Stress and its influence on reproduction in pigs: a review

The manifestations of stress, defined as a biological response to an event that the individual perceives as a threat to its homeostasis, are commonly linked to enhanced activity of the hypothalamo-pituitary-adrenal (HPA) axis and the activation of the sympathetic adreno-medullary (SA) system. Activation of the HPA system results in the secretion of peptides from the hypothalamus, principally corticotropin releasing hormone (CRH), which stimulates the release of adrenocorticotropic hormone (ACTH) and beta-endorphin. ACTH induces the secretion of corticosteroids from the adrenal cortex, which can be seen in pigs exposed to acute physical and/or psychological stressors. The present paper is a review of studies on the influence of stressors on reproduction in pigs. The effects of stress on reproduction depend on the critical timing of stress, the genetic predisposition to stress, and the type of stress. The effect of stress on reproduction is also influenced by the duration of the responses induced by various stressors. Prolonged or chronic stress usually results in inhibition of reproduction, while the effects of transient or acute stress in certain cases is stimulatory (e.g. anoestrus), but in most cases is of impairment for reproduction. Most sensitive of the reproductive process are ovulation, expression of sexual behaviour and implantation of the embryo, since they are directly controlled by the neuroendocrine system

Análise do desempenho reprodutivo e do uso de energia elétrica em instalações climatizadas de cachaços Analysis of reproductive performance and use of electrical energy in the acclimatized facilities of boars

Objetivou-se, com este estudo, avaliar e comparar dois sistemas de climatização do ambiente com dezoito machos da linhagem genética comercial AG337, provenientes da empresa AGROCERES–PIC. Os animais do grupo A foram submetidos à climatização por meio de ventilação artificial e nebulização com acionamento automatizado enquanto os do grupo B foram submetidos apenas a ventilação, sendo o acionamento dos equipamentos feito de forma manual e de acordo com o manejo já praticado. Foram considerados aspectos de desempenho reprodutivo e conforto térmico dos animais, além das variáveis climáticas mensuradas no ambiente externo ao galpão e o uso de energia elétrica pelos equipamentos de climatização. Os principais resultados demonstraram que os animais do grupo A permaneceram em condição ambiental mais segura, porém não houve melhora nos índices de qualidade seminal dos animais deste grupo. Ressalta-se que o incremento de custo relativo ao aumento no consumo de energia elétrica, ocasionado pelo uso dos equipamentos de climatização e automação, não acarretará acréscimo significativo na conta de energia pois se trata de equipamentos de baixa demanda de energia elétrica.<br>This study aimed to assess and compare two air conditioning systems in a setting where eighteen males of the commercial genetic line AG337, from AGROCERES - PIC, are housed. The animals in Group A were submitted to automated air conditioning through artificial ventilation and nebulization, while the animals in Group B were submitted only to manual triggering of the ventilation, according to the schedule practiced at the farm. The factors such as reproductive performance, animal thermal comfort, as well as climatic variables from the external environment of the housing and use of electrical energy by the environment controL&#955;i ng system were considered. The results showed that animals in Group A remained in a comfortable environmental conditions though there was no improvement in the mean values of seminal volume and sperm concentration. It is worthwhile to mention that monthly increase in energy costs due to use of acclimatization and automation equipments were not significant as the equipments are of low energy consumption