Yates W D, Kingscote B F, Bradley J A, Mitchell D
Can J Comp Med. 1983 Jul;47(3):375-8.
A group of 62 beef calves, born and raised in an institutional herd, were transferred at nine months of age to a commercial feedlot where they remained until slaughter seven months later. Clinical, immunological and microbiological monitoring was carried out during this period. No serious clinical illness occurred. One hundred percent seroconversion to bovine virus diarrhea virus took place after introduction of the calves into the feedlot as well as almost complete (59/62) seroconversion to bovine herpesvirus 1, a proportion of which could be related to a single vaccination. Significant increases in recoveries of Mycoplasma spp. from nasal swabs also occurred in the feedlot. At slaughter, the lungs of all animals were recovered and examined for pathological lesions: 23 were completely normal and 39 showed minor histological changes chiefly characterized by areas of lobular to sublobular atelectasis. For this group of calves, no relationship was found between the presence of potential pathogens in nasal mucus and the occurrence of lesions in the lung. The serological results are discussed in terms of vaccinations and other known events that occurred during the study period.
一组62头在机构牛群中出生并饲养的肉牛犊，在9个月大时被转移到一个商业饲养场，在那里一直待到7个月后被屠宰。在此期间进行了临床、免疫学和微生物学监测。未发生严重的临床疾病。将牛犊引入饲养场后，牛病毒性腹泻病毒的血清转化率达到100%，牛疱疹病毒1的血清转化率也几乎达到100%（59/62），其中一部分可能与单次疫苗接种有关。饲养场中鼻拭子支原体属的回收率也显著增加。屠宰时，取出所有动物的肺并检查病理损伤：23个完全正常，39个显示轻微的组织学变化，主要特征是小叶至亚小叶肺不张区域。对于这组牛犊，未发现鼻黏液中潜在病原体的存在与肺部病变的发生之间存在关联。根据研究期间发生的疫苗接种和其他已知事件对血清学结果进行了讨论。
