Effects of variety and botanical part on rates and amounts of ruminal nutrient disappearance from <i>Cannabis sativa</i>

Data on effects of hemp (Cannabis sativa L.) variety and botanical part on ruminal nutrient disappearance are currently limited. Plants were harvested from 2 fiber- (CFX-2 and CRS-1) and 2 flower-based (Grandi and Katani) hemp varieties. Plants were separated into stems, leaves and seeds by variety. In situ disappearance of dry matter (DM), organic matter (OM), detergent fiber and crude protein (CP) was obtained by incubating bags containing unique combinations of variety and botanical part in 2 ruminally cannulated heifers. Rates and amounts of ruminal nutrient disappearance were calculated using the NLIN procedures in SAS and data were analyzed using the GLIMMIX procedure with fixed effects of variety, botanical part and their interaction; animal was included as a random effect. Rates and amounts of DM, OM, detergent fiber and CP disappearance were influenced by the interaction of variety and botanical part, which seemed to be largely related to differences in nutrient disappearance from leaves and seeds between fiber- and flower-based varieties. CFX-2 had greater (P < 0.01) concentrations of soluble DM while Katani had the least, however, rates of DM disappearance were greater (P = 0.03) among Katani compared to CFX-2 and Grandi. Amounts of degradable DM and OM were greatest (P ≤ 0.03) in CFX-2. Among measures of fiber disappearance, CFX-2 had the least amount of soluble fiber (P < 0.01), and the greatest concentrations of slowly degradable fiber (P < 0.01). The nondegradable fraction was greatest (P = 0.03) in CRS-1 and least in Katani. Rates of disappearance (P = 0.02) were least for Katani. Amounts of soluble DM were greatest (P = 0.02) among leaves and the least in stems, but seeds were not different from either. Rates of DM disappearance were greatest (P < 0.01) among leaves, intermediate among seeds, and least in stems. Amounts of soluble OM and rates of OM disappearance were greater (P < 0.01) in leaves compared to stems and seeds; however, slowly degradable OM was greater (P < 0.01) in stems compared to leaves and seeds. Seeds had relatively small amounts of detergent fiber disappearance with less amounts (P < 0.01) of soluble material; however, they had greater amounts of CP degradation (P < 0.01). Effective degradability of CP was 25% less (P < 0.01) among Grandi compared to other varieties. These data clearly indicate that different varieties and botanical parts of industrial hemp impact measures of ruminal nutrient disappearance.