A Comprehensive Analysis of Bovine CSN2 Genotype, Parity, and Genetic Merit of the Dams on Neonatal Calf Disease Incidence and Colostrum Quality

Abstract

Neonatal calf morbidity remains a critical challenge in the global dairy industry, resulting in substantial economic losses and affecting long-term herd productivity and animal welfare. The etiology of neonatal diseases (predominantly enteritis, pneumonia, and omphalitis) is highly multifactorial, involving complex interactions between genetics, maternal factors, and environmental management. This study aimed to systematically evaluate the interactions among calf sex, dam parity, beta-casein (CSN2) genotype, and predicted transmitting ability (PTA) traits of the dams on neonatal disease incidence and colostrum quality. Utilizing a comprehensive dataset of Holstein-Friesian cows (n=1520) and calves (n=5438), statistical models including logistic regression, Pearson correlations, and analysis of variance (ANOVA) were applied. Results demonstrated no statistically significant difference in disease incidence between male and female calves. Conversely, dam parity was a highly significant predictor of calf morbidity, with calves born to primiparous (heifer) dams exhibiting an infection rate of approximately 18%, which progressively declined in multiparous dams, stabilizing at 5-8% for parities 3 and above. Analysis of the CSN2 genotype revealed that dams with the A1A1 genotype had significantly higher incidences of calf enteritis and overall disease than their A2A2 and heterozygous counterparts, supporting prevailing assumptions about the universal health benefits of the A2 allele. However, the CSN2 genotype did not significantly affect colostrum quality. Finally, colostrum quality, measured in degrees Brix, showed no significant association with dam PTA traits, including PTA milk, PTA fat, PTA protein, somatic cell score, and daughter pregnancy rate. These findings indicate that while neonatal disease susceptibility is strongly influenced by maternal parity and specific dam genomic loci (CSN2), colostrum quality appears largely independent of both calf genetic polymorphisms and dam production genetics, underscoring the critical importance of maternal management during the prepartum period.

Keywords

• CSN2 genotype
• A2 milk
• calf health
• colostrum quality
• Brix measurement

Ethical Statement

This study was conducted in accordance with all relevant national regulations and institutional guidelines for the care and use of animals. The study was conducted using routine farm records and milk samples without any invasive procedures involving animals; therefore, no specific ethical committee approval was required.

Thanks

The authors would like to sincerely thank Rumeli Farming for their valuable support.

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