Bonus Tydskrif WINTER 2024

Milk production can be influenced by many different factors, varying from nutrition to breed selection to health. Yet, even within the best managed herds, some factors decrease milk production and cannot be avoided. Most of these are environmental and influence the physiology of the dairy cow. The key to good seasonal management is to allow these factors to positively impact the cow and to reduce the negative influence as much as possible by making intentional choices regarding winter management. How winter impacts a dairy cow By Elzanne Fourie, technical advisor: Dairy, De Heus Like many other animals, dairy cows are sensitive to photoperiods. This means the length of daylight, on any given day, has a direct impact on the cow and not only on the quality of the pasture that they are consuming. They are also sensitive to changes in temperature, which occur naturally as seasons change. In combination, these two environmental factors can have a varying daily impact on a herd. In dairy cows, the transition of seasons to winter will affect: • Dry matter intake DMI – the amount of dry matter that the cow consumes. • Milk production – the quantity of litres produced by the cow. • Fertility – the likelihood of conception and the length of time between calvings. With day length shortening in winter and temperatures dropping, the mentioned factors are important to take into consideration when planning around seasonal changes. Cows in milk Exposure to a longer photoperiod typically results in increased dray matter consumption among cows in milk. This is to meet the demands caused by increased milk production. Contrary to popular belief, it is not DMI that increases milk production in a longer photoperiod, but the decreased melatonin produced as a side effect of longer exposure to light. Melatonin regulates the dairy cow’s internal clock. A longer physiological ‘day’ causes the cow to secrete more hormones related to Winter 2024 BONUS www.agribonus.co.za 8