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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC AND PHYSIOLOGICAL APPROACHES TO IMPROVING PERFORMANCE OF BEEF CATTLE GRAZING PASTURES IN WHICH ENDOPHYTE-INFECTED FORAGES DOMINATE

Location: Dale Bumpers Small Farms Research Center

2011 Annual Report


1a.Objectives (from AD-416)
The long-term objective of this project is to develop an improved understanding of livestock physiology and genetics to enhance the productivity and profitability of meat production from cattle grazing improved temperate pastures while reducing animal stress.


1b.Approach (from AD-416)
Physiological parameters (respiration rate, skin and rectal temperature, and blood metabolites) of cattle consuming endophyte-free and -infected fescue diets will be compared in environmentally-controlled chambers. Genetic markers of cattle tolerant to heat stress and/or fescue toxicosis will be assessed. Microarray hybridization will be utilized to obtain estimates of gene expression changes due to heat stress and/or fescue toxicosis within breeds of cattle. Replicated field experiments will evaluate cow-calf and stocker management practices and genotypes on novel, endophyte-free or -infected tall fescue pastures to alleviate fescue toxicosis and improve calf production. Ruminal microbes that are capable of degrading ergot alkaloids will be evaluated. In vivo and in vitro studies will be conducted to determine production practices affecting fecal shedding of E. coli and Salmonella.


3.Progress Report
Substantial findings were developed during the 4 years of the project to improve understanding of livestock physiology and genetics in order to enhance the productivity and profitability of meat production from cattle grazing improved pastures, while reducing animal stress. Knowledge was gained on the tolerance of Romosinuano cattle to heat stress; incorporation of novel endophyte-infected (animal-friendly) tall fescue into a grazing program increased performance of pregnant beef heifers compared with heifers consuming toxic tall fescue, partially due to alterations in grazing behavior; fall-calving herds can utilize toxic tall fescue when stockpiled for winter grazing with minimal impact on cow performance and no impact on calf gain; single changes in specific genes in cattle are related to tolerance of heat stress and fescue toxicosis; breakdown of ergot alkaloids (compounds responsible for toxicity of tall fescue) by microbes can decrease fescue toxicosis; forage and body fat interactions in cattle influence calving rates; and toxic tall fescue consumption affected fecal shedding of 'bugs' associated with food poisoning (for example, E. coli O157:H7). Novel information generated during this project is currently the basis for new and/or improved best management practices for beef production in forage systems in which tall fescue is a significant component. Further, increased knowledge of how compounds found in toxic tall fescue plants affect animal performance are being used to relate clinical signs of animals with actual concentrations of toxic compounds. During the life of this project, 72 peer-reviewed journal articles, 20 proceedings, 8 book chapters and numerous agricultural experiment station reports (> than 20), scientific meeting abstracts (> than 40), invited presentations (> than 30) resulted from this project. This project is being incorporated into 6227-21310-008-00D for FY12.


4.Accomplishments
1. Addition of heat-tolerant beef cattle breeds improves livestock production on toxic fall fescue. Combined losses likely exceed $1 billion annually from livestock grazing toxic tall fescue. Addition of heat-tolerant genetics from certain cattle breeds (for example, Romosinuano) to cattle grazing southern pastures of toxic tall fescue provided greater tolerance to toxins, and cows had heavier calves at weaning. This improved animal performance will enable producers to utilize pastures containing toxic fall fescue to a greater degree and reduce economic losses.


Review Publications
Aiken, G.E., Klotz, J.L., Looper, M.L., Tabler, S.F., Schrick, F.N. 2011. Disrupted hair follicle activity in cattle grazing endophyte-infected tall fescue in the summer insulates core body temperatures. Professional Animal Scientist. 27:336-343.

Caldwell, J.D., Coffey, K.P., Coblentz, W.K., Jennings, J.A., Hubbell, III, D.S., Krieder, D.L., Looper, M.L., Galloway, D.L., Kegley, E.B., Rosenkrans, C.F. 2011. Weaning and Post-Weaning Performance by Fall-Born Beef Calves Weaned on Different Dates in the Spring from Neotyphodium Coenophialum-Infected Tall Fescue Pastures. Livestock Science. 135:44-52.

Strickland, J.R., Looper, M.L., Matthews, J.C., Rosekrans, Jr, C., Flythe, M.D., Brown, K.R. 2011. BOARD-INVITED REVIEW: St Anthony's fire in livestock: causes mechanisms and potential solutions. Journal of Animal Science. 89:1603-1626.

Last Modified: 8/22/2014
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