Browse potential of bristly locust, smooth sumac, and sericea lespedeza for small ruminants

Abstract

Temperate grass and legume yield and quality are markedly reduced during hot, dry summer months in the southern USA; therefore, browse species could add feed options for small ruminants during this season. Our objective was to compare total biomass yield and forage nutritive value of two browse species, leguminous bristly locust (Robinia hispida) and smooth sumac (Rhus glabra), as well as a leguminous shrub known as sericea lespedeza (Lespedeza cuneate), during summer months (June, July, August and September). Plants were sampled monthly during growing-seasons in 2012 and 2013 to determine biomass yield (foliar, shoot, and total above ground) and foliar nutritive value [crude protein (CP), acid detergent fiber (ADF), acid detergent lignin (ADL), and condensed tannins (CT)]. There was a species × harvest time interaction for foliar biomass yield (P = 0.0125). This interaction was likely due to low yield in June for bristly locust compared with sericea lespedeza and smooth sumac, but in all other months (July, August, and September) yields were similar for each species. Bristly locust had the highest CP (16.9%), followed by sericea lespedeza (14.8%), and smooth sumac (12.3%). Acid detergent fiber and ADL were similar between bristly locust (ADF 38.5%; ADL 24.1%) and sericea lespedeza (ADF 38.4%; ADL 23.1%), but was lower for smooth sumac (ADF 22.1%, ADL 6.3%; P < 0.05). Condensed tannins, an anti-nutritive yet anti-parasitic phenolic compounds, were highest in smooth sumac, intermediate in bristly locust, and lowest in sericea lespedeza. Plant foliar percentage (ratio of foliar to shoot mass), was highest in smooth sumac (55.1%), followed by sericea lespedeza (47.7%), and bristly locust (42.6%). Overall, smooth sumac had the highest foliar biomass and lowest ADF and ADL; however, this species had the lowest CP and highest CT. Consequently, average foliar biomass yield of all three browse species in our study far exceeded forage yield from dominant forage species [tall fescue (Schedonorus arundinaceus) and bermudagrass (Cyanodon dactylon)] in this region and may provide high-yielding, low input, anti-parasitic fodder for small ruminants during this period in the Southeastern U.S.