Metabolic and luteal sequelae to heightened dietary fat intake in undernourished, anestrous beef cows induced to ovulate.
Two experiments were conducted to evaluate the effects of dietary fat supplementation and a synthetic progestogen on metabolic hormone patterns and(or) in vitro and in vivo characteristics of induced corpora lutea (CL) in undernourished, post-partum beef cows. Metabolizable energy intake was restricted in all cows in both experiments before calving to achieve a body condition (BC) score of 4 (thin), with cows fed to maintain BW and condition after calving. In Exp. 1, 16 cows were fed isocaloric and isonitrogenous diets after calving with either no added fat (NL, n = 8) or added fat (HL, n = 8; .374 kg of fat/500 kg BW). In Exp. 2, 32 pluriparous cows that had reached targeted body condition were divided randomly at calving into a 2 x 2 factorial treatment arrangement: 1) HL-no implant; HL-CON, 2) HL-norgestomet implant d 14 to 21; HL-NORG, 3) NL-CON and, 4) NL-NORG. Forty-eight-hour calf removal on d 21 and GnRH on d 23 were used to induce CL. The HL diet increased (P < .03) serum growth hormone (GH) concentrations, changed the puerperal pattern of serum insulin from cubic (P < .05) to linear (P < .05), and increased (P < .01) the in vitro production of IGF-I by luteal tissue (Exp. 1). In Exp. 2, both HL diets and NORG treatments (HL-NORG, HL-CON, NL NORG) tended to promote an increased (P < .09) frequency of luteal activity after GnRH, but only HL-CON and NL-NORG enhanced (P < .04) luteal lifespan.(ABSTRACT TRUNCATED AT 250 WORDS)
Ryan
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DP
Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville 78102, USA.
Bao
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B
Griffith
M K
MK
Williams
G L
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D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000503:physiopathology*; D002784:Cholesterol / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D004343:Drug Implants; D004971:Estrus / Q000502:physiology; D005260:Female; D018565:Food-Drug Interactions; D013006:Growth Hormone / Q000097:blood; D007328:Insulin / Q000097:blood; D008183:Luteal Phase / Q000187:drug effects / Q000502:physiology*; D009748:Nutrition Disorders / Q000503:physiopathology / Q000662:veterinary*; D010060:Ovulation / Q000502:physiology*; D010062:Ovulation Induction / Q000662:veterinary; D049590:Postpartum Period / Q000502:physiology; D011282:Pregnenediones / Q000008:administration & dosage / Q000494:pharmacology; D045167:Progesterone Congeners / Q000008:administration & dosage / Q000494:pharmacology; D011897:Random Allocation
D004041:Dietary Fats; D004343:Drug Implants; D007328:Insulin; D011282:Pregnenediones; D045167:Progesterone Congeners; C100284:norgestomet; D013006:Growth Hormone; D002784:Cholesterol