A luteinizing hormone-releasing hormone-induced serum luteinizing hormone surge is not detectable in the milk of cows.
Six lactating Holstein cows were used to determine whether a serum luteinizing hormone (LH) surge induced by luteinizing hormone-releasing hormone (LHRH) could be detected in milk. A double antibody radioimmunoassay was evaluated for measuring LH in whole milk. Cows (d 10 of the estrous cycle) were injected with saline (time zero), followed by LHRH 12 h later. Blood samples were collected hourly for 12 h via jugular cannula following each injection; milk removal was accomplished every 2 h by a portable milking machine. On d 10 of the next estrous cycle, treatment, order was switched, with the same cows receiving LHRH at time zero and saline 12 h later. Approximately 2 h following LHRH treatment, serum LH levels peaked at 29 ng/ml and remained elevated for 5 h. There was no corresponding change in milk LH detected during the 12-h to 24-h period following the induced serum LH surge. Our conclusion is that the measurement of LH in the milk of cows shows little promise for predicting ovulation time in the cow.
Johnson
H E
HE
Dept. of Anim. Sci., Washington State University, Pullman 99164-6332.
Reeves
J J
JJ
D000818:Animals; D002417:Cattle; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000032:analysis / Q000097:blood* / Q000378:metabolism; D008892:Milk / Q000032:analysis*; D010061:Ovulation Detection / Q000662:veterinary; D011863:Radioimmunoassay / Q000662:veterinary
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone