代谢信号对能量影响猪卵泡发育的作用

动物体内的许多激素和因子通过内分泌活动把能量摄入和繁殖系统联系起来。卵巢上卵泡的发育是雌性动物繁殖系统中的重要因素,是繁殖性能的基础。猪的生产是人们生活中主要的肉类来源之一,能量对猪卵泡发育的影响日益受到关注。日粮能量水平的变化会影响到体内循环与营养代谢相关的激素和因子,而这些激素和因子的变化可能会作为代谢信号对卵泡的发育产生影响。这些代谢信号包括胰岛素、瘦素和胰岛素样生长因子-Ⅰ等。研究表明,代谢信号对下丘脑、垂体和卵巢均有影响。在胰岛素、瘦素和胰岛素样生长因子-Ⅰ等代谢信号的介导下,日粮能量营养因素通过改变下丘脑-垂体-卵巢轴的活性,对雌性动物的卵泡发育产生影响。     

短期限饲对初情期前母猪和初产母猪繁殖机能的影响

作者探讨短期限饲对初情期前母猪和初产母猪繁殖机能的影响及其机理。当体重和脂肪与肌肉比例无变化,短期限饲影响初情期前母猪卵巢繁殖功能。葡萄糖和胰岛素在初情期前母猪繁殖机能中有重要作用。胰岛素是营养与繁殖之间的一个媒介。无内源性激素影响时,短期限饲调节卵巢繁殖功能。在限饲期间,促性腺激素在白天出现明显节奏性释放。短期限饲通过胰岛素影响初产母猪卵泡发育、断奶后发情间隔和排卵率。胰岛素是营养与胚胎存活率之间的介质。短期限饲由于限饲时间不同对初产母猪胚胎存活率影响也不同。分析营养与繁殖机能关系,调节营养使母猪发挥最大繁殖潜力,促进养猪业发展。     

能量负平衡对奶牛繁殖的影响及相关机理

高产奶牛繁殖力低下是世界性难题。能量负平衡(NEB)影响脂肪动员,改变血液代谢指标,诱发能量代谢紊乱及相关疾病,影响卵泡发育及子宫胚胎内环境,影响机体多种激素的分泌,损害奶牛生殖免疫机能,提高该状态下子宫疾病的易感性并诱发炎症反应,延缓产后子宫恢复,制约奶牛的繁殖性能。本文主要阐述NEB对奶牛繁殖的影响及相关机理,为奶牛生产和繁殖研究工作提供参考。     

奶牛繁殖障碍疾病的影响因素及防治措施

奶牛产后的子宫内膜炎、乳房炎、肢蹄病等疾病主要通过影响排出卵子的质量和促性腺激素、妊娠早期子宫腺体的分泌状态而对繁殖功能造成影响。高产奶牛围产期的能量负平衡会造成体内胰岛素、胰岛素样生长因子-I、雌二醇、孕酮的分泌量减少以及LH的脉冲频率下降，从而影响卵巢的发育，对繁殖性能造成影响。早期胚胎的发育则易受到孕酮分泌量、胚胎生长速度、干扰素tau分泌量以及子宫PGF2α分泌状况的影响。此外，奶牛易受霉菌毒素以及细菌、病毒、寄生虫等传染性因素的影响而引发流产。     

提高奶牛繁殖性能的技术发展现状

本文回顾了目前国际上对提高奶牛繁殖力的最新研究进展，从调控卵巢功能促进卵泡的发育和排卵、排卵后的黄体功能及提高胚胎存活力等方面讨论了目前可以用于提高奶牛繁殖性能或受胎率的各项技术研究进展。这些技术包括①促进排卵和定时排卵-输精技术；②在排卵后用GnRH、hCG和干扰素T处理抵抗子宫的溶黄作用，促进黄体功能从而提高受胎率的技术；配种时或早期妊娠阶段通过使用生长激素处理促进胚胎发育和提高胚胎存活率，从而来提高受胎率的技术；③从影响生殖系统功能、卵泡发育和子宫溶黄作用的营养水平各方面发展出来的营养管理技术。今后在这些研究进展的基础上，综合、灵活应用这些技术，发展出实用的提高奶牛受胎率和繁殖性能的技术。     

动物脂肪沉积程序化及精氨酸的调控作用

脂肪的过度沉积常伴随着胰岛素抵抗、Ⅱ型糖尿病等代谢病症,既危害人类健康,带来经济负担,也会在农业生产中影响畜牧产品的质量。脂肪的沉积,始于胚胎期脂肪组织的发育,是一系列程序化作用的结果。脂肪沉积受多方因素影响,营养干预可以通过胚胎环境中的糖皮质激素浓度、线粒体功能、表观遗传、食欲中枢发育等方面影响胚胎脂肪沉积程序化。论文阐述了动物出生前后营养状况对脂肪沉积程序化的作用,对脂肪沉积的机制进行了初步探讨,并介绍了精氨酸营养在脂肪沉积中的应用。饮食中添加精氨酸为治疗脂肪过度沉积,提高畜牧生产水平,改善人类生活质量,开拓了新的思路。     

蛋白质营养对动物卵泡发育的影响及其作用机制

卵泡的发育对于雌性动物繁殖性能具有重要影响.蛋白质是机体酶、激素合成以及组织器官构建的原料,对于卵泡发育必不可少.蛋白质营养状态能通过肝脏雌激素受体(ER)影响胰岛素样生长因子Ⅰ (IGF-Ⅰ)、瘦素(leptin)、胰岛素(insulin)等代谢信号,进而传递至下丘脑-垂体-性腺(HPG)轴,对卵泡发育进行调控.本文综述了蛋白质营养对卵泡发育的影响及其作用机制.     

羊超数排卵影响因素的分析

超数排卵(简称超排)是以各种外源性促性腺激素诱发动物卵巢的多个卵泡发育并排出多个具有受精能力卵的过程。超排是胚胎移植最重要的技术环节,对于提高优良母畜的繁殖能力和品种改良具有重要意义,同时也为动物克隆和转基因动物生产等提供卵子和胚胎来源。目前,尽管超数排卵的方法已广泛应用,但超排的胚胎回收率和可用胚胎数还不稳定,影响了胚胎移植的进一步推广和应用。本文通过对超排影响的动物品种、个体差异、激素、超排处理方案、采胚方法、重复超排、年龄、营养状况、季节等诸多因素的分析,旨在为提高动物的超排效率提供借鉴。1影响超…     

亚硒酸钠维生素E注射液对奶牛繁殖疾病的应用

硒和维生素E是畜禽营养和生长繁殖必须的物质,尤其对幼龄动物和母畜更为需要。我们于1989年开始应用上海兽药厂生产的亚硒酸钠维生素E注射液治疗奶牛繁殖疾病50多例,均收到满意疗效。 (一)治疗奶牛卵巢机能不全奶牛卵巢机能不全,常因饲管不当和一些疾病因素而造成母畜性周期紊乱长期不能妊娠。对奶牛一侧卵泡发育不全,用亚硒酸钠维生素E30毫升一次深部肌肉注射,两侧卵泡发育不全用50毫升分两     

热应激对奶牛繁殖性能的影响研究进展

环境温度、湿度和光照周期都会对奶牛的繁殖性能造成影响。夏季奶牛采食量减少可能会影响奶牛的能量平衡,或导致下丘脑-垂体-卵巢轴功能紊乱,进而降低卵母细胞、胚胎和卵泡的质量,导致奶牛繁殖性能降低。本文就夏季热应激对奶牛繁殖性能的影响做一综述。     

Influence of metabolic hormones and nutrition on ovarian follicle development in cattle: practical implications

Nutrition has long been known to have a profound influence on reproductive performance of female cattle, but the underlying mechanism remains poorly understood. Whilst early investigations focused on the modulation of nutrition on hypothalamic-pituitary axis, more recent studies have tested the hypothesis that metabolic hormones as nutritional signals exert a direct effect at the ovarian level. In cattle, treatment with recombinant bovine somatotrophin (rGH) significantly increases the population of small ovarian follicles. This is associated with increases in circulating concentrations of insulin and insulin-like growth factor-I (IGF-I). Subsequent studies, both in vitro and in vivo, have highlighted the importance of IGF-I and/or insulin acting in synergy with FSH and LH. More recently, we demonstrated that feeding heifers with 200% maintenance requirements for a short period significantly increases circulating insulin concentrations and population of small ovarian follicles. Based on these findings, our recent work has aimed at addressing some practical problems in cattle production. Firstly, we showed that both rGH pretreatment and increased dietary intake significantly enhance the response to standard superovulatory regimes. Secondly, we have demonstrated that feeding a diet to increase circulating insulin concentrations during the early lactation can advance the first ovulation postpartum and increase conception rate to the first service in dairy cows. In summary, nutrition influences ovarian follicle development in cattle possibly through changes in metabolic hormones. These interactions can be manipulated to improve reproductive performance.     

Use of Equine Chorionic Gonadotropin to Control Reproduction of the Dairy Cow: A Review

Equine chorionic gonadotropin (eCG) is a member of the glycoprotein family of hormones along with LH, FSH and thyroid‐stimulating hormone. In non‐equid species, eCG shows high LH‐ and FSH‐like activities and has a high affinity for both FSH and LH receptors in the ovaries. On the granulosa and thecal cells of the follicle, eCG has long‐lasting LH‐ and FSH‐like effects that stimulate oestradiol and progesterone secretion. Thus, eCG administration in dairy cattle results in fewer atretic follicles, the recruitment of more small follicles showing an elevated growth rate, the sustained growth of medium and large follicles and improved development of the dominant and pre‐ovulatory follicle. In consequence, the quality of the ensuing CL is improved, and thereby progesterone secretion increased. Based on these characteristics, eCG treatment is utilized in veterinary medicine to control the reproductive activity of the cow by i) improving reproductive performance during early post‐partum stages; ii) increasing ovulation and pregnancy rates in non‐cyclic cows; iii) improving the conception rate in cows showing delayed ovulation; and finally, iv) eCG is currently included in protocols for fixed‐time artificial insemination since after inducing the synchrony of ovulation using a progesterone‐releasing device, eCG has beneficial effects on embryo development and survival. The above effects are not always observed in cyclic animals, but they are evident in animals in which LH secretion and ovarian activity are reduced or compromised, for instance, during the early post‐partum period, under seasonal heat stress, in anoestrus animals or in animals with a low body condition score.     

Nutritional factors that regulate ovulation of the dominant follicle during the first follicular wave postpartum in high-producing dairy cows

During recent decades, milk production per cow has increased drastically due to improved management, nutrition, and genetic selection; however, the reproductive performance of high-producing dairy cows has been declining. One of the factors responsible for this low reproductive performance is negative energy balance (NEB). NEB affects the onset of first ovulation in early postpartum cows. It is generally accepted that early first ovulation positively relates to the resumption of normal ovarian function, first service, and conception rate in dairy cows. Hence, delayed first ovulation has a negative impact on subsequent fertility. The metabolic condition of cows in NEB shifts to catabolic metabolism, which in turn causes increased plasma growth hormone and non-esterified fatty acid concentrations and decreased plasma insulin-like growth factor-1, insulin, and glucose concentrations. On the other hand, plasma β-carotene concentrations decrease throughout the dry period and reach their nadir in about the first week postpartum, and this change reflects energy balance during the peripartum period. β-Carotene plays a role independently of vitamin A in the reproductive performance of dairy cows, and the positive relationship between supplemental β-carotene and reproductive function has been demonstrated in many studies during the past decades. However, β-carotene content in corn silage, which is a popular main feed in high-producing dairy cows, is very low. This review describes nutritional factors related to ovulation during the first follicular wave postpartum in dairy cows.     

Twinning in Dairy Cattle

Twinning in dairy cattle is an unavoidable outcome of reproduction and is undesirable because it reduces the overall profitability of a dairy operation through negative effects on cows calving twins as well as on calves born as twins. Cows calving twins are at greater risk for many periparturient reproductive and metabolic disorders than nontwinning herdmates, and incidences of abortion, stillbirth, neonatal calf mortality, and reduced birth weight are greater among twin compared with singleton calves. Twinning is a complex trait with multiple causative factors, and empirical evidence supports a role for both genetic and environmental risk factors in cattle. Risk factors for twinning include genetics, season, parity, ovulation rate, and milk production. The observation that twinning has increased in the dairy cattle population over time suggests a concurrent change in one or more of these causative factors during this same period. At present, dairy farmers and their consultants are ill prepared to make sound-management decisions to mitigate the negative effects of twinning on their operations because of a lack of applied scientific data on management strategies for periparturient dairy cows carrying twin fetuses. A clear understanding of the factors responsible for twinning is essential for future development of strategies to manage twinning in dairy operations.     

牛胚胎移植技术研究与应用

[目的]应用牛胚胎移植技术,可缩短牛的育种年限和迅速提高生产性能.[方法]本试验选购了1 334头受体母牛,对735头进行了移植,[结论果]表明受胎牛352头,平均受胎率47.86%,成活犊牛数296头.[结论]受体牛良好的繁殖机能、子宫状态、营养水平和发情鉴定等是实施胚胎移植的技术保证.     

Formation of follicular cysts in cattle and therapeutic effects of controlled internal drug release

Follicular cysts in cattle result from excessive growth of the dominant follicle without ovulation and still constitute a major reproductive disorder in this species. One key hormonal characteristic of cows with follicular cysts is the lack of an LH surge, although they have increased plasma estradiol concentrations. Another is a relatively high level of pulsatile secretion of LH that promotes continued growth of the dominant follicle. These LH characteristics seem to result from a functional abnormality in the feedback regulation of LH secretion by estradiol. Treatment with controlled internal drug release devices that increase circulating progesterone levels is effective in resolving follicular cystic conditions by 1) lowering pulsatile LH secretion and 2) restoring the ability of the hypothalamo-pituitary axis to generate an LH surge in response to an increase in circulating estradiol.     

Mechanisms linking metabolic status and disease with reproductive outcome in the dairy cow

Culling for infertility remains the main reason for disposal of dairy cows, limiting productive lifespan. In extreme cases, ovulation is inhibited, preventing the possibility of conception. More often cows do conceive, but fail to remain pregnant owing to intrinsic problems in the embryo and/or to a poor-quality reproductive tract environment. Both aspects have a genetic component and are also influenced by management practices affecting nutrition and health. The relative importance of these factors varies among heifers, first-lactation and older cows. A common theme, however, is that an internal signalling system exists which reduces fertility when the cow is in an unsuitable metabolic state to sustain a pregnancy. This may be directly related to nutrient shortage caused by inadequate feed intake, or because available nutrients are being prioritized towards growth or milk production, away from reproduction. Evidence is presented for the involvement of the somatotrophic axis (GH, IGF1, insulin, IGFBP2) and leptin as key metabolic signalling molecules. Another emerging theme is the interaction between metabolism and disease that affects the fertility. Common examples include (i) calf diseases causing inadequate heifer growth and increased age at first calving; (ii) poor peripartum energy status reducing the capacity of the uterus to involute and mount an effective immune response, thereby increasing the likelihood of endometritis; and (iii) development of mastitis after conception, a contributory factor to both early and late embryo mortality. Finally, recent evidence suggests that times of metabolic stress cause mitochondrial damage that also contributes to a reduction in longevity.     

Nutritional factors in bovine gastrointestinal disease

Gastrointestinal disorders may be prevented through proper nutrition. Attention should be placed on establishing optimum feeding programs for cattle in all stages of the life and production cycle. Normal reticuloruminal development in calves and maintenance of gastrointestinal function in adult cattle is dependent upon adequate nutrition. Nutrition is also an important part of therapy of many gastrointestinal disorders.     

奶牛子宫复旧期间FSH和LH动态变化规律研究

子宫复旧是奶牛产后生殖器官恢复的一个重要时期,复旧时间的长短会直接影响产后第一次发情的时间,子宫复旧的正常时间为产后30～46d。本试验为研究促卵泡素(FSH)与促黄体素(LH)在子宫复旧过程中的变化规律,选择了年龄、胎次相近,健康状况良好的产后奶牛15头,应用放射免疫分析法在子宫复旧期间每3天对奶牛血清中FSH与LH进行一次测定,前后持续10次。由试验数据可得出,FSH与LH分泌水平在子宫复旧的早期比较低,FSH浓度到产后第15天达到峰值,LH从产后第21天开始大幅上升,到产后第24天浓度达到峰值,之后二者浓度变动范围不大。