Heat stress
Advice from the Vet 

Why do you recommend concentrating the ration in periods of heat stress?

Cattle eat less during periods of heat stress. Ingestion decreases even though energy requirements increase. This occurs for various reasons: hyperventilation, inflammation due to leaky gut syndrome, an over-stressed immune system, etc. If nothing is done, animals quickly find themselves in an energy deficit situation. Therefore, the farmer’s goal has to be to limit the impact of the reduced feed intake and meet the increased needs with a smaller ration that has a higher energy content. This is called concentrating the ration.

How can this be done without increasing the risk of acidosis?

Heat stress is an aggravating factor in the risk of ruminal acidosis. Therefore, acidogenic feed cannot be used, e.g. concentrates containing a lot of starch. To increase the energy content of the ration, increase the amount of FUL per kg of DM using non-acidogenic solutions. This is the case for bypass protected fats, such as Vitafat® or Vegelin®, assimilated by the body directly in the intestine, as well as for protected cereals - alkalised - such as XL Grain®, designed to make the cereal non-acidogenic and to increase its protein content.

What is the benefit of providing a glucose precursor product?

Blood tests performed on cattle during heat stress conditions systematically have low levels of blood sugar. This is because a large proportion of the sugars synthesised by the body are used to fight the inflammation caused by leaky gut syndrome. Under these conditions, it is easy to understand why it is important to increase the blood glucose levels, in combination with an intake of chelated minerals. To do this, I recommend using precursors in the ration, particularly propylene-based products such as Glycoline®, which will provide energy in a non-acidogenic form and will be converted directly into glucose.

How should Glycoline® be used and what results can be expected?

Glycoline® doses between 150 and 200 ml/day should be added to the ration for dairy cows during hot periods. In 2016, Vitalac monitored a farm in Cyprus that used Glycoline® all summer long. When temperatures of 40°C are reached, milk production often decreases by 10 kg; with Glycoline®, production was reduced by only 5 kg. It has been estimated that the return on investment is close to €1 per cow per day. In France, you don't have to do this all summer long. It should be added during periods of persistent heat - temperatures over 28°C for several days in a row - starting a bit beforehand and extending for a bit afterwards. The cost is around €0.40/cow. This avoids a decrease of 2 l/cow, i.e. a gain of approximately €0.25/cow/day. Glycoline® is also very palatable. It can be used in top feeding, added to the ration in the middle of the day: the cows will come eat an additional serving.