Fresh water fuels healthy cows

As we hit the summer heat, our cows’ water consumption will increase. Photo by Geoff Adams

Water is the most important and yet often the most overlooked nutrient on a dairy farm.

Think about this — milk is around 87 per cent water, and a cow needs to consume between four to five litres of water for every litre of milk she produces, and a cow’s body is more than 60 per cent water.

From a veterinary point of view, water quality issues can result in reduced consumption and hence reduced production but in some cases, poor quality water can contain high levels of minerals that can bind or make unavailable other important macro or microminerals causing disease.

When water is contaminated with heavy metals or chemicals, there is a risk of residues in milk or meat.

Bacterial contamination of water sources can significantly impact the health and wellbeing of cattle, especially young stock.

I have seen extreme cases where liquid effluent or run off from yards or laneways is able to contaminate water sources used for drinking or dairy plant cleaning which can cause serious issues.

Nutrient contamination of the water storages can lead to algal blooms that can cause problems ranging from minor irritation to the skin all the way to severely toxic signs causing sudden death.

Water that is highly acidic or alkaline will not only be unpalatable (leading to reduced intakes), but also can affect the rumen pH stability causing sickness.

Regular water testing from a specialised laboratory with experience in dairy water is a good risk management strategy.

As we hit the summer heat, water consumption will increase, but if there is any restriction to intake due to access to water or water quality, the effect of the hot weather will be multiplied, and significant production losses will occur.

In extreme cases where water access has been restricted for a significant time due to things like extensive transport or failure of the water supply, clinical dehydration may occur affecting animal welfare and even toxicity can occur when the water access is restored.

In the summer heat, access to water becomes a significant potential limiting factor in dairy production.

The size and location of troughs becomes important as cows should not need to walk excessive distances to access water.

Reducing access to standing water and groundwater also becomes important to prevent cows standing in drains or dams to cool themselves as this can lead to increased mastitis risk.

Water should be available in the laneways and around the dairy exit as cows will often stop for a drink after milking and can consume large volumes at this time.

I encourage farmers to regularly clean out all water troughs, especially the troughs closest to the dairy exit which often become contaminated with grain and saliva, and the water quality can become unpleasant reducing intake at this critical time.

In some cases, high amounts of silt are suspended in the source water (channel or dam) and as it settles out over time, there can be a significant volume of silt that accumulates, reducing the volume of water the trough can hold.

This will make the water shallower, and the water will be warmer and therefore less attractive to the cows.

Water temperature is also affected by black poly pipes not being buried, causing the water to become extremely warm over long distances.

Keeping the area around troughs well maintained to prevent undermining or sharp or broken stones and ensuring leaks are promptly fixed so that troughs are not surrounded by mud will keep them accessible to stock and minimise lameness problems.

I have seen many troughs turned dry on hot days, thirsty cows standing waiting because the flow rate into the troughs are insufficient due to pump capacity, float valve type or insufficient supply pipe diameter.

If your water system struggles to keep up with demand during hot weather, investing in improved water infrastructure (bigger pipes, pumps or troughs) is an excellent investment.

I also recommend having a sound back up plan for your farm water supply that considers the risk of interruption due to natural disasters and power outages.

In the lead up to summer, I strongly recommend that all dairy farmers, no matter their location, put in place actions to ensure their cows always have unrestricted access to cool, clean and safe water.

Dr Robert (Rob) Bonanno is the Regional Veterinary Lead for ProDairy in Gippsland and northern Victoria.