202 In vitro digestibility of various browse species selected by goats over the growing season

Abstract

Abstract Goats naturally prefer to consume browse species given the choice. Browsing away from the ground may help avoid internal parasites; however, goats cannot consume more than 50% of their diet as browse due to the prevalence of toxins in the browse species. The objective of this project was to determine in vitro true digestibility (IVTD) of preferred browse species consumed by goats at Tuskegee University browsing demonstration site over the growing season. Three samples were collected from each of the 35 different browse species in April and July 2018. Samples consisted of leaves and edible twigs. Browse IVTD was determined according to the Van Soest et al. (1991) modification of the Tilley and Terry (1963) procedure using the Ankom Daisy II incubator system. Data were analyzed for the months of April and July utilizing the two-sample T-test of SYSTAT, Version 13. Browse IVTD values differed (Pteridium aquilinum (Brakenfern) to 94.7% in Phytolacca americana (pokeweed) while the July values ranged from 33.59% in Pteridium aquilinum to 88.5% for Morus rubra (Mulberry). Significant differences were also observed among browse species with regards to dry matter content. Dry matter content values ranged from 10.5 (Albizia julibrissin; White mimosa) to 81% (Prunus americana; American Plum) in April and 12.5 Phytolacca americana to 89% Pinus taeda (Loblolly Pine) in July. Results showed natural variability in IVTD of various browse species throughout the growing season. Future experiments will analyze additional nutritive value parameters such as ADF, NDF, total digestible nutrients, and lignin values over three collection times (April, July, and October). The experiment will be continued for two additional years to provide meaningful results.