Assessment of hemp meal as a protein supplement for non-lactating dairy cows

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Addo, Franklin
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Hemp meal (HM) may be a suitable protein supplement for dairy cows, but its use as a ruminant feed has not yet been approved in Canada. To obtain information regarding the potential to utilize hemp meal as a cattle feed, dry matter intake (DMI), rumen fermentation, blood metabolites, total tract digestibility, and concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in blood plasma, urine, muscle, and adipose tissues were compared between non-lactating dairy cows receiving either HM or canola meal (CM), or a combination of HM and CM. Six non-lactating, non-pregnant Holstein cows were used in a repeated 3 × 3 Latin Square design feed trial with three, 3-week experimental periods. The first two weeks served as an adaptation (washout) period, and sample collection occurred during the third week of each period. Cows were fed a basal, partially mixed ration (PMR) diet that was supplemented with either 10.2 % DM HM, 13.5 % DM CM or 6.25 % DM HM and 6.16 % DM CM (HC). All diets were isoenergetic and isonitrogenous. Total tract digestibility of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) were determined using acid insoluble ash contents of diets and feces as an internal marker. Supplement treatment did not affect DMI, pH, VFA, ammonia concentrations in the rumen, total tract DM digestibility, crude protein digestibility, urine nitrogen or blood serum concentration of glucose, urea, beta-hydroxybutyrate, and non-esterified fatty acids. However, the total tract NDF digestibility of the CM diet (43 %) was significantly higher (p < 0.05) than that of HM (38 %). No cannabinoids were detected in blood plasma, rumen fluid, kidney, liver, urine, muscle, and adipose tissues of cows. However, CBD and CBDA were detected in the feces of the cows (0.68 ug/g and 0.67 ug/g, respectively). Our data show that hemp meal may be a good and safe alternative to canola meal as a protein supplement for non-lactating dairy cows.
hemp, protein supplementation, non-lactating dairy cow