Water Requirementscows_at_trough

If cow production is falling quicker than 10% per month then one or a combination of the three factors listed below are likely to be contributing.

  • Quantity of feed
  • Quality of feed
  • Access to water

Restriction of water will lead to lower dry matter intakes and hence lowered milk production. This may be a significant factor on some farms.

It is estimated that a 50% reduction of water intake over a 24 hour period may lead to a 25 % drop in milk production. If cows are restricted for longer periods their milk production may not recover.

Restriction of water during very hot weather may lead to heat stress and a severe drop in milk production. Larger herd sizes and increased production per cow can put many existing stock watering systems under enormous pressure. Getting adequate water to troughs quick enough is often the major a problem.

Water quality is also important and if suspect it should be tested. Stray voltage to the trough or to the surface that the animal is standing on, may in some circumstances affect water intake and should be investigated if this is thought to be a problem.

Estimating Water Intake of Dairy Animals During The Summer Months

Where little moisture is being gained from pasture and for temperatures less than 20ºC then a rough estimate of water consumed by stock may be calculated by multiplying estimated Dry Matter intakes by six and adding the cows average milk production (litres). For higher temperatures consumption will increase considerably. eg. Cows giving 17 litres in January

chart_1_thirsty_cows

These are average figures only. Some high producing cows may be consuming a lot more.

During the Summer Months

Milking cows will drink 2 - 6 times a day. Dry cows and young stock will drink at least twice a day. If there is adequate water in the trough then cows drink for no longer than 1- 1½ minutes.On average cows will drink at least 20 - 40 litres during this time.

The problem arises when inadequate water is entering the trough. Cows will stay at the trough much longer than the normal 1½ minutes. Some cows will be bullied away from the trough and if it is nearly empty some cows may not be able to reach the water.

Silage and summer crops put more pressure on water troughs. Approximately half the herd will go to the trough to drink within one hour of leaving the dairy, having access to silage or grazing summer crop. This puts short term pressure on the water supply at critical times of the day.

Why aren’t My Cows Getting Adequate Water?

Common problems

1. Simply not enough volume of water being pumped.
Water pumped directly from the bore by submersibles at relatively low volumes. There is no capacity to increase flow rates at peak cow consumption (ie.pumping 3600litres/hr when the cows are drinking 9000 litres/hr.) This table indicates the number of litres consumed per hour when there are the following number of continuously at the trough at any one time:

  • 1 cow x 30 lts/90sec = 1200 lts/hr (264 gal/hr)
  • 2 cows x 30 lts/90sec = 2400 lts/hr (528 gal/hr)
  • 3 cows x 30 lts/90sec = 3600 lts/hr (792 gal/hr)
  • 4 cows x 30 lts/90sec = 4800 lts/hr ( 1056 gal/hr)
  • 5 cows x 30 lts/90sec = 6000 lts/hr ( 1320 gal/hr)
  • 6 cows x 30 lts/90sec = 7200 lts/hr ( 1584 gal/hr)
  • 7 cows x 30 lts/90sec = 8400 lts/hr ( 1848 gal/hr)
  • 16cows x 30 lts/90sec = 19200 lts/hr (4230 gal/hr)

Suggested minimum flow rates required at the trough (litres/hr). Half herd size (No. of cows) x 30 (litres) = litres/hr required.

2. Low pressure and consequently low flow rates at the trough outlet.
Many older dairy farms originally upgraded from 1” gal pipe to 1” or 1¼” poly which is now also inadequate. Often this is the size of the pipe that leads away from the dairy and this may be drastically restricting water flow.

It is simply impossible to pump large quantities of water through 1” poly or 1” galv.

Example:
chart_2_thirsty_cows

Pumping at 4500 litres/hr (1000 gals./hr.) the pressure lost through just 100 meters of 1” poly pipe is the same as if you were pumping at 1,000 gal./hr. through 2,700 meters of 2” poly.

It is just so much easier to pump large volumes of water through large pipe. By upgrading the main supply line the existing low pressure pump may still be adequate.

3. Diversion of water.
Water used through the plate cooler, watering the garden or watering another group of animals off the same line and closer to the dairy.

4. Partially blocked entry to troughs.
Galvanised and brass fittings that are touching will react causing corrosion and build up of material which may cause blockages. This is especially common where a galvanised nipple or elbow is used directly into the brass fitting of the trough.

Stone such as buck shot that has found its way into the water line and is partially blocking the water flow at the ball valve.

5. Low pressure gravity fed troughs from a tank.
In many cases you cannot get enough pressure by gravity feeding directly from a tank.

6. Trough size.
For herds greater than 150 cows it is the rate of water entering the trough and not the size of the trough that is critical.

Many farmers make the mistake of putting in larger troughs to cure the problem. If there is any small diameter pipe in the supply line then they should replace that first.

A herd of 400 cows may consume the equivalent of 6 one thousand gallon troughs of water between each milking.

7. Pumping up large hills.
If on a very hilly property it is important to do more calculations to determine if it is possible to get the required water up the hill to the trough point. Gravity feeding down very large hills ( >80 meters) may lead to increased pressures that require high pressure ball valves and high pressure pipe or other measures that can control excessive pressures.

8. Wastage of water.
Overflowing troughs and leakages.

Summary

On most farms that are experiencing water problems it is nearly always the amount of small diameter pipe in the main supply line that is restricting water flow. It may seem to be more difficult to upgrade to a larger main line diameter or to a loop line but this is often all that is required to fix the problem. Farmers should seek advice if they are unsure of what to do.