Bioavailability of bioactive phytochemicals in selected tissues and excreta from goats fed hempseed cake (Cannabis sativa L.) finisher diets

Tropical Animal Health and Production (2023) 55:262 https://doi.org/10.1007/s11250-023-03676-3 REGULAR ARTICLES Bioavailability of bioactive phytochemicals in selected tissues and excreta from goats fed hempseed cake (Cannabis sativa L.) finisher diets Farouk Semwogerere1 · Obert C. Chikwanha1 · Chenaimoyo L. F. Katiyatiya1 · Munyaradzi C. Marufu2 · Cletos Mapiye1 Received: 6 February 2023 / Accepted: 27 June 2023 / Published online: 5 July 2023 © The Author(s) 2023 Abstract Hempseeds are rich in bioactive phytochemicals,yet little is known about their bioavailability in tissues and excreta of animals fed hemp seed cake. The study evaluated the bioactive phytochemicals and their antioxidant activity in the blood, liver, meat, feces, and urine from goats fed finishing diets containing graded inclusions of hempseed cake (HSC). Twenty-five wether goats (26.8 ± 2.9 kg) of 4–5 months were randomly allocated to five experimental diets containing increasing levels of HSC (0, 25, 50, 75, 100 g/kg DM) substituted for soybean meal (SBM) as the main protein source. Goats were allowed for period of 21 days for adaptation, and blood, fecal, and urine samples were collected on the 28th day of the experiment. The liver and right longissimus thoracis et lumborum were respectively collected at 60 min and 24 h after slaughter. Linear increases (P ≤ 0.05) in blood, liver, and urine magnesium; fecal manganese; and fecal copper were observed with increasing HSC inclusion in the diet. Liver and fecal selenium exhibited a decreasing linear trend (P ≤ 0.05) with HSC increment in diets. Diet did not affect (P > 0.05) meat and urine mineral contents, except urine magnesium. The 2,2-diphenyl-1-picrylhydrazyl, and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) of the blood, liver, and meat linearly increased (P ≤ 0.05) with dietary inclusion of HSC. Blood and liver ferric reducing antioxidant power quadratically increased (P ≤ 0.05) with HSC inclusion reaching a maximum at 50 g/kg dry matter. Current results suggest that inclusion of HSC up to 100 g/kg substituting SBM in goat diets can improve bioavailability of bioactive phytochemicals in the blood, liver, and meat. Keywords Antioxidant · Bioefficacy · Cannabis seed cake · Small ruminants Introduction The concept of feeding livestock with hemp (Cannabis sativa L.) by-products (i.e., cake, oil, hulls and leaves) is gaining momentum (Klir et al. 2019; Bailoni et al. 2021). This is largely driven by the legalization of hemp cultivation (Russo 2019; Leonard et al. 2020) and escalating prices for cereal and legume grains including soybean meal (SBM), which is the primary protein feedstuff in ruminant diets (Klir * Cletos Mapiye 1 Department of Animal Sciences, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa 2 Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa et al. 2019; Šalavardić et al. 2021). Among the hemp byproducts, hempseed cake (HSC) has been the most utilized in livestock diets (Antunović et al. 2020; Bailoni et al. 2021; Šalavardić et al. 2021). This is due to its comparable composition of nutrients, specifically crude protein (34 ± 2.1 g/ kg DM) to SBM (39.2 ± 5.4 g/kg DM) (Abrahamsen et al. 2021; Bailoni et al. 2021). Numerous studies have reported similar or improved performance of ruminants fed HSC relative to SBM (Turner et al. 2012; Abrahamsen et al. 2021; Šalavardić et al. 2021). More so, hempseed contains several bioactive phytochemicals with the major ones being cannabinoids, tocopherols, terpenes, polyphenols, and microminerals (Andre et al. 2016; Small 2017). The contents of tocopherols, terpenes, and macro and microminerals in HSC have been widely researched (Mierliță 2018; Mierliţă 2019; Siano et al. 2019). However, there are few reports (Addo 2022; Smith et al. 2023) on the cannabinoids, which are unique to cannabis species, that 13 Vol.:(0123456789) 262 Page 2 of 9 are retained in HSC after oil extraction. Hempseed cake contains several cannabinoids with cannabidiol (CBD, 3–170 µg/g) and cannabidiolic acid (4.4–8.8 µg/g) being the major ones, and no or negligible amounts of delta9-tetrahydrocannabinol (Stastnik et al. 2020; Addo 2022; Smith et al. 2023). Studies on feeding diets containing HSC to cows (Addo 2022; Smith et al. 2023) and hemp stubble to sheep (Krebs et al. 2021) reported little or no CBD in the blood, liver, kidney, muscle, adipose tissue, urine, and feces. However, even at low concentrations, minor cannabinoids are able to exert antioxidant effects through synergistic interactions with other bioactive phytochemicals, a phenomenon known as the entourage effect (Andre et al. 2016; Russo 2019; della Rocca and Di Salvo 2020). The bioactive phytochemicals in HSC have shown both antioxidant and antimicrobial potential under in vitro conditions (Ali et al. 2012; Chen et al. 2012; Irakli et al. 2019). Nevertheless, little is known about the bioavailability of these bioactive phytochemicals in tissues from goats fed HSC-containing diets, and this warrants investigation. Evaluation of the bioavailability of bioactive phytochemicals involves assessing their digestion, absorption, circulation, assimilation, and excretion (Karaś et al. 2017; Santos et al. 2019). This can be achieved by measuring their concentration in feed and antioxidant activity in selected animal tissues and excreta (Karaś et al. 2017; Selby-Pham et al. 2020; Wise et al. 2020). In this regard, the antioxidant activity of the blood, liver, and meat can be used as a proxy for bioavailability of HSC bioactive phytochemicals in ruminants. Assessing the bioavailability of bioactive phytochemicals is critical in determining the minimum threshold required to improve animal health by reducing oxidative stress, protect animal products (i.e., meat and milk) against oxidation and microbial spoilage, and enhance the healthfulness of the fatty acid profile of animal products for human consumption (Gladine et al. 2007; Wise et al. 2020). The present study aimed to determine the bioavailability of cannabinoids, tocopherols, polyphenols, and bioactive minerals in selected tissues and excreta from goats fed diets containing increasing levels of HSC substituted for SBM. Materials and methods Study site The experiment was conducted at Welgevallen Experimental Farm (33° 56′ 33″ S 18° 51′ 59″ E; Stellenbosch University, Stellenbosch, South Africa) in winter between June and July 2021. The experimental site experiences a Mediterranean climate and was characterized by an average temperature of 12 °C, rainfall of 141 mm, and humidity of 77% during the experimental period. 13 Tropical Animal Health and Production (2023) 55:262 Diets, experimental design, and animal management HSC (Cannabis Sativa L. Fedora 17) was sourced from a local hemp oilseed processing company. Five pelleted (5 mm × 30 mm) total mixed diets were form (...truncated)