Hostname: page-component-745bb68f8f-b6zl4 Total loading time: 0 Render date: 2025-01-09T03:05:37.421Z Has data issue: false hasContentIssue false
  • English
  • Français

Circulating concentrations of LH and FSH and pituitary responsiveness to GnRH in intact and ovariectomized suckled beef cows in two levels of body condition

Published online by Cambridge University Press:  02 September 2010

I. A. Wright ,
S. M. Rhind ,
T. K. Whyte ,
A. J. Smith ,
S. R. McMillen  and
R. Prado
I. A. Wright
Affiliation:
Macaulay Land Use Research Institute, Pentlandfield, Roslin, Midlothian EH25 9RF
S. M. Rhind
Affiliation:
Macaulay Land Use Research Institute, Pentlandfield, Roslin, Midlothian EH25 9RF
T. K. Whyte
Affiliation:
Macaulay Land Use Research Institute, Pentlandfield, Roslin, Midlothian EH25 9RF
A. J. Smith
Affiliation:
Macaulay Land Use Research Institute, Pentlandfield, Roslin, Midlothian EH25 9RF
S. R. McMillen
Affiliation:
Macaulay Land Use Research Institute, Pentlandfield, Roslin, Midlothian EH25 9RF
R. Prado
Affiliation:
Macaulay Land Use Research Institute, Pentlandfield, Roslin, Midlothian EH25 9RF
Get access

Abstract

The effect of body condition on hypothalamic and pituitary function in post-partum suckled beef cows was studied. Thirty-eight Blue-Grey cows were calved at a body condition score of either 2·35 (L) or 2·80 (H), fed to maintain live weight and body condition thereafter and ovariectomized at either 5 or 9 weeks post partum. The H cows had higher LH pulse frequencies before ovariectomy (0·36 v. 0·28 pulses per h; P < 0·05) and 15 days after ovariectomy (0·86 v. 0·72 pulses per h; P < 0·01), indicating a direct effect of body condition on GnRH release from the hypothalamus. Body condition had no effect on the ability of the pituitary to release LH in response to a physiological dose (2·5 u.g) of GnRH in entire or ovariectomized cows at 5 or 9 weeks post partum. The magnitude of the increase in circulating levels of LH following GnRH injection was greater at 9 weeks compared with 5 weeks post partum (2·23 v. 1·73 u.g/1; P < 0·001) in entire cows, but there was no difference between 5 and 9 weeks in ovariectomized cows. Following ovariectomy there was a 2·5-fold increase in LH pulse frequency within 15 days and LH pulse frequency approached 1 pulse per h in all treatments groups. It is concluded that both the hypothalamus and the pituitary are capable of functioning normally by 5 weeks post partum in suckled beef cows, that the pulsatile release of GnRH from the hypothalamus is inhibited, possibly due to a very high sensitivity to oestradiol, and that the sensitivity of the pituitary to the negative feedback effect of oestradiol may decrease with time post partum.

Keywords

body conditioncowsgonadotropinspostpartum interval
Type
Research Article
Information
Animal Production , Volume 51 , Issue 1 , August 1990 , pp. 93 - 101
Copyright
Copyright © British Society of Animal Science 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Acosta, B., Tarnavsky, G. K., Platt, T. E., Hamernik, D. L., Brown, J. L., Schohnemann, H. M. and Reeves, J. J. 1983. Nursing enhances the negative effect of estrogen on LH release in the cow. Journal of Animal Science 57: 1530–1536.CrossRefGoogle ScholarPubMed
Adams, D. C., Short, R. E. and Knapp, B. W. 1987. Body size and body condition effects on performance and behaviour of grazing beef cows. Nutrition Reports International 35: 269–277.Google Scholar
Baird, D. T., Swanston, I. A. and McNeilly, A. S. 1981. Relationships between LH, FSH and prolactin concentration and the secretion of androgens and oestrogens by the preovulatory follicle in the ewe. Biology of Reproduction 24: 1013–1025.CrossRefGoogle ScholarPubMed
Clarke, I. J. and Cummins, J. T. 1982. The temporal relationship between GnRH and LH secretion in ovariectomised ewes. Endocrinology 111: 1737–1739.CrossRefGoogle Scholar
Echternkamp, S. E., Ferrell, C. L. and Rone, J. D. 1982. Influence of pre- and post-partum nutrition on LH secretion in suckled post-partum beef heifers. Theriogenology 18: 283–295.CrossRefGoogle ScholarPubMed
Eckersall, P. D. and Harvey, M. J. A. 1987. The use of a bovine plasma progesterone ELISA kit to measure progesterone in equine, ovine and canine plasmas. Veterinary Record 120: 5–8.CrossRefGoogle Scholar
Finlay, J. K. and Clarke, I. J. 1987. Regulation of the secretion of FSH in domestic ruminants. Journal of Reproduction and Fertility, Supplement 34, pp. 27–37.Google Scholar
Imakawa, K., Day, M. L., Zalesky, D. D., Clutter, A., Kittock, R. J. and Kinder, K. E. 1987. Effects of 17-P-estradiol and diets varying in energy on secretion of luteinizing hormone in beef heifers. Journal of Animal Science 64: 805–815.CrossRefGoogle Scholar
Jagger, J. P., Peters, A. R. and Lamming, G. E. 1987. Hormone responses to low-dose GnRH treatment in post-partum beef cows. Journal of Reproduction and Fertility 80: 263–269.Google Scholar
Lamming, G. E., Wathes, D. C. and Peters, A. R. 1981. Endocrine patterns of the post-partum cow. Journal of Reproduction and Fertility, Supplement 30, pp. 155–170.Google Scholar
Lawes Agricultural Trust. 1984. Genstat V Mark 4.04. Rothamsted Experiment Station, Harpenden, Hertfordshire.Google Scholar
Lowman, B. G., Scott, N. A. and Somerville, S. H. 1976. Condition scoring of cattle. Rev. ed. Bulletin, East of Scotland College of Agriculture, No. 6.Google Scholar
McCaughey, W. P., Rutter, L. M. and Manns, J. G. 1988. Effect of glucose infusion on metabolic and reproductive function in post partum beef cows. Canadian Journal of Animal Science 68: 1079–1087.CrossRefGoogle Scholar
McNeilly, A. S., Jonassen, J. A. and Fraser, H. M. 1986. Suppression of follicular development after chronic LHRH immunoneutralization in the ewe. Journal of Reproduction and Fertility 76: 481–490.CrossRefGoogle ScholarPubMed
McNeilly, J. R., McNeilly, A. S., Walton, J. S. and Cunningham, F. J. 1976. Development and application of a heterologous radioimmunoassay for ovine follicle-stimulating hormone. Journal of Endocrinology 70: 69–79.Google Scholar
Moss, G. E., Parfet, J. R., Marvin, C. A., Allrich, R. D. and Diekman, M. A. 1985. Pituitary concentrations of gonadotropins and receptors for GnRH in suckled beef cows at various intervals after calving. Journal of Animal Science 60: 285–293.Google Scholar
Prado, R., Rhind, S. M., Wright, I. A., Russel, A. J. F., McMillen, S. R., Smith, A. J. and McNeilly, A. S. 1990. Follicle populations, steroidogenity and micromorphology at 5 and 9 weeks post-partum in beef cows at two levels of body condition. Animal Production 51: 103–108.Google Scholar
Price, C. A. and Webb, R. 1988. Steroid control of gonadotropin secretion and ovarian function in heifers. Endocrinology 122: 2222–2231.CrossRefGoogle ScholarPubMed
Rutter, L. M. and Manns, J. G. 1987. Hypoglycemia alters pulsatile luteinizing hormone secretion in the postpartum beef cow. Journal of Animal Science 64: 479–488.Google Scholar
Short, R. E. and Adams, D. C. 1988. Nutritional and hormonal inter-relationships in beef cattle reproduction. Canadian Journal of Animal Science 68: 29–39.Google Scholar
Whisnant, C. S., Kiser, T. E., Thompson, F. N. and Hall, J. B. 1985. Effect of nutrition on the LH response to calf removal and GnRH. Theriogenology 24: 565–573.CrossRefGoogle ScholarPubMed
Wright, I. A., Rhind, S. M., Russel, A. J. F., Whyte, T. R., McBean, A. J. and McMillen, S. R. 1987. Effects of body condition, food intake and temporary calf separation on the duration of the postpartum anoestrous period and associated LH, FSH and prolactin concentrations in beef cows. Animal Production 45: 395–402.Google Scholar
Wright, I. A. and Russel, A. J. F. 1984. Partition of fat, body composition and body condition score in mature cows. Animal Production 38: 23–32.Google Scholar