title: Fertility responses and hormonal profiles in repeat breeding cows treated with insulin.
abstract: The influence of insulin treatment on conception rate and endocrine profile was studied on 21 repeat breeding cows divided randomly into two groups, i.e. insulin treatment (n = 11) and control (n = 10). Cows of the insulin treatment group were injected subcutaneously with a long acting purified form of bovine insulin at 0.2 IU/kg body weight/day on days 8, 9 and 10, and then with 0.75 mg tiaprost (PGF(2)alpha) intramuscularly on day 12 of the oestrous cycle (oestrus = day 0). The cows of the control group only received 0.75 mg tiaprost was injected intramuscularly on day 12. There was no difference (P > 0.05) in the interval to the onset of oestrus and subsequent cycle length between the treatment (84.5 +/- 6.6 h and 21.2 +/- 0.6 days, respectively) and the control (72.3 +/- 5.9 h and 19.7 +/- 0.4 days, respectively) groups. First service conception rate and overall pregnancy rate did not differ (P > 0.05) between the insulin treatment group (45.4 and 63.6%) and the control group (33.3 and 40.0%). Progesterone concentration following administration of insulin increased (P < 0.05) in the insulin treated cows (2.2+/-0.4 ng/ml versus 2.9 +/- 0.4 ng/ml) but the concentration of oestradiol-17beta did not differ. The insulin concentration was higher on day 10 of the oestrous cycle (P < 0.05) in the treatment group (71.0 +/- 12.5 microU/ml versus 38.1 +/- 4.5 microU/ml). The insulin and glucose concentrations were higher (P > 0.05) in animals, which subsequently became pregnant than in non-pregnant animals. The results may indicate that there is beneficial effect of insulin on fertility in repeat breeder cattle.
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001947:Breeding; D002417:Cattle / Q000502:physiology*; D015237:Dinoprost / Q000008:administration & dosage; D004958:Estradiol / Q000097:blood*; D004971:Estrus; D005260:Female; D005298:Fertility; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood; D011247:Pregnancy; D011374:Progesterone / Q000097:blood*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D011374:Progesterone; D004958:Estradiol; D015237:Dinoprost