Photo by JC Kiddo Campbell.

Assessing Nutritional Content of Browse Used by Mule Deer in Trans-Pecos, Texas

Thomas Janke, Louis A. Harveson, and Carlos Gonzalez

Mule deer (Odocoileus hemionus) are the most widespread and sought-after big games species throughout western Texas. Having a better understanding of their niche requirements (food, water, cover, and space), as well as the quantity and quality of those resources, allows landowners and resource professionals to better manage the species.

In the spring of 2018, BRI researchers initiated a study to determine seasonal and geographic variation in the nutrition of browse throughout the Trans-Pecos. The objectives of this study was to 1) find and identify as many browse (brush) species as we could across eight different subregions of the Trans-Pecos (e.g., mountain ranges), and 2) evaluate regional or seasonal differences in nutritional quality of the browse species.

To accomplish this study, we sampled browse from 13 different properties throughout eight mountain ranges (Apache Mtns., Cathedral Mtns., Chinati Mtns., Davis Mtns., Del Norte Mtns., Delaware Mtns., the Sanderson area, and south Brewster County). We sampled during three seasons March–June, July–October, and November–February. We collected each plant sample by hand, then dried, ground, and analyzed them for nutritional quality.

In total, we sampled more than 130 different species of browse across the region and ran nutritional analyses on more than 1,500 browse samples. We identified a suite of nutritional indices for all species, geographies, and seasons including moisture; dry matter; crude protein; adjusted crude protein; ADF; aNDF; Lignin; NFC; TDN; NEL, Mcal/Lb; NEM, Mcal/Lb; NEG, Mcal/Lb; calcium; phosphorus; magnesium; potassium; sodium; PPM Iron; PPM Zinc; PPM Copper; PPM Manganese; PPM Molybdenum; and Horse DE, Mcal/Lb. Our initial efforts showed the southern part of the Trans-Pecos had the greatest diversity of browse throughout the year.

Funding sources: Lyssey and Eckel Feeds and the Borderlands Research Institute.