Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.8.015
Z. Roth
Reduced reproductive performance of lactating cows during the summer is associated mainly with intensive genetic selection for high milk production, which places a great load on the thermoregulatory mechanism. Today, cooling is the predominant strategy used to alleviate the effects of heat stress. However, it cannot eliminate the decline in reproduction. A better understanding of the mechanism by which heat stress compromises fertility is required to develop new strategies to mitigate its effects. This review summarizes what is known about the multifactorial effect of thermal stress on reproductive functions, which includes alterations in the hypothalamus– pituitary–ovarian axis: gonadotropin secretion, follicular development, steroid production and corpus luteum function. The review provides some new insights into the cellular and molecular responses of oocytes and embryos to elevated temperature, discusses some potential underlying mechanisms, such as nuclear and cytoplasmic maturation, mitochondrial function, apoptotic pathways and oxidative stress, and suggests potential approaches to alleviating these effects. Given the complexity of heat-stress effects on reproduction, comprehensive reproductive management during the summer is suggested, based on: (1) an efficient cooling system as a prerequisite for any other strategies, (2) hormonal treatment targeted to specific subgroups of cows that will benefit from it, rather than the whole herd, and (3) combining two or more strategies in a program, rather than correcting the function of a single aspect of the reproductive system.
{"title":"Effects of heat stress on ovarian functions and embryonic development: mechanism and potential strategies to alleviate these effects in dairy cows","authors":"Z. Roth","doi":"10.1530/BIOSCIPROCS.8.015","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.8.015","url":null,"abstract":"Reduced reproductive performance of lactating cows during the summer is associated mainly with intensive genetic selection for high milk production, which places a great load on the thermoregulatory mechanism. Today, cooling is the predominant strategy used to alleviate the effects of heat stress. However, it cannot eliminate the decline in reproduction. A better understanding of the mechanism by which heat stress compromises fertility is required to develop new strategies to mitigate its effects. This review summarizes what is known about the multifactorial effect of thermal stress on reproductive functions, which includes alterations in the hypothalamus– pituitary–ovarian axis: gonadotropin secretion, follicular development, steroid production and corpus luteum function. The review provides some new insights into the cellular and molecular responses of oocytes and embryos to elevated temperature, discusses some potential underlying mechanisms, such as nuclear and cytoplasmic maturation, mitochondrial function, apoptotic pathways and oxidative stress, and suggests potential approaches to alleviating these effects. Given the complexity of heat-stress effects on reproduction, comprehensive reproductive management during the summer is suggested, based on: (1) an efficient cooling system as a prerequisite for any other strategies, (2) hormonal treatment targeted to specific subgroups of cows that will benefit from it, rather than the whole herd, and (3) combining two or more strategies in a program, rather than correcting the function of a single aspect of the reproductive system.","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44933350","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}
Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.6.015
M. Lucy
The fertility of dairy cows has declined worldwide and this change is surprising given the importance of good fertility to the dairy industry. The decline in fertility can be explained by management changes within the dairy industry and also negative genetic correlations between milk production and reproduction. Four primary mechanisms that depress fertility in lactating cows are anovulatory and behavioral anestrus (failure to cycle and display estrus), suboptimal and irregular estrous cyclicity (this category includes ovarian disease and subnormal luteal function after breeding), abnormal preimplantation embryo development (may be secondary to poor oocyte quality), and uterine/placental incompetence. The solution for improving fertility in high-producing dairy cows will include both short-term and long-terms components. For the immediate short-term, using high fertility sires and implementing controlled breeding programs will help. Controlled breeding programs improve reproductive efficiency in confinement-style dairy herds and can be combined with post-insemination treatments to enhance fertility. An additional immediate short-term solution involves changing the diet so that dietary ingredients invoke hormonal responses that benefit the reproduction of the cow. The short-term solutions described above do not address the fundamental need for correcting the underlying genetics for reproduction in high-producing dairy cows. Crossbreeding will improve reproductive performance perhaps because it alleviates inbreeding and also lowers production in cows with an extreme high milk production phenotype. The current crisis in dairy reproduction will be permanently solved, however, when the genetics for dairy reproduction are improved through a balanced genetic selection strategy.
{"title":"Fertility in high-producing dairy cows: reasons for decline and corrective strategies for sustainable improvement","authors":"M. Lucy","doi":"10.1530/BIOSCIPROCS.6.015","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.6.015","url":null,"abstract":"The fertility of dairy cows has declined worldwide and this change is surprising given the importance of good fertility to the dairy industry. The decline in fertility can be explained by management changes within the dairy industry and also negative genetic correlations between milk production and reproduction. Four primary mechanisms that depress fertility in lactating cows are anovulatory and behavioral anestrus (failure to cycle and display estrus), suboptimal and irregular estrous cyclicity (this category includes ovarian disease and subnormal luteal function after breeding), abnormal preimplantation embryo development (may be secondary to poor oocyte quality), and uterine/placental incompetence. The solution for improving fertility in high-producing dairy cows will include both short-term and long-terms components. For the immediate short-term, using high fertility sires and implementing controlled breeding programs will help. Controlled breeding programs improve reproductive efficiency in confinement-style dairy herds and can be combined with post-insemination treatments to enhance fertility. An additional immediate short-term solution involves changing the diet so that dietary ingredients invoke hormonal responses that benefit the reproduction of the cow. The short-term solutions described above do not address the fundamental need for correcting the underlying genetics for reproduction in high-producing dairy cows. Crossbreeding will improve reproductive performance perhaps because it alleviates inbreeding and also lowers production in cows with an extreme high milk production phenotype. The current crisis in dairy reproduction will be permanently solved, however, when the genetics for dairy reproduction are improved through a balanced genetic selection strategy.","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47275728","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}
Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.8.007
P. Pfeffer
Summary Early embryo mortality during the first two weeks of development is an important factor in the decreasing fertility of dairy cattle. During this period the embryo needs to correctly establish the first three lineages, namely epiblast, hypoblast and trophoblast so as to survive. The morphological and molecular events underlying these lineage decisions are discussed, drawing on information derived predominantly from mice and cattle. TE be traced the DiI TE donor cells maintain their original fate and contribute only to TE, they would be considered to have been committed to this fate at the stage that they had been isolated. If they were to contribute to both ICM and TE, they would be considered to have been uncommitted.
{"title":"Lineage commitment in the mammalian preimplantation embryo","authors":"P. Pfeffer","doi":"10.1530/BIOSCIPROCS.8.007","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.8.007","url":null,"abstract":"Summary Early embryo mortality during the first two weeks of development is an important factor in the decreasing fertility of dairy cattle. During this period the embryo needs to correctly establish the first three lineages, namely epiblast, hypoblast and trophoblast so as to survive. The morphological and molecular events underlying these lineage decisions are discussed, drawing on information derived predominantly from mice and cattle. TE be traced the DiI TE donor cells maintain their original fate and contribute only to TE, they would be considered to have been committed to this fate at the stage that they had been isolated. If they were to contribute to both ICM and TE, they would be considered to have been uncommitted.","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48322862","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}
Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.8.008
Jeremy T. Smith, P. Hawken, M. Lehman, G. Martin
Summary Kisspeptin is a hypothalamic neuropeptide that is critical for fertility. In virtually all species, kisspeptin neurons stimulate gonadotrophin-releasing hormone (GnRH) secretion and act as transmitters for sex-steroid feedback to GnRH neurons. In sheep, kisspeptin neurons are located in the preoptic area and the arcuate nucleus (ARC), with the latter involved in both oestradiol positive and negative feedback regulation of GnRH. In addition, sheep are seasonal breeders, with an annual cycle controlled by changes in the pulsatile secretion of GnRH. Kisspeptin neurons are also important in this phenomenon showing increased expression and terminal apposition to GnRH neurons during the breeding season. Reduced kisspeptin expression during the non-breeding season can be overcome by administration of kisspeptin, which causes ovulation in seasonally acyclic females. On the other hand, kisspeptin neurons do not appear to express the melatonin receptor, so the transduction of photoperiod to these neurons must be indirect, perhaps involving dopaminergic suppression during the non-breeding season. Importantly, kisspeptin neurons of the ARC do not operate in isolation. Autoregulation of kisspeptin expression by the neuropeptides neurokinin B and dynorphin is a key contributor to the “KNDy neuron” concept and the hypothesis that these neurons comprise the GnRH pulse generator. Indeed, the pheromone-induced interruption of seasonal anestrus, known as the male effect, appears to be mediated by KNDy signalling. However, the ‘KNDy hypothesis’ for GnRH pulse generation is still unproven and, indeed, the precise role of KNDy cells in seasonal breeding has yet to be determined.
{"title":"The role of kisspeptin in reproductive function in the ewe","authors":"Jeremy T. Smith, P. Hawken, M. Lehman, G. Martin","doi":"10.1530/BIOSCIPROCS.8.008","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.8.008","url":null,"abstract":"Summary Kisspeptin is a hypothalamic neuropeptide that is critical for fertility. In virtually all species, kisspeptin neurons stimulate gonadotrophin-releasing hormone (GnRH) secretion and act as transmitters for sex-steroid feedback to GnRH neurons. In sheep, kisspeptin neurons are located in the preoptic area and the arcuate nucleus (ARC), with the latter involved in both oestradiol positive and negative feedback regulation of GnRH. In addition, sheep are seasonal breeders, with an annual cycle controlled by changes in the pulsatile secretion of GnRH. Kisspeptin neurons are also important in this phenomenon showing increased expression and terminal apposition to GnRH neurons during the breeding season. Reduced kisspeptin expression during the non-breeding season can be overcome by administration of kisspeptin, which causes ovulation in seasonally acyclic females. On the other hand, kisspeptin neurons do not appear to express the melatonin receptor, so the transduction of photoperiod to these neurons must be indirect, perhaps involving dopaminergic suppression during the non-breeding season. Importantly, kisspeptin neurons of the ARC do not operate in isolation. Autoregulation of kisspeptin expression by the neuropeptides neurokinin B and dynorphin is a key contributor to the “KNDy neuron” concept and the hypothesis that these neurons comprise the GnRH pulse generator. Indeed, the pheromone-induced interruption of seasonal anestrus, known as the male effect, appears to be mediated by KNDy signalling. However, the ‘KNDy hypothesis’ for GnRH pulse generation is still unproven and, indeed, the precise role of KNDy cells in seasonal breeding has yet to be determined.","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49247254","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}
Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.8.014
S. Butler, S. Cummins, M. Herlihy, I. Hutchinson, S. G. Moore
The efficiency of milk production in pasture-based systems is heavily influenced by calving pattern, necessitating excellent reproductive performance in a short breeding season. Where grazed pasture is the major component of the diet, cows are underfed relative to their intake potential. A number of studies have identified body condition score measurements that are related to likelihood of both submission and conception. In general, fertility variables have favourable associations with circulating concentrations of glucose, insulin and insulin-like growth factor-1 and unfavourable associations with non-esterified fatty acids, beta-hydroxybutyrate and endogenous growth hormone. Nutritional strategies to impact these metabolic indicators have been utilised, but effects on herd fertility are inconsistent. Long term selection for improved genetic merit for fertility traits increases the likelihood of pregnancy establishment. This is achieved through more favourable metabolic status, advancing postpartum resumption of cyclicity, improved postpartum uterine health, stronger behavioural oestrous expression and increased luteal phase circulating progesterone concentrations. Use of synchronisation to maximise submission rates can advance the timing of pregnancy establishment and improve calving pattern. Incorporation of sexed semen into the breeding programme can increase the number of female calves born, but at the expense of reduced conception rates. Nevertheless, careful selection of the heifers and cows to be inseminated with sexed semen will minimize the reduction in fertility performance. This review outlines the unique challenges of pasture-based systems, and the roles of nutritional management, genetic improvement of fertility traits, synchronisation and incorporation of sexed semen in the breeding programme in regulating reproductive performance.
{"title":"Optimizing productive and reproductive performance in the grazing cow","authors":"S. Butler, S. Cummins, M. Herlihy, I. Hutchinson, S. G. Moore","doi":"10.1530/BIOSCIPROCS.8.014","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.8.014","url":null,"abstract":"The efficiency of milk production in pasture-based systems is heavily influenced by calving pattern, necessitating excellent reproductive performance in a short breeding season. Where grazed pasture is the major component of the diet, cows are underfed relative to their intake potential. A number of studies have identified body condition score measurements that are related to likelihood of both submission and conception. In general, fertility variables have favourable associations with circulating concentrations of glucose, insulin and insulin-like growth factor-1 and unfavourable associations with non-esterified fatty acids, beta-hydroxybutyrate and endogenous growth hormone. Nutritional strategies to impact these metabolic indicators have been utilised, but effects on herd fertility are inconsistent. Long term selection for improved genetic merit for fertility traits increases the likelihood of pregnancy establishment. This is achieved through more favourable metabolic status, advancing postpartum resumption of cyclicity, improved postpartum uterine health, stronger behavioural oestrous expression and increased luteal phase circulating progesterone concentrations. Use of synchronisation to maximise submission rates can advance the timing of pregnancy establishment and improve calving pattern. Incorporation of sexed semen into the breeding programme can increase the number of female calves born, but at the expense of reduced conception rates. Nevertheless, careful selection of the heifers and cows to be inseminated with sexed semen will minimize the reduction in fertility performance. This review outlines the unique challenges of pasture-based systems, and the roles of nutritional management, genetic improvement of fertility traits, synchronisation and incorporation of sexed semen in the breeding programme in regulating reproductive performance.","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42445487","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}
Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.7.005
K. Sinclair, A. Karamitri, D. Gardner
{"title":"Dietary regulation of developmental programming in ruminants: epigenetic modifications in the germline","authors":"K. Sinclair, A. Karamitri, D. Gardner","doi":"10.1530/BIOSCIPROCS.7.005","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.7.005","url":null,"abstract":"","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47791381","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}
Pub Date : 2019-04-05DOI: 10.1530/biosciprocs.19.0008
C. Zhou, S. Tsoi, W. Dixon, G. Foxcroft, M. Dyck
{"title":"Comparative transcriptomic analysis between in vivo derived porcine 4-cell and morula embryos","authors":"C. Zhou, S. Tsoi, W. Dixon, G. Foxcroft, M. Dyck","doi":"10.1530/biosciprocs.19.0008","DOIUrl":"https://doi.org/10.1530/biosciprocs.19.0008","url":null,"abstract":"","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67228734","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}
Pub Date : 2019-04-05DOI: 10.1530/BIOSCIPROCS.6.027
K. Sinclair, R. Lea, W. Rees, Young Le
{"title":"The developmental origins of health and disease: current theories and epigenetic mechanisms","authors":"K. Sinclair, R. Lea, W. Rees, Young Le","doi":"10.1530/BIOSCIPROCS.6.027","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.6.027","url":null,"abstract":"","PeriodicalId":93083,"journal":{"name":"Bioscientifica proceedings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42513710","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：