浅谈蛋鸡开产体重对生产性能的影响

1、产蛋高峰短而低的问题。当养殖户遇到产蛋高峰不高或高峰上去后，又很快下降的问题时，往往将问题归咎到种鸡或饲料上，其实除了上面的问题外，还有一个重要的问题被忽视，这就是开产前的体重问题。根据国外各个品种的饲养要求，正常的鸡群在6周龄平均体重应达到标准上限或超标10％，均匀度达到90％以上；12周龄平均体重达标即可，均匀度应在85％以上；18周龄平均体重应达标或超标，均匀度达到80％以上。     

一种利用制冷机产生的副热生产热水的技术

为了保持牛奶的新鲜程度,防止牛奶变酸和细菌数升高,各个规模牛场和收奶站均配备了牛奶冷却设备,同时还需要通过锅炉或电加热等方式生产大量的热水来清洗设备。利用锅炉或电加热生产热水不但浪费了大量的财力、物力和人力,还造成了环境污染。现介绍一种不额外消耗能源解决热水供应的方法,供大家参考。1原理冷冻机在制冷的同时,产生大于制冷量的热量。压缩机高压出来的温度一般超过90℃以上,这部分热量一般经过风冷的方式通过散热器散发到室外。特别是夏天,气温较高,散热器散热效率较低,需要浪费大量的冷却水冷却,即使这样,有时温度还是降不…     

奶牛胚胎性别控制技术的试验研究进展

应用LAMP法进行了613枚胚胎的性别鉴定结果，雌性胚胎302枚(49．3％)，雄性胚胎311枚(50．7％)，移植成功率平均为40．9％(122／298)，出生后代中与性别鉴定结果一致的121头，性别鉴定准确率为96．0％(121／126)。应用奶牛性腔胶囊后输精的14头供体母牛，共采集69枚可用胚胎，对其中64枚胚胎进行性别鉴定，确定雌性胚胎的比例为71．9％(46／64)，头均获4．9枚可用胚胎。应用奶牛性控液对3头供体母牛宫注后输精，共采集26枚可用胚胎，经性别鉴定后确定雌性胚胎比例为73．1％(19／26)，头均获可用胚胎8．7枚。应用分离X精子冷冻精液对12头供体母牛进行输精，对采集到的61枚胚胎进行性别鉴定后，确定雌性胚胎比例为100％(61／61)，头均获得可用胚胎5．5枚。11枚性控冷冻胚胎移植后，40d以上未返情率为63．6％(7／11)。用分离的X精子冷冻精液对供体母牛输精后，可获得与未分离冷冻精液输精后相接近的超排供体母牛采集胚胎的数量和质量。     

中草药添加剂提高密蜂春繁效果的研究

在早春繁殖期,以中草药作为饲料添加剂,观察蜜蜂群势变化和蜂群健康情况.结果表明,试验组A和对照组CK的蜂群繁殖效果差异极显著,试验组蜂群健康、活动正常,蜂群繁殖率提高了12.1%.     

园林布局中必然性和偶然性要素的辩识与运用

阐释了园林构成要素中的必然性要素和偶然性要素及其相互关系与运用意义；以昆明世博园中“齐鲁园”为例，辩识了“齐鲁园”中必然性与偶然性园林要素，分析了诸要素在特定园林环境布局中的运用。     

Comparison of morphology, viability, and function between blood and milk neutrophils from peak lactating goats

The morphological features of blood and milk neutrophils from peak lactating goats were compared using light microscopy, scanning electron microscopy and flow cytometry in order to investigate the cytological changes of neutrophils after migration into the mammary gland. The kinetics of reactive oxygen intermediates (ROI) generation and gelatinase release of blood and milk neutrophils, with or without stimulation of phorbol 12-myristate, 13-acetate ester (PMA), were used to characterize their responses to inflammatory stimuli. Neutrophils isolated from goat milk were highly segmented and contained multi-lobed nuclei. Ultrastructurally, milk neutrophils were more ruffled on the surface compared to blood neutrophils. Approximately 30% of milk neutrophils were undergoing cell death, either necrosis or apoptosis, in contrast to 8% of blood neutrophils. The ROI production of activated milk neutrophils peaked earlier than blood neutrophils, but the duration and the intensity were much less. Neutrophils from both sources augmented the release of gelatinase in response to PMA (1 ng/mL). However, the amount of gelatinase released from milk neutrophils was lower (P < 0.05) than that of blood neutrophils. In summary, more neutrophils become apoptotic and necrotic in the mammary gland, presumably due to spontaneous aging, the process of diapedesis, and the interaction with milk components. Milk neutrophils have impaired functionalities in comparison with blood neutrophils. The information is relevant when studying mammary gland immunity and related diseases, such as mastitis.     

Using antisense nucleic acid technology to study the influence of POLκ on genetic stability

AIM:To establish cell line FL-POLκ^- and to study the role ofPOLκ(polymerase kappa) on genetic stability.METHODS:A mammalian expression vector expressing antisense POLκ gene fragment pMAMneo -amp^--POLκ was constructed by cloning the 1 690-1 918 fragment of POLκ gene into the mammalian expression vector pMAMneo-amp^- in antisense orientation. FL cells were fransfected with this antisense RNA expressing vector and selected by G418. Based on the shuttle-plasmid pZ189, the mutation assay was made.RESULTS:The spontaneous mutation frequency of supF tRNA gene in the plasmid replicated in the FL- POLκ^- was 11.2×10^-4, while it was 4.9×10^-4 and 3.7×10^-4 in the control cells FL and FL-M, respectively.CONCLUSION: POLκ playes an important role in maintenance of genetic stability.     

Effect of Liucha extract on tumor K562 cell growth

AIM:To investigate the effects of Liucha extract on the growth of tumor cells in vitro and its possible mechanism.METHODS:The capability of colony forming of human leukemia K562 cell in vitro and the cells metabolism were studied by semi-solid agar culture and MTT staining. Then , the changes in morphology in the tumor cells were examined using electronic microscope.RESULTS:Semi-solid agar culture and MTT colorimetric analysis showed that Liucha extrats could significantly inhibit the growth of the tumor cells and their capability of colony forming. Also,under the electronic microscope,it was found that the tumor K562 cell had a narrower perinuclear space,condensation of chromatin and an enlarged mitochondria , in which the cristase disappeared.CONCLUSION:The extract from Liucha possesses an inhibitory effect on K562 cell growth in vitro through affecting the metabolism of the tumor cells.     

Effects of Sini decoction on atherosclerosis and ceramide content of aorta in rabbits

AIM:To observe the effects of Sini decoction on atherosclerosis(AS) and ceramide content of aorta in rabbits. METHODS:28 rabbits were randomly divided into three groups. Control group was fed with a normal diet; High cholesterol group was fed 1% cholesterol and 5% fat diet; Sini decotion+ high cholesterol group was fed 1% cholesterol and 5% fat diet plus Sini decotion (4.2 g·kg^-1·d^-1). At the end of study, the plaque area were measured, the atorta ceramide and cell apoptosis were also detected. RESULTS:Sini decotion diminished lipid plaque area on the aortic endothelium, reduced the levels of aorta ceramide and the apoptosis index. CONCLUSION:Sini decoction has an inhibitory effect on AS, the mechanism may be that Sini decotion reduces concentration of ceramide in aorta.     

陕甘宁老区脆弱生态环境定量评价——以榆林、延安两市为例

位于黄土高原中部的陕甘宁老区生态环境极为脆弱 ,近年来由于气候、人类开发资源等自然和人为原因 ,使生态环境的脆弱程度升高。选定年降水量、年均温、蒸发量等 8个指标 ,定量评价各县 1 970 - 2 0 0 0年的脆弱度状况 ,结果表明榆林、延安两市生态环境整体脆弱 ,脆弱度存在空间差异但差异不明显 ,时间段上的波动幅度不大。陕甘宁老区脆弱生态环境具有不稳定性 ,对外界干扰较敏感。