High-moisture alfalfa (Medicago sativa L.) silage and the impact of alternative agricultural additives: industrial hemp (Cannabis sativa L.) and freeze-dried orange powder (Citrus × sinensis)

Introduction The objective was to evaluate the effect of plant-derived additives from oranges ( Citrus × sinensis ) and industrial hemp ( Cannabis sativa L.) on the composition and characteristics of direct-cut alfalfa ( Medicago sativa L.) silage. Materials and methods A 2 nd cutting of Ameristand 433T RR alfalfa was ensiled in two groups: unamended or 20 mL DI water added (WA). Each group had three treatments with two application rates each:: T1 – hemp crude oil extract (2 or 4 g kg -1 ), T2 – 2mm ground hemp hurd (5 or 10 g kg -1 ), and T3 – freeze-dried orange powder (40 or 60 g kg -1 ). The treated or control (unamended or WA; a subset was retained for pre-ensiling compositional analysis) material (~ 120 g bag -1 ) was sealed in vacuum bags and ensiled at 25 °C over 40 days. Post-ensiling, two sub samples were taken for spore-forming bacteria counts and fermentation analysis. The remainder of the post-ensiled material underwent compositional analysis. Results and discussion The results indicate that addition of the freeze-dried orange powder facilitated a reduction in proteolysis, marked by a low pH and decreased ammonia. However, there were limited differences in lactic and acetic acids produced across the conditions. Propionic and butyric acids were consistently below the limits of quantification (< 1.0 mM). Addition of orange powder, particularly at 60 g kg -1 , increased % DM but lowered % CP. There were inter-treatment variabilities, however the hemp treatments did not have a significant impact on silage quality. Additionally, there were no differences in spore-forming bacteria counts regardless of condition or treatment. Conclusion High-moisture alfalfa is known to preserve poorly due to its high buffering capacity and low water-soluble carbohydrate content limiting the necessary rapid reduction in pH. Collectively, the data suggests that the use of freeze-dried orange powder, but not hemp crude oil or ground hurd, in direct-cut alfalfa appears to retain silage quality within an acceptable range for high-moisture legume silages.