Feeding for high milk quality in dairy cows under heat stress
Carolina Kyriacou, nutritional consultant from Vettaky LTD, Cyprus
MSc from the University of Wageningen, Netherlands
I am a dairy nutritionist in Cyprus, where the weather is among the hottest anywhere in Europe. Another fun fact about Cyprus is that in 2022 it was among the top 5 leading countries with the highest production of cheese production per capita (Figure 1). Milk quality matters to cheese production and dairy farm profitability. Therefore, an important role for me on dairy farms is to develop cost-effective feeding strategies for high milk quality even under high temperatures in the summer season. Let’s look at how adequate supplementation of trace elements in dairy rations can play an important role to alleviate the negative effects of heat stress on milk composition.
High yielding cows experience more heat-stress
The temperature humidity index (THI) (Figure 2) has been established as an indicator for heat stress risk. Collective data from research has shown that milk production in dairy cows can be affected when daily average THI exceeds 68. However, this also depends on the level of milk production in the dairy herd, as higher producing dairy cows are more susceptible to heat stress (Figure 3).
Figure 2. Temperature humidity index (THI)
Recent studies show that modern high producing dairy cows become heat-stressed at an average THI of 68. High producing dairy cows have a higher metabolic heat load due to processes such as lactogenesis and milk secretion. Consequently, as milk production and metabolic heat production rise genetically, heat stress will increasingly limit the expression of genetic potential. High producing dairy cows are also more prone to oxidative stress, which can further be exacerbated by heat stress with enhanced consequences for milk yield and quality.
Figure 3. Decline in milk yield in response to THI based on milk production level. Source: Summer et al 2019
Calculating the THI can provide a good indication for the risk of heat stress in dairy cows at any given time. However, what this value does not consider are differences in the type of farming system the cows are kept in. This means the real heat exposure the dairy herd experiences may differ from the calculated THI. Farming systems may or may not include cooling systems or shading. Thus, the real heat exposure may be lower than reported by nearby weather stations.
Effect of he...
Regístrate gratuitamente y accede a los mejores artículos sobre nutrición en nutriNews .
Regístrate en nutriNews to unlock this item and get more benefits like:
Iniciar sesión
Access to the
revista digital
Videos y podcasts exclusivos
Newsletters with the
últimas novedades
Regístrate en nutriNews
REGISTRARME
