SLA typing using the PCR‐SSP method and establishment of the SLA homozygote line in pedigreed SNU miniature pigs

Seoul National University (SNU) miniature pigs represent a closed colony with 24 founder pigs and a well preserved pedigree. Characterization using mRNA sequence analysis was conducted for 6 swine leukocyte antigen (SLA) loci in parental or founder pigs, and 17 defined alleles were detected. Based on these complete coding sequences, 17 sequence specific primers (SSPs) were designed for polymorphic sites. To validate the specificity of each allele SSP, the PCR‐SSP was conducted with defined allele clones as templates. PCR‐SSP was conducted with the hot start polymerase and touch‐down PCR. The parental or found SNU miniature pigs showed overall SLA class I and II heterozygotes. Using the established PCR‐SSP method, we conducted SLA typing for breeding stock including 2 pedigreed pigs and identified the novel SLA class II homozygote haplotye (DRA*0201, DRB1*0403, DQA*0102 and DQB1*0701) and 2 SLA homozygote pig lines: SLA class I Hp‐3.0 and class II Hp‐0.3, and SLA class I Hp‐2.0 and class II Hp‐0.2. We thought that our PCR‐SSP SLA typing method could be applicable for new SLA homozygote line establishment by assignment and scheduled breeding.     

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

Summary

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 oestradio1–170 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 ≤ 0.05). Furthermore, the post‐weaning basal and mean levels of LH were also significantly lower in anoestrous than in oestrous sows (P ≤ 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 Modified Eros Centre on Some Reproductive Parameters of the Sow

The effect of a modified eros centre on weaning to oestrus interval, follicle size, ovulation and farrowing rate and total born litter size was investigated. In modified eros centre 94.4% and in group housing 79.1% of the sows (p < 0.01) expressed oestrus within 10 days post‐weaning. Weaning to oestrus interval was shorter (p < 0.001) for sows kept in modified eros centre. The interval from onset of oestrus to the time of ovulation was longer for sows in group housing (p=0.05). The time of ovulation was negatively correlated (r=?0.50) with the interval from weaning to oestrus (p=0.005). The time of ovulation after onset of oestrus was significantly (p < 0.05) shorter for sows expressing oestrus within 2–4 days of weaning, compared with the animals that expressed oestrus between days 5 and 6 post‐weaning and was shortest for sows expressing oestrus after day 6 post‐weaning. Farrowing rate was not affected by a modified eros centre. Litter size tended to be smaller in group‐housed weaned sows (p=0.10). The timing of last artificial insemination relative to time of ovulation did not affect litter size (p > 0.10). The implication of these results is that a modified eros centre may improve some of the post‐weaning oestrous parameters of the sow.     

Management Factors Associated with Sow Reproductive Performance After Weaning

To achieve optimal reproductive performance in pig herds, sows need to become pregnant as soon as possible after weaning. The aim of this study was to investigate herd and management factors associated with reproductive performance of sows after weaning. A questionnaire pertaining to sow management at weaning and herd reproductive data were collected from 76 randomly selected commercial pig herds in Belgium. Associations between the herd factors and two reproductive parameters after weaning (weaning‐to‐oestrous interval: WEI and percentage of repeat breeders: RB) were analysed using general linear mixed models. A separated feeding strategy of breeding gilts from 60 kg onwards was significantly associated with a shorter WEI (5.54 vs 7.28 days; p = 0.040). Factors significantly associated with a lower percentage of RB were housing the newly weaned sows separated from the gestating sows (7% vs 12%; p = 0.003), using semen < 4 days after collection (7–9 vs 14%; p = 0.014) and stimulating oestrus twice a day (8 vs 11%; p = 0.025). In conclusion, some management practices, such as feeding strategy of breeding gilts, housing conditions of sows, method of oestrous stimulation and storage duration of semen, have an influence on the outcome of reproductive parameters such as weaning‐to‐oestrous interval and percentage of repeat breeders. These practices can be implemented rather easily by pig producers and may consequently lead to improvements of reproductive performance of sows after weaning.     

Multiple Factors Affecting Superovulation in Poll Dorset in China

To expand the breeding flock of Poll Dorset sheep in China, multiple ovulation and embryo transfer breeding program was applied to the limited number of imported Australian Poll Dorset sheep. This study investigated the effects of FSH from three different manufacturers, parity (nulliparous vs multiparous), repeated superovulation, oestrus induction, corpus luteum regression and oestrus delay on Poll Dorset superovulation. The results showed that gonadotropin FSH from Canada Folltropin‐V (Ca‐FSH) was successfully used for superovulatory treatment with 160 mg–200 mg dosage per ewe and recovered 12.91 ± 7.80 embryos. Multiparous ewes for superovulation treatment were significantly better nulliparous ewes (p < 0.05). The successive superovalution treatment reduced significantly embryo collection but did not affect transferable embryo number. Ewes with natural oestrus resulted in significantly higher number of embryos (13.83 ± 4.64) and of transferable embryos (12.00 ± 5.76) than ewes with induced oestrus (7.00 ± 4.92; 4.22 ± 3.42) and unknown oestrus cycle (5.94 ± 3.38; 3.19 ± 2.56, p < 0.05). The delayed oestrus ewes at 24 h after superovulatory treatment produced significantly fewer embryos and transferable embryos (0.92 ± 1.51 vs 0.42 ± 0.90) than those with normal oestrus (p < 0.01). Furthermore, the more transferable embryos were recovered from ewes with normal corpus luteum than those with corpus luteum regression (5.88 ± 5.09 vs 3.59 ± 4.30 and 8.83 ± 5.75 vs. 6.66 ± 5.41, p < 0.01). These results suggest that in our farm practice, a comprehensive treatment method by using the Canadian FSH (Folltropin‐V), plus choosing multiparous and natural oestrus ewes with normal corpus luteum might obtain an optimum embryo collection and embryos transfer in sheep.     

养殖环境对生猪的影响与对策

养殖环境对生猪的健康生长有至关重要的影响,会严重威胁不同年龄和不同猪的健康生长和繁殖。生猪养殖中如果不能严格控制养殖环境,易造成种公猪的精液质量下降,精子活性降低,母猪不能正常发情,隐性发情。不规律发情,影响母猪正常排卵,使繁殖率显著下降。对于养殖场的育肥猪养殖环境还会影响整体的育肥效果,使饲料的成本显著增加,不利于提高养殖效益。因此在发展生猪养殖中,注重做好养殖环境的控制,减少各种污染物的产生,确保生猪健康生长。该文主要论述养殖环境对不同年龄阶段猪的影响,并提出养殖环境的改善措施。     

Phylogenetic analysis for the Seoul National University (Minnesota) miniature pig by mitochondrial DNA sequence polymorphism

Seoul National University (SNU) miniature pigs are originated from the Minnesota miniature pig. This study was conducted to investigate the maternal origin of SNU (Minnesota) miniature pigs and their phylogenetic relationships by analyzing the mitochondrial DNA (mtDNA) D‐loop (control region) sequence. Two mtDNA D‐loop sequences of the SNU miniature pigs were identified. On an unweighted pair‐group method with an arithmetic mean (UPGMA) phylogenetic tree analysis, the large white was the pig breed closest to the SNU miniature pig, and the pairwise distance analysis showed the same result. While mtDNA sequences of 4 pig breeds which were used to establish Minnesota miniature pig were not known, our result might be different from the history of the Minnesota miniature pig development. In conclusion, we thought that some haplotypes of the Minnesota miniature pig maternally were originated from the Large white pig, or that wild pigs had similar mtDNA sequences to the Large white pig, and all SNU miniature pigs were derived from this colony.     

非洲猪瘟疫情下三元母猪轮回杂交繁育策略分析

非洲猪瘟导致能繁母猪产能断崖式下降，二元母猪价格居高不下，产能严重不足，而频繁引种不利于疫情防控，这给我国养猪业带来了前所未有的挑战。为快速恢复生猪产能，三元商品猪被迫留为种用；然而，三元母猪繁殖性能较差，如果选留、选配等管理措施不当会进一步降低其繁殖性能。文章针对这些问题介绍了非洲猪瘟对我国养猪业的影响，重点分析了杂种母猪的利用原理以及三元母猪的轮回杂交闭群繁育选配策略，期望实现三元母猪的种用价值最大化，提高商品猪养殖的经济效益，促进生猪产业的可持续性发展。     

显微注射转基因用猪胚胎获得研究

本文从猪胚胎的体外成熟和体内成熟两方面对显微注射用猪胚胎的获取进行了初步研究。实验结果表明 ;超数排卵母猪的手术冲胚是获取显微注射用猪胚胎的最佳方法 ,该方法获得的胚胎数量多 ,质量好 ,转基因效率高。体外成熟法获得可供显微注射用猪胚胎的效率低 ,基因转移的总效率也很低。     

Effects of Exogenous ACTH during Oestrus on Early Embryo Development and Oviductal Transport in the Sow

This study was conducted to assess the effects of ACTH injections on the early development of embryos and their transportation to the uterus. Fifteen sows were monitored for ovulation using transrectal ultrasonography during the first two oestrous periods after weaning. The sows were randomly divided into a control group (C group, n = 8) and an ACTH-treated group (ACTH group, n = 7), and were all surgically fitted with intra-jugular catheters. From the onset of the second standing oestrus after weaning, the sows were injected (NaCl/synthetic ACTH) every 4 h. Blood samples were collected immediately before and 45 min after each injection. All sows were inseminated once 10-33 h before ovulation in their second oestrus after weaning. At 48 (n = 4) or 60 (n = 11) h after ovulation during their second oestrus, the sows were killed and the embryos retrieved from the oviduct and uterus. The embryos were counted and compared with the number of corpora lutea, cleavage rate was noted and, finally, the embryos were prepared for confocal laser scanning microscopy and transmission electron microscopy. There was no difference between the groups regarding cleavage rate, the cytoskeleton, or the number of active nucleoli. However, the ACTH group had significantly (p < 0.05) fewer ova/embryos retrieved (51%) than the C group (81%), and there was a tendency towards faster transportation to the uterus in the ACTH group, possibly because of high progesterone concentrations during treatment. To conclude, administration of ACTH every 4 h from onset of oestrus to 48 h caused significant loss of oocytes or embryos, and possibly faster transportation through the oviduct.     

Enhancing Embryo Yield in Superovulated Holstein Heifers by Immunization Against Inhibin

Eight heifers, aged 16–17 months and showing normal oestrous cycles, were immunized against a recombinant porcine inhibin α subunit immunogen, together with another 10 heifers of the same age as controls and treated with placebo immunogen. Primary (1 mg immunogen) and two booster (0.5 mg immunogen each) immunizations were administered at 28‐day intervals. Ten days after the second booster immunization, both groups of heifers underwent a superovulation treatment. Each animal was given an intravaginal progesterone releasing sponge, which was withdrawn 7 days following an i.m. injection of 0.5 mg cloprostenol. Heifers were treated with FSH for 4 days and artificially inseminated after oestrus occurred. The embryos were flushed and evaluated 7 days after insemination. Immunization significantly (p < 0.01) increased blood antibody titres against recombinant porcine inhibin α subunit, from pre‐immunizaion and control values of approximately 0.06 of ELISA 450 nm reading to 0.6 to 0.7 after two or three immunizations. The immunized heifers produced on average 15.8 ± 2.8 embryos, significantly (p < 0.05) higher than the yield of 8.3 ± 1.5 in the controls. The number of transferable embryos were non‐significantly higher in immunized than in control heifers (9.6 ± 3.1 vs 5.8 ± 1.6, p > 0.05). The peak plasma oestradiol concentrations were significantly higher in immunized than in control heifers, both immediately after FSH treatment and 20 days thereafter. Plasma P4 concentrations after superovulation were in the range of 20 ng / ml in the immunized heifers, significantly (p < 0.05) higher than the values approximately 15 ng / ml in control heifers. These results indicated that prior immunization against inhibin α subunit stimulated production of antibodies against inhibin, which enhanced follicular developmental response to superovulation and lead to higher yield of total and transferable embryos. Therefore immunization combined with the conventional superovulatory gonadotrophin treatment, can be a simple and efficient method to produce low cost bovine embryos.     

Breed and swine lymphocyte antigen haplotype differences in agglutination titers following vaccination with B. bronchiseptica

Genetic differences in immune response to B. bronchiseptica after vaccination with a commercial B. bronchiseptica bacterin were investigated in 1,069 8-wk-old pigs. These pigs were from 65 litters born in the spring and 66 litters born in the fall of 1982 and were purebreds from the Chester White (n = 128), Duroc (n = 281), Hampshire (n = 143), Landrace (n = 309) and Yorkshire (n = 208) breeds. Each litter was raised separately. Individual pigs were vaccinated im at 4 and 6 wk of age with 2 ml of B. bronchiseptica bacterin. At 8 wk of age, 8 ml of blood were collected from each animal and serum prepared to determine agglutinating antibody titers against B. bronchiseptica bacterin by a bacterial agglutination method. In addition, lymphocytes were separated from 1 ml of heparinized blood and used to determine Swine Lymphocyte Antigen (SLA) haplotypes by using cytotoxic antibodies against the SLA complex. Antisera for 3 SLA haplotypes were made available by the National Institutes of Health. Results indicated that breed of pig (P less than .01) and dam of pig (P less than .01) affected the immune response of the pig after B. bronchiseptica vaccination. Higher immune response was also associated (P less than .05) with one of the SLA haplotypes tested. Heritability estimates for immune response following vaccination were .10 +/- .12 (half-sib) and .42 +/- .19 (full-sib). Results suggest that the relationship of the SLA complex to immune response in the pig and nonadditive genetic and maternal effects on immune response should be further investigated.     

Effects of Inulin Supplementation in Low‐ or High‐Fat Diets on Reproductive Performance of Sows and Antioxidant Defence Capacity in Sows and Offspring

This experiment was conducted to investigate the effects of inulin supplementation in low‐ or high‐fat diets on both the reproductive performance of sow and the antioxidant defence capacity in sows and offspring. Sixty Landrace × Yorkshire sows were randomly allocated to four treatments with low‐fat diet (L), low‐fat diet containing 1.5% inulin (LI), high‐fat diet (H) and high‐fat diet containing 1.5% inulin (HI). Inulin‐rich diets lowered the within‐litter birth weight coefficient of variation (CV, p = 0.05) of piglets, increased the proportion of piglets weighing 1.0–1.5 kg at farrowing (p < 0.01), reduced the loss of body weight (BW) and backfat thickness (BF) during lactation (p < 0.05) and decreased the duration of farrowing as well as improved sow constipation (p < 0.05). Sows fed fat‐rich diets gained more BW during gestation (p < 0.01), farrowed a greater number of total (+1.65 pigs, p < 0.05) and alive (+1.52 pigs p < 0.05) piglets and had a heavier (+2.06 kg, p < 0.05) litter weight at birth as well as a decreased weaning‐to‐oestrous interval (WEI, p < 0.01) compared with sows fed low‐fat diets. However, it is worth noting that the H diet significantly decreased the serum activities of superoxide dismutase (T‐SOD) and glutathione peroxidase (GSH‐Px) and increased the serum malondialdehyde (MDA) levels in sows and piglets (p < 0.05). In contrast, HI diet enhanced the activities of T‐SOD and GSH‐Px and decreased the serum MDA concentrations (p < 0.05) in sows and piglets. In summary, the fat‐rich diets fed to sows during gestation had beneficial effects on reproductive performance, but aggravated the oxidative stress in sow and piglets. Inulin‐rich diets fed to sow during gestation had beneficial effects on within‐litter uniformity of piglet birthweight and enhanced the antioxidant defence capacity of sows and piglets.     

Effects of season and superovulatory treatment on embryo yields in fine-wool Merinos maintained under field conditions

The aim of the study was to assess the effects of superovulatory treatment (multiple FSH‐dose vs single‐shot FSH treatment) and seasonality on embryo yields in fine‐wool Merino ewes. Treatment based on multiple FSH‐dose consisted of 200 mg of FSH (Folltropin^®) administered in seven decreasing doses. Single‐shot treatment consisted of a single dose of 70 mg of FSH + eCG. In ewes treated with multiple FSH doses, number of recovered embryos was higher (6.0 ± 0.5 vs 3.5 ± 1.0), while non‐fertilization rate was lower (12.8 ± 3.9 vs 40.3 ± 9.5) during the breeding season when compared to the non‐breeding season (p < 0.05); although similar values of recovered Grades 1–2 embryos were observed between seasons. During the breeding season, proportion of responding ewes (98.1 vs 57.1%), ovulation rate (13.9 ± 0.8 vs 3.2 ± 1.2), recovered structures (7.9 ± 0.6 vs 1.7 ± 0.7), total recovered embryos (6.0 ± 0.5 vs 1.2 ± 0.6) and good‐quality embryos (5.1 ± 0.5 vs 0.9 ± 0.6) were higher for the multiple FSH‐dose treatment than for the single‐shot protocol. In a similar way, in the non‐breeding season, ovulation rate (11.3 ± 1.8 vs 6.0 ± 1.1) and recovered structures (6.6 ± 1.2 vs 2.7 ± 0.6) were higher for the multiple FSH injections protocol than those for the single‐shot treatment, resulting in higher recovered Grades 1–2 embryos (3.2 ± 0.9 vs 1.4 ± 0.5). Current results indicate that seasonal anestrus affected embryo yields when applying multiple FSH‐dose superovulatory treatment in Merino ewes, by decreasing the number of recovered embryos although the number of recovered good‐quality embryos was not affected. During both seasons, multiple FSH injections produced higher ovarian response and number of viable embryos than the single‐shot treatment.     

Follicular Dynamics and Oestrous Detection in Thai Postpartum Swamp Buffaloes (Bubalus bubalis)

This study characterized follicular activity and oestrous behaviour from 5 to 9 days post‐calving up to the 4th ovulation postpartum (pp) in 16 multiparous (range 2–7 parities) Thai swamp buffalo cows (Bubalus bubalis), aged 4–12 years and weighing from 432 to 676 kg. Ovarian follicular activity was examined by transrectal ultrasonography (TUS) every morning. Oestrous detection was performed twice daily by direct personal observation of behaviour and for presence of clear cervical mucus discharge and indirectly by video camera recording during 21 h/day. A follicular wave‐like pattern was present before the 1st ovulation leading to short oestrous cycles. Growth rates and maximum diameters of the ovulatory follicles did not differ between the 1st and 4th ovulations. However, growth rate for non‐ovulatory dominant follicles (DF) before the 1st ovulation was lower than for the ovulatory follicle (p < 0.05). In addition, the diameter of all ovulatory follicles (14.3 ± 0.46 mm, n = 39) was significantly larger (p < 0.01) than those of the preceding last but one non‐ovulatory DF (10.8 ± 0.20 mm, n = 5), but similar to the last preceding non‐ovulatory DF diameter (12.92 ± 0.96 mm, n = 14). Short oestrous cycles were most common between the 1st and 2nd ovulations (93.75%, 15/16 cows, 10.2 ± 0.38 days) decreasing in prevalence thereafter (50%, 3/6 buffaloes, 12.0 ± 1.53 days). Oestrous signs were relatively vague around the 1st ovulation pp to become more easily detectable thereafter. This study suggests that properly fed swamp buffaloes could be mated successfully within 2 months pp, at their 2nd spontaneous ovulation, provided oestrous detection is at least performed daily at 06:00–08:00 hour.     

Improving the Quality of Miniature Pig Somatic Cell Nuclear Transfer Blastocysts: Aggregation of SCNT Embryos at the Four‐cell Stage

Miniature pigs share many similar characteristics such as anatomy, physiology and body size with humans and are expected to become important animal models for therapeutic cloning using embryonic stem cells (ESCs) derived by somatic cell nuclear transfer (SCNT). In the present study, we observed that miniature pig SCNT blastocysts possessed a lower total number of nuclei and a lower percentage of POU5F1‐positive cells than those possessed by in vitro fertilized (IVF) blastocysts. To overcome these problems, we evaluated the applicability of aggregating miniature pig SCNT embryos at the four‐cell stage. We showed that (i) aggregation of two or three miniature pig SCNT embryos at the four‐cell stage improves the total number of nuclei and the percentage of POU5F1‐positive cells in blastocysts, and (ii) IVF blastocysts with low cell numbers induced by the removal of two blastomeres at the four‐cell stage did not exhibit a decrease in the percentage of POU5F1‐positive cells. These results suggest that the aggregation of miniature pig SCNT embryos at the four‐cell stage can be a useful technique for improving the quality of miniature pig SCNT blastocysts and indicating that improvement in the percentage of POU5F1‐positive cells in aggregated SCNT embryos is not simply the consequence of increased cell numbers.     

Supplementation of diets for lactating sows with zinc amino acid complex and gastric nutriment‐intubation of suckling pigs with zinc methionine on mineral status,intestinal morphology and bacterial translocation in lipopolysaccharide‐challenged weaned pigs

Sixty‐four pigs from 16 sows were used to evaluate addition of zinc amino acid complex (ZnAA) to lactating sows and gastric nutriment‐intubation of zinc methionine (ZnMet) to suckling pigs on mineral status, intestinal morphology and bacterial translocation after weaning. Sows were fed a barley‐based diet supplying 120 ppm zinc (Zn; control) or the control diet supplemented with 240 ppm Zn from ZnAA. At birth, day‐10 and day‐21 (weaning) of age, pigs from each litter were nutriment‐intubated with 5 ml of an electrolyte solution without or with 40 mg Zn from ZnMet. At weaning, 24 h prior to the collection of small and large intestinal lymph nodes and sections of the duodenum, jejunum and ileum, the pigs received an intramuscular injection of saline without or with 150 μg/kg body weight of Escherichia coli O26:B6 lipopolysaccharide (LPS). With the exception of a tendency (p = 0.09) for lower serum concentration of copper in pigs at weaning from ZnAA‐supplemented sows, there were no differences (p > 0.1) than for pigs from control‐fed sows for mineral status or intestinal morphology. Nutriment‐intubation of ZnMet increased serum (p = 0.001) and liver (p = 0.003) Zn concentrations, number of goblet cells per 250 μm length of jejunal villous epithelium (p = 0.001) and tended (p = 0.06) to enhance jejunum mucosa thickness. Interactive effects (p < 0.05) for higher jejunal villi height and villi:crypt ratio and increased ileal goblet cell counts were apparent for pigs from ZnAA‐supplemented sows that also received nutriment‐intubation of ZnMet. Challenge with LPS increased (p = 0.05) ileal villous width. Nutriment‐intubation of ZnMet decreased (p = 0.05) anaerobic bacteria colony forming unit counts in the large intestinal mesenteric lymph nodes. In conclusion, nutriment‐intubation of ZnMet increased serum and liver tissue concentrations of Zn and resulted in limited improvement to intestinal morphology of weaned pigs.     

Folliculogenesis, embryo parameters and post-transfer recipient pregnancy rate following equine follicle-stimulating hormone (eFSH) treatment in cycling donor mares

Background Induction of multiple ovulations, or superovulation, may potentially increase the efficiency of equine embryo transfer programs. Our objective was to investigate the effects of equine follicle‐stimulating hormone (eFSH) treatment on the success rate of embryo transfer programs in mares. Methods In the research facility of the University of Saskatchewan, Canada, we studied 12 donor mares and 37 recipient mares during the physiological breeding season. Donor mares were used in two consecutive oestrous cycles: the first served as the control cycle and in the second an eFSH regimen was applied (eFSH cycle). In the control cycle, mares were administered human chorionic gonadotropin (hCG) to induce ovulation when a follicle ≥35 mm in diameter was detected by transrectal ultrasonographic examination. In the second oestrous cycle, twice‐daily eFSH treatment was initiated when a follicle ≥25 mm was detected and treatment ceased when a follicle ≥35 mm was present, at which time hCG was administered. All donor mares were artificially inseminated while in oestrus using fresh semen collected from a stallion of proven fertility. At 8 days post‐ovulation, embryos were recovered transcervically and transferred individually to the uterus of a synchronised recipient mare. Results The eFSH treatment stimulated the ovary and resulted in greater numbers of ovulations and recovered embryos; however the recovered embryos tended to have a lower morphological grade than the control embryos, and the recipient pregnancy rate per transferred embryo was lower than anticipated. Conclusion The numbers of recipient pregnancies and foals born that resulted from eFSH treatment were not different from the control.     

维生素及类维生素对母猪繁殖性能的影响

当前非洲猪瘟给我国养猪业造成很大的损失,繁殖母猪的存栏量急剧减少,造成猪肉供需平衡失调。那么,如何提高母猪的繁殖性能,提供更多的商品猪,成为养殖场管理者关注的焦点。文章就提高母猪繁殖性能的关键环节和维生素及类维生素对母猪繁殖性能影响进行综述。     

Impact of Exogenous ACTH During Pro-Oestrus on Endocrine Profile and Oestrous Cycle Characteristics in Sows

Sows housed in freely moving groups have elevated cortisol levels until the rank order is established, which takes place within approximately 48 h. The aim of this investigation was to study the effect of repeated administration of synthetic adrenocorticotropic hormone (ACTH; Synacthen Depot), during the follicular phase (pro-oestrus) on oestrus, ovulation and endocrine parameters. Four multiparous sows were used. Follicular growth and ovulation were recorded by ultrasonography. The first oestrous cycle after weaning was used as control cycle. Onset of oestrus in the sow occurs 3-4 days after the time when plasma progesterone reaches a concentration of 8 nmol/l. The progesterone profile in the control cycle of the individual sow was used for estimation when the ACTH injections should start. In the third pro-oestrus ACTH (2.5 microg/kg) was given via an indwelling catheter every 2 h for 48 h. The sows were euthanased 4-6 days after onset of the third oestrus and the ovaries were examined. Cortisol levels were elevated during the treatment period (p < 0.05). The second cycle, in which the sows were injected with ACTH, was prolonged with 2.5 days compared with the control cycle (p < 0.05). The oestradiol pattern during oestrus was similar in the control and the treatment cycle in ovulating sows. Three sows had ovulated (fresh corpora lutea), but the ovaries contained additionally one or several luteinized follicles/cysts. In conclusion, ACTH administration during pro-oestrus caused a prolongation of the oestrous cycle and a disturbed follicular development.