Confined cattle feeding trail to validate fecal DNA metabarcoding to inform rangeland free-roaming diet applications

Authors: SCASTA, J. DEREK - University Of Wyoming; Jorns, Tamarah; Derner, Justin; LAKE, SCOTT - University Of Wyoming; Augustine, David; WINDH, JESSICA - University Of Wyoming; SMITH, TRAVIS - University Of Wyoming

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/2017
Publication Date: 2/9/2018
Citation: Scasta, J., Plechaty, T.R., Derner, J.D., Lake, S., Augustine, D.J., Windh, J.L., Smith, T.L. 2018. Confined cattle feeding trail to validate fecal DNA metabarcoding to inform rangeland free-roaming diet applications. Society for Range Management Meeting Abstracts. Abstract Proceedings of the 71st Society for Range Management, Technical Training, and Trade Show. Jan 28 - Feb 2, 2018, Sparks, NV.

Interpretive Summary:

Technical Abstract: Diet composition of free roaming livestock and wildlife in extensive rangelands are difficult to quantify. Recent technological advances now allow us to reconstruct plant species-specific dietary protein composition using fecal samples. However, it has been suggested that validation of the method is needed through the comparison of known fed diets to laboratory results. At the University of Wyoming, we used 5 heifers (2 years of age, non-gestating, non-lactating) in a confined feeding study over a 6 week period (IACUC approved protocol # 20170208DS00258-01). Each week, a new diet was introduced and fecal samples were collected from each heifer after 7 days of intake. The six diets were: 1) C3 grass hay, 2) C4 grass hay, 3) C3 grass hay + C4 grass hay + alfalfa (equal proportions), 4) C3 grass hay + C4 grass hay + alfalfa (equal proportions) + minor component of sagebrush (Artemisia tridentata) leaves, 5) Alfalfa + minor components of crested wheatgrass (Agropyron cristatum), western wheatgrass (Pascopyrum smithii), and blue grama (Bouteloua gracilis), 6) alfalfa. Diets were fed ad libitum if there was only one component but diets comprising multiple components were fed metabolic weight based rations with minor diet components introduced five days prior to fecal collection. Constrained ordination suggests that fed diets and laboratory quantified diets using DNA metabarcoding analyses of fecal samples were dissimilar. Factors confounding quantification of diet composition are attributed to mis-identification in the field and the laboratory, and high numbers of “rare” species in diets attributed to fed hay sources that were not homogeneous. Detection of minor components was variable. Laboratory measured protein contributions by major components was also variable when compared to expected protein contributions and at times exceeded or did not meet expectations.