Effects of two commercial European modified-live vaccines against porcine reproductive and respiratory syndrome viruses in pregnant gilts

The purpose of this study was to assess the effects of two currently available commercial European-type modified-live virus (MLV) vaccines against porcine reproductive and respiratory syndrome in a reproductive pig model. Sixteen 90-day pregnant gilts were divided into four groups and allocated to one of the following intranasal treatments: group A gilts served as negative controls; group B gilts were exposed to a virulent European field strain; group C gilts were exposed to vaccine strain VP046 Bis and group D gilts to vaccine strain All-183. The results indicated that MLV strains can replicate in breeding animals and have the ability to cross the placenta. In particular, viraemia was detected in all gilts in group C and 2/4 gilts in group D, at least at one time point. In addition, transplacental infection was demonstrated in 3/4 gilts in group C and 2/4 gilts in group D. However, congenital and early postnatal infection did not have a marked detrimental effect on piglet performance when compared to negative controls, and no statistically significant differences were observed in most cases. Conversely, the reproductive performance of gilts in group B was significantly worse than that of the other groups. Specifically, the number of born-alive piglets, the survival rate of piglets during lactation and the mean weight of weaned pigs were significantly lower. It was concluded that the two commercial European-type MLV vaccines tested had no marked detrimental effects in pregnant gilts, although the MLV strains can cross the placenta leading to the birth of congenitally infected piglets.     

结合差额法和系统分析原理确定猪育种目标

本文结合差额法及系统分析原理模拟商品猪群生物经济学过程，计算北京迪卡猪育种目标性状的边际效益，目标性状包括窝产活仔数（头／窝），日增重（ｇ），饲料转化率（ｋｇ／ｋｇ），瘦肉率（％），肉质指数（％），它们的边际效益分别为８．５３、０．１１、－７８．８０，１０．４０及２．０７元。通过遗传标准差的校正，这些性状的经济权重分别为５．８５，５．０２，－９．４６，１３．１０及４．６６元，文章还分析了影响边际次     

关中黑猪与长白猪脂肪形成的细胞学和组织化学比较研究

本研究通过对初生～１８０日龄阶段的肥胖型关中黑猪和瘦肉型长白猪背部皮下脂肪组织中脂肪细胞的直径、体积和表面面积等细胞学参数的观测，以及羟脯氨酸、胶原蛋白、非胶原蛋白、蛋白质、ＤＮＡ和甘油三酯主要生化物质含量及其消长规律的测定与分析，证明脂肪细胞的肥大作用是猪脂肪形成的主要形式，脂肪细胞的增殖作用较小，且主要发生在生长发育的早期，发现肥胖型关中黑猪脂肪细胞的肥大作用和增殖能力都强于瘦肉型长白猪。     

五指山猪白细胞抗原血清学研究

用２４支标准血清对２５头五指山猪进行白细胞抗原的血清学分型，根据标准微量淋巴细胞毒试验结果，按国际ＳＬＡ－Ａ、Ｃ、Ｂ抗原血清学分型标准、共检出２１种单倍型，另有８条、占１６％的单倍型不能确定。在所检出的单倍型中，Ｈ４、Ｈ３２含量较高，频率分别达０．１２和０．１０；Ｈ９、Ｈ１０、Ｈ１７、Ｈ２３、Ｈ３５、Ｈ４２、Ｈ５３等单倍型为中等频率分布，频率从０．０４￣０．０８；Ｈ１、Ｈ２、Ｈ３、Ｈ６、Ｈ８、Ｈ２     

热应激对猪繁殖性能的影响及防止措施

温度对种猪的繁殖性能具有重要的影响,根据相关文献阐述热应激对种母猪发情、受胎率、胚胎成活率、产仔数以及种公猪繁殖性能的影响,提出了控制热应激对种猪繁殖性能影响的具体措施。     

重庆市猪球虫病流行病学调查与虫种鉴定

目的为了解重庆市猪场球虫感染情况。方法选取重庆市9个县14个猎场作为采样点,对被检猪采用直肠取粪法或采集猪刚排出的新鲜粪便,饱和食盐水漂浮法收集卵囊,镜检观察。对收集到的卵囊进行培养,待其孢子化后进行种类鉴定。结果14个猪场均感染了球虫,球虫的平均感染率为33.83%,阳性率最高的场为76.09%;仔猪感染率为41.87%,后备猪感染率为26.33%,种猪感染率为67.80%。发现8种艾美耳属球虫和1种等孢属球虫,分别是猪艾美耳球虫(检出率13.56%),豚艾美耳球虫(检出率41.59%),有刺艾美耳球虫(检出率12.84%),平滑艾美耳球虫(检出率4.70%),新蒂氏艾美耳球虫(检出率10.49%),蒂氏艾美耳球虫(检出率11.03%),粗糙艾美耳球虫(检出率2.35%),极细艾美耳球虫(检出率3.07%),及猪等孢球虫(检出率0.36%)。结论重庆市猪球虫感染率较高,应加强猪球虫病的防制。     

用ELISA检测接种猪瘟疫苗猪的血清抗体

用ＥＬＩＳＡ检测了接种猪瘟疫苗猪的血清抗体。共计４８６份猪血样,检测到血清抗体阳性者４４１份,阳性率为９０．７４％。同时对其中的１１１份血清进行了自然强毒血清抗体的检测,检测到强毒抗体阳性４份,阳性率为３．６０％。结果表明青海省猪瘟疫苗注射密度较高,但也反映出在青海省猪群中可能存在猪瘟自然强毒感染。     

Challenge differentially affects cytokine production and metabolic status of growing and finishing swine

Growing (35 kg body weight) and finishing (85 kg body weight) swine challenged with endotoxin (Escherichia coli O55:B5) at a dose of either 2 or 20 microg/kg produced tumor necrosis factor (TNF)alpha in a dose-response relationship as measured by bioassay. Peak TNFalpha plasma levels were observed 1-2 hr post-challenge, returning to basal values 4 hr post-challenge. However, both an enzyme-linked immunosorbent assay specific for swine TNFalpha and total human TNFalpha demonstrated no dose-response relationship; peak plasma levels of immunoreactive TNFalpha were also observed 1-2 hr post-challenge. Maximal plasma interleukin-6 levels occurred 1-2 hr post-challenge and remained elevated through 8 hr post-challenge; there was no effect of lipopolysaccharide dose or metabolic status. Although the metabolic status of the animals also affected glucose levels, with growing animals exhibiting greater sensitivity compared with finishing animals, endotoxin-induced decreases in blood glucose levels were primarily dose-dependent. In contrast, changes in plasma urea nitrogen and free fatty acid (FFA) levels were strictly related to the metabolic status. Urea nitrogen levels were unchanged in growing swine, whereas they were increased in finishing swine and remained elevated 24 hr post-challenge. FFA levels in growing and finishing swine increased 3-6 hr post-challenge. FFA levels returned to basal values for finishing swine 24 hr post challenge, but in growing swine remained elevated 24 hr post-challenge. Plasma aspartate transaminase levels were increased through 24 hr post-challenge; animals given a dose of 20 microg/kg exhibited the greatest increase. Similarly, swine challenged with a dose of 20 microg/kg also exhibited the greatest increase in levels of conjugated bilirubin; there was no effect on unconjugated (free) bilirubin. These results demonstrate that endotoxin challenge of swine result in a pattern of changes that are dependent on both the dose of endotoxin used and the metabolic status of the animal examined.     

猪高热病的发生及防控措施

分析猪高热病的发病症状及猪群高死亡率发生原因,并提出＂以生物安全为基础,保健为重,预防为主,治疗为辅＂的综合防控措施。