Endocrine changes in beef heifers superovulated with follicle-stimulating hormone (FSH-P) or human menopausal gonadotropin
Article Abstract:
The effects of human menopausal gonadotropin (HMG) and follicle stimulating hormone (FSH-P) and their administration route on the hormonal profile of 32 heifers were evaluated. This was done by measuring the heifers' serum hormone concentrations for luteinizing hormone, follicle stimulating hormone, estradiol and progesterone before and after HMG and FSH-P administration. Results showed that there were differential hormonal response between FSH-P- and HMG-treated heifers, but the route of administration did not affect response significantly. These imply that the use of human gonadotropin in inducing cattle to ovulate still needs much research.
Publication Name: Journal of Animal Science
Subject: Zoology and wildlife conservation
ISSN: 0021-8812
Year: 1992
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Factors affecting dystocia annd early calf mortality in Angus cows and heifers
Article Abstract:
Logistic regression models were used to analyze data on dystocia and perinatal mortality among purebred American Angus herds across the US. The odds of unassisted birth as compared to births with major difficulty were 11.58 times greater in cows than in heifers. Increased age of dam and decreased calf birth weight result in increased odds of unassisted birth in heifers. Birth weight also affects the survival of calves to 24 hours in heifers. Thus, age of dam and birthweight, especially in heifers, should be considered in evaluating sires for calf production in the Angus breed.
Publication Name: Journal of Animal Science
Subject: Zoology and wildlife conservation
ISSN: 0021-8812
Year: 1992
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Postweaning growth and reproduction of beef heifers exposed to calve at 24 or 30 months of age in spring and fall seasons
Article Abstract:
Heifer birth season and age effects on productivity were measured in 24- or 30-month-old heifers exposed to calving timed for spring or autumn birth. Although all 30-month-old heifers exposed to their first calving had longer estrus, higher pregnancy rate and larger pelvic opening, 30-month-old heifers born in spring were found to have the highest reproductive performance in terms of estrus activity and pregnancy rates. Breeding 30-month-old heifers increase reproductive performance, but the longer weaning-to-breeding period might affect production economics.
Publication Name: Journal of Animal Science
Subject: Zoology and wildlife conservation
ISSN: 0021-8812
Year: 1992
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