提高奶水牛人工授精受胎率的技术关键

为了提高奶水牛人工授精的受胎率,准确把握发情症状和适时的输精是技术的关键。本文就奶水牛发情表现、发情观察、适时输精技术要点及应注意的关键性技术措施等作了分析,为奶水牛产业化发展、提高人工授精受胎率提供参考及指导。     

优质细毛羊胚胎移植技术的研究与应用

１９９４～１９９７年分别在镇南种羊场宝山分场和白城市牧草良种繁育站等地进行了优质细毛羊胚胎移植技术研究。共超排处理３３只供体羊,获卵２６１枚,其中可用胚胎２０８枚,平均每只供体羊获可用胚胎６３枚。在超排羊中有优质细毛羊１８只,获可用胚胎１２３枚,平均每只供体羊获可用胚胎６８枚。４ａ间共用鲜胚胎移植受体羊１５６只,妊娠１０５只,受胎率为６７３％。共产羔羊１０３只,每只供体羊平均获羔羊３１２只,达到了自然繁殖水平的３倍。     

Spawning of ocean pout (Macrozoarces americanus L.): evidence in favour of internal fertilization of eggs

Sperm physiology, in vivo artificial insemination and spawning of the ocean pout (Macrozoarces americanus L.), a marine bottom fish, were studied. Milt was collected from the reproductive tract of mature males by suction using a catheter. The uncontaminated milt, having a very low sperm concentration, contains highly motile spermatozoa and sperm motility was retained in vitro at 4 °C for at least 24 h in both seminal plasma and ovarian slime collected from the oviduct of pre-spawning females. Instead of activating sperm, dilution in sea water instantly immobilized the spermatozoa of ocean pout. Osmolarity and pH of ocean pout seminal plasma were in the ranges 365–406 mOsM and 7.2–7.5, respectively. A study of the ionic composition of ocean pout seminal plasma demonstrated the presence of various ions including Na⁺, K⁺, Ca²⁺, Mg²⁺, and Cl⁻, with a remarkably lower K⁺ concentration compared to that from other fish species. Since injections of milt containing motile sperm into the ovaries of pre-spawning females, which spawned in the absence of males, yielded fertilized ocean pout eggs, it is concluded that the ocean pout exhibits internal fertilization. The larvae hatched after 3 months of egg incubation in ambient sea water (9–10 °C). With proper timing of in vivo artificial insemination of mature females, fertilized ocean pout eggs can be obtained from fish reared in captivity.     

The non-linear effect (determined by the penalised partial-likelihood approach) of milk-protein concentration on time to first insemination in Belgian dairy cows

The time to first insemination in dairy cows depends partly on the energy balance of the cow. Because milk-protein concentration is related to the energy balance, we investigated whether milk-protein concentration predicted the hazard of being inseminated. The main objective of the paper is to demonstrate that the relationship between milk-protein concentration and the hazard of being inseminated was not linear and that this non-linear relationship was modelled adequately using cubic–splines. The semiparametric Cox model was used to introduce protein concentration into the model as a time-varying covariate and additionally herd was added to the model as a frailty term to adjust for the clustering of the cows within a herd. We extended the penalised partial-likelihood technique to fit the frailty model with cubic–splines for the effect of the protein concentration. The model was fitted for a large database consisting of 5114 multiparous cows from 181 different farms. Low milk-protein concentration (<2.7%) was associated with a negative energy balance and this probably led to the decreased hazard. On the other hand, high milk-protein concentration (>4.0%) was linked with low milk production and it was probably a farmer’s decision not to inseminate such cows, leading to the observed decreased hazard.     

影响曲靖肉牛冻精冷配受胎率的因素

本研究围绕解冻后精液保存温度、母牛发情规律、输精部位和情期输精次数等影响牛冻精冷配受胎率的因素进行分析。结果表明，冻精解冻后，在低温（4℃）下保存6h、在常温（10-15℃）下保存4h和在高温（28℃）下保存2h输精对受胎率没有显著影响；曲靖母牛发情表现明显，在发情母牛卵泡发育至成熟期时冷配受胎率最高（84．40％）;母牛发情配种所占比重依次为秋季〉夏季〉春季〉冬季;母牛2-4胎时冷配受胎率最高，达72．03％，5胎以上的冷配受胎率则有所下降；母牛冷配最佳输精部位是卵泡发育好的一侧子宫角和子宫体内，同时输精可得到较高冷配受胎率（80．38％）。在同一个情期，输精1次与2次对受胎率的影响差异不显著。     

关于黄牛冻配最佳输精部位的探讨

每年选择160头可繁母牛均分成4组,通过对黄牛四个输精部位三年的研究结果,提出了输精器通过子宫颈,全部精液都输入到卵泡发育好的一侧子宫角内与将精液输入到子宫颈5～8cm处及输入到子宫分叉处,组间相比较差异显著(P<0.05)。其主要原因是此部位缩短了精子运行的距离,延长了精子的寿命,到达受精部位有受精能力的精子数量增多,有利于与卵子的结合,提高了受胎能力。因此情期受胎率较高。     

牛冷冻精液不同有效精子数输精效果的研究

[目的] 肉牛种业为肉牛生产发展的基础和前提,种公牛是肉牛业发展的“芯片”,直接关系到生产的质量和效率。为提高优秀种公牛的利用率和区域覆盖率,适当降低每剂量冷冻精液的有效精子数量,同时能够确保其输精受胎率不受影响而进行该研究。[方法]制作含有效精子数分别为8ｘ10₆^、4ｘ10₆^、2ｘ10₆^,三组牛冷冻精液,用上述冷冻精液进行输精试验,比较输精效果。[结果] 有效精子数为8ｘ10₆^、有效精子数为4ｘ10₆^、有效精子数为2ｘ10₆^,三个试验组间其人工输精后受胎率进行了比较。研究结果表明,输精总受胎率差异不显著,降低有效精子数,其输精受胎率未受影响。[结论]降低每剂冷冻精液的有效精子数量(2~8ｘ10₆⁾在适当范围内,其输精受胎率差异不显著。     

华北平原一年两熟区保护性耕作技术研究进展

冬小麦-夏玉米一年两熟的种植方式在华北平原区的农业生产中占有极为重要的地位,但传统耕作方式使该区的农业生产不可持续。保护性耕作是一种先进的保水保土的生产技术,对该区的农业可持续发展作用甚大。阐述了保护性耕作的定义、原理及保护性耕作的历史与发展,归纳总结了保护性耕作对播种、出苗、田间杂草、作物生长发育及作物产量等方面的影响研究。以期为华北平原一年两熟区的保护性耕作研究提供一定的参考。     

天目木兰的引种驯化研究

天目木兰为木兰科木兰属落叶乔木,渐危种,庐山植物园于1964年由浙江天目山引入,2001年开始开花结果,2005年采得种子850粒。我们用5种种子处理方式进行播种试验,结果表明,当年采集去除种皮后播种的种子萌芽率较高,可达61%,且生长整齐,保留种皮的萌芽率也能达到38%;自然条件下干藏的种子第二年播种,播种前经过浸种处理的萌芽率为21.2%,但生长不整齐,不经过浸种处理直接播种的萌芽率只有6%;经过沙藏层积处理后播种的种子萌芽率最高,可达75%。1年生苗平均高度9.9cm,平均根长10.2cm,平均侧根17级,苗木生长健壮,可在室外正常越冬、度夏。     

人工授精+胚胎移植(AI+ET)法诱发肉牛双胎的试验研究

应用AI ET法分别对3组试验牛处理,人工诱导生产肉牛双胎,双胎率达60.8%(79/130),产犊率147.7%(192/130).其中试验组Ⅱ(自然发情后AI ET)双胎率达66%(33/50),产犊率150%(45/30),显著提高了母牛的繁殖率.