FORT WAYNE, Ind. — Manipulating the amount of light cows receive can improve milk production and their overall health, according to a University of Illinois associate professor.

“Photoperiod offers a non-invasive, easily implemented option to improve performance and health,” said Geoffrey E. Dahl, an associate professor in the department of animal sciences.

Dahl spoke April 25 on the first day of the two-day Tri-State Dairy Nutrition Conference in downtown Fort Wayne.

The 15th annual conference was open to feed industry personnel, veterinarians, county extension officials, dairy producers and anyone interested in the dairy industry. It was sponsored by The Ohio State University, Purdue University and Michigan State University.

Increasing the amount of light cows receive during lactation can boost milk production, Dahl said.

“When lactating cows were exposed to 16 or 18 hours of light, they produce more milk than those on a 12 hours of light, 12 hours of dark, photoperiod,” he said.

Lactating cows also consume more feed to meet increased demand for energy to make milk, he said.

Cows exposed to fewer hours of light during dry period see later milk production increase, Dahl said. They also see improved immune function.

Lights should be placed all over the barn, especially in free stall barns, and not just over feed areas, Dahl said.

Farmers also need to be concerned with causes of poor reproduction efficiency, said Milo Wiltbank, of the department of dairy science at the University of Wisconsin-Madison.

“There are multiple factors that can cause problems with reproductive efficiency,” he said. “Some of them are farm or cow-specific factors.”

An example of a farm specific factor is research relating the amount of bunk space to the number of pregnant cows, he said.

“The smaller the amount of bunk space, the lower percentage of animals were pregnant,” Wiltbank said. “We aren’t sure what this means. Is it stress? Is it overcrowding?”

Dairy cows can have poor reproduction because of an inadequate supply of almost any nutrient, Wiltbank said.

Excessive amounts of certain nutrients or other dietary components may also cause problems, he said.

High feed intake can increase blood flow to the digestive tract and the liver, which causes increased hormone metabolism. That can cause the nutrient problems leading to poor reproduction in lactating dairy cows, Wiltbank said.

Milk production can be an indicator of the health status of dairy cows, he said.

“Higher producing cows are healthier than those producing less milk,” he said. “All of these factors need to be examined if you think there’s a problem.”

This farm news was published in the May 10, 2006 issue of Farm World.