Seasonal Trends in Holstein Milk Traits

The dairy industry acknowledges the seasonal nature of milk production and the fluctuations in milk component concentrations throughout the year. This variability in milk components, influenced by seasonal changes, assumes critical importance in light of the projected global population increase to 9.7 billion people within the next 20–50 years. Addressing the imminent need for major alterations in agricultural and livestock practices to accommodate this growth necessitates a comprehensive evaluation of all stages within the food production chain. An essential aspect of achieving sustainable agriculture involves identifying opportunities to reduce gaseous pollutants. This study aims to investigate how seasonal variations impact the specific properties of Holstein milk, with a focus on the daily milk yield, daily milk protein, daily milk fat, and urea content. Test-day records from Holstein dairy cows in Croatia, collected during routine milk assessments from January 2005 to December 2022, form the basis of this research. A meticulous process of logical scrutiny of milk recording data, compliant with the ICAR standards, and rectification of non-logical variable values ensured the inclusion of 5,164,920 Holstein test-day records in the refined database. Our analysis centers on the annual number of samples and the primary parameters of milk content (namely fat, protein, and urea). The examination of Holstein milk samples revealed recurring cyclical patterns, indicating higher values during winter and lower values in summer. These distinct variations likely correlate with the annual climatic fluctuations in Croatia. The implications of these findings warrant future research to monitor trends in the raw milk quality and assess the potential adverse effects of the identified changes on the milk properties.