Assessment of spent hemp biomass as a potential ingredient in ruminant diet: nutritional quality and effect on performance, meat and carcass quality, and hematological parameters in finishing lambs.

Spent hemp biomass (SHB), a byproduct of cannabinoid extraction from the production of industrial hemp has not been approved by FDA-CVM since its effects on animal health, performance, and product quality are unknown. Our objective was to investigate the effects of feeding two levels of SHB and a 4-wk withdrawal period on performance, carcass characteristic, meat quality, and hematological parameters in finishing lambs. A total of 35 weaned, Polypay male lambs kept in single pens were randomly assigned to five feeding treatments (n = 7) and fed diets containing either no SHB (CON) or SHB at 10% (LH1) or 20% (HH1) for 4 wk with 4 wk of clearing period from SHB, or SHB at 10% (LH2) or 20% (HH2) for 8 wk. Chemical analysis revealed SHB to have a nutritive quality similar to alfalfa with no mycotoxin, terpenes, or organic residuals as a result of the extraction process. Feed intake of lambs was negatively affected by 20% SHB in period 1 but not in period 2 where feed intake was the greatest in HH1 and LH2. In contrast, none of the performance data, including liveweight gains, were different across the groups and periods. In period 1, blood glucose, cholesterol, calcium, paraoxonase, and tocopherol were decreased by the level of SHB fed, while bilirubin and alkaline phosphatase (ALP) were increased. In period 2, the concentration in blood of urea, magnesium, bilirubin, ALP, and ferric reducing ability of the plasma (FRAP) were higher in LH2 and HH2 as compared with CON, while β-hydroxybutyrate was lower in HH2. Blood parameters related to liver health, kidney function, immune status, and inflammation were unaffected by feeding SHB. Most carcass and meat quality parameters did not differ across feeding groups either. Except carcass purge loss and meat cook loss were larger in lambs that were fed 20% SHB. Although lower feed intake of lambs that were fed 20% SHB initially in period 1 suggested SHB was not palatable to the lambs, increased feed intake at a lower level of inclusion at 10% in period 2 may point to a positive long-term effect of feeding SHB.