Goat Defoliation and Debarking on Eastern Redcedar with Rumen Undegradable Protein Supplement

Abstract

Eastern redcedar (ERC) (Juniperus virginiana L.) encroachment threatens long-term Great Plains health. Goats browse juniper by defoliation and debarking but are limited by aversive postingestive feedback from plant secondary metabolites. Protein supplementation may increase fed juniper foliage intake by offsetting nitrogen loss from plant secondary metabolites−protein binding, but little is known for goats browsing whole juniper, mimicking a field setting. Therefore, the objective was to study the effects of rumen undegradable protein (RUP) supplementation and tree height on goat browsing. Experimental design was two 3 × 3 Latin squares of two diets and three ERC tree height treatments. Within each square, 12 Savannah × Spanish × Boer crossbred 50 kg ± 3.9 kg does were fixed to a diet for 10 d (7 d adaptation and 3 d ERC browsing). Fed diets were control (grass hay and whole corn) and supplemented (grass hay and dried distiller's grain, an RUP source). Diets were isocaloric, and supplemented diet crude protein was fed at 2 × maintenance. Each pen (three pens of four goats per diet) was offered two trees from one of three tree height treatments for 8 h daily over 3 d in a rotation where pens received all tree height treatments. Supplemented RUP did not increase defoliation (P = 0.73), trunk debarking (P = 0.84), or branch browsing (P = 0.74). However, tree height may impact browsing as short (50 cm) trees were more defoliated and 50 cm and 100 cm trees had more branches browsed than taller (200 cm) trees (P < 0.05). Therefore, for field application relevance, it may be more important for pen studies to measure browsing of whole juniper rather than fed foliage intake. Future pen and/or field studies should explore alternative protein sources, consider tree height in their design, and offer goats whole juniper.