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1胚胎的呼吸和产热胚胎在孵化过程中最初几天,与外界进行气体交换的量很小。随着胚胎生长,需氧量逐渐增多,尤其是孵化后期,需氧量大约是孵化前两天的110倍左右。孵化到19胚龄尿囊绒毛膜动静脉开始萎缩,胚开始用肺呼吸,直接与外界进行气体交换。此时其耗氧量猛增。据试验,一个胚蛋的耗氧量,初期为0.5mL/小时,第17胚龄时17.34mL/小时,20~21胚龄时0.1~0.15L/小时。整个孵化期耗氧量4~4.5L,排出二氧化碳3~5L。胚胎发育至7胚龄时自身才有体温,此时胚胎所产的热量比损失的热少得多。在室温正常、胚胎发育良好的情况下,10~11胚龄时,胚胎的产热量才能超过损失热(因为气温、孵化箱的保温性能、室内空气的流速等各方面因素不同,上述情况也有所差别),此时应注意通风。特别是随胚龄增长,胚胎代谢不断加强,产热量日益增多,此时更要加强通风。2通风换气对胚胎的重要作用在孵化过程中,胚胎不断与外界进行气体交换和热能交换,其交换的量随胚龄增长而增加。胚胎的气体交换是通过蛋壳上的气孔和孵化器的进排气孔、孵化室与外界的通风系统来完成的。胚胎在气体交换的同时也散发热量。良好的通风,能为胚胎的正常发育提供足够的氧气,并使孵化... 相似文献
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浙江大部分地区鹅蛋孵化仍习惯采用母鹅抱窝天然孵化 ,机器孵化技术尚未普及。近年来 ,我们根据鹅蛋特点 ,采用前期机器孵化 ,后期摊床孵化方法 ,对鹅蛋孵化温度、湿度、翻蛋角度、通风换气等关键环节进行分析和研究 ,经 1 5批次 6 450 0枚鹅蛋的实际孵化测定 ,受精蛋孵化率 85.2 %,入孵蛋孵化率70 .9%,达到或超过母鹅抱窝孵化方法。1 温度鹅蛋人工孵化有恒温、变温孵化两种。我们采用变温孵化法 ,具体标准为孵化期的前1 0 d1 0 0 .5 ,1 0~ 1 6 d1 0 0 ,2 2 d前 99.5 ,2 2 d后 99~ 99.5 。另外 ,摊床孵化时 ,鹅蛋盖被 (棉絮等 )和放蛋 (… 相似文献
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在孵化实践中,常出现到出壳时有些弱雏鸡难以破壳的现象,有的甚至超过出壳时间10多个小时。在孵化后期(第19~21天),温度、湿度、凉蛋、通风换气等条件控制不当,则是发生破壳难的外在因素。可采取以下方法解决: 相似文献
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火鸡的饲养管理 总被引:1,自引:0,他引:1
1种蛋的孵化和出生后的温度要求农村孵化火鸡主要由母火鸡或一般抱窝母鸡代为完成。在夏季给抱窝的母火鸡窝内放置17~18枚种蛋,冬天为15~17枚。若用一般母鸡孵化,夏天和冬天则分别为9~11枚和7~9枚。母鸡在孵化时期,常有离开一会儿的时候,主要是寻食或饮水。因此,应在孵化的火鸡窝旁放置饲料槽和饮水盆,以便使抱窝鸡随时能吃到新鲜的饲料和干净的水。雏火鸡出壳后,应在温暖的房内饲养,房内的温度应保持稳定,不可忽低忽高,冬季可适当增加1~2℃。标准的室内温度如下:1~5日龄为31~30℃,6~10日龄29~27℃,11~20日龄为26~24℃,21~30日… 相似文献
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采用显微注射法,分别将人生长激素(hGH)基因和人组织激肽释放酶基因(KLK1)直接注射到孵化24h的鸡胚中,继续孵化。在注射的320枚鸡胚中,孵化前7d死亡194枚,8~18d死亡108枚,孵出雏鸡18只,孵出率为5.6%(18/320)。8只雏鸡分别于出壳后的第1、2、3、5天死亡。7只于3月龄死亡。3只鸡(1公2母)存活至今,并开始产蛋。死亡雏鸡具有脚瘫、体弱、斜颈、站立不稳等异常表现,存活鸡无外观异常,但有产蛋紊乱现象。从孵化4d后死亡的150放鸡胚和18只出壳雏鸡的组织提取基因组DNA,并用DNA杂交试验进行基因整合检测,结果发现其中的3枚鸡胚和3只雏鸡为人生长激素基因整合阳性,基因整合率为12.5%(6/48);18枚鸡胚和6枚雏鸡为KLK1整合阳性,整合率为22.2%(24/108)。结果表明:鸡胚盘内细胞通过显微注射法可以转染外源基因。 相似文献
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乐牧 《青海畜牧兽医杂志》1991,(2)
鸡蛋在孵化时,即进行抗病免疫已成为事实。如种蛋从孵化盘转移至发生盘时,采用蛋内注射系统(尿囊腔注射)每小时可免疫注射2—3万枚。美国密州家禽研究所沙马氏等报道:种蛋在孵化第18—21天内注射马立克疫苗后,孵出了有免疫性的小雏。Embrex公司也发现孵化第17—20天鸡胚的B与T细胞对抗原发生反应,出生后鸡 相似文献
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本试验旨在研究鹌鹑种蛋适宜孵化温度、相对湿度和翻蛋周期。采用单因素试验设计,孵化全程温度控制设置3种程序:1~3 d,3种程序均为38.5℃;4~14 d,程序1为37.8℃、程序2为38℃、程序3为38.3℃;15~17 d,3种程序均为37.5℃;相对湿度(RH)控制设置2种程序:程序1为1~4 d为65%、5~10 d为60%、11~17 d为70%;程序2为1~4 d为70%、5~10 d为65%、11~17 d为75%;翻蛋周期设置1 h和2 h 2个处理;7000枚种蛋按蛋重均等原则分为7个处理组,每组均10个重复,每重复100枚;检测孵化率、健雏率等6项指标。结果表明:4~14 d孵化温度38℃组和38.3℃组的受精蛋孵化率(P<0.01)和入孵蛋孵化率(P<0.05)高于37.8℃组;RH控制程序1和2的各项孵化指标差异均不显著;翻蛋周期1 h组种蛋孵化率和健雏率均稍高于2 h组(P>0.05)。本试验条件下,鹌鹑种蛋孵化适宜温度控制范围为1~3 d为38.5℃、4~14 d为38~38.3℃、15~17 d为37.5℃;适宜RH控制范围为1~4 d为65%~70%、5~10 d为60%~65%、11~17 d为70%~75%;适宜翻蛋周期范围为1~2 h。 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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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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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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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