IMPACT OF THERMAL STRESS IN DAIRY PRODUCTION
Thermal stress has significant repercussions several days after the heat. In the United States, the effects of this stress are estimated to cost the dairy industry between $ 897 million and $ 1.5 billion a year.
On our side, even if we sometimes have the impression that summer will never arrive, heat stress is also very real in our climate. As the impacts of this stress are multiple, your agronomist is the resource person to guide you to avoid any problem during the summer.
Less nutrients ingested
In hot weather, animals tend to reduce their voluntary dry matter intake. Since digestion generates heat production, it is normal for the animal to limit its consumption so as not to worsen its situation. Obviously, this has the direct impact of lowering milk yields and components, because fewer nutrients are ingested by the animal.
The percentage of milk fat, among other things, is reduced because of the change in rumen fermentation by diet changes and an altered rate of passage through the digestive tract. A decrease in digestive transit can also cause a problem of acidosis, as rumen acid production is increased.
By changing the energy balance, heat stress can also decrease the reproductive performance of dairy cattle, reproductive hormone levels and embryo survival.
Important impact on immunity
It has also been established that heat stress has a significant impact on immunity by reducing the efficiency of immune cells. It is therefore expected that an increase in leukocyte count and the incidence of mastitis in the herd will be felt if no strategy is put in place.
In addition, ensuring a good supply of water and feeding the animals during the cooler periods of the day will certainly help to prevent a drop in productivity. Do not hesitate to consult the professionals around you.
Definition of heat stress
How do we know if our animals are experiencing heat stress? There are several factors to consider, including ambient temperature, but also humidity. The rectal temperature as well as the number of breaths per minute are also to be taken into account.
Several tools at your fingertips
Your dairy production consultant has several tools to help your flock get through this stress without much impact on performance. Whether it is the increase in the energy and protein density of the diet, or the use of a high quality yeast, immunomodulator or buffering agent, there are several strategies to put in place to minimize impacts. heat stress on your dairy herd.
Gabrielle L. Dumas, agr., DCL nutrition + animal health