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

Herd investigations on sperm production in boars, and sow fertility under tropical conditions - with special reference to season, temperature, and humidity

In recent years, a new housing system called an evaporative cooling housing system (EVAP) or tunnel ventilation, has been introduced to improve the microclimate for livestock production in regions with hot climates. No comprehensive study on the variations in temperature and humidity in pig stables with conventional open–air housing systems (CONV) or EVAP housing systems have been performed. The aim of this present thesis is to investigate and describe the influence of (1) housing systems (CONV, EVAP), season, temperature, humidity, age and collection interval, on sperm production and sperm morphology of boars, as well as the fertility results of sows, inseminated with semen collected from boars kept in the CONV and the EVAP systems, and (2) of season, temperature, humidity, parity number and lactation length on the reproductive performance of the sows. The study is based on information collected from 11 herds, during the period January 2001 until June 2002. Six of these herds used the CONV system and five herds had the EVAP system for the boars. All herds had a conventional open–air housing system for the sows. Duroc boars and crossbred sows (Landrace x Yorkshire) were present in all herds and the analyses were restricted to data on these categories of animals. Ejaculates were collected from boars during the period January 2001 to February 2002. Reproductive data were recorded in the herd–monitoring programs, from January 2001 to June 2002. Temperature and humidity were recorded on a daily basis, in one boar stable and in one farrowing stable, in each of the five EVAP herds and in one boar stable in each of the six CONV herds, from January 2001 to February 2002. The analyses of ejaculate volume and total sperm numbers per ejaculate (TSP) were done on 15,630 ejaculates. 1,176 ejaculates were morphologically examined and included in the statistical analyses. There were 43,875 farrowing records included in the statistical analyses. Analysis of variance was applied to the data. There was a higher diurnal variation and range over the year for both temperature and humidity in the CONV system compared to the EVAP system. The average maximum temperature was lower and the average minimum humidity was higher in the EVAP system, than in the CONV system. There was no overall difference in sperm production and sperm morphology between boars kept in the CONV and the EVAP housing systems. During parts of the year, differences between systems in sperm production and sperm morphology were observed. There was a significant effect of the collection month, the age of the boar and the collection interval on both volume and TSP. Temperature had a significant negative effect on the ejaculate volume and TSP in both housing systems. Humidity had a significant negative effect on both the ejaculate volume and TSP in the EVAP system. There was a significant seasonal effect (2–month periods) on the percentage of morphologically normal spermatozoa (normal1), proximal cytoplasmic droplets (prox) and sperm head abnormalities. Temperature had a significant negative effect on normal1 and prox in both systems. Humidity had a significant negative effect on prox in the EVAP system. The housing system of boars had no significant effect on any of the reproductive variables analyzed. Season (2–month periods) as well as parity number had a significant effect on all the reproductive variables analyzed. A longer previous lactation had a significant and favourable effect on subsequent litter size and weaning–to–first–service interval. There were indications that high temperature and high humidity (recorded at herd level) at weaning/mating and at farrowing had negative effects on the later litter size, but these negative influences were not consistent. An EVAP housing system might be one way to reduce the variations that occur over the year in sperm production and sperm morphology, and it may also improve the reproductive performance of sows under tropical conditions

Simple Screening of Listeria monocytogenes Based on a Fluorescence Assay via a Laminated Lab-On-Paper Chip

Monitoring food safety is essential for protecting the health and safety of consumers. Conventional methods used are time consuming and laborious, requiring anywhere from three to seven days to obtain results. Thus, better monitoring methods are required. In this study, a laminated lab-on-paper chip was developed, and its use for the screening of ready-to-eat seafood was demonstrated. The assay on a chip was based on loop-mediated isothermal DNA amplification (LAMP) of the hly gene of Listeria monocytogenes and fluorescence signal detection via SYBR GoldTM. Overall assay processes were completed in 4.5 h., (including 3.5 h. incubation for the bacteria enrichment, direct DNA amplification with no DNA extraction, and signal detection), without relying on standard laboratory facilities. Only positive samples induced fluorescence signals on chip upon illumination with UV light (λ = 460). The method has a limit of detection of 100 copies of L. monocytogenes DNA per 50 g of sample. No cross-reactivity was observed in samples contaminated with other bacteria. On-site monitoring of the seafood products using this chip revealed that one of 30 products from low sanitation vendors (3.33%) were contaminated, and these agreed with the results of PCR. The results demonstrated a benefit of this chip assay for practical on-site monitoring

Colorimetric Detection of Ehrlichia Canis via Nucleic Acid Hybridization in Gold Nano-Colloids

Canine monocytic ehrlichiosis (CME) is a major thick-bone disease of dog caused by Ehrlichia canis. Detection of this causal agent outside the laboratory using conventional methods is not effective enough. Thus an assay for E. canis detection based on the p30 outer membrane protein gene was developed. It was based on the p30 gene amplification using loop-mediated isothermal DNA amplification (LAMP). The primer set specific to six areas within the target gene were designed and tested for their sensitivity and specificity. Detection of DNA signals was based on modulation of gold nanoparticles’ surface properties and performing DNA/DNA hybridization using an oligonucleotide probe. Presence of target DNA affected the gold colloid nanoparticles in terms of particle aggregation with a plasmonic color change of the gold colloids from ruby red to purple, visible by the naked eye. All the assay steps were completed within 90 min including DNA extraction without relying on standard laboratory facilities. This method was very specific to target bacteria. Its sensitivity with probe hybridization was sufficient to detect 50 copies of target DNA. This method should provide an alternative choice for point of care control and management of the disease

Colorimetric Detection of Ehrlichia Canis via Nucleic Acid Hybridization in Gold Nano-Colloids

Canine monocytic ehrlichiosis (CME) is a major thick-bone disease of dog caused by Ehrlichia canis. Detection of this causal agent outside the laboratory using conventional methods is not effective enough. Thus an assay for E. canis detection based on the p30 outer membrane protein gene was developed. It was based on the p30 gene amplification using loop-mediated isothermal DNA amplification (LAMP). The primer set specific to six areas within the target gene were designed and tested for their sensitivity and specificity. Detection of DNA signals was based on modulation of gold nanoparticles’ surface properties and performing DNA/DNA hybridization using an oligonucleotide probe. Presence of target DNA affected the gold colloid nanoparticles in terms of particle aggregation with a plasmonic color change of the gold colloids from ruby red to purple, visible by the naked eye. All the assay steps were completed within 90 min including DNA extraction without relying on standard laboratory facilities. This method was very specific to target bacteria. Its sensitivity with probe hybridization was sufficient to detect 50 copies of target DNA. This method should provide an alternative choice for point of care control and management of the disease

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