Effect of treatment of dairy cows with slow-release bovine somatotropin during the periparturient period on minerals in plasma and milk and on parathyroid hormone-related protein in milk.
Slow-release bST was given to dairy cows as a single injection prior to calving to determine whether such treatment prevented parturient hypocalcemia or modified the concentrations of Ca and parathyroid hormone-related protein in milk during the periparturient period. Cows were treated about 1 wk prepartum, and serial blood and milk samples were taken from these and similar prepartum control cows over a 3-wk period. Plasma growth hormone concentrations in the bST-treated group reached a peak 2 d after administration and then declined linearly to control concentrations over a 14-d period. Plasma Ca was unaffected by bST treatment 1 d prior to parturition, on the day of parturition, and at 1 and 6 to 9 d postpartum. Plasma P was higher, and plasma Mg was lower, in the bST-treated group on the day of parturition and 1 d postpartum. Concentrations of Ca, P, Mg, and protein in milk were lower in bST-treated cows than in controls at parturition. Milk production of the bST-treated and control groups was similar when measured at d 6 to 9 postpartum. Concentrations of parathyroid hormone-related protein in milk were substantial at parturition and remained high thereafter, although at parturition the concentration in the milk of the bST-treated group was lower than that of the control group.
St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
F M
FM
Law
D D
DD
Leaver
T J
TJ
Martin
K
K
Selleck
I J
IJ
Clarke
P J
PJ
Moate
D000818:Animals; D002118:Calcium / Q000097:blood / Q000378:metabolism; D002417:Cattle / Q000378:metabolism*; D003692:Delayed-Action Preparations; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D007743:Labor, Obstetric; D008274:Magnesium / Q000097:blood / Q000378:metabolism; D008892:Milk / Q000378:metabolism*; D008903:Minerals / Q000097:blood / Q000378:metabolism*; D044162:Parathyroid Hormone-Related Protein; D010758:Phosphorus / Q000097:blood / Q000378:metabolism; D011247:Pregnancy; D011506:Proteins / Q000378:metabolism*
D003692:Delayed-Action Preparations; D008903:Minerals; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D010758:Phosphorus; D013006:Growth Hormone; D008274:Magnesium; D002118:Calcium