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Nutritional effects on the pituitary-ovarian axis during the early post-partum period in autumn-lambing ewes

Published online by Cambridge University Press:  18 August 2016

L. M. Mitchell ,
M. Silveira ,
M. J. Ranilla ,
M. E. King ,
F. E. Gebbie  and
J. J. Robinson
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Abstract

Using primiparous autumn-lambing ewes, this study investigated nutritional effects on (i) pulsatile LH secretion, (ii) responsiveness of the pituitary-ovarian axis to exogenous GnRH, and (iii) oestrus and ovarian cyclicity during the early post-partum period. At lambing (25 October ± 0·3 days), 32 primiparous ewes rearing 2·1 ± 0·04 lambs were equally allocated to four dietary treatments in a 2 ✕ 2 factorial designed experiment. Diets comprised ad libitum hay and 1·5 kg per ewe per day of one of four concentrates (12·5 MJ metabolizable energy per kg dry matter) containing either fibrous (F) or starchy (S) ingredients with (P) or without (O) the inclusion of 120 g/kg fish meal. Throughout the study (lambing to 17 December) ewe body condition score was assessed and ewes and their lambs were weighed at weekly intervals. Blood samples were obtained from all ewes to measure circulating concentrations of progesterone and oestrous behaviour was monitored using vasectomized rams. On day 12 post partum, blood samples were obtained from all ewes at 2-h intervals (09:00 to 17:00 h) to measure concentrations of insulin and urea nitrogen, and at 15-min intervals (09:00 to 21:00 h) to measure pulsatile LH secretion. All ewes received 25 i. v. injections of GnRH (250 ng GnRH in 2 ml 0·9% saline) at 2-h intervals commencing 4 h before the end of the 15-min blood sampling period and their ovaries were examined via laparoscopy on day 17 post partum. There was no effect of dietary treatment on ewe live weight or body condition score throughout the study but inclusion of fish meal in the ewe diet increased lamb growth (FP/SP 255 (s.e. 8·9) v. FO/SO 234 (s.e. 8·2) g/day, P < 0·05). Circulating concentrations of insulin on day 12 post partum were lower in ewes given the fibrous compared with the starchy diets (P < 0·05) while dietary inclusion of fish meal increased (P < 0·001) urea nitrogen. Pulsatile LH secretion on day 12 post partum was not affected by dietary treatment. For ewes on diets F P, FO, SP and SO, the numbers that experienced an LH surge during the period of GnRH administration were 1, 2, 1 and 0, and that ovulated by day 17 post partum were 3, 5, 0 and 5 (FP/SP v. FO/SO, P < 0·05) respectively. Dietary treatment did not affect the intervals from parturition to the onset of ovarian cyclicity or oestrus (overall means were 23 (s.e.1·0) days and 38 (s.e.1·6) days respectively) but ewes on the fibrous compared with the starchy diet had a higher (P < 0·05) incidence of short (≤ 10 days) first ovarian cycles. Results of this study, which involved young growing animals, demonstrate that (i) inclusion of fish meal in the ewe diet influenced the sensitivity of the pituitary-ovarian axis to exogenous GnRH, and (ii) a fibrous compared with a starchy diet was associated with an increased incidence of premature luteal regression.

Keywords

ewesfood intakeGnRHpituitary-gonadal axispost-partum period
Type
Reproduction
Information
Animal Science , Volume 76 , Issue 3 , June 2003 , pp. 421 - 431
Copyright
Copyright © British Society of Animal Science 2003

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References

Al-Gubory, K. H. and Martinet, J. 1986. Comparison of the total ovarian follicular populations at day 140 of pregnancy and at day 5 post-partum in ewes. Theriogenology 25: 795–808.CrossRefGoogle Scholar
Backstrom, C. T., McNeilly, A. S., Leask, R. M. and Baird, D. T. 1982. Pulsatile secretion of LH, FSH, prolactin, oestradiol and progesterone during the menstrual cycle. Clinical Endocrinology 17: 29–42.Google Scholar
Beam, S. W. and Butler, W. R. 1997. Energy balance and ovarian follicle development prior to first ovulation postpartum in dairy cows receiving three levels of dietary fat. Biology of Reproduction 56: 133–142.CrossRefGoogle ScholarPubMed
Beam, S. W. and Butler, W. R. 1999. Effects of energy balance on follicular development and first ovulation in postpartum dairy cows. Journal of Reproduction and Fertility, Supplement 54: 411–424.Google ScholarPubMed
Boyd, J. S. and Ducker, M. J. 1973. A method of examining the cyclic changes occurring in the sheep ovary using endoscopy. Veterinary Record 90: 40–43.CrossRefGoogle Scholar
Cahill, L. P. and Mauleon, P. 1980. Influences of season, cycle and breed on follicular growth rates in sheep. Journal of Reproduction and Fertility 58: 321–328.Google Scholar
Fray, M. D., Lamming, G. E. and Haresign, W. 1995. Induction of ovulation in the acyclic postpartum ewe following continuous, low-dose subcutaneous infusion of GnRH. Theriogenology 43: 1019–1030.Google Scholar
Fredriksson, G. 1985. Release of PGF2α during parturition and the postpartum period in the ewe. Theriogenology 24: 331–335.CrossRefGoogle ScholarPubMed
Garnsworthy, P. C. 1989. The interaction between dietary fibre level and protein degradability in dairy cows. Animal Production 48: 271–281.Google Scholar
Gong, J. G., Lee, W. J., Garnsworthy, P. C. and Webb, R. 2002. Effect of dietary-induced increases in circulating insulin concentrations during the early postpartum period on reproductive function in dairy cows. Reproduction 123: 419–427.Google Scholar
Gonzalez, J. S., Robinson, J. J., McHattie, I. and Fraser, C. 1982. The effect in ewes of source and level of dietary protein on milk yield, and the relationship between the intestinal supply of non-ammmonia nitrogen and the production of milk protein. Animal Production 34: 31–40.Google Scholar
Haour, F. and Saxena, B. B. 1974. Characterization and solubilization of gonadotropin receptor of bovine corpus luteum. Journal of Biological Chemistry 249: 2195–2205.Google Scholar
Laven, R. A. and Drew, S. B. 1999. Dietary protein and the reproductive performance of cows. Veterinary Record 145: 687–695.Google Scholar
Lishman, A. W. and Inskeep, E. K. 1991. Deficiencies in luteal function during re-initiation of cyclic breeding activity in beef cows and ewes. South African Journal of Animal Science 21: 59–76.Google Scholar
McLeod, B. J., Haresign, W. and Lamming, G. E. 1982. Response of seasonally anoestrous ewes to small-dose multiple injections of Gn-RH with and without progesterone pretreatment. Journal of Reproduction and Fertility 65: 223–230.Google Scholar
McNeilly, A. S. and Fraser, H. M. 1987. Effect of gonadotrophin releasing hormone agonist induced suppression of LH and FSH on follicle growth and corpus luteum function in the ewe. Journal of Endocrinology 115: 273–282.Google Scholar
Mandiki, S. N. N., Bister, J. L. and Paquay, R. 1990. Effects of suckling mode on endocrine control of reproductive resumption in Texel ewes lambing in July or November. Theriogenology 33: 397–413.CrossRefGoogle ScholarPubMed
Mattos, R., Staples, C. R. and Thatcher, W. W. 2000. Effects of dietary fatty acids on reproduction in ruminants. Reviews of Reproduction 5: 38–45.Google Scholar
Miller, D. W., Blache, D., Boukhliq, R., Curlewis, J. D. and Martin, G. B. 1998. Central metabolic messengers and the effects of nutrition on gonadotrophin secretion in sheep. Journal of Reproduction and Fertility 112: 347–356.Google Scholar
Mitchell, L. M., King, M. E., Gebbie, F. E., Ranilla, M. J. and Robinson, J. J. 1998. Resumption of oestrous and ovarian cyclicity during the post-partum period in autumn-lambing ewes is not influenced by age or dietary protein content. Animal Science 67: 65–72.Google Scholar
Nett, T. M. 1987. Function of the hypothalamic-hypophysial axis during the post-partum period in ewes and cows. Journal of Reproduction and Fertility Supplement 34: 201–213.Google Scholar
Niswender, G. D., Reichert Jr, L. E., Midgley, A. R. and Nalbandov, A. V. 1969. Radioimmunoassay for bovine and ovine luteinising hormone. Endocrinology 84: 1166–1173.Google Scholar
Parr, R. A. 1992. Nutrition-progesterone interactions during early pregnancy in sheep. Reproduction, Fertility and Development 4: 297–300.Google Scholar
Rekwot, P. I., Ogwu, D., Oyedipe, E. O. and Sekoni, V. O. 2001. The role of pheromones and biostimulation in animal reproduction. Animal Reproduction Science 65: 157–170.Google Scholar
Royal, M. D., Darwash, A. O., Flint, A. P. F., Webb, R., Woolliams, J. A. and Lamming, G. E. 2000. Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility. Animal Science 70: 487–501.CrossRefGoogle Scholar
Russel, A. J. F., Doney, J. M. and Gunn, R. G. 1969. Subjective assessment of body fat in live sheep. Journal of Agricultural Science, Cambridge 72: 451–454.CrossRefGoogle Scholar
Schillo, K. K. 1992. Effects of dietary energy on control of luteinizing hormone secretion in cattle and sheep. Journal of Animal Science 70: 1271–1282.Google Scholar
Schirar, A., Cognie, Y., Louault, F., Poulin, N., Meusnier, C., Levasseur, M. C. and Martine, J. 1990. Resumption of gonadotrophin release during the post-partum period in suckling and non-suckling ewes. Journal of Reproduction and Fertility 88: 593–604.Google Scholar
Silva, W. J. and Raw, R. E. 1993. Regulation of pulsatile secretion of prostaglandin F2α from the ovine uterus by ovarian steroids. Journal of Reproduction and Fertility 98: 341–347.Google Scholar
Sinclair, K. D., Molle, G., Revilla, R., Roche, J. F., Quintans, G., Marongiu, L., Sanz, A., Mackey, D. R. and Diskin, M. G. 2002. Ovulation of the first dominant follicle arising after day 21 post partum in suckling beef cows. Animal Science 75: 115–126.Google Scholar
Sloan, B. K., Rowlinson, P. and Armstrong, D. G. 1988. Milk production in early lactation dairy cows given grass silage ad libitum: influence of concentrate energy source, crude protein content and level of concentrate allowance. Animal Production 46: 317–331.Google Scholar
Smart, D., Singh, I., Smith, R. F. and Dobson, H. 1994. Opioids and suckling in relation to inhibition of oestradiolinduced LH secretion in postpartum ewes. Journal of Reproduction and Fertility 101: 115–119.CrossRefGoogle ScholarPubMed
Stagg, K., Spicer, L. J., Sreenan, J. M., Roche, J. F. and Diskin, M. G. 1998. Effect of calf isolation on follicular wave dynamics, gonadotropin and metabolic hormone changes, and interval to first ovulation in beef cows fed either of two energy levels postpartum. Biology of Reproduction 59: 777–783.CrossRefGoogle ScholarPubMed
Starr, J. I., Horwitz, D. L., Rubenstein, A. H. and Mako, M. E. 1979. Insulin, proinsulin and C-peptide. In Methods of hormone radioimmunoassay (ed. Jaffe, B. M. and Behrman, H. R.), pp. 613–642. Academic Press, New York.Google Scholar
Thiery, J. C. and Martin, G. B. 1991. Neurophysiological control of the secretion of gonadotrophin-releasing hormone and luteinizing hormone in sheep – a review. Reproduction, Fertility and Development 3: 137–173.Google Scholar
Williams, G. L. 1990. Suckling as a regulator of post-partum rebreeding in cattle: a review. Journal of Animal Science 68: 831–852.Google Scholar
Wise, M. F., Glass, J. D. and Nett, T. M. 1986. Changes in the concentrations of hypothalamic and hypophyseal receptors for estradiol in pregnant and postpartum ewes. Journal of Animal Science 62: 1021–1028.CrossRefGoogle ScholarPubMed
Wright, P. J., Geytenbeek, P. E., Clarke, I. J. and Findlay, J. K. 1983. LH release and luteal function in post-partum acyclic ewes after pulsatile administration of LH-RH. Journal of Reproduction and Fertility 67: 257–262.Google Scholar
Zarco, L., Stabenfeldt, G. H., Kindahl, H., Quirke, J. F. and Granstrom, E. 1984. Persistence of luteal activity in the non-pregnant ewe. Animal Reproduction Science 7: 245–267.Google Scholar
Zurek, E., Foxcroft, G. R. and Kennelly, J. J. 1995. Metabolic status and interval to first ovulation in postpartum dairy cows. Journal of Dairy Science 78: 1909–1920.CrossRefGoogle ScholarPubMed