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Angus Journal


Don't Rely on Book Values

Mineral nutrition plays large role in fertility and reproductive success.

SIOUX FALLS, S.D. (Dec. 4, 2012) — Minerals are essential for growth, immune function, reproduction and many other things, but there is still quite a bit to learn, says a South Dakota State University animal science professor. Cody Wright explained the mystery of minerals to more than 300 participants of the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium in Sioux Falls, S.D., Dec. 3-4, 2012.

Cody Wright To calculate mineral needs, Cody Wright advised producers to first figure out the animals’ requirements and then determine mineral content of primary sources such as forage, feeds, supplements and water.

Wright explained that challenges include mineral concentration and availability in feed. For instance, mineral availability in grazed forages can vary simply by soil type. He mentioned that when he was with Extension, many producers asked about mineral availability in feeds or supplements. Most often, the formulation of minerals was fine, but the cow didn’t intake enough of it.

Required macro-minerals include calcium, phosphorus (the two largest requirements), magnesium, potassium, sulfur, chlorine and sodium. Micro-minerals include cobalt, iodine, manganese, zinc, copper, iron and selenium. Micro-minerals are needed in parts per million, but can drastically affect animal performance and function.

Those minerals that most affect reproduction are calcium, phosphorus, copper, iodine, manganese, selenium and zinc. Wright outlined in his proceedings paper how each affects reproduction.

He reported that research results are mixed as to whether organic or inorganic forms of mineral supplementation result in better animal performance.

To begin supplementing minerals, Wright recommended figuring out the animals’ requirements (which differ by production stage) and determining mineral content in primary sources such as forage, feeds, supplements and even water. Wright advised producersto not rely on book values as there is too much variability across a region to rely on book values.

“It’s a really worthwhile investment to do some testing to understand what those animals’ [unmet] requirements really are,” he asserted.

Knowing which supplements are needed most and which are available is integral, because too many minerals can produce toxicity and some minerals can interact adversely (such as copper and molybdenum), he warned. To avoid these issues, he recommended consulting professionals to help with mineral supplementation and analysis.

“At this point, minerals are more art than science,” he admitted, but more research is being done to answer those questions.

Wright spoke during Tuesday's session focused on herd fertility and nutrition. Visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation and view the accompanying PowerPoint and proceedings paper.

Click here to view larger image of Tables 1-3: Nutrient requirements
of beef cows. (1,000 lb., 1,200 lb., and 1,400 lb.)


Click here to view larger image of Table 4: Requirements and
maximum tolerable concentrations of minerals in beef cow diets.


Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and LiveAuctions.tv.

Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.