Effects of microalgae as dietary supplement on palatability, digestibility, fecal metabolites, and microbiota in healthy dogs

Abstract

The current trend of dog owners increasingly favoring the functional value of food to assure preventive health and wellbeing of their pets has been raising the interest in microalgae as natural additives with bioactive properties. However, scientific studies addressing the effects of microalgae supplementation in diets for dogs are scarce. This study aimed to evaluate the effects of dietary supplementation with three microalgae species (Chlorella vulgaris, Nannochloropsis oceanica, and Tetradesmus obliquus) on diet palatability, total tract digestibility, metabolizable energy content, fecal metabolites and microbiota of dogs. Twelve adult Beagle dogs were used in three two-bowl tests to compare the palatability of a commercial complete diet for adult dogs without (reference diet) and with 1.5% supplementation of each microalgae. From the results obtained, three digestibility trials were performed according to a replicated Latin square 3 × 3, with six adult Beagle dogs, three experimental periods of 10 days each, and three dietary supplementation levels of microalgae (0.5, 1.0, and 1.5%). In each trial, effects of microalgae supplementation levels on total tract digestibility, metabolizable energy content, fecal metabolites and microbiota of dogs were evaluated. First diet approached or tasted was not significantly affected by microalgae inclusion, but dogs showed a preference for the reference diet over the diets with 1.5% inclusion of C. vulgaris and N. oceanica, no difference being observed with 1.5% T. obliquus. In all digestibility trials, dietary supplementation with microalgae up to 1.5% did not greatly affected the dietary chemical composition and kept unaffected food intake, fecal output and metabolites, and digestibility of nutrients and energy. Compared with the reference diet, supplementation with C. vulgaris increased protein digestibility. Fecal characteristics and metabolites were affected by microalgae supplementation, being the effects dependent on the species. Fecal microbiota composition of dogs fed with microalgae-supplemented diets was modified by promoting the beneficial Turicibacter and Peptococcus genera associated with gut health and activation of the immune system. Overall, the results support C. vulgaris, N. oceanica, and T. obliquus as sustainable functional supplements that potentially enhance gastrointestinal health of dogs through the selective stimulation of microbiota without detrimental effects on food intake and digestibility.

Squid meal and shrimp hydrolysate as novel protein sources for dog food

“…Indeed, earlier studies found no negative or even positive effects on palatability with higher inclusion levels of marine by-products than the level used in the current study ( 12 , 95 ). The lower palatability of diets with 15% inclusion of squid meal or shrimp hydrolysate might be due to protein sources being mixed with the basal diet immediately before being offered to dogs, instead of included in the kibble, as previously shown with microalgae supplementation ( 11 ). Future research should be performed to evaluate the palatability of diets containing squid meal and shrimp hydrolysate included in the extruded complete diet.…”

“…The method of total fecal collection was used to assess the apparent total tract digestibility (ATTD) of the basal and experimental diets. The in vivo ATTD of the basal diet was determined previously to experiments 1 and 2, using 12 animals for 10 days (5 days for adaptation and 5 days for feces collection), as recommended by FEDIAF and earlier described ( 11 ). The two digestibility trials performed to evaluate the effects of inclusion levels of squid meal and shrimp hydrolysate were designed according to a replicated Latin square 3 × 3, with six animals (three males and three females, from the 12 animals used for the determination of the in vivo digestibility of the basal diet), three experimental periods of 10 days (5 days for adaptation to the diet and 5 days for total feces collection) and three dietary inclusion levels (50, 100 or 150 g kg −1 ).…”

“…Pet owner’s mindset on food ingredients choice is also changing. According to a recent survey ( 6 ), only 19% of respondents would continue to buy pet foods with conventional protein sources, while 54% of respondents were interested in foods containing by-products, although 66% of them were not familiar with the term “by-products.” Increasing interest has emerged in alternative protein sources from terrestrial ( 7–10 ) and aquatic ( 11 , 12 ) origin to replace conventional terrestrial ones due to their high nutritive value and lower environmental impact ( 13 , 14 ). Under a circular economy perspective, the utilization of by-products from aquatic sources offers additional advantages as it contributes to the reduction of waste and food-feed competition, and to a greater economic and environmental efficiency ( 15 , 16 ).…”

Protein hydrolysate and oil from fish waste reveal potential as dog food ingredients

“…Feces were thawed, and pH was determined using a potentiometer (pH and Ion-Meter GLP 22, Crison, Barcelona, Spain). Ammonia-N concentration was determined according to the method of Smith and Murphy ( 47 ) adapted to dog feces as described by Cabrita, Guilherme-Fernandes ( 48 ). Briefly, 1 g of feces were solubilized in 10 mL of KCl 2 M, centrifuged for 60 min at 5200 × g at 4°C, and the supernatant filtered using a 0.45 μm pore size polyethersulfone syringe filter (FILTER-LAB, Barcelona, Spain).…”