Assessment of the Effects of Edible Microalgae in a Canine Gut Model

Abstract

Microalgae are a source of bioactive compounds having recently been studied for their possible application as health-promoting ingredients. The aim of the study was to evaluate in an in vitro canine gut model the effects of four microalgae, Arthrospira platensis (AP), Haematococcus pluvialis (HP), Phaeodactylum tricornutum (PT) and Chlorella vulgaris (CV), on some fecal microbial populations and metabolites. The four microalgae were subjected to an in vitro digestion procedure, and subsequently, the digested biomass underwent colonic in vitro fermentation. After 6 h of incubation, PT increased propionate (+36%) and butyrate (+24%), and decreased total BCFA (−47%), isobutyrate (−52%) and isovalerate (−43%) and C. hiranonis (−0.46 log10 copies/75 ng DNA). After 24 h, PT increased propionate (+21%) and isovalerate (+10%), and decreased the abundance of Turicibacter spp. (7.18 vs. 6.69 and 6.56 log10 copies/75 ng DNA for CTRL vs. PT, respectively); moreover, after 24 h, CV decreased C. coccoides (−1.12 log10 copies/75 ng DNA) and Enterococcus spp. (−0.37 log10 copies/75 ng DNA). In conclusion, the microbial saccharolytic activities and the shift in fecal bacterial composition were less pronounced than expected, based on current literature. This study should be considered as a preliminary assessment, and future investigations are required to better understand the role of microalgae in canine nutrition.

Iron Bioaccessibility and Speciation in Microalgae Used as a Dog Nutrition Supplement

“…Microalgae samples were digested in triplicates. These supernatants and pellets were obtained from our previous study [ 15 ].…”

“…In this research, the term bioaccessibility is used to define the fraction of iron released from the algal biomass during the in vitro digestibility analysis performed by Delsante et al (2022) [ 15 ]. To determine the bioaccessible iron fraction, the following equation was used: ([Fe] supernatant/[Fe] algal biomass) × 100 …”

“… § The data were obtained from Delsante et al (2022) [ 15 ]. * DF: digested fractions (supernatants after in vitro digestion); ° UF: undigested fractions (pellets after in vitro digestion).…”

“…In vitro digestion models are widely used to study digestibility of individual ingredients as well as complete diets in both human and animal nutrition. Moreover, these in vitro digestion models have already been adopted to evaluate the digestibility of algal biomasses in both humans [ 13 , 14 ] and dogs [ 15 ], with the final purpose of investigating the effects which microalgae may exert on the intestinal microbiota in vitro.…”

Oral Palatability and Owners’ Perception of the Effect of Increasing Amounts of Spirulina (Arthrospira platensis) in the Diet of a Cohort of Healthy Dogs and Cats

“…To the authors’ knowledge, an in vitro study conducted on macrophages isolated with bronchoalveolar lavage in cats demonstrated increased macrophage phagocytic activity when incubated with Escherichia Coli and exposed to a water-soluble extract of A. platensis [ 26 ], whereas a recent study performed in dogs showed an immune-stimulating activity of A. platensis when they were fed an extruded diet supplemented with 0.2% DM spray-dried Spirulina compared to the control group: dogs fed diets supplemented with Spirulina showed significantly higher vaccine response and higher levels of fecal IgA than the control group [ 27 ]. Another recent publication [ 28 ] assessed the effect of four edible microalgae, including A. platensis , in a canine gut in vitro mode; the authors concluded that the microbial saccharolytic activities and the shift in fecal bacterial composition were less pronounced than expected based on current literature in other species. The nutraceutical and therapeutical applications of Spirulina in companion animals are thus largely unexplored.…”