Associations between colostrum management, passive immunity, calf-related hygiene practices, and rates of mortality in preweaning dairy calves

摘要

Calves are particularly vulnerable to health issuesbefore weaning and experience high rates of mortality.Poor colostrum quality or substandard colostrummanagement, combined with poor hygiene, can increasedisease susceptibility, contributing to elevated mortalityrates. This study aimed to assess colostrum and calfmanagement together with subsequent mortality ratesin preweaning calves. Forty-seven Irish spring-calving,pasture-based dairy herds were enrolled in the study.To investigate whether colostrum and hygiene practiceschange as the calving season progresses, each farm wasvisited in both the first and last 6 wk of the calving season.The concentration of IgG in 250 colostrum samplesand 580 calf serum samples was determined by radialimmunodiffusion assay. Mean colostrum IgG concentrationwas 85 mg/mL, and mean calf serum IgG concentrationwas 30.9 and 27.1 mg/mL, respectively, in thefirst and last 6 wk of the calving season. Smaller herdsize and younger age at sampling were associated withhigher calf serum IgG concentration. Dairy breed calveswere associated with higher serum IgG concentrationscompared with beef breed calves; no association wasdetected based on sex. For feeding equipment hygiene,we assessed the presence of protein residues and foundthat hygiene levels tended to worsen from the first tothe final 6 wk of the calving season. We found no associationbetween feeding equipment hygiene and herdsize or 28-d calf mortality rate. Colostrum and calfmanagement practices were not associated with eithercalf serum IgG concentration or 28-d calf mortalityrate. We found that IgG concentration in colostrumproduced in Irish dairy herds was generally good, althoughlarge variation existed, emphasizing the needfor assessment of colostrum before feeding. Results alsosuggested that hygiene practices associated with calfrearing can be improved, particularly in the latter halfof the calving season.