甜菜碱提高蛋鸡产蛋性能的机理研究

15 36只 30 0日龄罗曼蛋鸡 ,随机分为 4组 ,分别饲喂添加 0 ,5 0 0 ,10 0 0 ,15 0 0mg/kg甜菜碱的玉米—豆粕型日粮 ,研究甜菜碱提高蛋鸡产蛋性能的作用机制。结果表明 ,日粮中添加 10 0 0mg/kg甜菜碱对提高蛋鸡产蛋性能效果最佳 ,显著提高产蛋率 10 .11% (P <0 .0 5 ) ,提高饲料转化率 6 .4 1% (P <0 .0 5 )。进一步研究发现 ,日粮中添加 10 0 0mg/kg甜菜碱使血清促卵泡生成素 (FSH)、促黄体生成素 (LH)、极低密度脂蛋白胆固醇含量和脂肪酶活性分别升高了 5 6 .4 9%(P <0 .0 1)、86 .0 3% (P <0 .0 5 )、4 3.0 7% (P <0 .0 5 )和 30 .0 7% (P <0 .0 5 ) ,血清甘油三酯和尿酸含量分别下降了 2 2 .18%(P <0 .0 5 )、18.6 6 % (P <0 .0 5 )。上述结果提示 :甜菜碱通过增强腺垂体FSH和LH的分泌 ,同时促进卵蛋白和卵脂肪沉积 ,从而提高蛋鸡产蛋率和饲料利用率     

沂蒙黑山羊与济宁青山羊板皮组织结构的研究

对沂蒙黑山羊和济宁青山羊板皮的皮肤组织结构进行了系统的研究。结果表明 :两种羊同部位的表皮层厚相差并不显著 (P>0 0 5 )。就真皮层而言 ,济宁青山羊的真皮要明显比沂蒙黑山羊厚 (P <0 0 1) ,同种羊不同部位之间也存在差异。真皮层可分为乳头层和网状层 ,二者的变化与真皮层大致相似。两种羊的毛囊群均以 3毛囊群为主 ,均占 80 %左右。沂蒙黑山羊与济宁青山羊的S/P分别为 7 2 3和 5 97。胶原纤维在乳头层中呈网状较紧密 ,在网状层中呈水平走向较疏松。弹性纤维一般仅分布于乳头层。     

In vitro growth of bovine oocytes in oocyte-cumulus cell complexes and the effect of follicle stimulating hormone on the growth of oocytes

Several successful in vitro culture experiments have used oocyte-cumulus cell-mural granulosa cell complexes (OCGCs) from early antral follicles (0.5–0.7 mm) for the growth of bovine oocytes. However, in studies related to in vitro oocyte maturation and in vitro embryo production, oocyte-cumulus cell complexes (OCCs) that have no mural granulosa cells have been widely used instead of OCGCs. The purpose of this study was to determine whether cumulus cells alone support oocyte growth. First, OCCs and OCGCs were cultured in vitro for 14 days to compare the integrity of the complexes as well as antrum formation. After 14 days, the diameter and meiotic competence of oocytes in OCCs and OCGCs were examined. Oocytes in OCCs grew fully and acquired meiotic competence similar to OCGCs, whereas antrum formation occurred later in OCCs as compared to OCGCs. Subsequently, the effects of follicle stimulating hormone (FSH) on in vitro growth of OCCs were examined for 14 days. When FSH was added to the culture medium, OCCs formed antrum-like structures one day earlier than those cultured without FSH. Oocytes cultured with 1 mIU/ml FSH grew fully and acquired meiotic competence. In contrast, when oocytes were cultured in media containing high concentrations of FSH, some of the OCCs collapsed and the number of degenerated oocytes increased. In conclusion, bovine oocytes in OCCs grow and acquire meiotic competence similar to OCGCs and, 1 mIU/ml FSH supports the development of OCCs and oocyte growth as observed in our culture system.     

Divergent selection for total fleece weight in Angora rabbits: Correlated responses in wool characteristics

An experiment was carried out to study direct and indirect responses to selection in the Angora rabbit. There were two selection lines, one selected for high fleece weight and the other for low fleece weight. Data from 669 female rabbits born in 1994–2001 and having produced a total of 2923 harvest of wool were analysed to quantify the correlated responses to selection. By 2001, there had been eight cohorts of selection. The correlated responses analysed included compression, resilience, fleece quality traits (bristle and down length, average fibre diameter, comfort factor, bristle diameter) and secondary to primary follicle ratio (S/P). Genetic correlations were obtained by restricted maximum likelihood techniques. In response to selection, a positive difference of 0.92, 0.21 and 0.55 genetic standard deviation were observed for bristle length, comfort factor and S/P, respectively. No correlated response was observed on down length while negative differences of 1.00, 1.31, 0.38 and 0.50 genetic standard deviations were observed for compression, resilience, bristle diameter and average fibre diameter, respectively. Selection for increasing total fleece weight results in an increase of qualitative component traits of wool production in the French Angora rabbit. The quantitative traits were examined in the first (published) part of the paper.     

绵羊卵泡内Ghrelin的免疫组化定位

为探索Ghrelin在绵羊各级卵泡的存在和分布,采用免疫组织化学技术研究了Ghrelin多肽在绵羊卵泡中的分布情况。结果表明,初级卵泡、早期生长卵泡和晚期生长卵泡均有Ghrelin表达,卵母细胞呈阳性信号,而在各级卵泡中颗粒细胞Ghrelin呈弱阳性信号。各级卵泡内Ghrelin的表达,提示Ghrelin在卵泡发育过程中可能具有一定作用。     

提高发情期母牛发情效果的试验

通过对繁殖母牛口服催情散和生化散的方法提高了母牛的生殖机能和代谢水平,并改善了子宫内环境,提高了卵泡发育水平和黄体质量,缩短了排卵期,显著提高了第一情期受胎率。     

Changes in the immunostaining intensities of follicle-stimulating hormone and luteinizing hormone during ovarian maturation in the female Japanese flounder

The role of gonadotropin (GTH) in the reproduction of the Japanese flounder, Paralichthys olivaceus, was studied by assessing the changes in the apparent activity of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary gland during gonadal maturation by immunohistochemical analyses. Corresponding changes in plasma levels of testosterone (T), estradiol-17β (E₂), and 17α,20β-dihydroxy-4–pregnen-3-one (DHP) were also studied. Reared fish at the early spawning to termination stages were sampled from May to August and wild fish at the previtellogenic to termination stages were caught at 3- to 4-week intervals between April and September offshore from the northern mainland of Japan by gill nets. The gonadosomatic index of the reared fish decreased from the early spawning stage to the termination stage, while that of the wild fish increased significantly from the previtellogenic stage to the early spawning stage and decreased thereafter. In the reared fish, the immunostaining intensities of FSH and LH were high during the spawning period, accompanied by high plasma levels of T, E₂, and DHP. In the wild fish, the immunostaining intensities of FSH and LH were low during the previtellogenic stage but increased during the maturing and spawning stages. These results indicate that both FSH and LH are likely associated with oocyte maturation in the Japanese flounder.     

羔羊诱导卵泡发育及其应用的研究进展

幼畜体外胚胎移植(Juvenile In Vitro Embryo Transfer,JIVET)技术是利用幼畜对外源激素敏感的生理特点,采用外源促性腺素诱导幼畜卵泡超数发育,结合卵母细胞体外成熟、体外受精和胚胎移植等技术生产后代,该技术体系的研究与应用可以充分发挥优秀母畜繁殖潜能,快速扩繁良种畜群。近年来,国内外对绵羊JIVET技术研究比较多,但应用JIVET技术生产体外胚胎的效率低下、效果不稳定仍然是一个普遍问题。迄今为止,大多数的研究致力于加强供体羔羊选择、优化激素处理方案以及提高羔羊卵母细胞体外发育能力等方面。本文综述了羊JIVET技术的原理与最新研究进展以及影响JIVET技术效率所存在的内因和外因,旨在为深层次探索羔羊卵子发生和卵泡发育调控机制提供理论依据,促进JIVET技术的研究与应用。     

Subclinical,chronic intramammary infection lowers steroid concentrations and gene expression in bovine preovulatory follicles

Chronic, subclinical intramammary infection depresses fertility. We previously found that 30% of subclinical mastitic cows exhibit delayed ovulation, low circulating estradiol levels, and delayed luteinizing hormone surge. We examined the function of preovulatory follicles of cows experiencing subclinical mastitis or a past event of acute clinical mastitis. Cows were diagnosed for mastitis by somatic cell count and bacteriological examination. All clinical infections were caused by Escherichia coli, and most subclinical infections were caused by Streptococcus dysgalactiae and coagulase-negative staphylococci. On day 6 of the cycle, cows received PGF2α; 42 h later, follicular fluids and granulosa cells or theca cells were aspirated from preovulatory follicles in vivo or following slaughter, respectively. Overall, follicular estradiol and androstenedione concentrations in the subclinical group (n = 28) were 40% lower (P < 0.05) than those in uninfected cows (n = 24) and lower than in past clinical mastitic cows (n = 9). Distribution analysis revealed a clear divergence among subclinical cows: one-third (9/28) exhibited low follicular estradiol; the other two-thirds had normal levels similar to all uninfected (P < 0.01) and most clinical cows (P < 0.08) that had normal follicular estradiol levels. Subclinical normal-estradiol cows had twofold higher (P < 0.05) circulating estradiol concentrations and sevenfold and fourfold higher (P < 0.05) follicular androstenedione levels and estradiol-to-progesterone ratio, respectively, than subclinical low-estradiol cows. Follicular progesterone level was not affected. Reduced expression (P < 0.05) of LHCGR in theca and granulosa cells, CYP11A1 (mRNA and protein) and CYP17A1 in theca cells, and CYP19A1 in granulosa cells may have contributed to the lower follicular steroid production in the subclinical low-estradiol subgroup. StAR and HSD3B1 in theca cells and FSHR in granulosa cells were not affected. Mastitis did not alter follicular growth dynamics, and no carryover effect of past clinical mastitis on follicular function was detected. These data indicate that a considerable proportion (one-third) of subclinical mastitic cows have abnormal follicular steroidogenesis, which can explain the reproductive failure associated with this disease.     

Whole sunflower seeds as a source of polyunsaturated fatty acids for grazing dairy cows: Effects on metabolic profiles and resumption of postpartum ovarian cyclicity

Intake of polyunsaturated fatty acids (PUFA) could modify follicular dynamics and reduce the length of the interval from calving to first ovulation (ICOV) in dairy cows, associated with changes in metabolites (i.e. cholesterol) or hormones (i.e. IGF-I). To test this hypothesis, 48 cows were stratified in two groups (primiparous or multiparous) and within each group were randomly assigned to three treatments to begin at calving: 0 kg (SS0), 0.7 kg (SS0.7) and 1.4 kg (SS1.4) of whole sunflower seeds (WSS) per cow per day. The experimental period lasted for 60 days after calving and the diets, which consisted of direct grazing of improved pastures, whole-plant wheat silage and concentrates, were designed to be isocaloric and isoproteic (1.6 Mcal NEL/kg DM, 16.7% CP). Ovaries were examined by ultrasound three times per week from day 8 postpartum (PP) until first PP ovulation. Body condition score (BCS) was determined and blood samples were collected weekly from calving to characterize the metabolic profiles. In treatments SS0.7 and SS1.4, 7/8 and 6/8 primiparous cows ovulated the first follicular wave PP, compared with only 1/8 primiparous cow in treatment SS0, while there were no treatment differences in multiparous cows. The ICOV was 44, 21 and 19 days for the primiparous, and 22, 21 and 25 days for the multiparous cows, in treatments SS0, SS0.7 and SS1.4, respectively. Treatments had no effect on BCS, plasma IGF-I and metabolic profiles except that NEFA and urea were increased by WSS supplementation. Intake of PUFA (WSS up to 1.4 kg/day or 6.7% of the diet) during early lactation reduced the ICOV in primiparous grazing dairy cows in early lactation but not in multiparous cows, and while the precise mechanism for these results is unclear, it was not related to changes in the plasma concentrations of IGF-I or cholesterol.