Dose related effects of LPS on endometrial epithelial cell populations from dioestrus cows

Lipopolysaccharides (LPS) from Gram negative bacteria are involved in the pathogeny of uterine diseases in cows. This study aimed to investigate LPS effects on the growth of bovine endometrial epithelial cells (bEEC) and relationships between LPS response and tissue characteristics. Uteri from 35 females were characterized for parity and stage of oestrous cycle. Densities of glandular tissue (dGT), CD11b+ cells and Ki67+ cells were measured in the endometrial tissue. Cells from 13 dioestrus cows were exposed to 0, 2, 4, 8, 12, 16 or 24μg/mL LPS. Effects of parity and stage of the oestrous cycle on tissue characteristics and effects of LPS dosage, cow and tissue characteristics on changes in cell numbers were analyzed by ANOVA. The dGT was higher in metoestrus and dioestrus samples than in pro-oestrus ones whereas densities of CD11b+ and Ki67+ cells were higher at pro-oestrus (p<0.05-p<0.01). LPS influenced bEEC populations in a dose related manner. An increase in number of live cells was observed for dosages ranging from 2 to 12μg/mL LPS (p<0.0001 vs controls). No effect was found on numbers and frequencies of dead cells. With higher dosages, the numbers of live cells did not increase but the numbers of dead did increase. No relationships were observed between cow or tissue characteristics and growth patterns or frequencies of viable bEEC in controls nor in the response to LPS. To conclude this model is suitable for further studies on dysregulations induced by LPS in endometrial tissue.

Influence of post-ovulatory insemination on sperm distribution, pregnancy and the infiltration by cells of the immune system, and the distribution of CD2, CD4, CD8 and MHC class II expressing cells in the sow endometrium

This study investigates the distribution of leucocytes, CD2+, CD4+, CD8+ lymphocyte subpopulations and MHC class II expressing cells in the sow endometrium following post-ovulatory insemination in relation to clinical findings and pregnancy outcome. Crossbred multiparous sows were inseminated once either at 15-20 h after ovulation [experiment 1, slaughtered at 20-25 h (5-6 h after artificial insemination (AI), group 1-A, n = 4), at 70 h after ovulation (group 1-B, n = 4), on day 11 (group 1-C, n = 4, first day of standing oestrus = day 1) or on day 19 (group 1-D, n = 4)] or 30 h after ovulation [experiment 2, slaughtered at 5-6 h after AI (group 2-A, n = 4) or on day 19 (group 2-D, n = 3)]. The uterine horns were flushed to control for the presence of spermatozoa and neutrophils and/or for recovery of oocytes and/or embryos. Mesometrial uterine samples were plastic embedded and stained. Cryofixed uterine samples were analysed by immunohistochemistry using mAbs to lymphocyte subpopulations and MHC class II molecules. Light microscopy was used to examine surface (SE) and glandular epithelia (GE), and connective tissue layers, both subepithelially (SL) and glandular (GL). In experiment 1, group 1-A, only one sow had spermatozoa in the utero-tubal junction (UTJ). Marked/moderated numbers of neutrophils and spermatozoa were observed in the flushings of two sows. In group 1-B, altogether 23 of 48 oocytes were cleaved. Day 11 (1-C), embryos with small diameter were observed. Day 19 (1-D), no embryos were found but small pieces of foetal membrane were observed in one of the sows. In group 1-A, large numbers of neutrophils were found within the SE and SL but with high individual variation. For T lymphocyte subpopulations, in the SE, most CD2+ cells were found in group 1-A. For both SE and GE in all groups, the number of CD8+ cells was significantly larger than that of CD4+ cells. In experiment 2, group 2-A, no sow had spermatozoa in the UTJ or in the uterine flushings. At day 19, no sow was pregnant. In group 2-A, large numbers of neutrophils were found within the SE and SL but with high individual variation. At day 19, high E2 levels showed a hormonal prooestrous stage but the endometrial neutrophil infiltration normally expected at pro-oestrus was absent. In conclusion, post-ovulatory insemination (about 18 h after ovulation) resulted in impaired spermatozoa transport within the uterus and embryonic degeneration. In sows post-ovulatory inseminated at a later stage (30 h after ovulation), no sow was pregnant. In both experiments, disturbed immune cell patterns were observed in some individuals.

Immunization against gnRH in mature mares: antibody titres, ovarian function, hormonal levels and oestrous behaviour

The aim of the present study was to investigate the effect of active immunization against GnRH in mature Standardbred mares (three experimental and one control mare) on antibody titres, ovarian function, hormonal levels and oestrous behaviour. The mares were individually teased with a stallion once each day. During the first part of the experiment (period I: late April until November), blood was sampled every third day during the first 3 months, thereafter once per week. In the second part of the experiment (period II: December until August), sampling was carried out every second week. Progesterone, oestradiol-17beta and LH were analysed. Rectal gynaecological examination was made with the same intervals as the blood samplings and included palpation of the genital organs and ultrasonography. The experimental mares were immunized against GnRH with a GnRH-BSA conjugate. Equimune (Vetrepharm, Bracetown, Business Park, Clonee, Co. Meath, Republic of Ireland) was used as adjuvant. The mares were immunized on four occasions (20-30 day intervals) and GnRH antibody titre was determined. All immunized mares produced antibodies against GnRH but the maximum titres as well as the duration of a greater than 10% binding capacity varied between the mares (1 : 1600 to 1 : 50 000; 5 to 12 months, respectively). After the first injection, all mares showed one oestrus and ovulated at the regular time. In two of the mares, the immunization resulted in ovarian atrophy. Their hormone levels of progesterone, oestradiol- 17beta and progesterone decreased to basal levels and the cyclical hormone pattern was interrupted from approximately 30 days onwards. They continued to show oestrous signs but with irregular durations and intervals. The third mare showed ovarian suppression only for short periods and not in both ovaries at the same time; the hormone levels were basal for only about 20 days (days 50-70) and the mare ovulated on day 75 after start of immunization. The other mares ovulated after 13.5 and 15 months, respectively. It is concluded that the effect of immunization against GnRH in mature mares was individual concerning antibody titre response and the suppression of ovarian activity and hormone levels. Mares with totally inactive ovaries continued to show oestrous signs but with irregular intervals and durations.

Study of the distribution of inflammatory cells in the sow endometrium: effect of intravenous administration of adrenocorticotropin hormone

Seventeen multiparous cross-bred sows (Swedish Land-race x Swedish Yorkshire) were inseminated in their second oestrus after weaning and divided into two groups. One group (ACTH, n = 9) was given an intravenous injection of adrenocorticotropin hormone (ACTH) every 6 h commencing 4-8 h after ovulation, whereas another group (control, n = 8) was given saline solution at the same times. The sows were slaughtered 35-53 h after ovulation. Uterine samples, taken from the mesometrial side of the uterine horns immediately after slaughter, were fixed, embedded in plastic resin and stained with toluidine blue. The endometrium was then examined by light microscopy. There was no significant effect of the ACTH treatment on the distribution of lymphocytes and macrophages, but there was a tendency of an effect on the distribution of neutrophils (P = 0.1) in the sow 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: immunohistochemical study on the distribution of SWC3-expressing cells (granulocytes, monocytes and macrophages)

Uterine samples from sows taken immediately after slaughter at late di-oestrus, pro-oestrus, oestrus, early di-oestrus and di-ocstrus, were analysed by immunohistochemistry with an avidinbiotin-peroxidase method using a monoclonal antibody (anti-SWC3) to granulocyte, monocyte and macrophage populations. The endometrium was then examined by light microscopy. In the surface and glandular epithelium, the largest numbers of SWC3-expressing cells (P < or = 0.01 and P < or = 0.05) were found at oestrus, and at pro-oestrus and oestrus, respectively. The numbers of SWC3-expressing cells in the epithelium were positively correlated with the plasma levels of oestradiol-17beta. In the connective tissue of the subepithelial and glandular layers, no significant effect of the oestrous Cycle stage was found on the number of SWC3-expressing cells. The present study showed a variation in the distribution of SWC3-expressing cells in the sow endometrium, especially in the surface and glandular epithelium, during different stages of the oestrous cycle.

Repeat breeding and subsequent reproductive performance in Swedish Landrace and Swedish Yorkshire sows

The objective of the present study was to analyse the association between repeat breeding (RB) in gilts/sows and their subsequent reproductive performance as well as the impact of interactions between repeat breeding and factors like parity number, boar breed, season and mating type (MT) on subsequent reproductive performance in Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed included 7040 sows (3654 L and 3386 Y), farrowing during January 1994 until December 1999 in 11 L and 8 Y nucleus herds. The study was assigned as a cohort design and the aim was to study gilts/sows from their first mating as gilts until mating after third parity. Analysis of variance was applied to continuous data and logistic regression was applied to categorical data. Percentages of litters as a result of repeat breeding in sow parities 1-3 were 6.1, 12.0 and 6.3% for L sows and 6.7, 13.1 and 7.4% for Y sows. For parity 3, the incidence of litters resulting from repeat breeding was significantly higher (P<0.001) in Y than in L sows. The proportion of irregular return to oestrus (>24 days after first mating) was higher (P<0.01) in primiparous sows than in multiparous sows (69% versus 61%). On average, litters resulting from repeat breeding were larger (P<0.001) than litters resulting from non-repeat breeding (NR) (about 0.5 piglets per litter) in both L and Y sows. For Y sows, if the previous litter was a result of repeat breeding, the subsequent reproductive cycle had 2.7% higher RR (P<0.05) and 2.4% lower FR (N.S.) compared with sows that were not repeat bred. The same trend was found in L sows (1.4% higher RR and 1.3% lower FR) but the differences were not significant. Among the sows removed from the herds, about 24% of L and 28% of Y were culled due to reproductive problems (gilts not included). In addition, a number of sows from these nucleus herds were also culled due to low breeding value and poor conformation.

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.

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.

Effect of GnRH immunisation on hormonal levels, sexual behaviour, semen quality and testicular morphology in mature stallions

The aim of this study was to investigate the effect of gonadotrophin-releasing hormone (GnRH) immunisation on mature stallions that had been used for breeding. Four Standardbred stallions were used in the study: 3 experimental animals and 1 control animal. Semen was collected regularly, i.e. twice/week, during the 4 months prior to the experimental period. The stallions were immunised against GnRH with a GnRH-BSA conjugate. Equimune was used as the adjuvant. The stallions were immunised on 5 occasions, 4 at 2 week intervals, and the fifth 4 weeks after the fourth. Blood samples were taken once a week for analysis of GnRH antibody titre and every third week for testosterone and oestrone sulphate analyses. Semen was collected once a week, and libido and sexual behaviour were observed. Ejaculate volume, sperm concentration, total number of sperm in the ejaculate, sperm motility and sperm morphology were evaluated. Testicular size was measured once a week. At the end of the study, the stallions were castrated, and a histological examination of the testes performed. All immunised stallions produced antibodies against GnRH, and plasma testosterone concentration decreased. However, the effect of immunisation varied between stallions. In 2 of the stallions, high levels of antibodies were found, while in the third, the level was moderate. Four weeks after the first immunisation, a decrease in libido was observed. Two months after the first immunisation, marked changes in semen quality were observed in the 2 stallions with high antibody titres. Fourteen weeks after the first immunisation, the total number of sperm/ejaculate had decreased from >8.6 x 10(9) to <2.7 x 10(9), sperm motility from >59 to <10% and the frequency of morphological normal spermatozoa had decreased from >60 to <14%. The dominating abnormalities were abnormal head shapes, proximal cytoplasmic droplets and detached heads. In the third stallion, only slight changes in semen quality were found. No changes were observed in the control stallion. Decreases in testicular size were noted in all of the experimental stallions. Pronounced histological alterations in the testes were observed in 2 of the stallions. It is concluded that the vaccine was effective in stimulating production of GnRH antibodies and in suppressing testicular function and androgen secretion. However, there was an individual variation in the responses among the stallions and, further, libido was not totally suppressed.

Effects of lactation length and weaning-to-service interval on subsequent farrowing rate and litter size in Landrace and Yorkshire sows in Thailand

The aim of the present study was to investigate the influence of lactation length (LL) on weaning-to-service interval (WSI), and the effect of LL and WSI on the subsequent farrowing rate and litter size among purebred Landrace and Yorkshire sows under tropical conditions. The variation in litter weight at weaning (LWW) was also studied. Data were analyzed from three purebred sow herds located in the central part of Thailand, including sows weaned during the period from January 1993 to December 1996. Data were analyzed with analysis of variance using SAS software. The procedure MIXED was used for analysis of the continuous outcome variables (namely LL, LWW, WSI, number of total born and number of live born piglets). The GLIMMIX macro was used for analysis of the categorical outcome variable, farrowing rate (FR). In the statistical analyses, WSI was grouped into 7 groups, when it was an independent variable, as follows: 1 to 4, 5, 6, 7, 8, 9, to 10, and 11 to 21 days. Lactation length was grouped into 4 groups as follows: 17 to 24, 25 to 27, 28 to 30 and 31 to 35 days. Parities were grouped into 4 groups as follows: 1, 2, 3 + 4, and 5 to 8. Landrace sows had significantly higher LWW (P < 0.001) compared with Yorkshire sows (56.1 vs. 53.6 kg). The LL was significantly (P < 0.05) shorter during the cool season than during the other seasons while no difference was found in LWW between the hot and the cool season. The LL had no effect on WSI, FR and litter sizes. The FR was significantly lower when the WSI was 7 to 10 days than when the WSI was 1 to 6 days. An increase in WSI between Days 9 to 10 and Day 21 resulted in a significant increase in FR. Subsequent litter size decreased by about 0.5 piglets when the WSI increased from 1 to 5 days to 6 to 7 days. Thereafter, litter size increased as the WSI increased from 9 to 10 days to 21 days.

Factors influencing age at first mating in purebred Swedish Landrace and Swedish Yorkshire gilts

The aim of the present study was to retrospectively analyze causes of the variation in age at first mating in Swedish Landrace (L) and Swedish Yorkshire (Y) gilts. Production traits including growth rate from birth to 100kg body weight and backfat thickness at 100kg body weight were also studied. Data analyzed were obtained from 11 L and 11 Y nucleus herds and included gilts born during a 5-year-period from October 1993 until September 1998. The complete data set included information on 14,761 gilts (6997 L and 7764 Y). Traits analyzed included age of gilt at first mating, growth rate and backfat thickness. Seven statistical models were used for analyzing the data. Factors included were gilt breed, birth month, parity number and size of the litter in which the gilt was born as well as their interactions. Compared with Y gilts, L gilts grew faster (571 versus 556 g/day; P<0.001), had a thinner backfat (11.9 versus 12. 3mm; P<0.001) at 100kg body weight and were 12 days younger at first mating (237 versus 249 days; P<0.001). Birth month significantly (P<0.001) influenced age at first mating, growth rate and backfat thickness. Gilts born from smaller litters were mated at younger age than gilts born from larger litters even when age at first mating was adjusted for the effect of growth rate and backfat thickness. Growth rate of the gilts decreased when 'birth litter size' increased. Gilts born from primiparous sows grew slower, had a thinner backfat at 100kg body weight and were older at first mating compared with gilts born from multiparous sows. Gilts with a higher growth rate were younger at first mating than those with a lower growth rate. Gilts with a thicker backfat at 100kg body weight were mated earlier than the thin ones. However, the effect of growth rate on age at first mating was more pronounced in the gilts with a thinner backfat rather than the ones with a thicker backfat.

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).

Reproductive performance among sows group-housed during late lactation

Four farms (540 sows) that group-housed sows from 2 weeks of lactation until weaning (G-farms) and 3 farms (300 sows)--used as controls--that kept the sows individually penned throughout the 5- to 6-week-long lactation period (C-farms) were compared in terms of reproductive performance. All sows were crossbred Swedish Yorkshire x Swedish Landrace. Sows were kept in groups in the breeding section and were also grouped on deep litter in the dry-sow section on all farms. Batchwise farrowing routines were used on all farms, and batch size ranged between 8 and 22 sows. Fertility and culling data were collected in connection with monthly visits to the farms for 16 months. Among the older (> or = 5th parity) sows, litter sizes were significantly (p = 0.02) smaller in the G-farm group compared with the C-farm group. The percentage of sows mated within 10 days post weaning was lower (p < 0.001) in the G-farm group than in the C-farm group, with the difference being most evident among the older (> or = 5th parity) sows. The frequency of repeat breeders among primiparous sows was similar in the 2 housing systems, but among the multiparous sows repeat-breeder frequency was higher (p = 0.04) in the G-farm group than in the C-farm group. In both groups, repeat-breeder frequency seemed to be highest from July to September. Repeat breeding/failure to farrow was a common reason for culling in the G-farm group. These results indicate that reproductive performance was impaired in the group-housing system. This impairment could have been due partly to the occurrence of lactational oestrus, which makes it difficult to maintain adequate routines for oestrous detection and mating/insemination.

Pre- and post-weaning piglet performance, sow food intake and change in backfat thickness in a group-housing system for lactating sows

Four farms that group-housed sows from about 2 weeks of lactation until weaning (G-farms) and 3 farms, used as controls, that kept the sows individually penned throughout the 5 to 6-week-long lactation period (C-farms) were compared in terms of pre- and post-weaning piglet growth rate and mortality, sow food intake and change in backfat thickness. Piglets from 169 G-farm sows and 136 C-farm sows were individually weighed at the time of grouping and weaning. In addition, some of the piglets were weighed 2 weeks post weaning. Piglet mortality was recorded during the pre- and post-weaning periods. Sow backfat thickness was measured at the time of grouping (at a corresponding time in the C-farms) and weaning, and sow food consumption was determined during the group-housing period. Piglet weight, growth rate and within-litter variation in growth rate did not differ significantly between the two groups during the group-housing and post-weaning periods. However, the pre-weaning growth rate varied considerably between farms. For multiparous sows during the group-housing period, piglet mortality was higher (p = 0.002) in the G-farm group (6.5%) than in the C-farm group (1.4%). However, for primiparous sows the corresponding piglet mortality was similar (p = 0.21) in the two groups. Significant between-batch variation in mortality during the group-housing period was noted within the G-farms but not within the C-farms. At the time of weaning, backfat thickness tended (p = 0.09) to be higher in the G-farm group than in the C-farm group. For primiparous sows the decrease in backfat thickness was similar (p = 0.37) in the two groups. By contrast, multiparous G-farm sows gained backfat during the group-housing period, whereas multiparous C-farm sows lost some backfat (p = 0.02). G-farm sows consumed 23% more food than C-farm sows during the group-housing period. These results indicate that productivity is lower in the group-housing system, mainly owing to the poor performance of the older sows.

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

Over a period of approx. 15 months, post-mortem (PM) examinations were made on genital organs (34 gilts and 81 sows) from a sow-pool with reproductive disturbances. Anamnestic data on the animals included information about parity number, date of farrowing, dates of weaning, oestrus and service, and cause of culling. At the PM examination, the macroscopic appearance of the ovaries (follicles, corpora lutea, cysts) and uterus (content, endometrium) were studied. Specimens from the endometrium was examined histologically. The most common reason for culling was repeat breeding (67%), in most cases at irregular intervals. The non-productive period averaged 82 days in sows (weaning to slaughter) and 151 days in gilts (from 1st day of mating until slaughter). In 49.6% of the sows no pathological changes were found. Macroscopic examination of the ovaries in 108 animals showed that 69% were cycling normally, 17% were anoestral and 14% had multiple follicular cysts (7 animals were not included due to ovo-testis [1 case], pregnancy [3 cases] and with signs of recent abortion [3 cases]). As judged from the histological examination, 27% of the animals had endometritis, which was classified as mild in 50% of them. Anoestral animals had a higher incidence of endometritis (61%) than animals showing cyclic ovarian activity (19%). This indicates that ovarian inactivity is of importance for the development of endometritis. It was concluded that post-mortem examination of genital organs from animals with reproductive problems is a valuable diagnostic tool. The anamnestic data together with the PM results indicated that management routines (oestrous detection, insemination, grouping at early pregnancy) needed to be changed.

Ovarian activity at naturally attained oestrus in the sow. An ultrasonographic and LH study

In 6 multiparous crossbred sows (2nd to 4th parity, Swedish Landrace x Swedish Yorkshire), 15 proosestrous-oestrous periods during 2 oestrous cycles were studied after weaning. The animals were controlled for oestrus, and the follicular growth and ovulation in their ovaries were followed by transrectal ultrasonography. Blood was sampled through indwelling catheters for analyses of LH and progesterone (P4). The duration of oestrus (standing reflex) was 47 +/- 12.4 h, and the interval from onset of standing reflex until the end of ovulation was 39 +/- 12.4 h (range 20-64 h). The LH peak concentration was 3.7 +/- 0.8 microgram/l, and the interval from LH peak level until ovulation was 23 +/- 8.4 h (range 8-32 h). The onset of standing reflex occurred in average 13 h before the LH peak level (range -4 - +36 h). The peripheral plasma concentration of P4 showed a normal cyclic pattern in all animals. Low levels (mean levels, 1.1-1.3 nmol/l) were seen during prooestrus and oestrus, high mean levels were found on days 10-16 (45-75 nmol/l) in the oestrous cycle. It was concluded that for an accurate determination of ovulation, each animal has to be examined repeatedly. Ultrasonography is a most valuable tool for this purpose.

Ovulation as determined by transrectal ultrasonography in multiparous sows: relationships with oestrous symptoms and hormonal profiles

Twenty-four cross-bred multiparous sows in their second and fourth parities were studied during two consecutive oestruses after weaning. Careful oestrous control was done on the animals and ovulation was monitored by transrectal ultrasonography. Blood for analysis of LH and E2 contents was collected through an indwelling catheter. The sows were mated/inseminated once approximately 18 h before expected ovulation in their second oestrus. The interval between weaning and ovulation varied from 86 h-204 h (153 +/- 26). Onset of standing oestrus to ovulation was found to be longer in sows with long oestruses and ovulation occurred within a mean of 68% of the oestrous period. Duration of the first pro-oestrus was significantly shorter than the second pro-oestrus (40 h and 71 h, respectively). There was no significant difference within sows for the intervals from onset of oestrus to ovulation during the first and second oestrus after weaning (37 h and 39 h, respectively). The diameter of the largest follicles at onset of oestrus and at ovulation had very small variation between animals. The mean intervals from E2 peak to onset of oestrus and to ovulation were 1 h (range -10-(+)22 h) and 44 h (range 34-54 h) respectively, and from LH peak to onset of oestrus and to ovulation 12 h range -10-(+)32 h) and 35 h (range 27-48 h), respectively. The present study indicates that repeated ultrasonographic examination of ovaries during one oestrus can be used to predict the time of ovulation during the subsequent oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

A field study on group housing of lactating sows with special reference to sow health at weaning

Four farms that group-housed sows from 2 weeks of lactation until weaning (G-farms) and 3 farms that kept the sows individually penned throughout the 5 to 6-week-long lactation period (C-farms), were compared in terms of sow health. All sows were crossbred Swedish Yorkshire x Swedish Landrace. The daily food ration was similar on all farms except during the group-housing period, when G-farm sows were fed ad libitum. Sows were grouped in the breeding section and kept grouped on deep litter in the dry sow section on all farms. Individual health examinations were performed at the time of weaning (+/- 4 days) on 179 G-farm sows and on 167 C-farm sows. Teat- and udder skin wounds occurred less frequently (p < 0.001) in G-farm sows than in C-farm sows. In addition, preweaning atrophy of all mammary glands occurred in 6.6% of the G-farm-sows but not in a single C-farm sow (p < 0.001). This indicates that sow-piglet interactions decrease when sows are group housed. However, these differences did not occur in primiparous sows, suggesting that the relation between the primiparous sow and her litter is not affected. Mastitis frequency was the same in the 2 systems. Moreover, the frequency of locomotor disorders was the same in the 2 groups, and hoof overgrowth was common in both systems. These similarities could be due to the fact that all farms group housed dry sows on deep litter. A strong relation (p < 0.001) between hoof overgrowth and locomotor disorders was evident. Low access to food due to low rank among primiparous group-housed sows was indicated by a lower (p < 0.05) backfat thickness compared with multiparous sows, and a higher (p < 0.001) frequency of skin wounds compared with individually housed primiparous sows.

Ovarian activity at naturally attained oestrus in the sow. An ultrasonographic and LH study

In 6 multiparous crossbred sows (2nd to 4th parity, Swedish Landrace x Swedish Yorkshire), 15 proosestrous-oestrous periods during 2 oestrous cycles were studied after weaning. The animals were controlled for oestrus, and the follicular growth and ovulation in their ovaries were followed by transrectal ultrasonography. Blood was sampled through indwelling catheters for analyses of LH and progesterone (P4). The duration of oestrus (standing reflex) was 47 +/- 12.4 h, and the interval from onset of standing reflex until the end of ovulation was 39 +/- 12.4 h (range 20-64 h). The LH peak concentration was 3.7 +/- 0.8 microgram/l, and the interval from LH peak level until ovulation was 23 +/- 8.4 h (range 8-32 h). The onset of standing reflex occurred in average 13 h before the LH peak level (range -4 - +36 h). The peripheral plasma concentration of P4 showed a normal cyclic pattern in all animals. Low levels (mean levels, 1.1-1.3 nmol/l) were seen during prooestrus and oestrus, high mean levels were found on days 10-16 (45-75 nmol/l) in the oestrous cycle. It was concluded that for an accurate determination of ovulation, each animal has to be examined repeatedly. Ultrasonography is a most valuable tool for this purpose.

The effect of thiopentone-sodium anesthesia and surgery, relocation, grouping, and hydrocortisone treatment on the blood levels of cortisol, corticosteroid-binding globulin, and catecholamines in pigs

Eight crossbred, ovariectomized gilts (Swedish Landrace x Swedish Yorkshire x Hampshire), with a mean age of 7.5 mo, were studied during anesthesia and surgery, control-sampling, relocation, and grouping during a period of 3 wk. Acute treatment with a hydrocortisone injection (5 mg, i.v.) was also given. Blood samples were taken frequently (every 10 min) during the intensive part of the experimental days. The blood samples were analyzed for catecholamines (CA), adrenaline (A) and noradrenaline (NA), cortisol, and corticosteroid-binding globulin (CBG). The surgical period with anesthesia and surgery showed significant effects on CA, cortisol, and CBG. The A level increased immediately after the surgery. A biphasic increase in the cortisol level was observed on the day of surgery; the greatest increase was seen when the animals had regained consciousness after surgery but still were drowsy and staggering. The CBG level decreased on the day after the surgery. The study showed that the levels of the analyzed substances were back to normal 2 d after surgery. During relocation and grouping there was a short, significant increase in CA and cortisol levels, whereas the CBG level was not affected. Treatment with hydrocortisone significantly increased the cortisol level, but no change was seen in plasma CA or CBG levels. In conclusion, anesthesia and surgery induced significant effects on the levels of CA, cortisol, and CBG in gilts and the animals needed 2 d to recover before regaining their normal condition. During relocation and a limited grouping period, the significant increases in CA and cortisol levels were of short duration and CBG did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of transport stress on plasma levels of catecholamines, cortisol, corticosteroid-binding globulin, blood cell count, and lymphocyte proliferation in pigs

The effect of transport stress on the plasma levels of catecholamines, cortisol, and corticosteroid-binding globulin were studied in 6 gilts. To assess the effect on immune status, white blood cells were also counted and the cell-mediated immunity was estimated. The adrenaline level increased significantly during transport, from a basal mean level of 0.03 ng/ml to a plateau level of 0.11 to 0.12 ng/ml. The noradrenaline level fluctuated, but not constantly, during transport. The mean plasma cortisol level before loading was approximately 40 nmol/l and rose immediately after the start of transport to 70 nmol/l (p < 0.05) and to 87 nmol/l (p < 0.01) within 10 and 30 min, respectively. After unloading the cortisol level rapidly decreased and a minimum level was seen 4 h after the transport, whereafter the diurnal rhythm was resumed. The plasma corticosteroid-binding globulin level increased nonsignificantly during the day of transport, from 25 nmol/l to a level of 34 nmol/l, and it continued to increase until a plateau level was reached on the second day after transportation. The total white blood cell number increased significantly (from 13.7 to 15.5 x 10(9) cells/l), the number of lymphocytes decreased significantly (from 8.4 to 7.0 x 10(9) cells/l), and the number of polymorphonuclear neutrophils increased significantly (from 4.3 to 7.2 x 10(9) cells/l) during transport. No significant variation in the proliferation response was seen in the whole blood cell cultures. The main results were the significant signs of simultaneous activity of both the adrenal cortex and the adrenal medulla during transport.

Vasointestinal polypeptide (VIP)-immunoreactive nerves in the boar penis

Vasointestinal polypeptide (VIP)-immunoreactivity was localized at LM-level in cryostat sections using a peroxidase-anti-peroxidase technique, and at EM-level in glutaraldehyde-fixed, resin-embedded sections using an immunogold technique, of samples from the penis of 3 Hampshire boars with a history of normal erection and mating behaviour. One boar of the same breed with an impotence diagnosis was also examined. In the normal animals, VIP-immunoreactivity was localized into nerves associated to blood vessels and non-vascular smooth muscle in the capsular lamina propria and the fibromuscular layers, and intermingled under the penis epithelium. At EM level, the immunogold localization confirmed the above mentioned results, VIP being localized in nerve terminals. Nerve terminals without VIP-reactivity had EM appearance of cholinergic or adrenergic nerve terminals. No obvious differences in VIP innervation were noticed among the normal boars. In the impotent animal, a marked depletion of VIP-immunoreactivity was evident, as well as degenerative changes in the adrenergic and cholinergic nerve profiles. It is concluded that the porcine penis is well innervated, along with adrenergic and cholinergic components, by VIP-containing nerves. The depletion of the scattered VIP-containing nerves in the impotent case suggests its involvement in the mechanisms of penile erection in the boar.

Embryonic development of the porcine indifferent gonad and testis

The early gonadal development in the pig from day 18 to day 36 post conception, when distinct testes were present in male embryos, has been studied. The development of the porcine gonad followed the general mammalian pattern. During testicular differentiation, the germ cells and the relevant somatic cells, the Sertoli cells, became enclosed in testicular cords, thus creating an intracordal germ cell compartment and an extracordal compartment. The development of conspicuous cell junctions and the production of a basal lamina were evident in the Sertoli cells during the early testis development. Their origin in this species remains unclear.

Regulation of the uterine expression of messenger ribonucleic acids encoding the oestrogen receptor and IGF-I peptides in the pig uterus

The acute effects of oestradiol-17 beta on the expression of the oestrogen receptor (ER) and insulin-like growth factor I (IGF-I) in the endometrium of ovariectomized pigs were examined. The steroid receptor level was assayed by hormone binding techniques and specific mRNAs analyzed by solution hybridization using 35S-labelled RNA probes complementary to the ligand-binding domain of the ER receptor gene and a 160 bp PanI-Pvul fragment of the IGF-I gene. One hour after a single injection of oestradiol (1 micrograms/kg BW), the nuclear oestrogen receptor (ERn) mean level was increased 3-fold whereas the ER mRNA content had not changed significantly. After 3 hours the ERn mean concentration was still high; the mean ER mRNA level had decreased by 15% and the mean IGF-I mRNA had increased 3-fold above that in the samples collected prior to treatment from these ovariectomized animals. Six hours after the injection the ERn content had returned to the basal level and stayed there during the following six hours. The ER mRNA concentration continued to decline, reached its lowest value after six hours and had increased slightly by twelve hours. The IGF-I mRNA level increased steadily during the course of the experiment. At twelve hours after the injection it had increased 3-fold. From these data we conclude that in the pig uterus oestradiol down-regulates its own receptor and acts as a potent stimulator of endometrial growth by inducing IGF-I expression.

Developmental regulation of insulin like growth factor II gene expression in the pig

The expression of the insulin like growth factor II gene has been examined in the developing porcine embryo. It was found that IGF II transcripts were present in abundant quantities in first trimester embryos as well as in the extraembryonic tissues amnion and allantochorion. The expression of the IGF II gene was high in the fetal liver where a prominent 2.3 kB transcript and a less abundant 5.4 kB transcript were produced. However, neither of these transcripts could be traced in the adult liver. Instead we found two different IGF II transcripts with the sizes of 4.7 and 1.2 kB in the adult liver. These findings indicate that the IGF II gene is under developmental control with the possible existence of different promoters.

The effect of transportation/relocation on cortisol, CBG and induction of puberty in gilts with delayed puberty

Twenty-seven Swedish purebred Yorkshire gilts were transported 12 km to the clinic. In 8 gilts (Group A), blood samples were drawn in connection with transportation, while in the remaining 19 gilts (Group B) no samples were drawn at this time. After transportation the gilts were examined by laparoscopy and catheterized. Blood samples were then drawn 3 times and oestrus detection was performed twice daily. After 1 week the laparoscopy was repeated.

Twenty gilts (74 %) showed oestrus within 1 week, on average 5.4 days (4–7.5 days) after transportation. Elevated oestradiol-17β levels were seen in those gilts approximately 2 days after transportation. The Cortisol level was significantly higher (p < 0.001) on day 1 (the day of transportation) than on day 2 and a markedly higher level of Cortisol was seen on days 1 and 2 in the gilts which did not show oestrus (2 gilts), compared with the gilts in which oestrus was induced (6 gilts) by transportation. The difference was significant on day 2 (p < 0.05). The CBG level was significantly decreased (p < 0.001) on day 2 for all 8 gilts. During day 3 to day 8 there was no difference in the Cortisol level between days (groups A and B, 27 gilts), and no differences were seen in the levels of Cortisol and CBG between gilts showing (20 gilts) and not showing oestrus (7 gilts). The hypothesis propounded that the higher levels of Cortisol on days 1 and 2 inhibited induction of oestrus in those gilts which did not show oestrus after transportation.

Clinical, morphological and endocrinological studies in gilts with delayed puberty

Thirty-six gilts which had not shown oestrus at about 8 months of age or more were transported from the pig research station to the clinic, a journey of 12 km. The gilts were examined by laparoscopy and those which had only small follicles in the ovaries were catheterized and placed in pens, with sexually mature boars kept in adjacent pens. Oestrus detection was done twice daily and blood was sampled three times a day. After 7 days the laparoscopy was repeated and gilts which still had only small follicles in their ovaries were given 250 μg GnRH intravenously the following day. Blood samples were taken frequently before and after GnRH treatment. One week. after administration of GnRH the ovaries were inspected by laparoscopy once more.

The first laparoscopic examination showed that 42 % of the gilts were sexually mature. One gilt had no uterus or ovaries. Twenty gilts had only small follicles in the ovaries and fourteen of these gilts showed ovulatory oestrus 5.5 days (4-7.5 days) after arrival. In these fourteen gilts a rise in the oestradiol-17B level (>30 pmol/1) was seen at an average time of 1.9 days and a rise in LH (preovulatory peak) was seen at an averaged 4.5 days after the start of blood sampling. Six gilts were given 250 ug GnRH. An immediate rise in LH could be seen in all the gilts (mean peak level was 6.18 μg/l) and the elevated levels had a duration of 4 hours. None of the GnRH-treated gilts responded with oestrus symptoms or increased ovarian activity.

The effect of a PMSG/HCG preparation in anoestrous sows and gilts

In a field trial the effect of a commercial preparation containing 400 IU PMSG/200 IU HCG per dose (Suigonan vet) was studied in 20 anoestrous gilts and 39 anoestrous sows. Immediately before the hormone treatment blood samples were taken for determination of the plasma progesterone level. The correlation between the pretreatment plasma level of progesterone and the response to the hormone treatment was analysed. The mean number of litters per sow at treatment was 3.0 and the mean lactation period 38 days. The mean period from weaning until treatment was 21 days. The average age of the gilts at treatment was 263 days. In 38.5% of the sows and 35% of the gilts the plasma progesterone level was greater than 3 nmol/l, indicating that these animals had corpora lutea in the ovaries. In the sows a total of 79.5% showed oestrus, but only 56.4% within 7 days after treatment. The mean progesterone level for the sows showing oestrus within 7 days was low, 1.5 nmol/l. Sows showing oestrus more than 7 days after treatment (23.1%; mean 18 days) or not showing oestrus (20.5%) had a high mean progesterone level of 48.9 nmol/l and 23.6 nmol/l at treatment, respectively. A total of 75% of the gilts showed oestrus, 60% within 7 days after treatment, the latter with a mean plasma progesterone level of 2.4 nmol/l at treatment. Fifteen per cent showed oestrus more than 7 days after treatment (mean 32.3 days) and in 25% no oestrus was observed.(ABSTRACT TRUNCATED AT 250 WORDS)