Feeding Shinoak to Meat Goats Improves Four-wing Saltbush and Total Intake

Abstract

Herbivores consume a variety of foods that contain toxins in order to increase food intake, but typically avoid over ingestion of any single toxic food. Four-wing saltbush (Atriplex canescens) and shinoak (Quercus havardii) are two shrubs common to the southwestern United States that are consumed by ruminants, but intake is limited to avoid toxicity. Four-wing saltbush contains saponins while shinoak contains tannins. Saponins and tannins may chelate in the digestive tract of ruminants which would reduce the toxicity of both. We compared intake of four-wing saltbush and shinoak singly and together to determine if feeding both shrubs increased overall intake or intake of either shrub. In addition, alfalfa hay (saponin-containing plant) was fed with shinoak to determine if intake of shinoak would increase when alfalfa was fed. The study used 39 freshly weaned Boer-cross goats. Each was individually penned and then randomly assigned to 1 of 5 treatments. Eight were fed four-wing saltbush, eight were fed shinoak, eight were fed both, eight were fed shinoak and alfalfa, and seven were fed a basal ration for two weeks. Goats preferred shinoak to four-wing saltbush when each was fed alone. When both were offered simultaneously, goats ate more four-wing saltbush than when it was fed alone. Total intake was also increased when both shrubs were fed and when alfalfa was fed with shinoak. Feeding four-wing saltbush or alfalfa did not affect shinoak intake. Serum levels indicative of toxicosis were similar among treatments. Tannins and saponins may chelate in the digestive tract of ruminants when they are consumed simultaneously thereby increasing overall intake and decreasing the likelihood of experiencing toxicity.