Bonus Tydskrif AUTUMN 2024

As the summer heat gives way to the cooler temperatures of autumn, the dairy industry grapples with the lingering effects of seasonal transitions. One of the primary contributors to a decline in milk production during this period is the stress induced by calving in the summer. Navigating the autumn slump: Strategies for sustaining milk production in dairy cows By Sarah Harrison, technical advisor dairy, De Heus Here’s a detailed look at the reasons behind this decline: • Reduced milk peaks: Cows that calve during the summer experience a noticeable 2 to 4,5kg reduction in milk peaks compared to other times of the year. This lower peak during early lactation sets the stage for decreased overall production yields throughout the lactation period. • Heat stress impact: The challenges of calving in the summer months extend beyond reduced milk peaks. Cows that calved early in the summer find it challenging to overcome the lingering effects of heat stress, impacting their productivity well into the autumn months. • Long-lasting effects: The repercussions of calving stress in summer persist, affecting the overall health and milk production of the herd. This underscores the importance of addressing these issues with thoughtful and strategic interventions. As autumn sets in, additional challenges emerge, exacerbating the decline in milk production. The gradual shortening of daylight hours becomes a pivotal factor. This change is associated with a reduction in pasture growth and quality, as cows spend less time grazing. Moreover, variations in daylight duration can impact hormonal patterns in cows, influencing reproductive cycles and subsequently affecting milk yield. Studies suggest that milk production tends to be highest during exposure to 16 to 18 hours of daily bright light. The basic energy requirements of dairy cows also undergo a shift in autumn as they prepare for winter. This period witnesses a rise in energy needs driven by the elevation of basal metabolism, the growth of a winter coat, and the storage of fat under the skin for insulation against the impending cold. The quality of feed changes during the transition from summer to autumn. The degradation of kikuyu in pastures as summer progresses into autumn leads to reduced palatability and digestibility, resulting in decreased intakes. Dry matter (DM) intake is crucial for maintaining milk production, and the decline in the quality of available pasture Autumn / Herfs 2024 BONUS www.agribonus.co.za 38