Effects of Juniperus species and stage of maturity on nutritional, in vitro digestibility, and plant secondary compound characteristics

Rising feed costs and recurring feed shortages necessitate the investigation into alternative and underutilized feed resources. Nutritional characteristics of species are either unknown or limited to leaves and ground material from small stems. Therefore, the objective was to quantify nutritional characteristics, 48-h true IVDMD (tIVDMD), microbial gas production, and secondary compound characteristics of entire woody plant material of 4 Juniperus species—Juniperus pinchotii, Juniperus monosperma, Juniperus ashei, and Juniperus virginiana—at immature and mature stages of growth. Immature plants had greater CP concentrations and lower NDF concentrations (P < 0.001) than mature plants regardless of species. Mature plants also had greater (P < 0.001) concentrations of ADF compared with immature plants with the exception of J. virginiana. In general, immature J. pinchotii, J. monosperma, and J. ashei had greater (P < 0.02) tIVDMD and total 48-h and asymptotic gas production than mature plants. Immature J. monosperma and J. pinchotii were more digested (tIVDMD; P < 0.001) than immature J. virginiana and J. ashei, but tIVDMD did not differ in mature plant material across species. Condensed tannins (CT) were greater (P < 0.001) in immature and than mature plants; differences in CT concentrations among immature species were also detected (P < 0.04). Volatile oil yields were similar across maturity and species with 1 exception: immature J. Pinchotii yielded more (P < 0.02) volatile oil than mature material. Volatile oil composition across species varied and contained a range of 65 to 70 terpene compounds. The dominant terpenes across species were generally greater (P < 0.05) in immature vs. mature plant material with the exception of J. virginiana. Labdane acids were negligible in J. pinchotii, J. ashei, and J.virginiana and greater in J. monosperma (P < 0.001). Ground material from mature juniper species, although inferior in nutritional quality compared with immature plants, is comparable to traditional low-quality roughage ingredients. Given that J. pinchotii has been successfully fed in lamb feedlot diets, the similarities of J. pinchotii, J. ashei and J. monosperma suggest that all three species have potential to be effective roughage ingredients.