Once the threat of heat stress is over and autumn quickly turns into a long Canadian winter, we tend to forget that water is still important for the health and performance of high-milk-producing dairy cows. After all, water makes up 65 per cent of their bodies and milk is 87.5 per cent water. Producers should make a conscious effort to clean all water troughs and other waterers periodically and providing high-quality drinking water to cows on the milk-line.
Leave it to Mother Nature, who says there is absolutely no substitute for good drinking water for dairy cows in winter. She dictates that a mature dairy cow must drink a lot of water, which provides about 90 per cent of the cow’s overall water requirements for vital functions as well as supports good milk production, while a small remainder comes from moisture found in her lactation diet.
Although, the actual amount of water depends on the dairy cow’s age, health status, body size, and milk production; water consumption by most milk cows during a typical lactation cycle can be estimated with relative accuracy in two major ways:
- provide four to five litres of water for every one kilo of dry matter feed consumed or,
- provide three to 3.5 litres of water for every litre of milk produced.
A typical water consumption chart for lactating dairy cows is illustrated below:
While supplying water is the first step, producers must then accommodate the natural behaviours and preferences of cattle to encourage frequent drinking visits for optimum water consumption.
At water trough 30 minutes per day
University research observations have shown that dairy cows spend approximately six to eight hours per day at the feed bunk, and a nominal total of 20 to 30 minutes per day drinking water. They also demonstrated that most dairy cows prefer to do the majority of their drinking time, right after exiting the milking parlor. Cows have been shown to consume about 50 to 60 per cent of their daily water intake within an hour after each milking.
These facts highlight that good design and placement of any water system should help optimize water consumption by the lactating dairy herd. For example, in a free-stall loafing barn, it is recommended that at least two feet of trough space be provided per 20 cows and at a height of about 24 to 30 inches off the floor. The tank should also have enough depth that allow cows to submerge their muzzles by a couple of inches.
Furthermore, a freestall trough should be placed near the milking parlour exit and within 20 metres of the feed bunk or at the cross-alleys in the barn. Tanks should also have a recovery fill rate of about 30 to 40 litres per minute. Since most troughs are metal (plastic ones are becoming popular), each tank should be occasionally checked to be free of stray voltage.
Along with the planned-out accessibility, drinking water for lactating dairy cows must be high quality and good tasting. Although, much water of questionable quality (re: high salinity) is often non-life threatening, it can still have a negative effect upon other aspects of otherwise well-balanced dairy nutrition, namely; decrease normal feed digestion and/or lower essential nutrient uptake for optimum milk production. As a result the potential for good milk production might be lost due to ignoring or failing to take appropriate corrective action.
Water samples from incoming water sources should be taken on a seasonal basis (including winter) to determine actual water quality entering the dairy barn. Proper sample bottles and procedures for collecting water samples should be obtained from the provincial agriculture office or the commercial labouratory that perform water quality tests. This collection should be then be tested for the earlier mentioned TDS, pH, mineral concentrations and bacteria contamination. Once, these analyses are completed and reviewed, appropriate action can be taken if water quality problems are identified.
Even if no water quality problems are discovered, a typical water analysis sheet is written confirmation that a clean source of water is available for that particular dairy herd.