Post-mortem examination of genital organs from sows with reproductive disturbances in a sow-pool

General and comparative aspects of endometritis in domestic species: A review

Endometritis is a leading cause of sub- and infertility in domestic animal species. The healthy uterus is colonized by commensal bacteria, viruses and yeast/fungi that represent the nonpathogenic microbiota. A shift in the number or type of organisms accompanied by immune dysfunction, however, may trigger uterine infection and inflammation. Metritis is associated with inflammation of all uterine layers (endometrium, myometrium and perimetrium), whereas endometritis is a more superficial inflammation involving solely the endometrium. Endometritis generally occurs at two time points in domestic animal species, postpartum and postmating. Postpartum endometritis may chronically persist, either as a low-grade disease that often manifests as a vaginal discharge but not a systemic illness (in some species termed clinical endometritis) or sometimes subclinical where features are only detected by endometrial sampling. Contamination of the uterus at the time of mating occurs by direct deposition of semen (ejaculated or artificially inseminated) into the uterus. Improper drainage of the ejaculatory fluid or an inadequate immune response may result in persistent mating-induced endometritis. Both postpartum and postmating endometritis interferes with fertility by creating a suboptimal environment for embryo development and placentation, and chronic endometritis may have an impact on sperm survival and fertilization ability. In the postpartum animal, there may also be changes in milk production and maternal behaviour, which can affect offspring health and survival. Preventive strategies for endometritis largely depend on monitoring their known risk factors, which are sometimes specific with regard to the species. Effective, nonantibiotic therapy for endometritis is not available to date. Overall, extensive research has been performed in cattle and horses to unravel key aspects of endometritis, but in sows and bitches, the available literature is scant. Thus, the need and opportunity to investigate the condition vary considerably among domestic species and necessitate their comparative assessment. This article reviews general and comparative aspects of the diagnosis and classification, pathogenesis, preventive strategies and therapeutics of endometritis in domestic species with a specific focus on cows, mares, sows and bitches.

Longitudinal Projection of Herd Prevalence of Influenza A(H1N1)pdm09 Virus Infection in the Norwegian Pig Population by Discrete-Time Markov Chain Modelling

In order to quantify projections of disease burden and to prioritise disease control strategies in the animal population, good mathematical modelling of infectious disease dynamics is required. This article investigates the suitability of discrete-time Markov chain (DTMC) as one such model for forecasting disease burden in the Norwegian pig population after the incursion of influenza A(H1N1)pdm09 virus (H1N1pdm09) in Norwegian pigs in 2009. By the year-end, Norway's active surveillance further detected 20 positive herds from 54 random pig herds, giving an estimated initial population prevalence of 37% (95% CI 25-52). Since then, Norway's yearly surveillance of pig herd prevalence has given this study 11 years of data from 2009 to 2020 to work with. Longitudinally, the pig herd prevalence for H1N1pdm09 rose sharply to >40% in three years and then fluctuated narrowly between 48% and 49% for 6 years before declining. This initial longitudinal pattern in herd prevalence from 2009 to 2016 inspired this study to of test the steady-state discrete-time Markov chain model in forecasting disease prevalence. With the pig herd as the unit of analysis, the parameters for DTMC came from the initial two years of surveillance data after the outbreak, namely vector prevalence, first herd incidence and recovery rates. The latter two probabilities formed the fixed probability transition matrix for use in a discrete-time Markov chain (DTMC) that is quite similar to another compartmental model, the susceptible-infected-susceptible (SIS) model. These DTMC of predicted prevalence (DTMCP) showed good congruence (Pearson correlation = 0.88) with the subsequently observed herd prevalence for seven years from 2010 to 2016. While the DTMCP converged to the stationary (endemic) state of 48% in 2012, after three time steps, the observed prevalence declined instead from 48% after 2016 to 25% in 2018 before rising to 29% in 2020. A sudden plunge in H1N1pdm09 prevalence amongst Norwegians during the 2016/2017 human flu season may have had a knock-on effect in reducing the force of infection in pig herds in Norway. This paper endeavours to present the discrete-time Markov chain (DTMC) as a feasible but limited tool in forecasting the sequence of a predicted infectious disease's prevalence after it's incursion as an exotic disease.

Streptococcus suis in Swedish grower pigs: occurrence, serotypes, and antimicrobial susceptibility

BACKGROUND

Streptococcus suis is a major cause of meningitis, arthritis, and pneumonia in pigs worldwide, and an emerging pathogen in humans. In Sweden, S. suis has previously received little attention but has in recent years become increasingly recognized as affecting the pig production. The aim of the present study was to investigate the occurrence, serotypes and antimicrobial susceptibility of S. suis in Swedish grower pigs from herds with and without reported S. suis associated disease, as well as possible associations between S. suis associated disease and selected environmental and production factors. Swab samples were taken from the tonsils of clinically healthy 8-13-week-old grower pigs from ten case herds and ten control herds. Isolates were cultured, identified using MALDI-TOF MS, and serotyped using latex agglutination. The antimicrobial susceptibility of 188 isolates was tested using broth microdilution. Production data was gathered and environmental parameters were measured on the farms.

RESULTS

Streptococcus suis was isolated from 95% of the sampled pigs in both the case and the control herds. Serotypes 3, 4, 5, 7, 9, 10, 11, 15, 16, and 17-34 were detected, although a majority of the isolates (81.5%) were non-typeable. There was less diversity among the serotypes isolated from the case herds than among those from the control herds; four and nine different serotypes, respectively. Isolates resistant to penicillin (3.8%) were reported for the first time in Sweden. Tetracycline resistance was common (88.4%). No association was noted between the production and the environmental factors investigated, and the carriership of S. suis.

CONCLUSIONS

The carriership of S. suis was found to be higher in clinically healthy Swedish pigs than previously estimated, and for the first time, the presence of Swedish isolates resistant to penicillin was reported. Many of the most commonly disease-associated serotypes, e.g. serotypes 2, 9, 3, and 7, were detected in healthy grower pigs although further studies are needed to investigate the virulence of these isolates.

Lectin histochemical pattern on the normal and cystic ovaries of sows

The lectin histochemical pattern (LHP) was characterized and compared in normal and cystic ovaries of sows. Six biotinylated lectins (PNA, SBA, WGA, RCA-1, DBA and UEA-1) were used on tissue sections. In the normal ovaries, the reaction to UEA-1 and SBA was mild to moderate in mesothelial and endothelial cells. RCA-1 staining was mild to moderate in theca interna of growing follicles, corpora luteum and mesothelium. In addition, this lectin presented strong reaction in endothelial cells, granulosa cells of atretic follicles, zona pellucida of growing follicles and plasma. DBA showed strong intensity in mesothelial and endothelial cells. There was mild to moderate reactivity to WGA in granulosa cells, corpus luteum and theca interna of follicles in development, and moderate in zona pellucida, in granulosa cells of atretic follicles and mesothelium. PNA staining was mild to moderate in oocytes and in the adventitia and media of medullary arteries. Changes in the LHP of the cystic ovaries were noted; however, there were no differences in these findings between the follicular and luteinized cysts. UEA-1 reactivity in the cystic ovaries was moderately reduced in the mesothelial and endothelial cells, whereas there was mild reduction in the DBA staining in the granulosa cells. Reaction to RCA-1 and WGA in the cysts also was decreased in theca interna, zona pellucida and granulosa cells of atretic follicles. Furthermore, endothelium and theca interna in the cystic ovaries presented mild reduction of marcation to SBA, whereas there was decreased reactivity to PNA in the oocytes and adventitia and media layers of the medullary arteries. The results of the current study show that cysts modify the LHP in swine ovaries. These changes of glycoconjugates in many ovarian structures could modify diverse process and may be one of the reasons for decreased fertility in sows.

Animal welfare aspects in respect of the slaughter or killing of pregnant livestock animals (cattle, pigs, sheep, goats, horses)

This scientific opinion addresses animal welfare aspects of slaughtering of livestock pregnant animals. Term of Reference (ToR) 1 requested assessment of the prevalence of animals slaughtered in a critical developmental stage of gestation when the livestock fetuses might experience negative affect. Limited data on European prevalence and related uncertainties necessitated a structured expert knowledge elicitation (EKE) exercise. Estimated median percentages of animals slaughtered in the last third of gestation are 3%, 1.5%, 0.5%, 0.8% and 0.2% (dairy cows, beef cattle, pigs, sheep and goats, respectively). Pregnant animals may be sent for slaughter for health, welfare, management and economic reasons (ToR2); there are also reasons for farmers not knowing that animals sent for slaughter are pregnant. Measures to reduce the incidence are listed. ToR3 asked whether livestock fetuses can experience pain and other negative affect. The available literature was reviewed and, at a second multidisciplinary EKE meeting, judgements and uncertainty were elicited. It is concluded that livestock fetuses in the last third of gestation have the anatomical and neurophysiological structures required to experience negative affect (with 90-100% likelihood). However, there are two different possibilities whether they perceive negative affect. It is more probable that the neurophysiological situation does not allow for conscious perception (with 66-99% likelihood) because of brain inhibitory mechanisms. There is also a less probable situation that livestock fetuses can experience negative affect (with 1-33% likelihood) arising from differences in the interpretation of the fetal electroencephalogram, observed responses to external stimuli and the possibility of fetal learning. Regarding methods to stun and kill livestock fetuses at slaughter (ToR4), sets of scenarios and respective actions take account of both the probable and less probable situation regarding fetal ability for conscious perception. Finally, information was collated on methods to establish the dam's gestational stage based on physical features of livestock fetuses (ToR5).

Parturition effects on reproductive health in the gilt and sow

In this review, we address significant characteristics of parturition in the pig and their connection to post-partum reproductive health and fertility. We discuss the normal physiology and behaviour around parturition and the effect of the second phase (expulsion of foetuses) on the third phase of parturition (expulsion of foetal membranes). In addition, we intend to cover retained placenta, and the connection to post-partum uterine health and fertility in the contemporary prolific sow. We also explore factors that support successful parturition or can cause potential problems. Successful parturition in the pig includes the possibility to express adequate maternal behaviour, rapid expulsion of the piglets, complete expulsion of the placenta, neonatal activity and colostrum intake. Abnormal incidents during any phase of parturition can cause subsequent problems. Duration of the expulsion phase of foetuses can be used as a simple measure of whether parturition is considered successful. Prolonged parturition can impair health of the sow and piglet and fertility after weaning. New insights, such as adding more fibre to sow diets during pregnancy, and especially during the period prior to farrowing, may prevent constipation, increase water intake of the sow around parturition and increase milk intake and performance of piglets. Maternal characteristics, including maternal behaviour, ease of parturition, colostrum production and piglet quality parameters, may be utilized to improve success rate of reproductive management during farrowing and early lactation. Additionally, we share some of the recent developments in methods, including ultrasonography in evaluation of post-partum uterine health. In conclusion, successful farrowing is of the greatest importance for reproductive health of the sow and survival of the piglets. We suggest connections exist among prolonged farrowing and yield of colostrum, retained placenta, development of PDS, and impaired involution of the uterus and reduced subsequent fertility.

Occurrence and spread of influenza A(H1N1)pdm09 virus infection in Norwegian pig herds based on active serosurveillance from 2010 to 2014

The incursion of influenza A(H1N1)pdm09 virus was detected by Norway's active serosurveillance of its pig population in 2009. Since then, surveillance data from 2010 to 2014 revealed that 54% of 5643 herd tests involving 1567 pig herds and 28% of 23 036 blood samples screened positive for antibodies against influenza A virus. Positive herds were confirmed to have influenza A(H1N1)pdm09 virus infection by haemagglutination inhibition test. In 50% of positive herd tests, ⩾60% of the sampled pigs in each herd had antibodies against influenza A(H1N1)pdm09 virus. This within-herd animal seroprevalence did not vary for type of production, herd size or year of test. The overall running mean of national herd seroprevalence, and annual herd incidence risks fluctuated narrowly around the means of 45% and 32%, respectively, with the highest levels recorded in the three densest pig-producing counties. The probability of a herd being seropositive varied in the five production classes, which were sow pools, multiplier herds, conventional sow herds, nucleus herds, and fattening herds in descending order of likelihood. Large herds were more likely to be seropositive. Seropositive herds were highly likely to be seropositive the following year. The study shows that influenza A(H1N1)pdm09 virus is established in the Norwegian pig population with recurrent and new herd infections every year with the national herd seroprevalence in 2014 hovering at around 43% (95% confidence interval 40–46%).

Relationship between the concentration of bone morphogenetic protein-15 (BMP-15) and growth differentiation factor-9 (GDF-9) in pre-ovulatory follicles, ovarian cysts and serum in sows

The aim of the study was to compare and assess the relationship between peripheral and ovarian bone morphogenetic protein-15 (BMP-15) and growth differentiation factor-9 (GDF-9) concentration in cysts-bearing and non-cysts-bearing sows. The research involved multiparous sows (cysts-bearing sows, n = 20; non-cysts-bearing sows, n = 26). Serum, cystic follicular fluid or fluid from the ovulatory follicles was collected from each of the sows at the time of the slaughter. The collected serum and cystic/follicular fluid samples were tested for BMP-15 and GDF-9 concentrations. BMP-15 and GDF-9 concentrations in fluid from ovarian cysts were significantly higher than in the follicular fluid (P < 0.01). The concentration of BMP-15 and GDF-9 in the serum of sows with cysts was also higher than in ovulating sows (P < 0.05 and P < 0.01, respectively). The concentration of BMP-15 in serum was positively correlated with the concentration of said protein in pre-ovulatory follicles and cysts (r = 0.70; P < 0.01 and r = 0.50; P < 0.05, respectively). A positive correlation was also found between the concentration of serum GDF-9 and cyst GDF-9 (r = 0.55; P < 0.05). Moreover, another positive correlation was detected between the BMP-15 and GDF-9 concentrations, with the highest correlation coefficient recorded in the cyst fluid (r = 0.87; P < 0.01). This study for the first time demonstrates the presence of BMP-15 and GDF-9 in the cyst fluid in sows and determines a positive correlation between the concentration of the above factors in the follicular/cystic fluid and serum. Therefore, it is possible that the determination of BMP-15 and GDF-9 serum concentration may assist diagnosing ovarian cysts in sows. However, it is suggested that further studies involving a more in-depth analysis of the role of BMP-15 and GDF-9 in the pathogenesis of ovarian cysts in pigs are needed.

Cytoskeletal proteins in the follicular wall of normal andcystic ovaries of sows

The expression of cytoskeletal proteins was evaluated immunohistochemically in 36 normal ovaries sampled from 18 sows and 44 cystic ovaries sampled from of 22 sows, was evaluated. All sows had history of reproductive problems, such as infertility or subfertility. The immunohistochemically stained area (IHCSA) was quantified through image analysis to evaluate the expression of these proteins in the follicular wall of secondary, tertiary, and cystic follicles. Cytokeratins (CK) immunoreactivity was strong in the granulosa cell layer (GC) and mild in the theca interna (TI) and externa (TE) of the normal follicles. There was severe reduction of the reaction to CK in the GC in the cystic follicles, mainly in the luteinized cysts. The immunoreactivity for vimentin was higher in the GC from normal and cystic follicles in contrast with the other follicular structures. In the luteinized cysts, the IHCSA for vimentin was significantly higher in TI and in both observed cysts, the labeling was more accentuated in TE. Immunohistochemical detection of desmin and α-SMA was restricted to the TE, without differences between the normal and cystic follicles. The results of the current study show that the development of ovarian cysts in sows is associated to changes in the expression of the cytoskeletal proteins CK and vimentin.

Ovarian activity and uterus organometry in delayed puberty gilts

About 30% of the total number of gilts selected for reproduction at the large breeding farm units in Vojvodina (Republic of Serbia) are culled due to prolonged pre-insemination anoestrus (estrus not detected until 8 mo of age). The aim of this study was to provide the answer to the following question: do the culling gilts reach cyclic ovarian activity at all? One hundred seventy five culled gilts in which external estrus manifestations were not detected by 8 mo of age were sacrificed and their reproductive organs were examined for determination of sexual maturity (ovaries exhibiting pre-ovulatory follicles 8 to 11 mm in diameter, corpora hemorrhagica, corpora lutea and corpora albicantia). Uterine weights and horn length were also determined. Functional ovaries were observed in 107 (61.1%) examined gilts, with 62 animals having one and 45 having two puberty ovarian cycles (57.9% and 42.1%, respectively). Pathomorphological changes which could result in prolonged pre-insemination anoestrus were not observed on the reproductive organs of sexually mature gilts. Our results indicate that most of the culling gilts have reached cyclic ovarian activity. The main reason for culling due to the absence of external estrus manifestations in sexually mature gilts could be inadequate estrus detection technology.

Uterine insemination with a standard AI dose in a sow pool system

The effect of uterine AI with a standard dose of spermatozoa on fertility of the sow was studied in a field trial. The trial involved a sow pool system with 440 sows using AI as the primary method of breeding. Sows were twice a day checked for oestrus symptoms by back pressure test in front of a boar on days 3-6 after weaning. When in standing heat, sows were randomly allocated into either a uterine insemination group (UTER, n = 157) or standard AI group (CONT, n = 169) and bred accordingly using 3 billion spermatozoa in 80 ml of extender. In both treatment groups, insemination was repeated once if the sow was still receptive 24 h later. Using pregnancy (farrowed or not) and live-born litter size as the outcome variables, a logistic and linear regression approach, respectively, was taken to study the effect of the following factors: treatment (UTER vs CONT), AI operator, breed, satellite herd preceding weaning, parity, weaning-to-oestrus interval and length of lactation. Overall, live-born litter size was 11.3 +/- 2.9, repeat breeding rate 4.2% and farrowing rate 91.2%. In the UTER group, 93.6% of inseminated sows farrowed, whereas farrowing rate for the CONT group was 88.8% (p = 0.13). Intrauterine insemination with a standard AI dose did not result in a significant improvement in the live-born litter size (11.5 +/- 2.8 for the UTER and 11.1 +/- 3.0 for the CONT sows, respectively, p = 0.13). However, the preceding satellite herd had a highly significant effect on the live-born litter size (12.4 +/- 2.6; 11.1 +/- 2.9; 10.8 +/- 2.9 and 10.9 +/- 2.9 for the four satellite herds, p < 0.01). We conclude that uterine insemination did not have a significant effect on live-born litter size and farrowing rate and we also conclude that satellite herd appears to have a major effect on fertility in a sow pool system.

Relationships among specific reasons for culling, reproductive data, and gross morphology of the genital tracts in gilts culled due to reproductive failure in Thailand

The present study aims to investigate genital organs of replacement gilts culled due to reproductive failure, and the relationship between gross morphological findings and historical reproductive data. The study was conducted from July 2005 to September 2006 and included a random sample of 200 genital organs from six swine herds in Thailand. Historical data and the reasons for culling were analyzed. Gross morphological examinations focused on the normality and abnormalities of the ovaries, as well as the remainder of the reproductive tract. Descriptive statistics and frequency analysis were conducted for all reproductive parameters. On average, the gilts were culled at 321.2+/-51.1d of age, at a body weight of 145.3+/-24.2kg. Gilts expressed first estrus at 253.2+/-32.7d and were artificially inseminated for the first time at 268.2+/-30.8d of age. The interval from entry to culling averaged 96.9+/-53.7d. Reasons for culling included anestrus (44.0%), vaginal discharge (20.5%), repeat breeding (15.5%), not being pregnant (10.0%), and miscellaneous causes (10.0%). Overall, 50.5% of gilts had normal genital organs, whereas 49.5% had at least one abnormality. Abnormalities of the ovary, oviduct, uterus, cervix and vagina-vestibule were found in 15.5%, 14.0%, 22.0%, 16.2%, and 17.6% of the gilts, respectively. The most common post-mortem abnormalities included endometritis (14.0%), cystic ovaries (10.5%) and congenital abnormalities of the reproductive tract (8.0%). Of the gilts culled due to anestrus, 52.2% were pre-pubertal. Most of the gilts culled due to vaginal discharge or repeat breeding had been cycling (90.2% and 96.8%, respectively).

Feeding sows with high fibre diet around farrowing and early lactation: impact on intestinal activity, energy balance related parameters and litter performance

The effects of fibre in diets for periparturient sows are poorly documented. Three weeks before farrowing, 41 sows (LACT) were fed a diet containing 3.8% crude fibre. Other 40 sows (FIBRE) received a diet containing 7% crude fibre. We estimated the intestinal activity of the sows with a daily qualitative evaluation of their faeces. The FIBRE group had a qualitative faeces score value of 2.1+/-1.3 and the LACT group had a value of 1.2+/-1.1 (P<0.001). Individual daily water consumption was higher in the FIBRE group than in the LACT group (P<0.001). Piglet weight gain at day 5 was higher in the FIBRE group (P<0.05). The energy balance related parameters did not differ between the treatments. Concluding, diets containing more fibre can be successfully used around farrowing reducing prolonged constipation of sows with no negative effect on their energy balance related parameters.

The association between growth rate, body weight, backfat thickness and age at first observed oestrus in crossbred Landrace x Yorkshire gilts

The present study aims to investigate the association between growth rate (GR), body weight (BW), backfat thickness (BF) and age at first observed oestrus in crossbred Landrace x Yorkshire (LY) replacement gilts in the tropics. The study was carried out on five commercial swine herds in Thailand between 2004 and 2006. A total of 6946 LY gilts were included. The gilts entered the herd at about 163 days of age. The BW (kg) and BF (mm) of the gilts were measured when the gilts entered the gilt pools and again when the gilts were sent to the breeding house. The GR from birth to entry into the gilt pools (birth to 90 kg BW) (GRe), the GR from entry into to exit from the gilt pools (91-134 kg BW) (GRi) and the GR from birth until the gilts were sent to the breeding house (birth to 134 kg BW) (GRs) were calculated. The relationship between age at first observed oestrus and GRe, GRs, GRi, BW and BF were analyzed. Pearson's correlation and four general linear models (GLMs) were conducted. On average, the gilts showed first observed oestrus at 200+/-28 days of age. The means of age at first observed oestrus varied from 188 to 251 days (P<0.001) among the herds. The GRs of the gilts significantly correlated with the BW (r=0.55, P<0.001) of the gilts when they were sent to the breeding house and the age at first observed oestrus (r=-0.40, P<0.001). Gilts with a high GRe and GRs were younger at first observed oestrus compared to gilts with a low GRe and GRs. On average, the gilts with GRs of over 604 g/day showed first observed oestrus before 5 months of age. GRi was not correlated with the age at first observed oestrus (P>0.05). Neither the BF of the gilts at entry nor the BF that the gilts gained within the gilt pools significantly correlated with age at first observed oestrus (P=0.29 and P=0.69, respectively). But the gilts with a higher BF at entry tended to have a higher BW when they were sent to the breeding house (r=0.44, P<0.001). The present study indicates that replacement gilts with a high GR (both GRe and GRs) tend to show sign of oestrus earlier than gilts with a low GR (both GRe and GRs).

A descriptive survey of lesions from cull sows harvested at two Midwestern U.S. facilities

Physical and reproductive conditions of cull sows (3158) from two U.S. Midwestern harvest plants were assessed. Body condition, feet, shoulders, teeth, lungs, and reproductive tracts were visually evaluated for gross lesions on harvested sows. PROC FREQ (SAS, Cary, NC) was used to calculate the frequency of each binary trait event. Pearson chi-square tests were used to test the alternative hypothesis that a linear association existed between binary traits and body condition score (BCS). The most common foot lesions observed were rear (n=2064, 67.5%) and front (n=1024, 32.9%) heel lesions. Cracked hooves were found on the front feet of 703 (22.6%) and rear feet of 552 (18.1%) sows. Rear digital overgrowth was observed in 644 (21.1%) sows. The most common reproductive gross lesion observed among harvested cull sows was acyclic ovaries (n=277, 9.0%). Presence of acyclic ovaries increased (p<0.01) as BCS decreased. Cystic ovaries were found in 192 (6.3%) sows, which increased (p<0.01) as BCS increased. Pneumonia was observed in 298 (9.7%) sows, and increased in frequency as BCS decreased (p<0.01). The most frequently observed shoulder lesion among harvested cull sows was shoulder abrasions (n=394, 12.5%). The presence of shoulder abrasions increased (p<0.01) as BCS decreased. The prevalence of reproductive lesions detected in the present study was less than the reported percentage of sows culled for reproductive failure from previous studies based on record keeping summaries.

Post-mortem Examination of Sows Genital Organs Culled for Reproductive Disturbances and Immunohistochemical Studies on ER? and PR A Receptors in the Anoestral Sows Uterus

The aim of present study was post-mortem examination of ovaries, uterus and plasma oestradiol-17beta (E2) and progesterone (P4) concentrations in the blood of sows with reproductive disturbances and the distribution of oestradiol receptor (ERalpha), as well as progesterone (PR-A) in the anoestrous sows uteri. Reproductive organs of 150 crossbred sows (Lithuanian White x Danish Landrace) culled for the reasons of reproductive disturbances, were collected in local abattoir over a period of 3 months (September-November). Organs were assessed to determine the stage of the oestrous cycle or anoestrus and their development. Blood samples were collected for E2 and P4 analysis from the jugular vein 1 h prior to slaughter. For this study uterine samples only from pathological anoestrous sows were subjected to immunohistochemical staining to assess the distribution of ERalpha and PR-A in surface epithelium, subepithelial connective tissue, glandular epithelium and myometrium. Macroscopic examination of the ovaries showed that 68.7% sows had active cycling ovaries, 26.6% sows were anoestrus, ovaries were small without CL, and 4.7% of sows had multiple follicular cysts. In anoestrous sows (n = 27) the number and intensity of the nuclear staining of ERalpha varied between different uterine tissue compartments. The highest number (>80%) and the strongest intensity (+++) of positively stained cells for ERalpha was seen in myometrium and glandular epithelium. In other uterine wall compartments the number and intensity of positively stained for ERalpha nuclei was lower (+/++). The PR-A was absent from all tissue compartments. The intensity of the nuclear staining for ERalpha varied not only between the different uterine compartments but also between the sows. The 11.1% of the sows presented ERalpha in surface epithelium, 74.1% of the sows in glandular epithelium and 63.0% of sows in the myometrium.

An update on the use of B-mode ultrasonography in female pig reproduction

After technological advances allowed for the adaptation of B-mode ultrasonography equipment for use in pig facilities, ultrasonography quickly established itself as an ideal diagnostic aid for determining pregnancy status in pigs. In recent years, B-mode ultrasonography has found increased application in its use for monitoring ovarian activity and in estimating time of ovulation in pigs. B-mode ultrasonography is also valuable in providing a detailed assessment of the sow's ovaries and uterus to determine if pathological conditions exist, which could be contributing to poor individual or herd reproductive performance. In its most recent application in pigs, the gilt genital tract has been characterized peripubertally by ultrasonography in order to detect onset of puberty. The purpose of this review is to provide an update on the current status of B-mode ultrasonography in pig reproduction, and how this technology can be of value when used in pig production medicine.

Factors affecting fertility in loosely housed sows and gilts: vulvar discharge syndrome, environment and acute-phase proteins

The effect of vulvar discharge syndrome (VDS) on sow and gilt fertility was studied on 26 farms. Of 824 animals inspected in 21 randomly selected and five VDS problem farms, 19 (2.3%) were afflicted with VDS. Altogether 542/799 of the examined animals (67.8%) farrowed thereafter. Nine of the 19 VDS animals (47.4%) and 533/780 non-VDS animals (68.3%) farrowed at the first chance after the examination (p = 0.05). None of the unmated gilts in this study had VDS. Environmental and individual factors likely to be associated with fertility and VDS were tested. In multivariate analysis, factors associated with farrowing were VDS, reproductive status, availability of roughage and confinement to individual stalls. None of the variables tested was associated with VDS. However, all of the VDS problem farms were overcrowded and had concrete, partly slatted floors with little or no bedding. The median value of haptoglobin (Hp) was 2.5 (range 1.3-3.1) g/l in VDS animals and 2.3 (0.5-4.3) g/l in controls (p = 0.6). The median C-reactive protein (CRP) in VDS animals was 30.3 (3.3-171.3) mg/l and in controls 25.9 (3.3-361.1) mg/l (p = 0.7). In conclusion, VDS decreased fertility of gilts and sows in the absence of a systemic acute-phase response, as indicated by stable concentrations of Hp and CRP.

The endometrium of the anoestrous female pig: studies on infiltration by cells of the immune system

The aim of this study was to investigate the distribution of immune cells in the endometrium of anoestrous female pigs, five sows in anoestrus by lactation and five pre-pubertal gilts (Swedish Landrace x Swedish Yorkshire). Uterine samples, taken immediately after slaughter, were fixed, embedded in plastic resin and stained with toluidine blue or cryo fixed and stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method. Immune cells in the surface (luminal) and the glandular epithelium as well as the subepithelial and the glandular connective tissue layers were counted using light microscopy. In the surface (luminal) and the glandular epithelia of gilts and sows, lymphocytes were the predominant immune cells found. There were no significant differences between gilts and sows. Macrophages were detected in the glandular epithelium of sows but not in gilts. In the subepithelial and the glandular connective tissue layers of both gilts and sows, lymphocytes were also the most common immune cells found. The numbers of lymphocytes and macrophages were significantly higher in the sows than in the gilts (p <or= 0.05) in both the layers of connective tissue. Numbers of plasma cells, mast cells, eosinophils and neutrophils in the connective tissue were low and not significantly different between sows and gilts. In both the surface (luminal) epithelium and the subepithelial connective tissue, higher numbers of CD2 than CD3 positive cells were found (p <or= 0.01). The numbers of CD2 positive cells in both epithelium and connective tissue and the number of CD3 positive cells in the epithelium were significantly higher in the sows than the gilts (p <or= 0.05). A few CD79 positive cells were found in the subepithelial connective tissue and none in the epithelia. A few CD14 and SWC3 positive cells were found in the epithelia. The numbers of CD14, SWC3 and MHC class II positive cells were significantly higher in the sows than in the gilts (p <or= 0.05) in the subepithelial connective tissue. In conclusion, the distribution of immune cells in the endometrium of anoestrous female pigs was affected by experienced pregnancy and parturition. In sows with lactation-induced anoestrus, there was a markedly higher cell infiltration (lymphocytes and macrophages) than in the pre-pubertal gilts. In pre-pubertal gilts, lymphocytes dominated, which indicates a role in the maturation of the endometrium.

A field study into the appropriateness of transcutaneous ultrasonography in the diagnoses of uterine disorders in reproductively failed pigs

This study was conducted to define the characteristics of the uterus of reproductively failed pigs by transcutaneous ultrasonography (SONO) in order to investigate the appropriateness of SONO to diagnose presumptive uterine disorders. Zearalenone (ZEA) is known to affect uterine function and causes endometrial liquid accumulation and was also determined. In 33 sows and 14 gilts, of unknown reproductive stages and culled for failing to conceive, the uterus was scanned transcutaneously and the females slaughtered on the same day or the day after scanning. Parameters determined by SONO were uterine echotexture (UET; graded 1 for homogeneous to 4 for highly heterogeneous), uterine size (US; expressed as the mean sectional area of two to three cross-sections of the uterine horns given in cm2) and intrauterine content. Post mortem, the ovarian structures were assessed and females grouped accordingly into those in estrus (n=2), early diestrus (n=14), diestrus (n=15), late diestrus (n=1), anestrus (n=10) and having polycystic ovarian degeneration (n=5). The uterine weight (UW) was recorded and uterine specimens microscopically evaluated for an endometrial oedema (EO; grades 1 for none, to 4, if an oedema was clearly evident) and for immune cells to assess endometritis. Total ZEA was analysed in bile and females with >or=50 ng/ml judged as positive. The uterus could be examined in all animals. UET, US, UW and EO was found to be different between groups, and a positive correlation (P<0.001) established for US and UET (r=0.71), US and EO (r=0.51), UET and EO (r=0.57), US and UW (UW=357.6 x US(0.801); r=0.88). One female had intrauterine fluid and an acute-chronic endometritis diagnosed. Almost all females had a chronic endometritis and a majority found ZEA positive. No differences were observed between groups and a relationship between ZEA or chronic endometritis and UET, US, UW and EO were not established. In conclusion, transcutaneous SONO is appropriate to examine the uterus in reproductively failed pigs on farms, and the estimation of UET and US gives information on EO and UW. Intrauterine fluid is indicative for a severe uterine inflammation. Since groups differed in UET and US, but were equally ZEA positive and the uteri chronically inflamed, an UET and US specifically associated with ZEA or chronic endometritis is questioned.

The Effect of Post-ovulatory Insemination on the Subsequent Embryonic Loss, Oestrous Cycle Length and Vaginal Discharge in Sows

The aim of present study was to study the effect of post-ovulatory insemination on the subsequent embryonic loss, oestrous cycle length and vaginal discharge in sows. Ten Large White multiparous sows were divided into two groups. Group A sows were inseminated once at 15 h after ovulation. Thereafter, they were ovariohysterectomized on day 11 (n = 5, first day of standing oestrus = day 1) and flushed for recovery of embryos. Group B sows were also inseminated once at 15 h after ovulation. They were further observed for return to oestrus and vaginal discharge (n = 5) after insemination. The endometrium tissues were biopsied from sows with vaginal discharge, embedded with paraffin, stained with haematoxylin and eosin and examined under light microscope. Only two embryos were observed in one of four sows from group A. All embryos had a spherical shape but differed in size (range 1-2 mm). In group B, only one sow had a regular return to oestrus (i.e. on day 23) and another sow had an irregular return to oestrus (i.e. on day 27). The other two sows in this group had shown vaginal discharge on days 20 and 38 after standing oestrus. For the number of leucocytes in the endometrium of sows with vaginal discharge, a large number of lymphocytes and plasma cells were observed in the connective tissue of the subepithelial layer. In conclusion, post-ovulatory insemination resulted in early embryonic loss, a subsequent prolonged oestrus interval and also vaginal discharge (i.e. endometritis) in sows.

Immune cell infiltration of normal and impaired sow endometrium

The paper reviews the physiological infiltration of immune cells, leukocytes, in the sow endometrium during different stages of the normal oestrous cycle, after mating and during early pregnancy. The mechanisms for development of endometritis in relation to oestrous cycle stages are also described.

Association between endometritis and urocystitis in culled sows

Slaughterhouse sampling and examination of urogenital tracts of 499 sows and gilts culled for reproductive reasons from 21 Hungarian herds were performed over a 6-year period. The aim was to estimate the prevalence of different urogenital tract lesions, and to provide sensitivity and specificity estimates for macroscopic and bacteriological examinations in the diagnosis of urocystitis and endometritis. Furthermore, the association between endometritis and urocystitis was assessed. The prevalence of main lesions of the urogenital tract was similar to that reported in other studies. The 'sensitivity' of macroscopic and bacteriological methods was determined statistically by taking histopathology as the 'Gold Standard'. As a result, the 'sensitivity' of macroscopic methods for the diagnosis of endometritis and urocystitis was < or = 18.1% and 47.9%, respectively, while the 'sensitivity' of bacteriology for the diagnosis of the same conditions was < or = 31.8% and 63.0%, respectively. The presumed positive association between urocystitis and endometritis was confirmed; it was not confounded by parity. Animals affected by urocystitis had a 3.5 times higher odds to simultaneously have endometritis than animals without urocystitis.

Corrigendum to "The sow endometrium at different stages of the oestrus cycle: studies on morphological changes and infiltration by cells of the immune system." [Anim. Reprod. Sci. 65 (2001) 95-114]

The aim of this study was to investigate the distribution of leukocytes and the morphological changes of the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4+/-0.7 (mean+/-S.D.) were used. Blood samples were collected from the jugular vein 1 h before slaughter for analyses of oestradiol-17beta and progesterone levels. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus, prooestrus, oestrus, early dioestrus and dioestrus, were fixed, embedded in plastic resin and stained with toluidine blue. The surface and glandular epithelium as well as subepithelial and glandular connective tissue layers were examined by light microscopy (LM). The significantly highest surface and the glandular epithelium were observed at oestrus and dioestrus, respectively. The largest number of capillaries (underneath the surface epithelium) was found at oestrus. In the surface epithelium, the largest number of intraepithelial lymphocytes (IELs, round nucleus) was found at early dioestrus. The largest number of lymphocytes and macrophages within the glandular epithelium were found at early dioestrus and oestrus, respectively. In the subepithelial connective tissue layer, the most common type of leukocytes during all stages was the lymphocyte. The largest numbers of lymphocytes and neutrophils were found at oestrus while the largest number of eosinophils was found at dioestrus. The dominating cells of the immune system in the connective tissue of the glandular layer were lymphocytes and macrophages. The significantly largest numbers of lymphocytes and plasma cells were found at early dioestrus and dioestrus, respectively. The number of lymphocytes in the connective tissue of the glandular layer and the number of plasma cells in the subepithelial layer were positively correlated with the plasma level of progesterone (P < or = 0.05). The numbers of capillaries and neutrophils in the subepithelial layer underneath the surface epithelium as well as the number of macrophages in both surface and glandular epithelium were positively correlated with the plasma level of oestradiol-17beta (P < or = 0.05). In conclusion, the present study showed a variation om the infiltration and distrobution of lymphocytes, neutrophils, eosinophils, macrophages, mast cells, and plasma cells in the sow endometrium during different stages of the oestrous cycle. Also morphological parameters (e.g. height of surface and glandular epithelium, capillaries density and degree of oedema) varied throughout the oestrous cycle.

Corrigendum to "The sow endometrium at different stages of the oestrous cycle: studies on the distribution of CD2, CD4, CD8 and MHC class II expressing" cells. [Anim. Reprod. Sci. 68 (2001) 99-109]

The aim of this study was to investigate the distribution of CD2(+), CD4(+), CD8(+) lymphocyte subpopulations and MHC class II expressing cells in the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4 +/- 0.7 (mean +/- S.D.) were used. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus (day 17, n = 3), prooestrus (day 19, n = 3), oestrus (day 1, n = 3), early dioestrus (day 4, n = 3) and dioestrus (days 11-12, n = 3), were stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method using monoclonal antibodies to lymphocyte subpopulations and MHC class II molecules. The surface and glandular epithelium as well as connective tissue layers in subepithelial and glandular areas were examined by light microscopy. For the T lymphocyte subpopulations, all oestrous cycle stages and different tissue layers taken together, the most commonly observed cell type was CD2(+) cells. The largest number of CD2(+) cells within the surface and glandular epithelium were observed at oestrus and early dioestrus. In the surface epithelium, a larger number of CD8(+) cells compared with CD4(+) cells were observed and no CD4(+) cells were found within the glandular epithelium at any stage of the oestrous cycle. In the subepithelial and glandular connective tissue layers, during the oestrus cycle stages, a larger number of CD4(+) cells compared with CD8(+) cells were found. Endothelial cells in the connective tissue generally expressed MHC class II. However, no obvious differences between oestrous cycle stages were observed. For other cells than endothelial cells, the result was as follows. In the surface epithelium, a large number of MHC class II expressing cells was observed at oestrus compared with the other stages. No MHC class II expressing cells were found at late dioestrus and dioestrus. MHC class II expressing cells were also found in the glandular epithelium, and in the subepithelial and glandular connective tissue layers during all oestrous cycle stages but with no significant differences between stages. In conclusion, the present study showed a variation in the distribution of T lymphocyte subpopulations (CD2(+), CD4(+) and CD8(+)) and MHC class II expressing cells in the sow endometrium during different stages of the oestrous cycle. Also a variation between different tissue layers was found. It is suggested that helper and cytotoxic function of the immune system have primary locations in different tissue layers of the endometrium.

The sow endometrium at different stages of the oestrous cycle: studies on the distribution of CD2, CD4, CD8 and MHC class II expressing cells

The aim of this study was to investigate the distribution of CD2+, CD4+, CD8+ lymphocyte subpopulations and MHC class II expressing cells in the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4+/-0.7 (mean+/-S.D.) were used. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus (day 17, n=3), prooestrus (day 19, n=3), oestrus (day 1, n=3), early dioestrus (day 4, n=3) and dioestrus (days 11-12, n=3), were stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method using monoclonal antibodies to lymphocyte subpopulations and MHC class II molecules. The surface and glandular epithelium as well as connective tissue layers in subepithelial and glandular areas were examined by light microscopy. For the T lymphocyte subpopulations, all oestrous cycle stages and different tissue layers taken together, the most commonly observed cell type was CD2+ cells. The largest number of CD2+ cells within the surface and glandular epithelium were observed at oestrus and early dioestrus. In the surface epithelium, a larger number of CD8+ cells compared with CD4+ cells were observed and no CD4+ cells were found within the glandular epithelium at any stage of the oestrous cycle. In the subepithelial and glandular connective tissue layers, during the oestrus cycle stages, a larger number of CD4+ cells compared with CD8+ cells were found. Endothelial cells in the connective tissue generally expressed MHC class II. However, no obvious differences between oestrous cycle stages were observed. For other cells than endothelial cells, the result was as follows. In the surface epithelium, a large number of MHC class II expressing cells was observed at oestrus compared with the other stages. No MHC class II expressing cells were found at late dioestrus and dioestrus. MHC class II expressing cells were also found in the glandular epithelium, and in the subepithelial and glandular connective tissue layers during all oestrous cycle stages but with no significant differences between stages. In conclusion, the present study showed a variation in the distribution of T lymphocyte subpopulations (CD2+, CD4+ and CD8+) and MHC class II expressing cells in the sow endometrium during different stages of the oestrous cycle. Also a variation between different tissue layers was found. It is suggested that helper and cytotoxic function of the immune system have primary locations in different tissue layers of the endometrium.

The sow endometrium at different stages of the oestrous cycle: studies on morphological changes and infiltration by cells of the immune system

The aim of this study was to investigate the distribution of leukocytes and the morphological changes of the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4 +/- 0.7 (mean +/- S.D.) were used. Blood samples were collected from the jugular vein 1h before slaughter for analyses of oestradiol-17beta and progesterone levels. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus, prooestrus, oestrus, early dioestrus and dioestrus, were fixed, embedded in plastic resin and stained with toluidine blue. The surface and glandular epithelium as well as subepithelial and glandular connective tissue layers were examined by light microscopy. The significantly highest surface and the glandular epithelium were observed at oestrus and dioestrus, respectively. The largest number of capillaries (underneath the surface epithelium) was found at oestrus. In the surface epithelium, the largest number of intraepithelial lymphocytes (IELs, round nucleus) was found at early dioestrus. The largest number of lymphocytes and macrophages within the glandular epithelium were found at early dioestrus and oestrus, respectively. In the subepithelial connective tissue layer, the most common type of leukocytes during all stages was the lymphocyte. The largest numbers of lymphocytes and neutrophils were found at oestrus while the largest number of eosinophils was found at dioestrus. The dominating cells of the immune system in the connective tissue of the glandular layer were lymphocytes and macrophages. The significantly largest numbers of lymphocytes and plasma cells were found at early dioestrus and dioestrus, respectively. The number of lymphocytes in the connective tissue of the glandular layer and the number of plasma cells in the subepithelial layer were positively correlated with the plasma level of progesterone (P < or = 0.05). The numbers of capillaries and neutrophils in the subepithelial layer underneath the surface epithelium as well as the number of macrophages in both surface and glandular epithelium were positively correlated with the plasma level of oestradiol-17beta (P < or = 0.05). In conclusion, the present study showed a variation in the infiltration and distribution of lymphocytes, neutrophils, eosinophils, macrophages, mast cells and plasma cells in the sow endometrium during different stages of the oestrous cycle. Also morphological parameters (e.g. height of surface and glandular epithelium, capillaries density and degree of oedema) varied throughout the oestrous cycle.