Initially, the nutritional value of the three main by-products of Cannabis sativa (hempseed cake, second-rate quality hemp seed and hemp hay), cultivated under Greek conditions and collected from four plantations in the Macedonian region was estimated. A second part of the study was the investigation of the effects of diet inclusion with hempseed cake (HSC) on the performance of Holstein dairy cows. The HSC used for this experiment was the one analyzed in the first part of the study. A total number of 20 lactating cows were allocated into two equal groups in a randomized block design. Cows of both groups were offered a total mixed ration (TMR) on the same feed allowance. The diet of the experimental group was formulated with 3.5 % hemp cake, at a quantity of 1kg of hemp cake per cow per day. Milk yield was recorded individually, and feed refusals were recorded on a pen basis daily, during the first 40 days of lactation. Individual milk samples were analyzed for their chemical composition, lipid oxidative stability and fatty acid composition and tetrahydrocannabinol (THC) and cannabidiol (CBD) content, as well as feed samples of each group. Individual blood samples were received for biochemical indices assessment. All data were subjected ANOVA statistical analysis. The results of hemp by-products chemical profile showed similar nutritional values among the different cultivation regions. The experimental results indicated that the inclusion of HSC did not affect milk production and composition (P > 0.05). However, diet inclusion with HSC favorably influenced milk fatty acid profile. Finally, serum NEFA concentration was lower for the HSC group while serum urea levels were higher (P < 0.05).
