Author: 800 CHAB News/Sask Ag and Food

Scientists at the Department of Animal and Poultry Sciences of the University of Saskatchewan will be able to take a nutritional look at the prevention of milk fever in beef cows, thanks to funding from Saskatchewan Agriculture and Food's (SAF) Agriculture Development Fund.

John McKinnon of the Department of Animal and Poultry Sciences at the University will direct the project.

"This project is based on a Saskatchewan Beef Development Fund project that we carried out in 2002 and 2003. In the North Battleford area during the 2002 calving season, there was a wide incidence of tetany-like symptoms, such as nervousness and muscle twitching, among cattle. They would stagger, and become paralyzed and even comatose. Some were dying.

"We were trying to decide whether we were dealing with milk fever or with another condition called tetany. These are both disruptions in the electrolyte balance in the animal. A lot of the herds experiencing these symptoms had been fed on cereal silage and barley or oat greenfeed.

McKinnon and his team worked with SAF Livestock Development Specialist Bryan Doig and Dr. Tom Schmidt of Lakeland Veterinary Services to conduct a survey of what was fed to the animals. After examining the symptoms and analyzing blood samples, they concluded they were dealing with milk fever.

"We concluded that the problem was caused by the high potassium content in the greenfeed that had been fed to these cows, which led to an imbalance of electrolytes," says McKinnon. The problem has now been identified in cattle herds across Western Canada.

McKinnon explains that scientists look at the Dietary Cation Anion Balance (DCAB) ratio to evaluate blood electrolytes. This compares the ratio of cations to anions in the diet, and, in particular, the ratio of sodium and potassium to chloride and sulphate. Pregnant dairy cows with a DCAB ratio very close to zero or slightly negative will have few problems with milk fever; the beef cattle MacKinnon studied had DCAB ratios of nearly 450.

"We believe that it was the potassium content in the greenfeed that caused this high DCAB ratio, which eventually led to milk fever. There is very little research on beef cattle, so the intent of our current research is to try to define the actual DCAB ratio that is needed to minimize milk fever in beef cows approaching calving."