Trace Mineral Supplementation for Summer Grazing

Source: Saskatchewan Agriculture and Food

As cattle producers look ahead to placing their cows on to summer pasture, ensuring that these cows receive a proper supply of minerals throughout the summer grazing period is important, according to Saskatchewan Agriculture and Food Livestock Development Specialist Bryan Doig.

“A large number of pastures in the province are commonly deficient in trace minerals," he says. "In addition to iodine and cobalt, copper, zinc and manganese are three of the trace minerals of which cattle are often deficient."

Selenium deficiency problems are also common, especially in the black, thin-black, brown and grey-wooded soil zones, Doig says.

“Copper deficiency due to low copper levels in the forage is compounded when there are high levels of the mineral molybdenum in the feed and/or high levels of sulfates and iron in the water source or feed. The molybdenum, sulfates and iron act like a magnet in the cow's rumen, attracting most of the available copper in the feed and causing it to pass through the animal rather then being absorbed by the body. This can cause a number of problems, including low rates of conception."

The easiest method of providing adequate amounts of trace minerals to cattle on summer pasture is to feed the minerals as a supplement. Salt, minerals or a combination of salt and minerals, which contains a balance of trace minerals, can provide proper supplementation to grazing animals. Supplying a trace mineralized fortified salt (TM fortified salt) is a convenient method of providing trace minerals. Cattle tend to seek out salt and will almost always eat it every day, he explains. Blue salt blocks contain salt, cobalt and iodine. TM fortified salt blocks (brown blocks) contain salt, cobalt and iodine, as well as copper, zinc, manganese and sometimes selenium.

“Providing a range mineral—a mix of calcium and phosphorus—which often contains salt, encourages intake by cattle on pasture," says Doig. Another option is to mix loose, TM fortified salt with a salt-free cattle mineral supplement to encourage intake. A common mixture is one part TM fortified salt to two parts salt-free mineral.”

Doig warns that all salt blocks must be removed from the pasture for this method to work. Ensure that both the salt and mineral contain adequate levels of the trace minerals. Look for products containing at least 2,500 mg/kg of copper. The levels of zinc and manganese are usually balanced with the copper.

“If selenium deficiencies are common in your area, select a TM fortified salt with added selenium. Mineral supplements may also contain selenium. Be careful, though. Product labels caution to supply selenium from one source only. Selenium is extremely toxic, and the effects of over-supplementation are as bad—if not worse—than a selenium deficiency.”

Additional information on trace minerals is available in the publication Trace Minerals for Beef Cattle on the Saskatchewan Agriculture and Food website at www.agr.gov.sk.ca under the sub-headings Beef, Feeds and Nutrition.

To find out more, contact the Agriculture Knowledge Centre at: 1-800-457-2377.

Bryan Doig
Livestock Development Specialist
Saskachewan Agriculture and Food
North Battleford
(306) 446-7477