胎次对大白母猪产死胎数与弱仔数的影响

为探究胎次对母猪产弱仔、死胎的影响,实验对广西某猪场2015年12月——2017年11月的8 028窝大白母猪的胎次和产弱仔数、死胎数进行统计分析。结果表明:不同胎次母猪产弱仔数和死胎数具有极显著差异(P<0.01),其中第1胎次母猪弱仔数显著高于其他胎次母猪(P<0.05),且弱仔数均值呈逐渐下降趋势;第5胎次母猪的死胎数显著低于其他胎次(P<0.05),且死胎数均值近似呈先下降后上升的趋势;对产弱仔数和死胎数占总产仔数的比例进行分析进一步证明了上述结果。综上,第2～6胎次母猪产弱仔数和死胎数都相对较少,产仔性能最好,规模化猪场可以考虑淘汰7胎以上的母猪;对第1胎次的母猪建设P1场(第1胎次母猪场),制定更为严格的"驯化"和饲养工作。     

非传染病因素对母猪死胎与木乃伊胎发生的Logistic回归分析

目的:探讨除疾病以外对母猪死胎,木乃伊胎的影响因素。方法,用Logistic回归分析对胎次,配种月份、产仔月份、产活仔数、总产仔数、木乃伊胎率和死胎率进行回归分析。结果表明,在死胎的回归分析中,产活仔数、木乃伊胎率和总产仔数3个因素被选入多因素Logistic回归模型中,其OR值分别为:36.266、0.030和0.002。在木乃伊胎进行回归分析中,分娩月份、产活仔数、死胎率和总产仔数4个因素被选入多因素Logistic回归模型中,其OR值分别为:1.092,0.404,0.227,2.561。结论:死胎的发生与环境温度、胎次无回归关系,木乃伊胎与分娩时环境温度或临近分娩时的环境温度有正回归关系,死胎和木乃伊胎都与产活仔数有负回归关系,与总产仔数有正回归关系,互相进入对方的回归方程。     

Reproductive disease and congenital malformations caused by Menangle virus in pigs

OBJECTIVE: To describe a new syndrome characterised by embryonic mortalities, stillbirths, mummified foetuses and congenital malformations in a herd of intensively farmed pigs. DESIGN: Field observations, laboratory investigations and examination of breeding records. PROCEDURE: Pathology examinations were performed on mummified and congenitally deformed piglets during an outbreak of reproductive disease at a 2600 sow intensive piggery in New South Wales from April to October 1997. Reproductive performance was monitored during the outbreak and breeding records were examined retrospectively. Serum and tissue samples from pigs were tested for evidence of infection with known porcine pathogens and for a new virus, Menangle virus, isolated from stillborn piglets with deformities from the affected piggery in August 1997. RESULTS: Reproductive disease occurred sequentially in all four breeding units at the affected piggery over a period of 21 weeks. The farrowing percentages in each unit decreased from 80 to 82% before the outbreak to 63 to 78% during the outbreak and the number of live piglets per litter declined from a mean of 9.6 to 9.8 before the outbreak to 7.2 to 8.9 during the outbreak. The proportion of affected litters (litters with less than six liveborn piglets) was highest (64%) in the sixth week of the outbreak. Mummified foetuses, stillborn piglets with arthrogryposis, craniofacial deformities and degeneration of the brain and spinal cord, were observed along with occasional abortions. Sera from sows that produced affected litters contained neutralising antibodies against Menangle virus and there was evidence that this virus had been introduced to the piggery in February 1997. CONCLUSIONS: Reproductive disease in pigs due to Menangle virus was characterised by stillbirths, mummification, embryonic death and infertility, along with abortions, skeletal deformities and degeneration of the brain and spinal cord in affected foetuses and stillborn piglets.