Feeding spent hemp biomass does not adversely affect fertility in rams.

Objective: To determine the reproductive effects of feeding spent hemp biomass (SHB) to rams. Several studies suggest cannabidiols negatively affect reproductive characteristics, and the reproductive effects of SHB ingestion have not been investigated in any species. Spent hemp biomass is high in protein and essential fatty acids, indicating a potential use in livestock diets pending studies investigating its safety in animals.

Methods: Polypay rams approximately 6 months old were randomly assigned to 5 feeding trial groups (n = 7/group): either a low or high concentration of SHB in diet for either 4 or 8 weeks plus a control group. Blood samples were collected for hormone assays. At the conclusion of the feeding trial, the testes were removed, and sperm collected directly from the vas deferens were evaluated for motility (total, progressive, and speed), morphology, and concentration. A section from each ram's testes was formalin fixed, paraffin embedded, and subjected to routine immunohistochemistry to determine the expression of fertility-associated proteins deleted in azoospermia-like and Boule, followed by quantitative image analysis.

Results: Rams fed either 10% or 20% SHB for 8 weeks had significantly higher progressive sperm motility compared to controls. There were no significant differences between the treatment and control groups in the other parameters studied. Boule immunoexpression was adversely affected, whereas deleted in azoospermia-like immunoexpression was differentially affected by SHB ingestion.

Conclusion: We conclude that up to 20% of the diet can be fed as SHB to rams for 8 weeks without adversely affecting testicular or sperm function.

Clinical relevance: Supplementing young rams with SHB is unlikely to affect fertility.