Suppression of ovarian progesterone production in dairy cows using an implant of GnRH-agonist (deslorelin) for the purpose of evaluating progesterone metabolism

OBJECTIVE: To evaluate the potential of an implant of a GnRH-agonist (deslorelin) to create a progesterone free animal suitable for studying progesterone (P4) metabolism in intact cows by measuring blood P4 and faecal P4 metabolites. METHODS: Experiment 1: Eighteen non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to one of three groups to study plasma P4 concentrations preceding an intravaginal insert. These groups comprised: i) a deslorelin group (GnRH-agonist implanted); ii) a PGF group receiving two injections of prostaglandin (PGF2alpha) 12 days apart; and, iii) an ovariectomised (OVX) group. An intravaginal device (CIDR) was inserted into the vagina of each animal and left in place for 11 days. Plasma P4 concentrations were measured during the study period. Experiment 2: Twelve non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to two groups: i) a deslorelin group (GnRH-agonist implanted); and ii) an ovariectomised group. Plasma P4 and faecal P4 metabolites (20-oxo-pregnanes, 20alpha-OH and 20beta-OH) were monitored for a period of 5 weeks. RESULTS: Experiment 1: Average plasma P4 concentration did not differ between the three groups (1.28, 1.43 and 1.55 ng/mL for deslorelin, OVX and PGF cows, respectively, P = 0.8) during the period of supplementation. Experiment 2: There was no difference in plasma P4 (mean plasma P4 < 0.02 ng/mL, P = 0.9) and faecal P4 metabolites between deslorelin and OVX cows 2 weeks after the implantation (P = 0.7). CONCLUSIONS: These data showed that a GnRH-agonist (deslorelin) implant may be used as an alternative to ovariectomy to create a progesterone free animal suitable for studying the metabolism of administered P4.     

Efficacy of oral clorsulon in the treatment of Fasciola hepatica infections in calves

Twenty calves at each of 2 Arkansas locations were inoculated with infective Fasciola hepatica metacercariae. After 56 days, the calves at each site were randomly assigned by weight to 2 treatment groups of 10 calves/group; vehicle control or clorsulon at the rate of 7 mg/kg of body weight. All treatments were given orally as a suspension. Calves were killed 6 weeks after treatment and F hepatica counts were performed for all animals. At the 2 sites, mean levels of efficacy were 96% and 91%. Adverse reactions to clorsulon or the vehicle were not observed in the calves.     

催乳素对内蒙古绒山羊毛囊体外培养影响的研究

【目的】 研究催乳素（PRL）对内蒙古绒山羊初级毛囊和次级毛囊体外生长及形态变化的影响。【方法】 机械法结合切割法分离内蒙古绒山羊的初级毛囊和次级毛囊,在初级毛囊培养液中分别添加0、5、10、50、100 ng/mL催乳素进行体外培养,每组24根,共培养5 d,每天在显微镜下观察其形态并拍照,统计其生长长度、生长速度和存活率,筛选出最适催乳素处理浓度。然后将初级毛囊与次级毛囊分别分为初级毛囊对照组（PF-K）、初级毛囊试验组（PF-PRL）、次级毛囊对照组（SF-K）、次级毛囊试验组（SF-PRL）,每组24根,对照组用基础培养液培养,试验组在基础培养液中添加最适浓度的催乳素,培养5 d,每天观察毛囊的形态并拍照,同时测量各组毛囊的生长长度。【结果】 10 ng/mL催乳素组毛囊的平均日生长长度均极显著高于其他浓度组（P<0.01）,最终生长长度和存活率均最高,因此,后续试验选择10 ng/mL催乳素处理毛囊。试验组和对照组初/次级毛囊的毛干与根鞘部位同时伸长,随着培养时间的增加均出现不同程度的弯曲。PF-PRL、SF-PRL组毛囊在2~5 d的总长度分别极显著高于PF-K、SF-K组（P<0.01）。PF-K组除第1天与第0天差异不显著外,1~5 d毛囊的总长度依次显著增加（P<0.05）;PF-PRL组0~5 d毛囊的总长度依次显著增加（P<0.05）。SF-K组毛囊第5天的总长度显著高于0~4 d （P<0.05）;SF-PRL组第4、5天毛囊的总长度均显著高于0~3 d （P<0.05）,第3天毛囊的总长度显著高于0~2 d （P<0.05）。PF-PRL、SF-PRL组毛囊在2~5 d的平均日生长长度分别极显著高于PF-K、SF-K组（P<0.01）。【结论】 10 ng/mL催乳素是体外促进毛囊生长的最适浓度,10 ng/mL催乳素对体外培养的内蒙古绒山羊的初级毛囊和次级毛囊均有极显著的促生长作用。     

巴美肉羊发情期外周血E2和P4浓度变化规律与排卵数关系研究

绵羊在发情周期中各生殖激素浓度变化与卵泡发育、成熟和排卵有着密切的关系。为了研究巴美肉羊血清生殖激素的动态变化及其与排卵数关系,试验采用电化学法,测定了12只成年母羊发情期血清中2种类固醇激素(E₂和P₄)的浓度水平,分析其动态变化规律,并用SAS 9.0的方差分析程序分析激素浓度与排卵数的关系。结果表明,两种激素在排单卵组和排双卵组绵羊间变化规律不同,E₂在排单卵组表现为先下降后升高的变化趋势,在排双卵组表现为持续下降趋势;P₄在排单卵组表现为持续上升的趋势,在排双卵组为先上升后下降的变化趋势。排单卵和排双卵组绵羊在各时间点的E₂和P₄激素浓度差异均不显著(P＞0.05)。     

The Expanding Role of Recombinant Gonadotropins in Assisted Reproduction

Using recombinant gonadotropins for assisted reproduction of domestic species is still in its infancy. Yet, the purity, potency and pathogen-free nature of recombinant gonadotropins make them attractive alternatives to tissue-derived gonadotropic agents. In this study, the authors summarize the work to date using recombinant gonadotropins to enhance the - fertility of domestic animals and they discussed their recent studies examining the biopotency of single chain analogues of human gonadotropins. In these studies, single chain analogues of follicle stimulating hormone (Fcα), chorionic gonadotropin (CGβα) or a gonadotropin construct with dual activity (FcCGβα) were administered to sheep pre-treated with antisera directed against GnRH. Ovulation was induced 3 days after analogue administration using hCG (1000 IU, iv). Although Fcα or CGβα alone induced only modest oestradiol production during the pre-hCG period, serum concentrations of oestradiol were markedly increased (p < 0.05) 3 days after administration of FcCGβα or the Fcα + CGβα combination. Final ovarian weight was significantly increased (p < 0.05) in animals receiving Fcα, Fcα + CGβα or FcCGβα. Collectively, these observations demonstrate that the single chain analogues of the human gonadotropins are active in sheep.     

蓟马取食对苜蓿氨基酸组成及含量的影响

为了探究蓟马取食对苜蓿(Medicago sativa L.)氨基酸组成及含量的影响,本研究以'草原2号'(Medicago varia Martin.'Caoyuan No.2')感蓟马品种和'草原4号'(Medicago sativa L.'Caoyuan No.4')抗蓟马品种为材料,分别进行牛角花齿蓟马(Odo...     

世界林产品研究开发组织概况

林产品研究开发组织应有良好的组织结构、高效的管理,高水平的业绩,才能完成其使命,做出应有的贡献。2004--2005年,美国林产品研究所和明尼苏达大学对美国以外的林产品研发组织进行了一次考察。首先,选定了93个组织,然后从中选出属于23个国家的40个组织进行了深入考察。选定的原则是：1）代表世界范围不同的国家;     

中国蒙药资源可持续利用现状和对策

蒙药是蒙医师用于防治疾病的药物,是蒙医药事业发展的物质基础。蒙医药事业的可持续发展必须保障药材的质量和供应。随着蒙药资源使用量的增加和蕴藏量的减少,蒙药资源的可持续利用显得越来越重要。因此,一定要重视蒙药资源的可持续利用研究。文章着重介绍了蒙药资源可持续利用情况。     

The antiparasitic activity of ivermectin in horses

Parenteral administration of ivermectin (22,23-dihydroavermectin B₁) significantly reduced the numbers of adult large and small strongyles, the immature stages of small strongyles, pinworm and ascarid, the microfilariae of Onchocerca cervicalis and gastrophilid bots from naturally infected horses. Strongylus vulgaris, S. edentatus and S. equinus were effectively removed by 0.02 mg/kg. Adult small strongyles, Cyathostomum pateratum, C. catinatum, Cylicocyclus nassatus, C. leptostomus, Cyliostephanus minutus, C. longibursatus and C. goldi, were effectively removed by 0.1 mg/kg. Fourth stage small strongyles (cyathostomes), 4th stage Oxyuris equi, 5th stage Parascaris equorum and the microfilarie of Onchocerca cervicalis were significantly reduced by 0.1 mg/kg also. The stomach bots, Gastrophilus intestinalis and G. nasalis, were effectively removed by 0.02 mg of ivermectin/kg. Analysis of the dose response curves obtained for the nematode and larval dipteran parasites found in these naturally infected horses suggests that a parenteral dose of 0.2 mg/kg ivermectin would produce 95% or more removal of these parasites. The antiparasitic efficacies observed for ivermectin in this controlled trial were equivalent to the efficacies found in an abbreviated critical trial contained within the controlled trial. However, it was calculated that the man—day effort required for data collection from one critical trial horse was the same as for 6 controlled-trial horses.