Cows Prefer LED Lights - Study

12:00AM May 24, 2012
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ATaranaki dairy automation specialist is challenging New Zealand academic opinion that denies the relevance here of an American study of LED lights.

The study, overseen by Oklahoma State University, has just found LED (light emitting diode) lights are easier on cows' nerves and help them produce more milk.

Lincoln University has said the study is not relevant to outdoor-living Kiwi dairy cows.

However, Steve Corkill, the owner of Opunake company Corkill Systems, which specialises in electrical design and the manufacture of dairy automation equipment, is challenging that view.

Cows' proximity to lighting during milking, at a time when they need to be relaxed, should be taken into account, he said.

Cows could also be upset by high- frequency currents from inadequately wired variable speed drives (VSDs) on milk pumps, vacuum pumps, rotary platform drives, water pumps and backing gates and fluorescent light tubes.

Cows reacted when the high frequencies, which were impossible to detect with conventional equipment, were introduced or eliminated.

Corkill said while the acceptable level of stray voltage in contact with cows was contentious, most professionals believed it should not exceed 300 millivolts (mV). The Ministry of Economic Development's new code of practice for the installation and use of VSDs in cowsheds, to be released shortly, would be a great help to those installing them.

Scientists undertook the study in the United States because they were concerned LED lights could affect cows' feeding and might cause a drop in milk production. Instead, the results showed LED lighting did the opposite, with cows at one of the dairy farms producing 6 per cent more milk when LED lights were used instead of fluorescent lights.

One theory was that the light reduced the animals' stress, a factor known to improve productivity.

Corkill Systems sales manager Vern Coxhead, of Opunake, who has received extensive training to find and measure voltage, travels the country checking VSDs and testing voltage levels in cowsheds. He uses a specialised meter, one of only a few in New Zealand, to measure cowshed voltages which he believes should be at the same level as the human body - between 30 and 70mV.

"At that level, the somatic cell count [SCC] in the milk returns to normal and mastitis disappears. It's not scientific, but it works."

A dairy farmer who milks 500 cows on 275 hectares at Te Kiri in South Taranaki, Coxhead said stray voltage caused chronic mastitis, unhappy cows and stressed farmers.

"A lot of people in the industry don't believe high-frequency voltages are a problem because it is hard to find unless you have the right gear.

"The stress of jumpy cows, high SCC dockets and stripping cows is unbelievable and unless you are a cow cocky you can't understand how bad it can be.

"We have had people who have been ready to sell up because they have been having so many problems with their stock, and when I sorted it out for them they were so grateful."

He discovered the effects of stray voltage from fluorescent lights on cows when he extended his cowshed about three years ago and the cows' somatic cell count rose. "I tracked it back to the lights."

Coxhead said his herd's somatic cell count was about 180,000 when the herd was drying off this month, but it was generally about 120,000. "And I don't spend any money on teat sprays or dry cow therapy."

Stray voltage also occurred in older sheds when the 50 hertz power supply was poor or unbalanced and earthed metal and pipe work was poorly bonded.

Replacing a standard $10 fluorescent tube with an LED tube cost about $100, offset because an LED tube lasted much longer, used much less power and did not upset cows.

"I don't know why the high-frequency voltage affects cows, but it does. It's nice to know that universities are finding what we have found," Coxhead said.



Off the scale: A meter used by Vern Coxhead to test high-frequency voltage from a fluorescent light in a cowshed on a dairy farm near New Plymouth registers 1700 millivolts (mV), well above the level of 300mV in the Ministry of Economic

Development's new Code of Practice to be released shortly.

Cowshed voltage: Dairy farmer and voltage expert Vern Coxhead says the voltage in a cowshed should be the same as the human body, at around 70 millivolts.