鸭流感是A型流感病毒感染禽类的一种以出现呼吸道症状、产蛋率下降为主要特征的一种高度接触性、致死性传染病.该病对鸭有高度的感染性,而且某些亚型可以直接感染人类.

<正> 近年来,随着生活水平的提高,人们对牛奶的消费日益增加,促进了农村奶牛业的发展,饲养奶牛成为农民增收的一个途径。但在养殖过程中,由于一些农村养殖户防疫意识淡薄,致使人畜共患传染病频繁,特别是布鲁氏菌病和结核病(简称"两病")的发生,影响了牛奶的质量,危害了人体健康,阻碍了奶牛业的发展。 1 存在的主要问题 1.1 防疫条件不符合要求选址、布局不合理:牛舍多是简易结构或其他简陋房

The investigation of reproduction performance in 581 Xianan cows for 1240 gestations showed that the average age of the first estrus was 472.3 days,estrus cycle was 19.6 days,first insemination was 493.2 days,gestation period was 285.9 days,First estrus after calving were commonly at the 60.3 days,and dystocia rate was 1.05 percent.The rate of first calving before 2.5 years was 94.0 percent.Calving rate between 2 and 10.5 years old was 86.0 percent.