Immunological and bacteriological quality of fresh cow colostrum and passive immunity transfer in selected dairy farms in Fars, Iran

Background: The quality of colostrum is affected by IgG level and microbial load.

Aims: The quality of colostrum used in feeding dairy calves and passive immunity transfer in selected dairy farms in Fars province, Iran was investigated.

Methods: A total of 75 colostrum and neonatal blood samples were collected from 11 herds. The immunological quality of colostrum was assessed using a Brix digital refractometer. The bacteriological quality was assessed by performing total plate count (TPC), total coliform count (TCC), spore-former count, fungi count, and species-specific PCR assay to detect some bacterial species.

Results: The mean Brix of colostrum samples was 25.4% and 72% of the samples had a Brix score ≥22%. The mean serum Brix and the prevalence of failure of passive transfer (FPT) were 10% and 4%, respectively. The mean TPC, TCC, spore-former count, and fungi count were 3.6 × 10⁵, 2.8 × 10⁴, 3.2 × 10⁴, and 1.1 × 10⁴ CFU/ml, respectively. The results showed that 50, 5.9, and 4% of colostrum samples were positive for Staphylococcus spp., Salmonella spp. and Maycobacterium paratuberculosis, respectively. There was no evidence of contamination with Brucella spp., Corynebacterium bovis and Mycoplasma bovis.

Conclusion: Considering all colostrum quality indicators comprehensively, only 37.3% of the studied samples met the industry standard. A large number of calves were at risk of receiving poor quality colostrum, especially in terms of microbial contamination. Further researches are needed to evaluate the colostrum management and the effect of bacterial contamination of colostrum on the health of neonate calves in this region.