Effect of nutrition during calfhood and peripubertal period on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls

The objective of the present study was to characterize the effects of nutrition on circulating concentrations of metabolic hormones, gonadotropins, and testosterone during sexual development in bulls. Nutrition regulated the hypothalamus-pituitary-testes axis through effects on the GnRH pulse generator in the hypothalamus and through direct effects on the testes. Pituitary function (gonadotropin secretion after GnRH challenge) was not affected by nutrition. However, nutrition affected LH pulse frequency and basal LH concentration during the early gonadotropin rise (10-26 weeks of age). There were close temporal associations between changes in insulin-like growth factor-I (IGF-I) concentrations and changes in LH pulse frequency, suggesting a role for IGF-I in regulating the early gonadotropin rise in bulls. The peripubertal increase in testosterone concentration was delayed in bulls with lesser serum IGF-I concentrations (low nutrition), suggesting a role for IGF-I in regulating Leydig cell function. Serum IGF-I concentrations accounted for 72 and 67% of the variation in scrotal circumference and paired-testes volume, respectively (at any given age), indicating that IGF-I may regulate testicular growth. Bulls with a more sustained elevated LH pulse frequency during the early gonadotropin rise (high nutrition) had greater testicular mass at 70 weeks of age relative to the control group (medium nutrition), despite no differences in metabolic hormone concentrations after 26 weeks of age. Therefore, gonadotropin-independent mechanism regulating testicular growth might be dependent on previous gonadotropin milieu.     

丙酮酸盐对牛精液冷冻效果的影响

在常用的果糖-柠檬酸钠-卵黄-甘油液的基础上,分别添加1.25 mmol/L或2.00mmol/L的丙酮酸钾、丙酮酸钠或丙酮酸钙,以观察丙酮酸盐在牛精液冷冻中的应用效果。冷冻前各组稀释液隔15min分2次加入,之后平衡4h。结果表明,各组精子的冻后活力、复苏率、畸形率和顶体完整率之间没有显著差异,但6个试验组的冻后活力、复苏率和对照组相比有提高趋势。     

种公牛的饲养管理技术

种公牛是提高牛群质量最关健的因素,一头种公牛自然交配,与配母牛一年大约几百头。利用人工授精技术每年比本交能增加几倍。而用牛冷冻精液结合人工授精技术进行冷配每年配种母牛数量少则上万头,多则几万头。本文从饲养种公牛的基本要求出发,对种公牛的特性,营养与日常饲养管理、防疫和疾病防治,以及安全生产多方面做了整理介绍,以供同行参考。     

牛冷冻精液质量评估研究进展

人工授精(AI)是第一代动物繁殖生物技术,最近几十年以来,研究人员已经探索出了许多评估冷冻-解冻后精液品质的新技术。由于精子质膜在低渗条件下的功能状态、离子分布及浓度和各种细胞器的功能都与冷冻解冻后精子的存活能力相关,冻精质量的评定也从最初的形态和主观活率分析,发展到更精确的染色质、质膜完整性及分解代谢活性的分子变化分析。但是,在实际应用当中,许多方法花费很大,况且单个的评估参数都与动物精子实际的受精力相关性不强。因此,要提高牛冻精质量的预言强度,应该将这些独立的参数结合起来,利用多元回归分析,建立一套更完美更精确的评估体系。     

淘汰小公牛育肥

为开发肉牛资源和合理利用人工草地，于１９９１－１９９４年在大面积建植人工草地的基础上，对贵阳市乌当奶牛场未去势淘汰小公牛进行育肥试验结果是：（１）１７７头淘尖以牛舍饲育肥，以青粗饲料为主，适当补给精料，１８月龄出栏，平均体重达４３１．９６ｋ头，每头日增重０．７２ｋ；（２）１４头淘汰小公牛草地地全放牧育肥，１５个月零６天出栏平均体重达２７３．５ｋｇ每头日增重０．４９８ｋｇ。     

A KCNJ10 mutation previously identified in the Russell group of terriers also occurs in Smooth-Haired Fox Terriers with hereditary ataxia and in related breeds

Background

Hereditary ataxias with similar phenotypes were reported in the Smooth-Haired Fox Terrier, the Jack Russell Terrier and the Parson Russell Terrier. However, segregation analyses showed differing inheritance modes in these breeds. Recently, molecular genetic studies on the Russell group of terriers found independent mutations in KCNJ10 and CAPN1, each associated with a specific clinical subtype of inherited ataxia. The aim of this study was to clarify whether or not Smooth-Haired Fox Terriers with hereditary ataxia and dogs of other related breeds harbor either of the same mutations. A sub goal was to update the results of KCNJ10 genotyping in Russell group terriers.

Findings

Three Smooth-Haired Fox Terriers with hereditary ataxia and two Toy Fox Terriers with a similar phenotype were all homozygous for the KCNJ10 mutation. The same mutation was also found in a heterozygous state in clinically unaffected Tenterfield Terriers (n = 5) and, in agreement with previous studies, in Jack Russell Terriers, Parson Russell Terriers, and Russell Terriers.

Conclusions

A KCNJ10 mutation, previously associated with an autosomal recessive spinocerebellar ataxia in Jack Russell Terriers, Parson Russell Terriers, and Russell Terriers segregates in at least three more breeds descended from British hunting terriers. Ataxic members of two of these breeds, the Smooth-Haired Fox Terrier and the Toy Fox Terrier, were homozygous for the mutation, strengthening the likelihood that this genetic defect is indeed the causative mutation for the disease known as “hereditary ataxia” in Fox Terriers and “spinocerebellar ataxia with myokymia, seizures or both” in the Russell group of terriers.     

木耳属4个野生菌株的培养特性研究

通过研究不同营养和环境条件对木耳属4个主要种类的野生菌株生长速率和生长势等培养特性的影响,明确了黑木耳、毛木耳、皱木耳、紫木耳菌丝生长的最适温度范围以及最佳碳源和氮源。     

牛精液中药复方稀释液配方筛选研究

在种公牛精液商业稀释液的基础上,按6%、12%、24%和48%的4个水平向稀释液中分别添加4种中药复方提取液,制作0.25 ml细管冻精,解冻(40 ℃,10 s)后比较分析精子活率、顶体完整率、质膜完整性3个指标,以确定较优的中药稀释液配方.结果表明:添加了中药复方提取液的稀释液能更有效的冷冻保存牛精子细胞.其中,复方一和复方二的冷冻效果最佳.复方一在添加量为12%时精子活率、顶体完整率及质膜完整率分别为41.50%、40.14%和38.16%(P＜0.05),分别比对照组提高了10.67%、3.92%和5.50%;复方二在添加量为6%时,精子活率、顶体完整率、质膜完整率3项指标分别达到41.33%、41.59%和40.00%(P＜0.05),分别比对照组提高了10.50%、5.37%和7.34%.