S. Einarsson

Effect of birth litter size, birth parity number, growth rate, backfat thickness and age at first mating of gilts on their reproductive performance as sows

The present study was performed to evaluate retrospectively the influence of birth litter size, birth parity number, performance test parameters (growth rate from birth to 100kg body weight and backfat thickness at 100kg body weight) and age at first mating (AFM) of gilts on their reproductive performance as sows. Traits analysed included remating rate in gilts (RRG), litter size, weaning-to-first-service interval (WSI), remating rate in sows and farrowing rate (FR). Data were collected from 11 Swedish Landrace (L) and 8 Swedish Yorkshire (Y) nucleus herds and included 20712 farrowing records from sow parities 1-5. Sows that farrowed for the first time during 1993-1997, having complete records of performance test and AFM, were followed up to investigate their subsequent reproductive performance until their last farrowing in 1999. Analysis of variance and multiple regression were applied to continuous data. Logistic regression was applied to categorical data. The analyses were based on the same animals and the records were split into six groups of females, i.e. gilts, primiparous sows, and sows in parities 2-5, respectively. Each additional piglet in the litter in which the gilt was born was associated with an increase of her own litter size of between 0.07 and 0.1 piglets per litter (P<0.001). Gilts born from sow parity 1 had a longer WSI as primiparous sows compared with gilts born from sow parity 4 (0.3 days; P<0.05) or parity 5 (0.4 days; P<0.01). Gilts with a higher growth rate of up to 100kg body weight had a larger litter size (all parities 1-5; P<0.05), shorter WSI (all parities 1-5; P<0.05) and higher FR (parities 2 and 5; P<0.05) than gilts with a lower growth rate. Gilts with a high backfat thickness at 100kg body weight had a shorter WSI as primiparous sows (P<0.001) compared with low backfat gilts, and 0.1 piglets per litter more as second parity sows (P<0.01). A 10 day increase in AFM resulted in an increase in litter size of about 0.1 piglet for primiparous sows (P<0.001) and a decrease (P<0.05) for sow parities 4 and 5.

Distribution, number and membrane integrity of spermatozoa in the pig oviduct in relation to spontaneous ovulation

The pattern of distribution, number and membrane integrity of spermatozoa in the utero-tubal junction (UTJ) and isthmus during three oestrous stages were related to spontaneous ovulation in flushed and fixed oviducts of multiparous sows. Three unrelated boars were each used once to mate or artificially inseminate (neat ejaculate) six out of 18 sows, 18 h prior to expected ovulation. The sows were slaughtered 6-8 h before, during or 6-8 h after ovulation. The ad-uterine oviductal region (UTJ and isthmus) was divided into UTJ, lower isthmus, middle isthmus and upper isthmus segments. A higher fraction of middle and upper isthmus segments contained spermatozoa during the peri- and post-ovulatory periods than during the pre-ovulatory period. The distribution, numbers and membrane integrity of spermatozoa in the UTJ-isthmus region were influenced by the ovulation event. Numbers and distribution of spermatozoa varied depending on the boar used. The flushing technique allowed a better assessment of the distribution, number and membrane integrity of tubal spermatozoa than in situ observation with a scanning electron microscope (SEM).

Reproductive performance of purebred Landrace and Yorkshire sows in Thailand with special reference to seasonal influence and parity number.

The purpose of this study was to analyze reproductive performance in purebred Landrace and Yorkshire sows with special reference to seasonal influence and parity number, under tropical conditions where day length is almost constant throughout the year. Data from three purebred sow herds in Thailand during the period from 1993 to 1996 were analyzed. The two breeds were present in all three herds. The analysis comprised records of 3848 Landrace sow litters and 2033 Yorkshire sow litters. The statistical models included the fixed effects of month, year, parity, breed of the sow, herd, and two-way interactions of breed-parity, breed-herd, breed-month, breed-year, parity-month, month-herd, year-herd and month-year. The random effect of sow within breed was included in all models. Analysis of covariance was performed to analyze the effect of temperature, humidity and heat index on number of total born per litter (NTB), weaning to first service interval (WSI) and farrowing rate (FR). Landrace sows had significantly higher NTB (0.6 piglets), number of live born per litter (0.5 piglets), and average birth weight (0.13 kg) than Yorkshire sows (P<0.001). Farrowing rate was 3.9% higher in Landrace sows than in Yorkshire sows (P<0.01). However, Yorkshire sows had significantly shorter WSI (P<0.001) and significantly higher proportion of sows served within 7 days after weaning (P<0.01) than Landrace sows. No breed differences were found in number of stillborn per litter and weaning to conception interval. Parity had significant effect on all reproductive parameters analyzed. Number of total born and live born per litter was significantly lower for sows farrowing during the rainy season than in other seasons. Farrowing rate was low for sows mated during the hot and rainy season. Weaning to service interval and WSI7 were prolonged for sows weaned during the hot and rainy season. Reproductive performance was significantly unfavorably influenced by elevated temperature and heat index after mating (NTB and FR) or during lactation (WSI).

Changes in sperm ultrastructure and localisation in the porcine oviduct around ovulation

Changes in the morphology and localisation of spermatozoa in the utero-tubal junction (UTJ) and three equal segments of the isthmus (lower, middle and upper isthmus) within +/-8 h of ovulation were studied with scanning and transmission electron microscopy. Spermatozoa were located at specific sites within the UTJ-isthmic environment. Two sperm subpopulations were evident, one with epithelial contact and one without such contact. Most of the sperm population with epithelial contact maintained intact plasma membrane during the pre-ovulatory period and showed acrosome reacted-like membrane changes during the post-ovulatory period. In contrast, plasma membranes in most of the spermatozoa with no epithelial contact were already broken before ovulation. Ovulation was also accompanied by a relocation of spermatozoa from the mucosal crypts/interfolds towards the more central part of the mucosal surface.

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.

Morphology and motility of spermatozoa from different regions of the epididymal duct in the domestic cat

Spermatozoa undergo important maturational changes as they pass through the epididymal duct. Some domestic cats and many species of wild felids have high proportions of abnormal spermatozoa in their ejaculates. The epididymis has been shown to be able to remove certain abnormal sperm forms in some species while other sperm abnormalities originate in the epididymis. So far, it has not been shown how the epididymis affects sperm morphology in the domestic cat. Therefore, motility and sperm morphology were studied in spermatozoa from the efferent ducts and from the 6 regions of the epididymal duct. There were significant decreases in the proportions of spermatozoa with abnormalities of the sperm head, acrosomal defects, acrosomal abnormalities and in the proportion of midpiece abnormalities. In contrast, there was a small but significant increase in the proportion of spermatozoa with abnormalities of the tail. Spermatozoa acquired the capacity for motility in Region 4, where the cytoplasmic droplet also moved from a proximal to a distal position, indicating that important maturational changes take place in this region. The results of this study demonstrate that the proportions of sperm abnormalities originating in the testes decrease during epididymal transport, while some sperm tail abnormalities may actually originate in the epididymis.

Effect of food deprivation during early pregnancy on endocrine changes in primiparous sows

Abstract The effect of food deprivation during early pregnancy on maternal plasma endocrine levels and on embryonic survival was studied in primiparous sows. Twelve cross-bred (Swedish Yorkshire × Swedish Landrace) primiparous sows at the same stage of pregnancy were used. Six sows were fasted on Days 10 and 11 of pregnancy, with free access to water. The other six sows were fed as usual and used as controls. Blood samples were collected from Days 7 to 14 of pregnancy for cortisol, corticosteroid-binding globulin (CBG), progesterone (P4), oestradiol-17β (E2), oestrone sulphate and prostaglandin F2α metabolite (PG-metabolite) analysis. The sows were slaughtered on Day 17 of pregnancy and embryos recovered. Cortisol concentrations rose (P

Ultrastructure of the uterotubal junction in preovulatory pigs.

The ultrastructure of the surface epithelia from the uterotubal junction (UTJ), and the adjacent tuba1 isthmic and endometrial regions, was studied in preovulatory oestrus gilts, either unmated or inseminated 12 h before with fresh boar semen. The simple columnar epithelium of the UTJ consisted of non‐ciliated (secretory) and ciliated cells. Secretory vesicles occurred in the secretory cells, especially in inseminated gilts. Lymphocytes, monocytes and macrophages were found dispersed basally among the epithelial cells. Phagocytosis of epithelial cells undergoing apoptosis was seen throughout the UTJ at oestrus, increasing after insemination. Neutrophilic granulocytes were found in the lamina propia of the uterine component of the UTJ, but only occasionally in the epithelium. After insemination, neutrophils invaded the uterine epithelium, to actively participate in intraepithelial phagocytosis or move into the lumen, engulfing spermatozoa. Neutrophils were absent from the UTJ proper and the isthmic epithelium, irrespective of the presence of spermatozoa in the lumen. Those spermatozoa in the uterine lumen that escaped phagocytosis had severely damaged plasma membranes, whereas those in the UTJ proper — concentrated towards the deep furrows of the diverticulae — mostly showed normal sperm ultrastructure.

Influence of season, age, breed and some other factors on the variation in sperm morphological abnormalities in Swedish dairy A.I. bulls

Abstract Fifty-two dairy A.I. bulls aged from 14 months to 6 and a 1 2 years old were used to study the effects of age, breed, season and, dehorning and dihydrostreptomycin treatments on the incidence of sperm morphological abnormalities in fresh semen. The highest mean value of sperm abnormalities was recorded for abnormal heads (6.1%), but most of the recorded abnormalities only occurred in approximately 1–2% of the studied spermatozoa. Significant seasonal variation occurred in the incidences of sperm head abnormalities and total sperm abnormalities. Least-squares means for sperm abnormalities were significantly higher during the warmer seasons (spring, summer) compared with the colder ones (autumn, winter). The incidence of sperm abnormalities (abnormal heads, proximal droplets, total abnormalities) was relatively constant over time within bull (repeatability estimates varied between 0.36 and 0.54), but was significantly affected by age (abnormal heads and acrosomes, total abnormalities) and breed (abnormal heads, detached heads). The incidence of total sperm abnormalities was also found to be significantly increased in semen from a group of bulls submitted to both dehorning and double injections of dihydrostreptomycin (DHS) when comparing pre- and posttreatment periods. The results indicate that age, breed and seasonal effects as well as repeated stressful treatments influence the sperm characteristics and must be considered when evaluating bulls for sperm morphological traits.

Postweaning grouped sows: effects of aggression on hormonal patterns and oestrous behaviour

Abstract The concentration of cortisol, oestradiol-17β, prolactin and the amount of social behaviour shown during oestrus were measured in three groups of three sows (Swedish Landrace×Swedish Yorkshire) grouped after weaning and correlated with aggressive behaviour. No relations between the amount of aggression received and any of the hormone levels were found. In contrast, the frequency and characteristics of the oestrous behaviour were related to the amount of received aggression; the sows that received the highest amount of aggression showed significantly less social behaviour during oestrus compared with the other sows.