammary respiratory quotient therefore decreased significantly after bGH treatment. The results suggest that bGH exerts effects at a number of separate loci.
Fleet
I R
IR
AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Fullerton
F M
FM
Heap
R B
RB
Mepham
T B
TB
Gluckman
P D
PD
Hart
I C
IC
D000085:Acetates / Q000097:blood; D000596:Amino Acids / Q000097:blood; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects*; D007279:Injections, Subcutaneous; D007774:Lactation / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D012756:Sheep / Q000502:physiology*
D000085:Acetates; D000596:Amino Acids; D001786:Blood Glucose; D013006:Growth Hormone