Beam A L, Lombard J E, Kopral C A, Garber L P, Winter A L, Hicks J A, Schlater J L
USDA:APHIS:VS, Centers for Epidemiology and Animal Health, 2150 Centre Ave., Fort Collins, CO 80526-8117, USA.
J Dairy Sci. 2009 Aug;92(8):3973-80. doi: 10.3168/jds.2009-2225.
Failure of passive transfer of immunity (FPT) in dairy replacement calves has been linked to increased neonatal morbidity and mortality and long-term decreases in productivity. The purpose of this study was to estimate the prevalence of FPT in US dairy heifer calves in 2007 and to use nationally representative data to investigate associations of FPT with colostrum and calf management practices. A cross-sectional study was conducted by the USDA's National Animal Health Monitoring System between January and August 2007. Producers from 394 operations in 17 states completed survey questions about colostrum and calf management practices, and serum samples were collected from 1,816 healthy heifer calves on those operations. Serum immunoglobulin G (IgG) levels were determined by radial immunodiffusion, and calves were classified as having FPT if the IgG concentration was less than 10 mg/mL. To investigate associations between FPT and management practices, a multivariable analysis was completed using a weighted logistic regression model. The estimated prevalence of FPT in US dairy heifer calves was 19.2%. The odds of FPT were higher for calves on operations that pooled colostrum [odds ratio (OR = 2.2)], allowed nursing (OR = 2.4), or hand fed colostrum more than 4 h after birth (OR = 2.7). The odds of FPT were also higher for calves on operations that did not provide a source of heat during cold weather for calves experiencing a dystocia (OR = 1.6), would not seek veterinary assistance when unable to correctly position a calf for delivery (OR = 2.6), or did not routinely monitor serum proteins in calves as a measure of passive transfer (OR = 13.8). The prevalence of FPT in dairy heifer calves has decreased in the last 15 yr, so progress has been made in this important area of calf management. This study identified several management practices associated with FPT that could be targeted for educational campaigns or further research.
奶牛后备犊牛免疫被动转移失败（FPT）与新生犊牛发病率和死亡率增加以及长期生产力下降有关。本研究的目的是估计2007年美国奶牛小母牛犊牛中FPT的患病率，并使用具有全国代表性的数据调查FPT与初乳及犊牛管理措施之间的关联。美国农业部国家动物健康监测系统于2007年1月至8月进行了一项横断面研究。来自17个州394个养殖场的生产者完成了关于初乳和犊牛管理措施的调查问卷，并且从这些养殖场的1816头健康小母牛犊牛中采集了血清样本。通过放射免疫扩散法测定血清免疫球蛋白G（IgG）水平，如果IgG浓度低于10mg/mL，则将犊牛分类为患有FPT。为了研究FPT与管理措施之间的关联，使用加权逻辑回归模型完成了多变量分析。美国奶牛小母牛犊牛中FPT的估计患病率为19.2%。对于初乳混合的养殖场中的犊牛，FPT的几率更高[优势比（OR = 2.2）]，允许犊牛吮乳的养殖场（OR = 2.4），或出生后4小时以上人工饲喂初乳的养殖场（OR = 2.7）。对于难产犊牛在寒冷天气期间未提供热源的养殖场中的犊牛，FPT的几率也更高（OR = 1.6），犊牛分娩时无法正确定位时不寻求兽医帮助的养殖场（OR = 2.6），或未定期监测犊牛血清蛋白作为被动转移指标的养殖场（OR = 13.8）。在过去15年中，奶牛小母牛犊牛中FPT的患病率有所下降，因此在犊牛管理这一重要领域已取得进展。本研究确定了几种与FPT相关的管理措施，可作为教育活动或进一步研究的目标。
