Research Accomplishment Reports 2010

Use of a Carbohydrate-based Toxin Adsorbent Supplement, Provided Through a Mineral Carrier, to Alleviate Endophyte Toxicosis in Beef Cows and Calves Grazing Tall Fescue

D.G. Ely, D.K. Aaron
Department of Animal and Food Sciences

 

Non-Technical Summary

Volumes have been written that describe the negative aspects of grazing endophyte-infected tall fescue with beef cattle. Similarly, hundreds of research studies have attempted to alleviate some or all of the toxicity problems associated with consumption of this pasture forage by cattle.

Although some of these have been successful in alleviating some toxicity symptoms in rigidly controlled experimental conditions, none have successfully relieved toxicity symptoms under practical, on-the-farm conditions. Plant geneticists have had some success in developing fescue genotypes that are non-toxic to grazing animals, but incorporation of these genotypes into existing pastures requires extensive renovation.

Adoption of this technology by beef producers has been slow because producers are either reluctant to renovate or are unable to do so because of shallow topsoil, presence of rocks, and (or) steepness of slope of their land area.

Research at the University of Kentucky Eden Shale Farm at Owenton has shown two methods of alleviating some of the toxicity symptoms associated with consumption of endophyte-infected Kentucky tall fescue: (1) Application of a plant growth regulator in spring to prevent seed head formation and (2) Daily supplementation to cows with a modified yeast cell wall preparation (MTB-100) developed by Alltech, Inc. Although currently used for lawns, golf courses, roadsides, etc., the plant growth regulator has never been accepted for use in animal grazing systems. This leaves MTB-100 as the only product available to beef producers that will potentially alleviate some fescue toxicity.

Six years of research at the Eden Shale Farm has demonstrated the beneficial effects of a daily supplementation of MTB-100 to lactating beef cows during a May to October grazing season. Calves nursing cows that consume 40 g MTB-100 per day in 0.45 kg ground shelled corn weigh more at weaning than calves nursing cows receiving 0.45 kg ground shelled corn without MTB-100. Cows consuming the 40 g levels maintained heavier weights and higher body condition scores than cows that consumed corn without MTB-100. Performance of calves nursing cows that consumed 20 g MTB-100 was similar to calves nursing cows that consumed 40 g MTB-100 daily.

Two questions now arise. First, how can MTB-100 be delivered to cows in a less labor intensive system Second, can 20 g MTB-100 produce an equivalent advantage to 40 g if delivered in a minimum labor system

If a system can be developed that will increase weaning weights by 4 to 10 kg, gross income to Kentucky beef producers from calf sales could be increased by $11 to $25 million annually. The economic value of maintaining heavier weights and higher body condition scores of lactating cows is harder to ascertain. But, measures of reproductive efficiency over the 5-year period of this research will be determined from conception rates, calving dates and rates, and birth weights. Overall economic benefits of MTB-100 supplementation will be a function of these variables as they affect weights of calves weaned per cow over the 5-year period.