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Dairy Farm Management Notes: 04/08/2009

The Dairy Cow has a carbon footprint too

John Donworth

Very little attention is paid to the cost of energy on our dairy farms. In terms of the overall scheme of things, it is viewed as something which one can do very little about. When the ESB bill arrives, one pays it without question, unless, of course, it is totally at variance with previous bills. But the general consensus out there is that energy costs may continue to rise in the future and, perhaps, it is time to look at energy costs in the same way as we forensically examine feed and fertiliser costs.

If you have a separate ESB meter for the farm, then you know, to the last kilowatt, how many units of energy you are using each year. The vast bulk of this usage is occurring in the dairy and parlour. This final figure will also be affected by whether one is on a ‘mains’ supply for water or whether one is pumping water from one’s own well.

So, in energy terms, how much does it cost to milk the cows for the year, cool the milk in the bulk tank, heat the water to hot wash the milking machine and bulk tank and, finally, using water to clean the parlour and collecting yard after each milking.

In January 2009, a detailed electricity audit commenced on three Teagasc research farms. John Upton, research office in Moorepark, is carrying out the audit and, of course, this work is ongoing.

However, John has produced figures for a seven day period, commencing on the 30th March 2009 and ending on the 5th April 2009. So, which item was using the largest amount of electricity (see table)?

Items Electricity use
Milk Cooling 32%
Water Heating 27%
Vacuum Pumps 19%
Lighting 18%
Wash Pumps 1%
Milk Pump 1%
Misc. 3%

As one would have expected, milk cooling is the single biggest user of electricity. Both direct expansion and icebank bulk tanks were part of the audit. Direct expansion and icebank bulk tanks use the same amount of electricity but the icebank is usually run at night rate electricity.

Also, the cost of cooling the milk is going to be influenced by whether the milk was pre-cooled before entering the bulk tank. Incidentally, the size of the milking machines involved in the audit were 20, 16 and 12 units, with an approximate herd size of 100 cows.

Water heating, at 27%, was the next single biggest cost. Each plant was hot-washed once a day. So both the bulk tank and the provision of hot water accounted for nearly 60% of the electricity charges.

Vacuum pumps, at 19%, were the next biggest user of electricity, followed by lighting, at 18%. These two were a surprise. One would have expected the vacuum pumps to be higher and, of course, it is important to switch off the lights. These two items accounted for 37% of the electricity use. Other items, such as wash pumps, milk pumps, feed augers and air compressors made up the balance (.5%).

Electricity charges are classified as a fixed cost item on the farm. The Teagasc audit of its three farms is showing that electricity costs in the dairy are contributing, on average, 0.6 cent/litre to milk production costs. In a 5000 litre herd, this equates to €30/cow. This is approximately 8% of overall fixed costs.

While 0.6 cent per litre was the average cost, the figures varied from 0.4 cent/litre to 0.62 cent per litre. In terms of electricity consumption per dairy cow milked, the figures varied from 3.59 kwh per cow per week to 6.7 kwh/cow/week. So there is potential savings of 30 to 40 per cent to be made and this work would hope to identify these savings.

However, you can do the simple things right away. Fixing hot-water leaks, insulating hot water piping, using lights only when necessary and making use of night rate electricity where available, will reduce energy costs without capital expenditure.

But, looking at the big picture, reducing energy consumption, will also reduce carbon dioxide (CO2 production. Each kwh of electricity generated from fossil produces 543 grams of CO2. Should you be concerned about that? Yes, is the short answer. Remember, I mentioned that each dairy cow milked, used 3.59 to 6.7 kwh of electricity each week. That’s how her carbon footprint clocks up the miles, not to talk of her methane production. My thanks to John Upton, Research Officer, from Moorepark for his valuable information for this article.