Conversations: Ask your veterinarian & nutritionist about proper hydration

As the temperature goes up, are cows going down? As producers and their advisors meet in the conference room (or kitchen), one conversation should lead to a better understanding of an issue that might be begging for intervention.

By Mike Bettle, B.Sc. Hons.

Your cows can’t talk, but weakness and lethargy may be signs every body cell is missing an important component – water.

Mike Bettle, B.Sc. Hons. (Animal Physiology and Nutrition), is dairy technical support for TechMix North America. Contact him via e-mail:

While dehydration can occur in any season, we typically associate it with hot weather. Now that temperatures are slowly on the rise, it may be time to have a conversation about hydration strategies before signs such as body shrink, lower milk production, loss of appetite and, in severe cases, metabolic acidosis, impact your herd. Following are some questions and ideas to discuss with your veterinarian and nutritionist.

1) What’s the main contributor to dehydration?

Dehydration can be defined as a reduction or deficiency in the amount of water required for health/normal biological function. Anytime a cow is challenged, from disease or dramatic environmental changes, she undergoes some level of stress. Heat, humidity, surgery, transportation, freshening and health challenges – are all stressful events that happen  frequently on the modern dairy. All these challenges cause a cow to change her eating and drinking habits which may lead to her consuming less water than normal, or certainly less than  she needs to maintain good health and high production levels. Other contributing factors to dehydration include scouring and ingestion of toxins from moldy feeds.

Monitor eating and drinking habits to identify any changes, and ask your veterinarian/nutritionist about ways  to counter such stressful conditions on your operations.

2)  How does a cow’s body respond when she isn’t taking in enough fluids?

Mature cows carry 50%-60% of their total body weight in fluids and are unique in that their rumen can serve as a reservoir for water. Body fluids carry and distribute nutrients and disease combating agents throughout the body, they help dilute and eliminate wastes and toxins, and  keeping their levels in homeostasis is essential for both good health and production. When stressed or challenged, the cows body calls on these reserves to alleviate the potential damages of these challenges. For a cow to produce 1 lb. of milk it takes nutrients from nearly 400 lbs. of blood circulating through the udder. When a cow is dehydrated, blood loses its capacity to function properly and fails to efficiently carry nutrients around the body. This sets up the cow, especially at freshening, to succumb to a variety of metabolic diseases such as milk fever, hypocalcaemia and ketosis.

Ask your veterinarian/nutritionist if your cows could experience other dangerous health conditions due to dehydration.

3) Will my cows actually “shrink” if they don’t stay properly hydrated?

Cows severely challenged from disease – or perhaps have elevated body temperatures (as during periods of heat stress) – often shrink or dehydrate in excess of 10%  of their body weight. Shrink is due to fluids being pulled from tissues and the blood, to be used for other vital functions. This degree of dehydration can be life threatening, and procedures such as intravenous fluid therapy and oral fluid rumen supplementation procedure should be initiated right away. By paying close attention to your herd this level of severe dehydration can usually be avoided.

Ask your veterinarian/nutritionist about the dangers of excessive fluid loss and increased nutrient demands that are incurred after calving or during off-feed events and heat stress.

4) How can I tell if a cow is dehydrated?

Other than body shrink, there are a number of indications that suggest a cow may be experiencing some level of dehydration.

• Reduced feed intake

• Sunken eyes

• Drop in milk production

• Low energy

• Increased respiration rate

• Sluggish body movement

• Reduced ability to respond to vaccines and treatments

• Lower immune response

Think about the impact this type of loss can have on the health of your cows and your dairy business.

5) How do I get a cow back to proper hydration status?

Be sure to always practice good cow cooling husbandry in hot weather, have plenty of clean water easily accessible, and be observant of fresh cows and of any signs of sickness in cows throughout the herd. For most events a rehydration product that provides energy-balancing electrolytes, vitamins and energy sources work quickly and well. Most of these treatment products can be administered either through a water application or applied directly to feed. Most veterinarians and nutritionists recommend stocking rehydration products at all times and especially during periods where heat stress or other dehydration stressors could be an issue.

Ask about having rehydration products on hand and what you can do to promote consistent water intake.