Nutrient digestibility, rumen parameters, and (cannabinoid) residues in sheep fed a pelleted diet containing green hemp (Cannabis sativa L.) biomass.

Sarah Stevens, Gaye Krebs, Glenys Noble, Colin Scrivener, Bronwyn Blake, Kenneth Dods, Christopher May, Zi Tai, Edward Clayton, Emma Lynch, Kristen Johnson

Research output: Contribution to journalArticlepeer-review

Abstract

The feeding value for ruminants of green hemp biomass, from the low Δ9-tetrahydrocannabinol (Δ9-THC) variety of Cannabis sativa L. is unknown. Twelve Merino ewes were randomly allocated on a stratified liveweight basis to one of two pelleted dietary treatments, Control (0% hemp) or Hemp (42% green hemp biomass). The experimental period consisted of a 17 d dietary and housing adaptation, followed by 7 d total urine and faeces collection for determination of apparent nutrient digestibility. A ruminal fluid sample was collected on day 27 and assessed for pH, and ammonia, volatile fatty acid (VFA) and cannabinoid concentrations. A blood sample and incisional subcutaneous fat biopsy were collected on day 28 with an additional incisional subcutaneous fat biopsy taken 35 d post feeding to measure cannabinoids. The dry matter (DM), organic matter (OM) and crude protein (CP) digestibility, along with total VFA concentration did not differ (p > 0.05) between the two diets; however, acid detergent fibre (ADF) and neutral detergent fibre (NDF) digestibility, water intake and faecal water output were significantly lower (p < 0.05) for the sheep fed Hemp. Rumen pH did not vary (p > 0.05) between diets, but ruminal ammonia concentration was significantly lower (p < 0.05) for sheep consuming Hemp, likely due to the high polyphenolics content creating rumen undegradable protein (RUP). Sheep fed Hemp had significantly higher (p < 0.05) molar proportions of butyric and hexanoic acids and lower molar proportions of propionic acid, potentially due to changes in the composition of the rumen microbiome. There were no differences (p > 0.05) between diets for N intake, faecal N output or N balance, with all sheep in positive N balance; however, there were significantly lower (p < 0.05) urinary N outputs for sheep fed Hemp, indicating a potentially higher efficiency of N utilisation. Cannabidiolic acid (CBDA) and tetrahydrocannabinolic acid (THCA) were detected in plasma of all sheep fed Hemp. ∆9-tetrahydrocannabinol was present in the subcutaneous fat of four of the six sheep on the final day of being fed Hemp, and in all (six) sheep 35 d post feeding Hemp. Thus, despite green hemp biomass being nutritionally a suitable feed for ruminants, under current Food Standards in Australia, the presence of these cannabinoid residues restricts its use in ruminant diets.
Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalTranslational Animal Science
Volume6
Publication statusPublished - 2022

Grant Number

  • PRJ-013007

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