Abstract

Effective colostrum management is essential to ensure adequate transfer of passive immunity (TPI) and reduce neonatal morbidity in calves. This study evaluated the impact of pasteurization on colostrum microbiological and immunological quality and its association with TPI and calf health on a dairy farm in Italy. A total of 79 colostrum samples were included: 39 pasteurized (PC) and 40 non-pasteurized (NPC). Immunoglobulin concentration was estimated by Brix refractometry, while bacterial contamination was assessed by total bacterial count (TBC) and total coliform count (TCC). In a second phase of the study, 80 newborn calves received either pasteurized (C-PC, n = 40) or non-pasteurized colostrum (C-NPC, n = 40). TPI was evaluated at 48 h and calves were clinically monitored for 21 days. Overall, colostrum showed not only high Brix values but also elevated bacterial contamination. Pasteurization significantly reduced the microbial load in colostrum (TBC, 5.7 vs. 2.9 log CFU/mL; TCC 4.6 vs. 1.5 log CFU/mL) (p < 0.0001). Brix values differed significantly between PC and NPC colostrum (p < 0.001), although the magnitude of the difference was minimal (27.8% in NPC vs. 27.6% in PC), suggesting limited biological relevance. Calves receiving pasteurized colostrum showed significantly lower odds of developing neonatal diarrhea than calves receiving unpasteurized colostrum (C-PC: OR 0.1, 95% CI 0.0–0.3; C-NPC: OR 9.9, 95% CI 3.4–32.6). These findings indicate that colostrum pasteurization reduces contamination effectively even in colostrum with high bacterial loads without substantial impact on its Brix values and was associated with improved calf diarrhea outcomes in the investigated herd.

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