Stress, strain, and pregnancy outcome in postpartum cows

Abstract

Stress affects the productivity and fertility of cattle. Stress causes strain and individual animals experience different amounts of strain in response to the same amount of stress. The amount of strain determines the impact of stress on fertility. Typical stresses experienced by cattle include environmental, disease, production, nutritional, and psychological. The effect of stress on the reproductive system is mediated by body temperature (heat stress), energy metabolites and metabolic hormones (production and nutritional stresses), the functionality of the hypothalamus-pituitary-gonadal (HPG) axis and (or) the activation of the hypothalamuspituitary-adrenal (HPA) axis. The strain that occurs in response to stress affects uterine health, oocyte quality, ovarian function, and the developmental capacity of the conceptus. Cows that have less strain in response to a given stress will be more fertile. The goal for future management and genetic selection in farm animals is to reduce production stress, manage the remaining strain, and genetically select cattle with minimal strain in response to stress.

Ovarian follicular dynamics, progesterone concentrations, pregnancy rates and transcriptional patterns in Bos indicus females with a high or low antral follicle count

“…All the contexts discussed here are highly relevant because although reproductive biotechniques have been developed for livestock, their use has been associated with epigenetic alterations 49 due to the various management practices and environmental influencing factors to which the animals are submitted. The intensification of livestock has certainly generated greater nutritional, sanitary or behavioural/animal welfare challenges that somehow contributed to greater environmental stress on gametes and embryos, compromising the fertility of the herd 50 – 53 . Therefore, the present study also stands out as highly relevant due to the association of basic science with practical field results, revealing that a low AFC is associated with the high expression of genes responsible for cell maintenance, resistance to cell stress and apoptosis.…”

Effect of follicular growth promoters on timed artificial insemination in dairy cows.

“…Lo ideal es usar vacas durante 45 días después del parto en protocolos IATF (31). Sin embargo, 30 días después del puerperio, ya hay una liberación de la hormona liberadora de gonadotropina (GnRH) y pulsos de la hormona luteinizante, lo que caracteriza los signos de la restauración del eje hipotalámico-pituitario-ovárico-uterino (32).…”

Heat stress on cattle embryo: gene regulation and adaptation

“…The hypothalamus secretes corticotropin-releasing hormone (CRH). This CRH travels through the hypothalamic-pituitary portal system and causes the release of adrenocorticotropic hormone (ACTH) from the pituitary gland, which leads the adrenal gland to synthesize and secrete glucocorticoid ( Lucy, 2019 ). There are indirect inhibitory effects of glucocorticoids on GnRH (Gonadotropin-releasing hormone) and LH (luteinizing hormone).…”

“…stressor) that causes an imbalance of homeostasis and alters physiological conditions ( Fraisse and Cockrem, 2006 ; Koolhaas and Van Reenen, 2016 ; Chrousos and Gold, 1992 ; Smith and Vale, 2006 ). The stress response is divided into acute and chronic phases ( Koolhaas and Van Reenen, 2016 ), and its physiological consequences are influenced by the individual's perception of their ability to cope with the stressor ( Fink, 2016 ; Koolhaas and Van Reenen, 2016 ; Lucy, 2019 ). The acute stress responses can last from minutes to days after the beginning of the exposure to the stimuli, and it is driven by the autonomic nervous system, promoting the release of catecholamines and glucocorticoids ( Koolhaas and Van Reenen, 2016 ; Collier et al., 2017 ).…”