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奶牛养殖过程中,围产期被认为是最重要的时期之一,在该时期奶牛从干奶状态转为泌乳状态,生理上所受的应激造成奶牛泌乳早期采食量降低,易发生能量负平衡.此外,奶牛生产性能和繁殖性能也会降低,并常常伴有一些围产期疾病的发生,如脂肪肝、酮症、乳房炎等.胆碱能影响奶牛的生产与繁殖性能,参与奶牛的脂肪代谢,可降低脂肪肝发生率,提高免疫性能.对围产期奶牛饲喂过瘤胃保护胆碱(rumen protected choline,RPC),可改善奶牛机体代谢,增加小肠胆碱供应,进而提高奶产量、改善乳成分、缓解脂肪肝、减少围产期疾病的发生.本文综述了RPC对围产期奶牛干物质采食量、生产性能、乳成分以及健康状况的影响,旨在为围产期奶牛的养殖提供理论参考依据. 相似文献
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缩短奶牛干乳期时间不损坏乳房健康。犊牛健康和免疫力的获得不受奶牛干乳期缩短的影响。缩短经产奶牛干乳期降低泌乳早期能量负平衡,减少酮病,提高繁殖性能,产奶量不受影响,而初产奶牛的产奶量的减少会受到泌乳期产奶总量的补偿。该文对缩短干乳期技术方案的进一步研究作了设想:可探讨缩短干乳期的精确管理条件以及对奶牛特征性影响的合理性。 相似文献
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郭咏梅李佳荣闫素梅史彬林 《饲料研究》2023,(14):174-179
随着全球气候变暖，奶牛养殖中的热应激成为畜牧养殖行业的研究热点之一。热应激对奶牛的生产性能及机体健康福利均会造成不同程度的负面影响，不仅会降低奶牛的采食量和产奶性能，还会损害其繁殖能力和机体免疫力。文章总结了热应激对奶牛的危害，并从饲粮结构、饲料添加剂等方面阐述了预防与缓解奶牛热应激的营养调控措施，从而降低热应激对奶牛的负面影响。文章对提高高温季节奶牛产奶量、改善乳品质具有重要意义。 相似文献
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影响奶牛产奶性能的因素较多,但归纳起来可分为九大因素. (一)品种 奶牛是家牛的一种.牛按用途又可分为乳用、肉用和兼用型.乳用型又有黑白花奶牛、荷斯坦牛、娟姗牛、瑞士褐牛、爱尔夏牛、更赛牛等.由于奶牛不同品种,其产奶量均有较大差异,少的只有500～600千克,多的可达20 000千克以上.要想多产奶,应首选黑白花奶牛和荷斯坦牛. 相似文献
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随着人们生活水平的提高,牛奶、奶粉等奶制品已成为人们日常生活餐饮中的必备品,这也促进了我国奶牛养殖业的繁荣发展。如何有效地提高奶牛产量,尤其是产奶量,成为奶牛养殖者所关心的重点。笔者就奶牛养殖过程中的品种选择、饲养及高产的技术要领进行简单的介绍,供参考。1奶牛的品种奶牛的品种较多,如荷兰牛、娟姗牛、瑞士褐牛、短角牛、西门塔尔牛等,每个品种的奶牛都有其自身的特点．养殖户要根据养殖条件进行合理选择。我国一般养殖较多的是中国荷斯坦奶牛，又被称为中国黑白花奶牛．是我国黄牛与荷兰牛经过几十年杂交而培育成的品种．具有产奶量高、性能优良的特点。奶牛养殖切不可急功近利．在品种选择上要宁缺毋滥．只有选择优良的品种才能带来良好的经济效益。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献