Ovarian follicular populations in lactating dairy cows treated with recombinant bovine somatotropin (sometribove) or saline and fed diets differing in fat content and energy.
Interactions of dietary energy and fat with recombinant bST (sometribove) injections were tested for their effects on ovarian function. Lactating dairy cows were fed one of three diets differing in energy concentration (NEL) and percentage of DM of calcium salts of long-chain fatty acids: diet 1, 1.68 Mcal/kg and 0%; diet 2, 1.68 Mcal/kg and 2.2%; and diet 3, 1.78 Mcal/kg and 2.2%. Cows were injected daily with bST or saline during one of two 19-d interestrous periods (crossover design) in which ovarian follicles were measured by ultrasonography. The bST-treated cows produced more FCM and were in lower energy balance than saline-treated cows. Before d 12 (first follicular wave, estrus = d 0), bST-treated cows had more ovarian follicles in classes 1 (3 to 5 mm; cows on diet 3) or 2 (6 to 9 mm; cows on diets 1 and 2) than saline-treated cows. After d 12 (preovulatory follicular wave), numbers of follicles in different size classes were similar for bST-treated and saline-treated cows, but cows fed diet 2 had larger preovulatory follicles. Lower dietary energy and bST treatment were both associated with larger subordinate follicles. Ovarian follicles less than 10 mm were stimulated by bST, and calcium salts of long-chain fatty acids increased diameters of preovulatory follicles.
Lucy
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Dairy Science Department, University of Florida, Gainesville 32611-0920.
De La Sota
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Staples
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Thatcher
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D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D002784:Cholesterol / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage*; D002149:Energy Intake; D004971:Estrus / Q000187:drug effects; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D013006:Growth Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D019382:Human Growth Hormone; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology*; D010060:Ovulation / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D011994:Recombinant Proteins / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology
D001786:Blood Glucose; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D012965:Sodium Chloride; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D002784:Cholesterol