Is rumen function responsible for detoxifying terpenoids in redberry juniper? Dunson, Wayne^*,1, Scott, Cody¹, Campbell, Erika², Taylor, Charles², Carr, Mandy¹, Callaway, Todd², ¹ Angelo State University, San Angelo, Texas, USA² Texas Agricultural Experiment Station, Sonora, Texas, USA

ABSTRACT- Some goats are able to increase intake of redberry juniper (Juniperus pinchotii Sudw.) through exposure early in life even though the plant contains terpenoids that limit intake. The objective of this study was to determine if changes in rumen function enabled goats to adapt to relatively high amounts of redberry juniper in the diet. In Experiment 1, 26 Boer-cross goats were placed in individual pens and fed alfalfa at 2% BW for 14 days. Thirteen were randomly chosen and offered fresh redberry juniper for 2 hrs each day. Intake and serum metabolite levels were monitored to assess toxicosis. Rumen fluid was collected from 6 rumen cannulated goats (3 fed juniper and 3 fed alfalfa alone) to assess in vitro terpene degradation, volatile fatty acid (VFA) production, and ammonia levels. In Experiment 2, 10 goats unfamiliar with juniper were inoculated with rumen fluid either from goats fed juniper or goats fed alfalfa. Juniper intake was monitored for 10 days thereafter. Juniper intake increased daily throughout each trial. During Experiment 1, some serum metabolite levels were elevated in goats consuming juniper, but none were outside the range for healthy goats. In vitro terpene degradation was similar for both goats fed or naive to juniper. For the most part, VFA and ammonia levels were similar between treatments. In Experiment 2, juniper intake was similar irrespective of the source of rumen fluid. Rumen adaptation does not appear to be responsible for a goat's ability to increase intake of juniper.

KEY WORDS: intake, microbes, VFA, ammonia