Due to global warming, the number of days per year that cows are exposed to heat stress will grow dramatically104
(see figure 1).
Figure 1: Number of days per year on average which exceed a temperature-humidity index of 70 during 20-year periods (a) 1998–2017 and (b) 2051–2070. (c) is the difference between the 2051–2070 period and the 1998–2017 period.
Heat stress in dairy cows results in a significant decrease of milk production74, (see heat stress article). Next to that, it reduces fertility67,68 and increases the incidence of lameness.
A heat stress programme should include providing shade, cooling of the animals and ensuring they all have a comfortable bed. Nutritional intervention should include supplementation with Selko Nutricool to normalise rumen pH and reduce systemic immune activation71.