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Iowa State exploring trace mineral absorption challenges

By Aerin Curtis

- Last updated on GMT

Iowa State exploring trace mineral absorption challenges

Related tags Dietary mineral Mineral

Trace mineral impact is a central focus of current beef nutrition research at the Iowa State University, said the organizers of that US institute’s upcoming showcase of study priorities.

Next Friday’s event, which is sponsored by Elanco Animal Health, gives producers the opportunity to put questions to faculty staff, said Stephanie Hansen, professor of beef feedlot nutrition at Iowa State University.

Besides mineral nutrition, attendees will also hear about the university’s other beef program research themes from feed efficiency to novel feedstuffs to grazing management techniques.

High sulfur diets

The trace mineral exploratory work by Iowa State’s cattle nutrition team is examining the influence of high sulfur diets on copper and zinc absorption in cattle, Hansen told FeedNavigator.

Increasingly feeds have been including items like distillers grains, condensed distillers solubles and gluten feed that have additional sulfur, she said.

However, the sulfur can bind in the rumen with trace minerals like copper and prevent the minerals from being absorbed when needed. Trace minerals are important to the health, growth and development of young calves and cattle.

“Trace minerals are always a tough one,”​ she said. “At the end of the day, they’re needed at small quantities in the diet, but they’re important for the immune system, growth and reproduction (so we have to) make sure they’re adequate to meet the animal’s needs.”

The ongoing research in the area is looking at what happens with trace minerals in high- and low-sulfur diets and at how to optimize their supplementation in a high-sulfur cattle diet, she said.

The work also will look at alternative delivery forms of trace minerals and different versions of such as inorganic or organic varieties.

Growth promotion

The Iowa State researchers are also trying to understand why use of extra supplemental zinc appears to boost growth promotion, said Hansen.

“We’ve found that we’re feeding three to five times the zinc as what’s required, and we’re getting a growth response,”​ she said. “We think there are opportunities there to supplement zinc, and maybe reduce days on feed. So we’re going to be continuing down that path, looking at zinc in the next couple of years.”

The group is trying to fathom the mechanism behind such growth promotion, she added.

Beta agonist and zinc tie-up

Previous work by Hansen and a colleague, funded by Zinpro, looked at the interaction between supplemental zinc and use of a beta-agonist, a product known commercially as Optaflexx.

The study, published in Iowa State University’s Animal Industry Report 2014​, found that an additional 60 ppm of zinc improved cattle performance during the first part of the finishing period. Once the beta-agonist had been added to the diet, 90 ppm of zinc produced the greatest effect.

The study looked at 41 steers that were initially fed one of four diets for 86 days. The diets included a finishing diet of dry-rolled corn, and that diet supplemented with 30 ppm, 60 ppm and 90 ppm of a zinc additive, researchers said. Animal weights were taken on day 0, day 1 and every 28 days through the first period of the trial.

At the end of the period, the cattle getting the additional 60 ppm of zinc had the highest body weight and average daily gain, along with the lowest gain to feed ratio, researchers concluded.

On day 90, cattle were divided into additional groups and some received a supplemental beta-agonist at 300 mg/steer/day for 29 days, researchers said. At the end of the period, cattle weights were taken and the steer were harvested. Carcass data also was collected.

The combination of 90 ppm of zinc and the beta-agonist resulted in the highest body weights and average daily gain for cattle, the scientists said.

Carcass quality tended to follow the same trend, they said, although there were no differences in dressing percentage, ribeye area or marbling scores.

“However, as Zn90 was the highest Zn [zinc] inclusion in this study, it is unknown whether a plateau in performance has been reached,”​ researchers said. “It is unclear from our results whether there would be an additional benefit in supplementing OPT-fed cattle with greater than 90 ppm Zn; however, further investigation seems warranted.”

Research source: Animal Industry Report

Title: "Effects of Supplemental Availa Zn on Growth and Carcass Characteristics of Finishing Cattle Fed Diets with or without Optaflexx."

Location: http://lib.dr.iastate.edu/ans_air/vol660/iss1/14/

Authors: O. Genther, S. Hansen 

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1 comment

thiomolybdate toxicity is the clinical problem -not copper deficiency

Posted by Dr Stewart B Telfer,

Iowa researchers should look at the work of Phillipo and Humphries at the Rowett research institute in the 1980s. The Bimeda web site is excellent and explains what we now know about the interaction between copper,molybdenum,sulphur and iron. The training video for vets by Peter Bone should be looked at.

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