Animal Reproduction (AR)
Animal Reproduction (AR)
Thematic Section: 36th Annual Meeting of the Association of Embryo Technology in Europe (AETE)

Understanding the trade-off between the environment and fertility in cows and ewes

Hilary Dobson; Jean Elsie Routly; Robert Frank Smith

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Abstract: The environment contributes to production diseases that in turn badly affect cow performance, fertility and culling. Oestrus intensity is lower in lame cows, and in all cows 26% potential oestrus events are not expressed (to avoid getting pregnant). To understand these trade-offs, we need to know how animals react to their environment and how the environment influences hypothalamus-pituitary-adrenal axis (HPA) interactions with the hypothalamus-pituitary-ovarian axis (HPO). Neurotransmitters control secretion of GnRH into hypophyseal portal blood. GnRH/LH pulse amplitude and frequency drive oestradiol production, culminating in oestrus behaviour and a precisely-timed GnRH/LH surge, all of which are disrupted by poor environments. Responses to peripheral neuronal agents give clues about mechanisms, but do these drugs alter perception of stimuli, or suppress consequent responses? In vitro studies confirm some neuronal interactions between the HPA and HPO; and immuno-histochemistry clarifies the location and sequence of inter-neurone activity within the brain. In both species, exogenous corticoids, ACTH and/or CRH act at the pituitary (reduce LH release by GnRH), and hypothalamus (lower GnRH pulse frequency and delay surge release). This requires inter-neurones as GnRH cells do not have receptors for HPA compounds. There are two (simultaneous, therefore fail-safe?) pathways for CRH suppression of GnRH release via CRH-Receptors: one being the regulation of kisspeptin/dynorphin and other cell types in the hypothalamus, and the other being the direct contact between CRH and GnRH cell terminals in the median eminence. When we domesticate animals, we must provide the best possible environment otherwise animals trade-off with lower production, less intense oestrus behaviour, and impaired fertility. Avoiding life-time peri-parturient problems by managing persistent lactations in cows may be a worthy trade-off on both welfare and economic terms – better than the camouflage use of drugs/hormones/feed additives/intricate technologies? In the long term, getting animals and environment in a more harmonious balance is the ultimate strategy.


oestrus, adrenal, GnRH, neurotransmitters, behaviour


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Sanhouri AA, Jones RS, Dobson H. Preliminary results on the effects of diazepam on physiological responses to transport in male goats. Br Vet J. 1991a;147(4):388-9. PMid:1913136.

Sanhouri AA, Jones RS, Dobson H. Prazosin and propranolol and the stress response to transport in male goats; a preliminary study. J Vet Pharmacol Ther. 1991b;14(4):421-5. PMid:1774819.

Sanhouri AA, Jones RS, Dobson H. Pentobarbitone inhibits the stress response to transport in male goats. Br Vet J. 1991c;147(1):42-8. PMid:2018916.

Sanhouri AA, Jones RS, Dobson H. Effects of xylazine on the stress response to transport in male goats. Br Vet J. 1992;148(2):119-28. PMid:1576515.

Scanlan N, Dufourny L, Skinner DC. Somatostatin-14 neurons in the ovine hypothalamus: colocalization with estrogen receptor alpha and somatostatin-28(1–12) immunoreactivity, and activation in response to estradiol. Biol Reprod. 2003;69(4):1318-24. PMid:12773414.

Schiml PA, Rissman EF. Effects of gonadotropin-releasing hormones, corticotropin-releasing hormone, and vasopressin on female sexual behaviour. Horm Behav. 2000;37(3):212-20. PMid:10868484.

Scott CJ, Clarke IJ. Evidence that changes in the function of the subtypes of the receptors for gamma-amino butyric-acid may be involved in the seasonal-changes in the negative-feedback effects of estrogen on gonadotropin-releasing-hormone secretion and plasma luteinizing-hormone levels in the ewe. Endocrinology. 1993;133(6):2904-12. PMid:8243318.

Scott CJ, Rose JL, Gunn AJ, McGrath BM. Kisspeptin and the regulation of the reproductive axis in domestic animals. J Endocrinol. 2018;240:R1-16. PMid:30400056.

Sheldon IM, Owens SE. Postpartum uterine infection and endometritis in dairy cattle. Anim Reprod. 2017;14(3):622-9.

Smart D. Adrenocorticotrophin (ACTH) 1–39 and corticotrophin releasing hormone (CRH) induced changes in luteinizing hormone secretion from perifused ovine pituitaries. Anim Reprod Sci. 1994;37(1):25-34.

Smith RF, Dobson H. Individual and temporal differences in the cortisol response of sheep to repeated transport. Anim Welf. 2001;10:S235-51.

Smith RF, Ghuman SPS, Evans NP, Karsch FJ, Dobson H. Stress and the control of LH secretion in the follicular phase of ewes. Reproduction. 2003a;(Suppl 61):267-82. PMid:14635941.

Smith RF, French NP, Saphier PW, Lowry PJ, Veldhuis JD, Dobson H. Identification of stimulatory and inhibitory inputs to the hypothalamic-pituitary-adrenal axis during hypoglycaemia or transport in ewes. J Neuroendocrinol. 2003b;15(6):572-85. PMid:12716408.

Tebble JE, O’Donnell MJ, Dobson H. Ultrasound diagnosis and treatment outcome of cystic ovaries in cattle. Vet Rec. 2001;148(13):411-3. PMid:11327649.

Thomas I, Dobson H. Oestrus during pregnancy in the cow. Vet Rec. 1989;124(15):387-90. PMid:2728283.

Tsousis G, Sharifi R, Hoedemaker M. Associations between the clinical signs of chronic endometritis with ovarian cysts and body condition loss in German Holstein Friesian cows. J Vet Sci. 2009;10(4):337-41. PMid:19934600.

Vellucci SV, Parrott RF. Bacterial endotoxin-induced gene expression in the choroid plexus and paraventricular and supraoptic hypothalamic nuclei of the sheep. Brain Res Mol Brain Res. 1996;43(1-2):41-50. PMid:9037517.

Walker SL, Smith RF, Jones DN, Routly JE, Dobson H. Chronic stress, hormone profiles and estrus intensity in dairy cattle. Horm Behav. 2008a;53(3):493-501. PMid:18206887.

Walker SL, Smith RF, Routly JE, Jones DN, Morris MJ, Dobson H. Lameness, activity time-budgets and estrus expression in dairy cattle. J Dairy Sci. 2008b;91(12):4552-9. PMid:19038930.

Walker SL, Smith RF, Jones DN, Routly JE, Morris MJ, Dobson H. Effect of a chronic stressor, lameness, on detailed sexual behaviour and hormonal profiles in milk and plasma of dairy cattle. Reprod Domest Anim. 2010;45(1):109-17. PMid:18992112.

Walsh JP, Rao A, Simmons DM, Clarke IJ. Proopiomelanocortin mRNA levels in ovine hypothalamus are not reduced at the time of the preovulatory luteinising hormone surge. J Neuroendocrinol. 1998;10(10):803-8. PMid:9792332.

Ward WR, Ribadu AY, Harvey D, Dobson H. Ultrasound and hormone profiles to monitor follicular activity in cattle after treatment with high doses of progesterone and oestradiol. Anim Sci. 2000;71(3):577-83.

Whitaker DA, Kelly JM, Smith S. Disposal and disease rates in 340 British dairy herds. Vet Rec. 2000;146(13):363-7. PMid:10803980.

Williams J, Ntallaris T, Routly JE, Jones DN, Cameron J, Holman-Coates A, Smith RF, Humblot P, Dobson H. Association of production diseases with motor activity-sensing devices and milk progesterone concentrations in dairy cows. Theriogenology. 2018;118:57-62. PMid:29885641.

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