Tuesday 24 April 2018

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# One simple measure to boost milk yields

A fact often overlooked by Irish dairy farmers is that improving water supply can result in an increase in milk yield.

A dairy cow can be satisfied long before she is full, so if the water is slow to come through to the trough, she may be quite contented, but milk yield can suffer by over 20pc.

One trial on water on display at the Teagasc Moorepark 2017 open day investigated the impact of pipe size and type of ballcock had on the flow of water.

Four 150 gallon troughs were set up each fed from a buffer tank at equal pressure (20 PSI).

Two troughs were fed with 12.5mm (half inch) piping and the other two with 25mm (inch piping).

Varying jet sizes were inserted in the ballcocks and the flow rates were measured, the outcome of which are outlined on the table 1.

It should be noted that when it comes to jet size, the high pressure jet has the smallest hole and the low pressure jet the biggest. Two different jet sizes were installed in trough 3 during the day, hence the reason table 1 shows five troughs.

A flow rate of 0.2litres/cow/minute is the required flow rate to have adequate water supply on a dry summers day.

If we assume that half inch (12.5mm) piping and standard ballcocks (with high pressure jets) are the standard on most Irish dairy farms, then you can see that this flow rate is only sufficient for a 30 cow herd.

By changing the jet size in the ballcock to medium pressure, a small gain of 2 litres/minute was achieved which would be adequate for a 40 cow herd size.

Gains

Where the real gain was achieved was where the pipe size was increased to 25mm (inch inside) and where either a medium or low pressure jet size were used.

These systems were capable of supplying water to herds of between 135 and 200 cows (at 20 PSI water pressure).

How to check the flow rate on your farm;

* Mark the level of water in a trough

* Tie up the ballcock and empty, say, 25litres from the trough

* Release the ballcock, hold it down and measure the length of time it takes (in minutes) to refill to the original mark

* divide the 25 litres by the time taken to refill, eg if it takes a minute to refill, then the flow rate is 25 litres per minute

* Divide the flow rate by 0.2 - this will tell you how many cows your water supply is capable of feeding on a dry day

* If the flow rate measured is less than that required for your herd, then your water supply system needs to be improved

If your flow rate is inadequate, then the first place to look is at the ballcock.

As can be seen from the table, changing the jet size which will only cost a few cents can double your flow rate in certain instances.

After this pipe size and water pressure should be investigated.

Joe Kelleher is a Teagasc advisor based in Newcastle West, Co Limerick

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