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With every likelihood of increasingly hot British summers, the issue of heat stress for dairy cows is becoming an important consideration for UK dairy farmers. There are few places hotter and more stifling than a building filled with dairy cows or other livestock on a hot summer’s day.

Cows begin to suffer from heat stress at much lower temperatures than humans. If a farmer is beginning to feel the heat and humidity, then it is quite likely the milking cows are already under stress, and this can have a severe impact on milk production and fertility.

It has been estimated that heat stress can result in the loss of up to four litres of milk per animal per day, as well as sharply reduced pregnancy rates.

Many farmers have addressed this problem by installing box fans in cattle sheds, but to achieve the required level of cooling a large number of units are usually required which can be noisy and expensive to run.

MegaFan Technologies representatives in the Dairy sector are TH White

T H White completed the first two HVLS ‘MegaFan’ installations in the UK. The very first application on this side of the Atlantic was for Jimmy Ludwell who farms at Holsworthy, North Devon.
This comprised two 24ft (7.4m) units which have already proved their worth in maintaining a comfortable temperature and atmosphere in Jimmy’s cattle shed.

The second installation, this time for four 24ft fans, was for the Hawker family who farm 1,200 acres at Hullavington, Wiltshire, where they have a herd of 400 dairy cows.

Ashton Hawker specified two 24ft fans in each of his two adjacent cattle sheds: “After just a few weeks the MegaFans have already made a considerable difference,” said Ashton Hawker. “The beds are definitely drier, increasing comfort for the cows, and because the fans can be run in either direction they
can also be used to extract air from the sheds, greatly improving the atmosphere. Now I am looking forward to the difference they will make in the hot months ahead.”

Added Benefits

Moving air breaks up the moisture-saturated boundary layer surrounding the cow’s body, accelerating evaporation to produce a cooling effect. On hot days a MegaFan will equalize uneven temperatures that occur at different levels in the shed’s air space, forcing unused heated air from the ceiling down to floor where it can have a positive impact. This heat differential can be in excess of 9 deg C from ceiling to floor. One MegaFan consumes less electricity than one high-speed box fan, while moving over 12 times as much air.

A MegaFan will consume around ½ kw of electricity per hour, costing less than £2.00 per day if run for a full 24 hour period. When cooled by a MegaFan cows tend not bunch up as air moves over the whole herd, regardless of their position in the shed. Flying insects stay away, or on the ground, and birds also react to the large, slow moving air foil blades and stay out! MegaFans are also very quiet and nonintrusive in operation.

Cost savings

Repeated American studies have shown that HVLS fans lower the temperatures in dairy buildings by 6 to 8 degrees, resulting in maintained milk production. The resulting avoidance of loss of milk profits, coupled with energy savings, mean that the cost of installing MegaFans can be recouped in a relatively short period, with excellent cost savings after ‘pay back’.

HVLS fans also provide an ideal means to distribute warm air from overhead heat systems during the colder months. Even buildings with large always-open doors or an open shed type of construction can reap the benefits of this efficient and cost effective technology.

If you would like further information or are interested in a site visit, please contact Adrian Moore at TH White on 01373 465941 or 07860 247367.

Research carried out at the University of Minnesota has produced some startling results. Cows can begin to suffer from the effects of stress at temperatures as low as 75 deg F (24 deg C), and humidity is also a significant factor.

Many farmers do not realise just how rapidly the stress effect increases as temperature and humidity rise, but reference to the chart shows that at 90 deg F (32 deg C) stress levels in cows can become severe. This level of temperature is by no means uncommon in many animal sheds on hot summer days.

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