Anoestrous Sows Research Articles

Gut microbiota and blood metabolomics in weaning multiparous sows: Associations with oestrous.

This study was conducted to detect the potential relationship between changed plasma metabolites, intestinal microbiota and the weaning-to-oestrous interval in multiparous sows after weaning. Multiparous sows were allocated to two groups after weaning: the oestrous group (n=15) with a weaning-to-oestrous interval ≤7days or the anoestrous group (n=15) with a weaning-to-oestrous interval >14days. The levels of plasma reproductive hormones: oestradiol, follicle-stimulating hormone and luteinizing hormone, plasma total protein; blood urea nitrogen; cholesterol; high-density lipoprotein; and ammonia (NH3 ) were significantly lower in the anoestrous sows compared with the oestrous sows (p<.05). The plasma metabolomics analysis identified 14 metabolites (lactose, l-cysteine, cytosine, hydantoin, palmitoleic acid, arachidic acid, linoleic acid methyl ester, α-ketoglutaric acid, N(ε)-trimethyllysine, threo-β-hydroxyaspartate, 3-(3-hydroxyphenyl) propionic acid and others) with lower concentrations and 12 metabolites (noradrenaline, 5-dihydrocortisone, p-cresol, 1,4-cyclohexanedione, 2,3-dimethylsuccinic acid and others) with higher concentrations in the anoestrous group compared with the oestrous group (p<.05). The 16S rRNA pyrosequencing analysis showed the relative increase in abundance of the Prevotella and the Bacteroides at the genus level in the anoestrous group (p<.05). At the phylum level, lower proportions of Firmicutes and Lentisphaerae were observed in the anoestrous group (p<.05). This study provided a comprehensive assessment of metabolic differences in the blood and differences in the gut microbiome composition between anoestrous and oestrous sows. And suggesting that this profiling approach may offer new insights into explaining the alteration of the gut microbiota and blood metabolomics are correlated with sex hormone secretion and the weaning-to-oestrous interval of sows after weaning.

Post‐mortem Examination of Sows Genital Organs Culled for Reproductive Disturbances and Immunohistochemical Studies on ERα 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.

Are oestrous feral pigs, Sus scrofa, useful as trapping lures?

Eight feral pigs (two boars, four sows and two piglets) were caught in traps using oestrous sows as lures during a control program on a remnant pig population in part of Namadgi National Park during spring, 1990. The program was mostly based on aerial baiting with warfarin. No pigs were caught in traps containing anoestrous sows or in traps containing bait only. Seven unmarked pigs (caught seven days after the cessation of baiting) did not appear to have eaten any warfarin bait. In an earlier pilot trial, two boars were caught at a trap containing an oestrous sow, one of these again in a trap baited only with fermented grain, but no pigs were caught at a trap containing an anoestrous sow. Although not cost-effective as a general technique, this method could be useful in specific circumstances, such as eradication campaigns on islands, if the last few pigs are, or have become bait shy, or are impossible to cull by other methods.

Hormone profiles around weaning in cyclic and anoestrous sows.

Peripheral plasma patterns of LH, cortisol, corticosteroid-binding globulin (CBG) and beta-endorphin were studied around weaning in sows that resumed cyclicity and those that remained anoestrus after weaning. Average LH concentration in both groups of sows, and basal LH concentration, LH pulses/6 h and the sum of LH pulses and peaks/6 h in the cyclic sows, increased from the day before weaning to significantly higher (P < 0.05) levels on the days after weaning. Overall, average and basal LH concentrations were higher (P < 0.05) in the sows that resumed cyclicity than in those that remained anoestrus. Cortisol and beta-endorphin concentrations were high before weaning and on the day of weaning in both groups of sows. Cortisol in the cyclic sows, and beta-endorphin in both groups of sows, decreased (P < 0.05) after weaning. CBG levels were unchanged until the second day after weaning when there was an increase (P < 0.05) in both groups of sows. Before and even after weaning cortisol, CBG and beta-endorphin levels tended to be higher in the sows that remained anoestrus compared with those that resumed cyclicity. Findings in the present study show higher levels of cortisol, CBG and beta-endorphin before weaning that persisted even after weaning, and lower LH concentrations around weaning in sows that failed compared with those that resumed oestrous activity.

Post-weaning anoestrus in primiparous sows: LH patterns and effects of gonadotropin injection and boar exposure.

Post-weaning anoestrus was studied in eighteen primiparous sows, selected from a breed showing a high proportion of anoestrous sows. The sows were studied from late lactation, through weaning at day 29 post-partum (p.p.), until day 21 post-weaning (p.w.). Blood samples were taken once daily, and frequently (every ten minutes) on several days before and after weaning. Out of a total of ten anoestrous sows, three were exposed to a boar and seven were given gonadotropins (PG600) on day 21 p.w.. Serial blood samples were analysed for LH only and daily samples were additionally analysed for oestradiol-17 beta and progesterone, by validated radioimmunoassay procedures. Analysis of variance of the basal level, pulse frequency, pulse amplitude and mean level of LH showed, retrospectively, that during lactation the basal and mean levels of LH were significantly lower in anoestrous than in oestrous sows (P < or = 0.05). Furthermore, the post-weaning basal and mean levels of LH were also significantly lower in anoestrous than in oestrous sows (P < or = 0.05). However, because of the small number of oestrous animals (n = 3), these results should be interpreted with caution. Exposure of anoestrous sows to a boar did not result in oestrus and/or ovulation within seven days, but did increase LH pulse frequency. Injection of gonadotropins resulted in an LH surge, oestrus and ovulation in only three sows, but oestradiol levels were increased in six sows. From our experiments and from reports in the literature we conclude that a lowered secretion of LH may play a role in the aetiology of post-weaning anoestrus in the sow.

Effect of Transportation and Relocation in Post-Weaning Anoestrous Primiparous Sows

The object of this investigation was to study the clinical and endocrine responses to transportation and relocation in 8 post-weaning anoestrous sows. They had been anoestrous for at least 24 days after weaning before transportation/relocation was performed. Laparoscopy, performed at the beginning of the experiment, revealed that the ovaries contained many follicles (less than or equal to 6 mm in diameter), but no corpora lutea. Blood samples, taken before and after transportation/relocation, showed that LH activity was low at the beginning of the experiment and increased after transportation/relocation in the majority of the sows. Peripheral plasma concentrations of of oestradiol-17 beta increased 1-4 days after transportation/relocation in 6 out of 8 sows which was followed by oestrus and ovulation. Progesterone concentrations were also below the practical detection limit until the end of oestrus. This study has demonstrated that a change in environment by transportation and relocation can induce oestrus by increasing the LH activity in post-weaning anoestrous sows.

Effects of electroacupuncture and gonadotropin-releasing hormone treatments on hormonal changes in anoestrous sows.

The therapeutic effects of acupuncture in treating reproductive disturbances of man and animals have been proven in the past and is used clinically already. However, the mechanism of such therapy is not known yet. In this study, anoestrous sows were used to investigate the mechanism. Anoestrous sows with luteal ovaries were allocated to three groups. Four sows received electroacupuncture treatment at Pai-Hui and Wei-Ken (acupuncture treated group; group 1). Three sows received electroacupuncture treatment at Chiang-Feng and Chou-Shu (acupuncture control group; group 2). Four received 50 micrograms of gonadotropin-releasing hormone (GnRH) intravenously (drug control group; group 3). The concentrations of luteinizing hormone, progesterone, oestradiol and cortisol in serum were measured by radioimmunoassay. Oestrus return was monitored during 14 days after treatment. At the end of this observation period, the number of animals returned to oestrus were 3, 1 and 1 in groups 1, 2 and 3, respectively. It suggests that only treatment with acupuncture at Pai-Hui and Wei-Ken had therapeutic effects in inducing oestrus. This finding is further supported by the changes of serum sex hormone concentrations. Serum LH concentrations decreased for about 2 hours after electro-acupuncture treatment both in groups 1 and 2, whereas those in group 3 increased sharply at 10 minutes, reached to a peak at 20 minutes and returned gradually to basal level between 4 and 6 hours after GnRH injection. Serum progesterone concentrations rose between 4 to 6 hours after treatment in groups 1 and 3 but not in group 2. Five sows become oestrus, showed a decreased progesterone level 2 days after treatments whereas the other six anoestrous sows did not. Oestradiol levels did not have meaningful changes during the blood sampling period of 5 to 7 days in these 3 groups. Cortisol levels elevated in 15 minutes after the electroacupuncture in groups 1 and 2. However, the increment of cortisol induced by the electroacupuncture was less than that induced by the first bleeding, indicating that the adrenal stimulation may not be the main reason of the therapeutic action. The results indicated that the electroacupuncture treatment and GnRH injection could alter the release of LH from the pituitary in different ways but only electroacupuncture at Pai-Hui and Wei-Ken has a specific action on ovary and a significant therapeutic effect. Therapeutic effects of electroacupuncture on reproductive disturbance may involve a synergism of somatic-ovary and uterus reflex and central nervous-endocrine system (the hypothalamo-pituitary-ovary axis).

Follicular Development in Lactating, Post Weaning and Anoestrous Primiparous Sows

The ovarian follicular system was studied in 4 lactating sows (6 or 8 weeks lactation period), 4 post weaning sows (2 or 4 days after weaning) and 5 post weaning anoestrous sows (22 days after weaning) by macroscopical and microscopical examinations. Blood sampling was performed daily in the post weaning anoestrous sows. The results showed that none of the sows had ovulated during lactation and after weaning. Only small and medium sized follicles were present in the ovaries of the sows. The blood levels of oestradiol-17β and progesterone were low throughout the post weaning period in the anoestrous sows. Microscopical examination showed that all sows had more normal than atretic follicles. In the lactating sows all follicles were below 5 mm in size, the majority being small (1.00–2.99 mm in diameter). The post weaning sows had follicles up to 5.00–5.99 mm and 23–24% of the follicles were medium sized (3.00–5.99 mm in diameter). The post weaning anoestrous sows had no follicles above 5 mm in diameter but many normal medium sized follicles.

Weaning at birth: the effect on the reproduction of the sow

AbstractThirty-six Landrace × Large White sows were allocated at random to one of three treatment groups. Sows on treatment A (no. = 6) did not lactate at all and the piglets from these sows were removed at birth. Sows on treatment B (no. = 15) lactated for 1 day after parturition and sows on treatment C (no. = 15) acted as controls and lactated for 42 days. The reproductive performance of each treatment group was recorded and all sows were bled every 2nd day from parturition to 30 days post partum. All blood samples were assessed for oestradiol-17β and progesterone concentrations. In treatments A and B, a high proportion of anoestrous sows was seen (0·28). None of the sows in treatment C became anoestrous. The mean interval from weaning to the onset of oestrus for treatments A and B (19·0 (s.e. 6·5) days and 19·7 (s.e. 3·8) days respectively) were not significantly different, while that for treatment C (5·6 (s.e. 0·4) days) was significantly shorter (P &lt; 0·01). The number of piglets born alive at the subsequent farrowing for treatments A, B and C respectively was 7·3 (s.e. 0·8), 9·1 (s.e. 0·8) and 10·5 (s.e. 0·67) (P &lt; 0·05). The calculated annual sow productivity (piglets born alive per sow per year), excluding the first litter born, for treatments A, B and C respectively was 18·4, 22·8 and 22·9. Weaning at, or close to, parturition did not, therefore, influence sow productivity compared with weaning after 6 weeks of lactation.

Induction of oestrus in anoestrous, first litter sows with pregnant mares' serum gonadotrophin

The effectiveness of pregnant mares' serum gonadotrophin (PMSG) to stimulate ovarian activity and to induce oestrus in anoestrous sows after weaning of their first litter was evaluated. Anoestrous sows were given an intramuscular injection of 1000 i.u. PMSG 14 days after weaning and a greater number of PMSG-treated sows exhibited oestrus by day 21 after weaning than control sows (16/22 vs 7/24, x 2 = 8.7, P < 0.01). There was no significant effect on farrowing rate, ovulation rate, subsequent litter size or embryo mortality. Thirty-six anoestrous sows were treated with 1000 i.u. PMSG on either day 14, 21, 28 or 35 post weaning and 78% exhibited oestrus within 5 days of treatment. A greater number of sows with quiescent ovaries on the day of treatment exhibited oestrus than sows whose ovaries were either cycling or had preovulatory follicles (25/29 vs 3/7, x 2 = 6.2, P < 0.05). These results indicated that treatment of anoestrous, first litter sows with 1000 i.u. PMSG at least 14 days after weaning effectively induced oestrus and ovulation in these sows within 5 days of treatment without reducing their subsequent reproductive performance.

Induction and synchronisation of oestrus in prepuberal gilts and anoestrous sows by a PMS-HCG-compound.

Induction and synchronisation of oestrus in prepuberal gilts and anoestrous sows by a PMS-HCG-compound.