共查询到20条相似文献,搜索用时 607 毫秒
1.
蛋壳虽不属于被消化的营养成分,但对生产者和消费者来说,都是非常重要的。据统计,商品蛋的破蛋率占总产蛋数的5%~8%或更多,给生产者和经营者造成巨大的经济损失。因此,提高蛋壳的质量对增加养鸡业的经济效益具有重要意义。影响蛋壳质量的因素很多,有营养因素和管理因素等。前者如蛋白质、钙、磷、维生素D、维生素C等;后者如鸡的品种、年龄、饲养管理、疾病等。因而,提高蛋壳质量也应从这两方面着手。1营养措施营养因素是影响蛋壳质量的主要决定性的因素。因而,在蛋鸡饲粮中保证产蛋所需的各种营养成分是提高蛋壳质量最为重… 相似文献
2.
蛋壳性状的变异与表型相关叶湘海(江苏农学院牧医系225001)蛋壳质量是蛋的品质之一,对蛋的经济价值有重要影响。在蛋鸡工业,每年平均有7~8%的蛋破损,经济损失严重。蛋破损的直接原因主要是蛋壳质量偏低,而间接原因是遗传、营养、环境和管理等因素影响着蛋... 相似文献
3.
现代养禽业把蛋壳质量归结为蛋壳颜色、蛋壳重、蛋的破损率、蛋壳强度 (豆彩红等, 1999)。随着遗传育种、营养、生理及环境知识的综合运用,蛋壳质量有了显著的提高。然而,蛋壳质量的改进还不能适应迅速发展的养禽业的需要,中心问题是蛋壳破损问题。据各国报道,蛋的破损率约为 5%~ 7% (Roland et al,1985)。许多复杂因素影响和控制蛋壳质量,如蛋鸡的品种、日龄、环境、疾病、饲养管理、营养水平等等 (杨宁, 1994)。 1蛋壳的成分、结构与其质量的评定 1.1蛋壳的成分 鸡蛋的平均重约 58 g,其大小受日龄、品种、环境、营养… 相似文献
4.
5.
蛋鸡暗斑蛋形成机理的研究进展 总被引:1,自引:0,他引:1
《中国家禽》2016,(8)
蛋壳暗斑是一种蛋壳质量问题,主要是在内容物水分、蛋壳结构、环境等因素的相互作用下形成。文章综述了蛋壳暗斑的发生、分布、变化等规律,并从暗斑蛋蛋壳结构和基因变异等角度介绍了影响暗斑蛋形成的因素和可能导致暗斑蛋形成的原因。基于暗斑蛋蛋壳乳突层结构变异、蛋壳孔隙率增大、蛋壳基质蛋白含量增多、蛋鸡子宫部钙结合蛋白mRNA表达量的减少,蛋壳乳突层变异被认为可能是形成暗斑的根本原因。此外,近年来有研究证明,暗斑蛋的蛋壳膜厚度显著低于正常蛋,这可能是形成壳暗斑的一个重要因素。因此,关于蛋壳膜结构变异的研究还有待推进。 相似文献
6.
为研究鸡蛋壳有机成分与蛋壳质量之间的关系,随机选取相同饲养管理条件下38周龄的北京油鸡、快大乌骨鸡、边鸡、茶花鸡、藏鸡及金湖乌凤鸡同日所产的蛋各30枚,测定其蛋壳品质及蛋壳中有机物的含量等.结果表明:不同品种间蛋壳质量和蛋壳有机成分的差异显著(P<0.05);蛋壳蛋白质含量与蛋壳强度呈极显著正相关(r=0.839,P<0.01),与蛋壳厚度呈显著的正相关(r=0.224,P<0.05),蛋壳内糖醛酸和酸性氨基葡聚糖浓度与蛋壳强度呈极显著正相关(P<0.01).鸡蛋壳内有机成分含量的差异是影响蛋壳质量的重要因素之一. 相似文献
7.
8.
随着蛋鸡饲养业的蓬勃发展,人们对鸡蛋品质的要求越来越高,特别是蛋壳质量问题一直受到人们极大的关注。虽然对蛋壳质量的研究已持续60年,但劣质蛋壳仍然是造成蛋鸡业经济损失的一个重要原因(Keahavarz,1 995)。蛋壳的形成是极其复杂的,造成蛋壳品质下降的原因较多,涉及到遗传、营养、疾病、环境和管理等诸多因素。为了控制鸡蛋破损现象,畜牧工作者对影响蛋壳质量的营养、环境、遗传和疾病等因素及其改进措施进行了大量研究,取得了可喜成绩。1 蛋壳质量、色泽的主要指标与成分蛋壳的质量主要指其厚度、强度及比重,蛋壳质量下降表现为薄壳… 相似文献
9.
虽然对蛋壳质量的研究已经进行了60多年,但劣质蛋壳仍然是造成全世界经济损失的重要原因(Keshavarz,1995)。调查结果表明,破蛋发生率约为5%~8%(Washburn,1992;郝正里,1989)。为了控制鸡蛋破损现象,畜牧工作者从遗传、环境、营养及其它诸多方面对影响蛋壳质量的因素进行了大量的研究,取得了较大的进展。1遗传因素Stout(1981)发现厚壳蛋品系较之薄壳蛋品系鸡蛋壳钙的沉积速度快。王晓明(1992)研究表明伊莎褐壳蛋鸡高强度蛋壳的百分率明显高于星杂288鸡,原因是其蛋壳构成材料的强度高且超微… 相似文献
10.
蛋壳质量差,造成破损蛋增加,合格种蛋减少,孵化率降低。从而导致经济效益的重大损失。本文就结合生产实际探讨影响蛋壳品质的原因与对策。1 影响蛋壳品质的因素 1.1 营养因素 蛋壳的主要成分是碳酸钙。钙源的质量和浓度以及钙磷的比例影响蛋壳的形成。另外,维生素D对蛋壳的品质也起着重要作用。最近国外的研究结果还表明:为改善蛋壳质量,还必须考虑酶介导的碳酸酐酶激活和糖蛋白形成过程中锌、锰的生物利用率和生物活性。因此蛋壳品质与多种维生素、矿物质、微量元素都有密切关系。1.2 管理因素 各种环境因素的变化,如光照、温度、湿… 相似文献
11.
12.
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
13.
14.
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
15.
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
16.
17.
18.
19.
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
20.
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