Passive immunity and colostrum management practices on Ontario dairy farms and auction facilities: A cross-sectional study

摘要

Failed transfer of passive immunity (FTPI) in dairycalves has substantial health consequences, but therehave been no recently published estimates of the prevalenceof FTPI on Ontario dairy farms. The major objectivesof this cross-sectional study were to determinethe level of FTPI in dairy calves across the provinceof Ontario and to determine colostrum managementpractices used. A convenience sample of 109 dairyfarms in Ontario were visited from June to August2019, along with 4 auction facilities from January toFebruary 2019. At the single visit to each dairy farm,an in-person questionnaire was administered, and allcalves between 24 h and 9 d of age had a blood samplecollected to determine the levels of serum total protein(STP). At the auction facility, a blood sample was collectedon all calves that arrived on the day of the visit.The dairy farms were distributed throughout Ontario,and the farms milked on average 151 dairy cows. Of the444 calves sampled on Ontario dairy farms, 46% weremale, 54% were female, and the mean weight and ageat sampling were 46.3 kg and 4.4 d, respectively. Themean STP of calves sampled on the dairy farm was5.69 g/dL (standard deviation = 0.78), and 107 calves(24%) had FTPI. The likelihood of FTPI was not associatedwith sex (female vs. male, risk ratio = 0.89,95% confidence interval = 0.64–1.24), age (per day, riskratio = 1.02, 95% confidence interval = 0.94–1.11), orweight (per kg, risk ratio = 0.98, 95% confidence interval= 0.96–1.01). In contrast, at the auction facilities,386 male dairy calves were sampled and had a meanSTP of 5.79 g/dL (standard deviation = 0.83). Usinga cut point of ≥5.2 g/dL, 91 calves (24%) had FTPI.From the in-person questionnaire administered on thedairy farms, it was reported that the median time tofirst feeding of colostrum was 2.5 h (range = 0–12 h).The farms reported providing a mean of 3.3, 2.9, and3.4 L of colostrum from 0 to 6 h after birth, 6 to 12h after birth, and 12 to 24 h after birth, respectively.Ninety-one farms (83%) fed colostrum from the damof the calf as their predominant source of colostrum.The most common method used to deliver the firstfeeding of colostrum was a nipple bottle (89 farms,82%). Twenty-seven farms (25%) reported managingcolostrum differently for male calves, which includeda different colostrum source, use of poorer qualitycolostrum, a smaller quantity of colostrum, a longertime from birth to feeding, and generally having a lowerfocus on colostrum management for male calves. Theprevalence of FTPI on Ontario dairy farms appearsto have decreased since previous estimates, and substantialroom for improvement remains. Although nooverall differences were found in FTPI between maleand female calves, differential reported colostrum managementby sex indicates this may be a risk for malecalves on a proportion of Ontario dairy farms.