Serum LH Concentrations and Ovarian Activity in Cows with Repetitive Administration of LH-RH/FSH-RH2

Abstract

Eight 2-year-old Angus heifers were assigned randomly to two groups. Treatments consisted of each animal receiving either 150 µg of LH-RH/FSH-RH in 1 ml of acidified saline or 1 ml of acidified saline alone via an indwelling jugular catheter at 4-hr intervals for 96 hr on days 16 through 19 of the estrous cycle. Blood samples were collected at various intervals before and after each administration. The second part of this study consisted of treating 20 mature Angus cows in the same manner as described above and ovariectomizing them at the end of the 96-hr injection period. No blood samples were collected in this study. The mean LH value in the LH-RH/FSH-RH-treated heifers was significantly higher than the mean of the control heifers. Peak serum LH values were significantly higher during the first half of the treatment period than the second half in the LH-RH/FSH-RH-treated animals. Serum LH values in the LH-RH/FSH-RH treated animals did return to basal levels within the 4-hr period following each injection. No detectable differences were noted in the follicular fluid volume or corpora lutea weight in the LH-RH/FSH-RH- and saline-injected cows. Copyright © 1975. American Society of Animal Science . Copyright 1975 by American Society of Animal Science.