Technical article published in number 251 of the Spanish Frisona magazine
Introduction
In this third installment on heat stress (CE) we intend to explain the visible and not so visible signs of heat stress in dairy cows, so that they can serve as an alarm signal about what is happening and that harms, to a greater or lesser extent. to a lesser extent, the welfare of these animals.
Likewise, we will explain the consequences that CS has on the animal, at different levels: physiological, reproductive, behavioral. It is evident that the very consequences of the CS become obvious signs of it when we are able to see or measure them, although some of them do not manifest immediately, so they will not serve to give an immediate response to the CS, but rather, and it is also important to prepare the farm so that the heat episodes of the following year have fewer negative effects.
After the long and very hot summer that we have spent this year 2022, and that when these lines are being written (mid-October) we still have temperatures higher than usual, the interest in understanding the negative consequences on dairy cattle of the EC seems evident to us and the need to arbitrate effective measures to mitigate these effects, and that will be addressed in subsequent works.
Cow responses to heat stress
The animal needs to have sensitive mechanisms to be able to maintain thermal balance and to respond quickly to be able to compensate for changes in heat production. In response to this stress, the dairy cow activates physical, biochemical and physiological mechanisms (in addition to behavioral ones) to try to counteract its negative effects and maintain thermal balance. These adjustments seek to remove heat and reduce metabolic heat production.
The response of cows to CS occurs in a progression of steps that are presented sequentially. This progression depends on the severity and duration of the stress.
The main effects of this stress are of three types and their economic valuation is summarized in the Figure 1although some of them will be explained in more detail in the following pages.
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Technical article published by Antonio Callejo Ramos in the number 251 of the magazine Frisona Espaola.
All the articles this animal welfare series:
– Well-being in dairy cattle farms (I): Concept of well-being
– Well-being on dairy cattle farms (II): stress
– Well-being on dairy cattle farms (III): Well-being assessment (1)
– Well-being on dairy cattle farms (IV): Well-being assessment (2)
– Well-being on dairy cattle farms (V): Well-being assessment (3)
– Well-being on dairy cattle farms (VI): Well-being assessment (and 4)
– Well-being on dairy farms (VII): Heat stress (1)
– Well-being on dairy cattle farms (VIII): Heat stress (2): Evaluation
– Well-being on dairy farms (IX): Heat stress (3): Symptoms and consequences
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