Reproductive performance in sows in relation to Japanese Encephalitis Virus seropositivity in an endemic area

Japanese Encephalitis Virus (JEV) is considered an important reproductive pathogen in pigs. Most studies of the reproductive impact of JEV have been conducted in areas where the disease occurs in seasonal epidemics. In this study, the associations between seropositivity for JEV, measured with an IgG ELISA, and the number of piglets born alive and stillborn were investigated in a tropical area endemic for JEV in Vietnam. Sixty percent of sows from four farms in the Mekong delta of Vietnam were seropositive to JEV and the Odds Ratio for a sow being infected was highest (6.4) in sows above 3.5 years (95% confidence interval 2.2–18.3). There was an association between increasing Optical Density (OD) values from the ELISA and the number of stillborn piglets in sows less than 1.5 years, but no effect of seropositivity could be shown when all sows were studied. OD values had an effect (p = 0.04) on the number of piglets born alive in the statistical analysis only when interacting with the effect of the breeds. An increase in mean OD value of the herd was correlated (p < 0.0001) with an increase in the number of piglets born alive. In this study, there was evidence of a negative association between seropositivity for JEV and the reproductive performance only in sows less than 1.5 years in endemic areas. This could be explained by a year-round infection with the virus, which would lead to immunity in many gilts before their first pregnancy. This, in turn, may imply that JEV infection in pigs is of minor importance for the reproductive performance in endemic areas

Effect of Parity and Stage of Gestation on Maternal Growth and Feed Efficiency of Gestating Sows

The objective of this study was to evaluate the effect of parity and stage of gestation on maternal weight gain and efficiency of feed use in group-housed gestating sows from a commercial sow farm. A total of 712 females (Camborough, PIC, Hendersonville, TN) were group-housed from d 5 to 112 of gestation and individually fed with electronic sow feeders (ESF). Feed intake and BW were recorded daily throughout gestation via the ESF and a scale located in an alleyway just after sows exited the feeding station. Gilts (parity 1) and sows received 6.5 and 7.3 Mcal ME per d. Maternal weight gain, not including products of conceptus, and feed efficiency were predicted using a series of equations to model nutrient utilization in gestation. Data were divided into 3 parity groups: 1, 2, and 3+, and gestation was divided into 3 periods: d 5 to 39, 40 to 74, and 75 to 109.After dividing energy requirements into tissue pools for maintenance, growth (maternal protein and fat deposition) and products of conceptus, the greatest portion of the energy requirement was for maintenance and maternal growth. The predicted energy used for maternal protein and fat deposition decreased (P \u3c 0.05) in each period of gestation, regardless of parity group. Parity 2 sows had the greatest (P \u3c 0.05) energy use for maternal protein and fat deposition in all stages of gestation while parity 1 sows had a negative energy balance during the final stage of gestation. Parity 1 sow maternal BW increased (P \u3c 0.05) in each period of gestation; however, parity 2 and 3+ sow maternal BW remained static after d 74 of gestation. Parity 3+ sows had the greatest (P \u3c 0.05) maternal BW throughout the course of gestation in comparison to other parity groups. Regardless of parity, maternal ADG decreased (P \u3c 0.05) from d 39 to 74 before increasing (P \u3c 0.05) during the final stage of gestation. Parity 1 sows had the greatest (P \u3c 0.05) ADG in all gestation periods. Parity 1 sow G:F decreased (P \u3c 0.05) in each sequential period of gestation. Parity 2 and 3+ sow G:F decreased (P \u3c 0.05) from d 39 to 74 but improved (P \u3c 0.05) during the final period of gestation. Parity 1 sow G:F was greater than parity 2 and 3+ sows in most gestation periods. Overall, this study demonstrates how feed usage, stage of gestation, and parity affect sow maternal BW and tissue pool composition in highly prolific sows

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

Sow reproductive performance in Thailand : effects of climate, breed, parity, lactation length, weight loss during lactation and weaning-to-service interval

The aims of this thesis were to study causes of variation in reproductive performance in sows under tropical conditions. The influences o f climate, breed, parity, lactation length, weight loss during lactation and weaning-to-service interval were studied. In total, data from 7 purebred herds and 14 crossbred herds were included. Data were recorded in PigCHAMP® (version 2.0, Univ. of Minnesota) software. Both Landrace and Yorkshire sows were present in all purebred herds. Sows that were exposed to high ambient temperature during lactation, around mating and during early pregnancy had the lowest reproductive performance. Farrowing rate and number o f total bom piglets decreased significantly with increasing temperature and heat index (combining temperature and humidity) during the first four weeks after mating. Farrowing rate decreased by 1.8% and number of total bom piglets decreased by 0.07 piglets for each 1°C increase within the range 26° to 38°C. An increase in maximum temperature by 1°C led to an increase in weaning-to-service interval (WSI) by 0.17 days Landrace sows had, in general, better reproductive performance than Yorkshire sows. However Yorkshire sows had a shorter WSI, a higher percentage mated within 7 days after weaning and a higher ovulation rate compared with Landrace sows. The seasonal pattern did not differ between Landrace and Yorkshire sows. Crossbred primiparous sows had a shorter WSI and a higher percent mated within 5 days after weaning compared with purebred sows. Reproductive performance changed with parity number. Parity 2 sows lost more weight during lactation than sows o f other parities. There was no significant difference in ovulation rate among first to fourth parity sows. Lactation length within the range o f 17-35 days had no significant effect on WSI, ovulation rate, subsequent farrowing rate or subsequent litter size. Relative weight loss during lactation had a significant effect on WSI in parity 1 and 2 sows, but not in older sows. Sows with high weight loss had significantly longer WSI than sows with medium or low weight loss. Relative weight loss during lactation had no effect on ovulation rate. Sows with WSi 7-10 days had significantly lower farrowing rate in subsequent reproductive cycles than sows with WSI 30 days had the lowest lifetime piglet production. Sows with WSI > 30 days had 1.7 times higher risk o f culling compared with sows with WSI 0-4 days

Lipid profiles of sperm and seminal plasma from boars having normal or low sperm motility

Sperm plasma membrane lipids have an important role to play in determining membrane fluidity and sperm motility. The objective of the present study was to determine whether there are differences in the lipid and fatty acid (FA) composition of boar sperm and seminal plasma in the ejaculates of boars having different sperm motilities. Semen was collected from two groups of boars having normal (> 60%; n = 53) or low (< 60%; n = 53) motility sperm and the semen was evaluated for motility, morphology and vitality. The semen was then centrifuged to separate the sperm from the seminal plasma and both were kept at -20 °C until analyzed for lipid content and FA profile by gas chromatography. Total antioxidant status (TAS) of seminal plasma was determined using a commercial kit. There were differences (P ≤ 0.05) in sperm total lipids, cholesterol, saturated fatty acids (SFA), phospholipids, n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and the ratio of n-6:n-3 PUFA between boars with normal and low motility sperm. Total lipids, cholesterol, phospholipids, PUFA, DHA and n-3 PUFA were positively correlated with sperm motility, viability, normal morphology and normal plasma membrane. In contrast, SFA and the ratio of n-6: n-3 PUFA were negatively correlated (P ≤ 0.05) with sperm motility, viability, normal morphology and normal plasma membranes. The TAS of seminal plasma from boars having normal motility sperm was higher (P ≤ 0.05) than that of boars having low motility sperm and TAS was positively correlated (P = 0.0001) with sperm motility, viability, normal morphology and normal plasma membranes. In summary, differences in sperm motility were related to n-3 PUFA content in the sperm plasma membrane and extracellular antioxidants in seminal plasma which protect sperm plasma membranes from lipid peroxidation during periods of oxidative stress.N. Am-in, R.N. Kirkwood, M. Techakumphu, W. Tantasuparu

Atrazine contamination of sow feed and water affects the litter sex ratio and increases fetal mortality in Thailand

Feed and water samples for 828 sows collected at weaning and weekly during gestation were assayed for atrazine content. Atrazine intake >3 µg d−1 resulted in reduced litter size and increased female:male litter sex ratio (P < 0.05). Of 1483 mummified fetuses, the majority of them were male (2.5:1), and mortality primarily occurred in weeks 7 and 8.Nutthee Am-in, Roy N. Kirkwood, Wichai Tantasuparu

Effect of site of sperm deposition on fertility when sows are inseminated with aged semen

Abstract in English, Spanish and FrenchWith conventional insemination, farrowing rate and litter size were lower (P < .05) when sperm was aged (≥ 4 days; n = 30) rather than fresh (≤ 3 days; n = 29). Farrowing rate, but not litter size, was maintained with intrauterine insemination of aged sperm (n = 29). = Con las inseminación convencional, el porcentaje de fertilidad y el tamaño de la camada fueron menores (P < .05) cuando el esperma era viejo (≥ 4 días; n = 30) en vez de fresco (≤ 3 días; n = 29). El porcentaje de fertildiad, pero no el tamaño de la camada, se mantuvo con la inseminación intrauterina de semen viejo (n = 29). = Lors d’insémination conventionnelle, le taux de mise-bas et la taille des portées étaient plus faibles (P < .05) lorsque le sperme était âgé (≥ 4 jours; n = 30) plutôt que frais (≤ 3 jours; n = 29). Le taux de mise-bas, mais pas la taille des portées, était maintenu avec l’insémination intra-utérine de sperme âgé (n = 29).Nutthee Am-in, Wichai Tantasuparuk, R. Manjarin, R. N. Kirkwoo