Feeding hempseed cake alters the bovine gut, respiratory and reproductive microbiota

Authors: WINDERS, T - North Dakota State University; HOLMAN, D - Agriculture And Agri-Food Canada; SCHMIDT, K - North Dakota State University; LUECKE, S - North Dakota State University; Smith, David; Neville, Bryan; DAHLEN, C - North Dakota State University; SWANSON, K - North Dakota State University; AMAT, S - North Dakota State University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2023
Publication Date: 5/19/2023
Citation: Winders, T.M., Holman, D.B., Schmidt, K.N., Luecke, S.M., Smith, D.J., Neville, B.W., Dahlen, C.R., Swanson, K.C., Amat, S. 2023. Feeding hempseed cake alters the bovine gut, respiratory and reproductive microbiota. Scientific Reports. https://doi.org/10.1038/s41598-023-35241-1.
DOI: https://doi.org/10.1038/s41598-023-35241-1

Interpretive Summary: Hempseed cake is a nutrient-rich by-product of hempseed oil extraction which has a historical precedence for use in cattle feed. Although studies have been conducted on the impacts of dietary hempseed cake on cattle performance, no studies have investigated its impacts on microbial communities (microbiota) associated with cattle, even though hempseed cake may contain bioactive and antimicrobial compounds. A feeding study was conducted that compared gastrointestinal, respiratory, and reproductive microbiota of finishing feedlot heifers that were fed rations containing either 20% dietary hempseed cake or 20% distillers dried grains plus solubles (a grain product) for 16 weeks. The gastrointestinal microbiota of hempseed cake fed cattle was altered early and sustained through feeding, especially with respect to community structure, microbial richness, and composition. Microbiota associated with the respiratory and reproductive tract were also impacted but to a lesser degree by hempseed cake late in the feeding period. The study illustrates that microbial communities may change in response to inclusion of hempseed cake in the diet, even in mucosal surfaces not necessarily associated with the gastrointestinal tract.

Technical Abstract: A growing number of studies have investigated the feasibility of utilizing hemp by-products as livestock feedstuffs; however, their impact on livestock microbiomes remains unexplored. Here, we evaluated the effects of feeding hempseed cake on the gastrointestinal, respiratory, and reproductive microbiota in beef heifers. Angus-crossbred heifers (19-months old) were fed a corn-based finishing diet containing 20% hempseed cake as a substitute for 20% corn dried distillers’ grains with solubles (DM basis; Control; n = 16/group) for 111 days until slaughter. Ruminal fluid and deep nasopharyngeal swabs (days 0, 7, 42, 70 and 98), and vaginal and uterine swabs (at slaughter) were collected, and the microbiota assessed using 16S rRNA gene sequencing. Diet affected the community structure of the ruminal (d7– 98; 0.06 = R2 = 0.12; P < 0.05), nasopharyngeal (d 98; R2= 0.18; P < 0.001), and vaginal (R2 = 0.06; P < 0.01) microbiota. Heifers fed hempseed cake had increased microbial diversity in the rumen, reduced microbial richness in the vagina, and greater microbial diversity and richness in the uterus. In addition to the distinct microbial communities in the rumen, nasopharynx, vagina and uterus, we identified 28 core taxa that shared (= 60% of all samples) across these sampling locations. Feeding hempseed cake can appeared to alter the bovine gut, respiratory and reproductive microbiota. Our findings also highlight the need for research evaluating the impact of hemp-associated food and personal care products on the human microbiome.