Journal of reproduction and fertility. Supplement最新文献

{"title":"Management of boars for efficient semen production.","authors":"W. Flowers","doi":"10.1530/biosciprocs.15.005","DOIUrl":"https://doi.org/10.1530/biosciprocs.15.005","url":null,"abstract":"Consistent production of large quantities of fertile semen is a primary concern of boar management programmes. Common visual tests such as motility are poor indicators of the fertilizing capacity of an ejaculate. Research studies have demonstrated that, in general, if motility is 60% or greater, there are no relationships among the percentage of motile spermatozoa, in vitro sperm penetration rates, farrowing rates and litter size. Biological and environmental factors that influence the production of total numbers of spermatozoa are either inhibitory or stimulatory. Chronic undernutrition and heat stress inhibit spermatogenesis, while photoperiod and genetic factors are stimulatory. A consistent stimulatory effect of photoperiod does not appear to occur under all environmental conditions. In contrast, selection for increased testis size consistently results in greater sperm production. In addition, libido is decreased by heat stress and undernutrition. However, failure to allow boars to interact socially with other pigs during pubertal development appears to be the most damaging factor. Effective boar management programmes must minimize the occurrence of factors that adversely affect spermatogenesis and simultaneously accentuate those with a stimulatory role.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"73 1","pages":"67-78"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88514008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Culture and storage of pig embryos.","authors":"D. Davis","doi":"10.1530/biosciprocs.12.009","DOIUrl":"https://doi.org/10.1530/biosciprocs.12.009","url":null,"abstract":"Studies have consistently demonstrated that 4-cell pig embryos can be cultured to the blastocyst stage in a simple salt solution containing bovine serum albumin (BSA). Pig embryos appear to be detrimentally affected by lower levels of lactate and pyruvate than are mouse embryos, but in general their in-vitro requirements are similar. Results from embryos cultured between the 4-cell and blastocyst stages are consistent enough to allow the use of culture for the storage and shipment of pig embryos. However, results obtained after culture and transfer indicate a reduction in viability similar to that observed for cultured cattle and mice embryos. Embryos collected earlier than the 4-cell stage have been difficult to support in vitro beyond one or two cleavage divisions. Pig blastocysts may benefit from serum in their in-vitro environment: lamb, fetal calf and human serum supported continued development but pig serum was detrimental. There are conflicting reports on the efficacy of a more complete medium (Minimum Essential Medium) on the growth of pig embryos. Embryo culture will almost certainly contribute to the application of biotechnology to embryos by providing more appropriate environments for in-vitro manipulations and also, possibly, by providing a system for the early selection of desirable embryonic genotypes.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"104 1","pages":"115-24"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90587289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of follicular development and ovulation rate in pigs.","authors":"N. M. Cox","doi":"10.1530/biosciprocs.15.003","DOIUrl":"https://doi.org/10.1530/biosciprocs.15.003","url":null,"abstract":"There is considerable evidence that nutritional and metabolic control of follicular growth is mediated by metabolic hormones and growth factors, particularly with processes mediated by insulin-like growth factor I (IGF-I) and its binding proteins (IGFBPs). From knowledge that hormones and growth factors which can be affected by diet also positively affect ovarian function, the concept has emerged that metabolic modifiers of gonadotrophin action, rather than gonadotrophins themselves, could affect follicle development. While ovulation rate can be enhanced under certain conditions in cyclic gilts, assessing influences of metabolic modifiers on the post-lactational sow is confounded by variability in the return to oestrus after weaning. In a series of studies involving insulin administration between weaning and oestrus, successive experiments produced different results, but several measures of reproductive performance were enhanced. Administration of somatotrophin (ST) has also been shown to increase follicular development in both gilts and sows. Both insulin and ST increase IGF-I production by pig ovarian follicles, and insulin is more effective than IGF-I in reducing atresia and increasing progesterone in cultured pig follicles. Whether increases in litter size are achieved after an increase in ovulation rate involves many factors, including the quality of ova and whether the increase in ovulation rate exceeds the uterine capacity to maintain pregnancy. Given the variation in genetics and management practices, development of treatments to enhance follicle quality leading to maximal litter size is challenging.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"216 1","pages":"31-46"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74170569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extracellular matrix and the implantation cascade in pigs.","authors":"R. Burghardt, Jeffery A. Bowen, G. Newton, F. Bazer","doi":"10.1530/biosciprocs.15.0011","DOIUrl":"https://doi.org/10.1530/biosciprocs.15.0011","url":null,"abstract":"The structural and functional alterations of uterine epithelial cells that permit the apical-apical union of conceptus and uterine epithelium are complex and are likely to involve many different adhesion molecules with distinct but inter-related functions. A number of changes in the molecular composition at the apical surface of uterine epithelial cells associated with the transition from the pre-receptive to the receptive state in the pig uterus are reviewed. Molecules that function in the adhesion cascade resulting in implantation are represented by a variety of adhesion systems. However, integrins are probably the dominant adhesion systems because their capacity to mediate adhesion is linked to their activation by engaging other surface molecules.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"52 1","pages":"151-64"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89741696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Behavioural perspectives on piglet survival.","authors":"D. Fraser","doi":"10.1530/biosciprocs.13.0025","DOIUrl":"https://doi.org/10.1530/biosciprocs.13.0025","url":null,"abstract":"Litters of domestic piglets show strong sibling competition, large differences among litter-mates in birth weight and rate of growth, and, in the absence of human intervention, a high mortality rate. This combination of traits suggests that pigs are using a reproductive strategy similar to that of certain bird species which produce one or more small 'spare' young whose death or survival is determined by sibling competition. Death through competition is natural in such species. Prevention of death requires the early identification and separate rearing of unsuccessful competitors. The major behavioural pathways leading to piglet deaths are considered to be malnutrition through unsuccessful suckling behaviour, and crushing of piglets by the sow. Crushing involves two distinct behavioural sequences: posterior crushing (beneath the sow's hind quarters) and ventral crushing (beneath the udder and rib cage). Farrowing crates are designed to prevent posterior but not ventral crushing. Malnourished piglets appear to be more vulnerable to crushing, perhaps because persistent suckling attempts cause them to spend more time near the sow. Prevention of crushing thus requires a reduction in malnutrition, not merely restriction of the sow's movements. Under certain conditions, dehydration may be an important but neglected aspect of malnutrition. Some litters of piglets have much higher death losses than others, presumably because of risk factors that apply to the litter as a whole. Early malnutrition, resulting from hypogalactia in the sow in the first days after farrowing, appears to be an important risk factor. Farrowing difficulties leading to piglet hypoxia during the birth process may be another. Risk factors that affect whole litters deserve greater emphasis in future research.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"38 1","pages":"355-70"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91551675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influencing prolificacy of sows by selection for physiological factors.","authors":"R. Johnson, D. Zimmerman, W. Lamberson, S. Sasaki","doi":"10.1530/biosciprocs.12.0011","DOIUrl":"https://doi.org/10.1530/biosciprocs.12.0011","url":null,"abstract":"The potential to improve prolificacy, with major emphasis on selection for components of litter size, ovulation rate and prenatal survival, and selection for physiological factors are reviewed. Response to selection for physiological factors is superior to direct selection if physiological factors have moderate heritabilities and moderate to high genetic correlations with the trait to be improved. There are very few estimates of the genetic parameters needed to calculate the relative efficiency of direct and indirect selection. Testis size is highly heritable and positively correlated genetically with ovulation rate in both mice and pigs and may be potentially useful in an index with litter size to improve ovulation rate and prenatal survival. Selection for growth, ovulation rate or litter size has increased ovulation rate in mice, but the physiological explanations are different. Selection for litter size in a line of pigs previously selected for ovulation rate was effective; the realized heritability was 0.18 +/- 0.06. Potential improvements in litter size from index selection for ovulation rate and prenatal survival are discussed and compared to direct selection for litter size.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"90 1","pages":"139-49"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83910766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selection of breeds, strains and individual pigs for prolificacy.","authors":"C. Legault","doi":"10.1530/biosciprocs.12.0012","DOIUrl":"https://doi.org/10.1530/biosciprocs.12.0012","url":null,"abstract":"Prolificacy, defined as litter size at birth, is currently considered to be the most important component of sow productivity. However, in spite of a spectacular increase in productivity due to management advances, litter size at birth has remained constant for the past 20 years. This situation seems to question the long-term efficiency of the classical methods of genetic improvement such as within-herd selection and crossbreeding between European or American breeds. Some recent developments and research results suggest that one can be optimistic about the possibilities of increasing litter size in the near future. A survey of available breeds world-wide illustrates the important differences in average litter size (5-15 piglets), embryo mortality (15-40%) and heterosis (ranging from 5 to over 30%) on litter size. In particular the high prolificacy of some Chinese breeds can be used to speed up gentic progress in improving litter size either through systematic 3-way (3-4 additional piglets per litter in the F1 compared with European breeds) or 4-way crosses with Western breeds, or by developing composite lines selected for heritable traits such as growth rate and backfat thickness. The efficiency of this system might be improved by combining Chinese breeds with 'hyperprolific' western strains. When using Chinese breeds, special attention should be paid to the choice of the terminal boar, which should be as lean as possible, in order to produce acceptable carcasses for sale. Another potential solution would be to use modern computerized recording systems to detect extreme individuals and then to apply a strong selection intensity. Using this approach, it is then possible to develop a gene pool for prolificacy. Results obtained in France, Great Britain and Australia are encouraging. The expected progress is about 0.5 piglets per litter when strain selection is limited to one sex and about 1 piglet when it includes both sexes. Moreover, using crossbreeding, the heterosis effect seems to be cumulated with the genetic changes mentioned above. The computer can also be an aid in eliminating chromosomal translocations responsible for a reduction in prolificacy ranging from 5 to 50%.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"42 1","pages":"151-66"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82824129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mathematical models of sow reproduction.","authors":"W. Close, J. Pettigrew","doi":"10.1530/biosciprocs.13.006","DOIUrl":"https://doi.org/10.1530/biosciprocs.13.006","url":null,"abstract":"Nutrition affects reproduction, but the physiological mechanisms are not known. Defining those mechanisms is a high priority for animal scientists. This paper briefly describes mathematical models developed to aid in elucidating those mechanisms and which may be applied to predict animal performance. Two types of mechanistic mathematical models of sows are described, based respectively on nutrient partitioning and on metabolic and physiological principles. The nutrient partitioning model is relatively mature but the metabolic/physiological model is still at an early stage of development. The use of such models in the design and evaluation of feeding programmes, in understanding the biological system and in improving research efficiency are outlined. These two models are now being used as described, and it is anticipated that they, and other models, will make important contributions to the marked improvements in reproductive performance in commercial pig production that is anticipated during the next few years.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"140 1","pages":"83-8"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82881395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of neuropeptides and amino acids in controlling secretion of hormones from the anterior pituitary gland in pigs.","authors":"M. Estienne, J. Harter-Dennis, C. Barb","doi":"10.1530/biosciprocs.15.001","DOIUrl":"https://doi.org/10.1530/biosciprocs.15.001","url":null,"abstract":"All reproductive processes involve one or more of the protein hormones secreted from the anterior pituitary gland: LH, FSH, prolactin, growth hormone, ACTH and thyroid-stimulating hormone (TSH). Primary hormones of reproduction, such as LH and FSH, directly regulate a reproductive activity. For example, LH and FSH stimulate follicular growth and the associated secretion of oestradiol in sows. In contrast, secondary hormones of reproduction such as TSH are permissive and regulate other physiological systems that indirectly, but profoundly, influence reproduction. Reproduction in pigs can be enhanced by developing strategies to alter and control secretion of hormones from the anterior pituitary gland. However, the successful manipulation of adenohypophysial hormone secretion will require a sound understanding of the mechanisms controlling the function of the hypothalamic-pituitary axis. Hypothalamic hormones including GnRH, dopamine, growth hormone-releasing hormone (GHRH), somatostatin, corticotrophin-releasing hormone (CRH) and thyrotrophin-releasing hormone (TRH) are synthesized in perikarya that possess axons that terminate at the median eminence. These hormones are released into the hypothalamo-hypophysial portal vasculature, travel to the anterior pituitary gland and stimulate or inhibit secretion of adenohypophysial hormones. Secretion of hypothalamic hormones is ultimately controlled by a variety of neurotransmitters and neuropeptides, the most studied in swine being the endogenous opioid peptides (EOP) and more recently, the excitatory amino acids (ExAA). In general, EOP inhibit GnRH and hence LH secretion, and this effect involves the central catecholaminergic system. A definitive role for EOP in the modulation of FSH release remains to be determined. EOP stimulate secretion of GHRH and thus growth hormone release, and depending on the animal model studied, EOP exert either stimulatory or inhibitory influences on prolactin secretion. ExAA, working via N-methyl-D-aspartate (NMDA) receptors at the central nervous system, stimulate secretion of LH, FSH, growth hormone and prolactin in appropriate animal models. However, in certain situations, an inhibitory effect of ExAA on LH secretion has been demonstrated. The modulation of growth hormone and prolactin secretion by ExAA involves EOP. Research investigating the function of ExAA and EOP in the physiological control of swine reproduction warrants further scrutiny.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"69 4 1","pages":"3-17"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77149411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sources and biological actions of relaxin in pigs.","authors":"C. Bagnell, Q. Zhang, B. Downey, L. Ainsworth","doi":"10.1530/biosciprocs.14.0009","DOIUrl":"https://doi.org/10.1530/biosciprocs.14.0009","url":null,"abstract":"Although the major source of relaxin in pigs is the corpus luteum of pregnancy, there is now evidence for relaxin gene expression and translation into protein in the theca interna cells of the preovulatory follicle, the corpus luteum of the cycle and the uterus. The theca interna cells retain their ability to express the relaxin gene and protein following ovulation. During the early stages of development of the corpus luteum, the theca-derived small lutein cells are the source of the relaxin transcript. As the corpus luteum becomes fully functional, there is a switch in the site of relaxin synthesis from small theca-derived lutein cells to large granulosa-derived cells. In the absence of luteolysis, this switch is accompanied by a dramatic rise in relaxin synthesis. Relaxin has been identified in boar seminal plasma and can maintain or increase sperm motility. However, a source of relaxin in the boar has not been identified. Relaxin is an important regulator of uterine function during pregnancy acting systemically to suppress myometrial activity and promote cervical dilation at parturition. The changes in thecal relaxin production during follicle development and its ability to promote growth and changes in proteolytic enzyme activity of granulosa cells in vitro have led to the concept of an autocrine or paracrine role for relaxin within the follicle. Uterotrophic effects of relaxin have been reported in rodents and swine and support the hypothesis that relaxin promotes uterine growth and expansion in early pregnancy to accommodate the growing fetuses. Mammotrophic effects of relaxin in rodents have now been extended to pigs, with evidence that relaxin is necessary for normal mammary parenchymal development in late pregnancy. In most instances the mechanisms responsible for, and the physiological significance of, these diverse biological effects remain to be elucidated.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"44 1","pages":"127-38"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81153920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}