Nutritional Composition and Untargeted Metabolomics Reveal the Potential of Tetradesmus obliquus, Chlorella vulgaris and Nannochloropsis oceanica as Valuable Nutrient Sources for Dogs

Abstract

The growing pet population is questioning the sustainability of the pet food system. Although microalgae may constitute a more sustainable food resource, the assessment of their potential for canine diets is almost non-existent. The present study aimed to evaluate the potential of three microalgae species (Tetradesmus obliquus, Chlorella vulgaris and Nannochloropsis oceanica) grown locally in industrial photobioreactors as alternative food resources for dogs. A detailed characterization of their nutritional composition and metabolomic profile was carried out and related to the nutritional requirements of dogs. Overall, the essential amino acid content exceeded the amounts required for dogs at all life stages, except methionine and cysteine. The three microalgae were deficient in linoleic acid, N. oceanica presented a linolenic acid content below requirements and T. obliquus and C. vulgaris were deficient in arachidonic and eicosapentaenoic acids. The fiber was mainly composed of insoluble dietary fiber. The mineral profile varied greatly with the microalgae species, demonstrating their different potential for dog feeding. Untargeted metabolomics highlighted glycolipids, glycerolipids and phospholipids as the most discriminating compounds between microalgae species. Overall, the results support the potential of T. obliquus, C. vulgaris and N. oceanica as valuable macro- and micro-nutrients sources for dog feeding.

Enhancing Digestibility of Chlorella vulgaris Biomass in Monogastric Diets: Strategies and Insights

“…However, its protein content is highly dependent on the cultivation conditions and can be as low as 13.6% DM [ 24 ] under nitrogen-limiting conditions [ 25 ]. The protein quality of CV is high, as it contains all essential amino acids, including a significant amount of leucine and lysine (average of 9 to 10% of total amino acids) [ 26 , 27 ]. Lysine, in particular, is a limiting amino acid for poultry and swine, and can be found in C. vulgaris at levels as high as 10.4 to 13.2% [ 26 , 27 ].…”

“…The dried biomass of CV also contains significant amounts of ash, reaching up to 27.3% [ 28 ]. The ash is rich in essential minerals such as phosphorus, potassium, iron, manganese, and zinc [ 24 , 26 ]. While there may be some concern about heavy metal toxicity in Chlorella spp., studies have shown that such toxic elements, including arsenic, cadmium, and mercury, are present in concentrations as low as 0.59–1.1 mg/kg, 0.01–0.10 mg/kg, and 0.02–0.10 mg/kg, respectively, and no lead was detected [ 25 ].…”

“…Environmental stress, such as high light intensity and nitrogen deprivation, has also been shown to increase lipid production in other microalgae [ 33 ]. The essential PUFA 18:2n-6 and 18:3n-3 are the most predominant fatty acids in CV biomass, averaging 21.6% and 18.8%, respectively [ 23 , 26 , 32 ]. The 18:3n-3 and 18:2n-6 are converted into n-3 LC-PUFA and n-6 LC-PUFA, respectively, although the efficiency of these pathways is low [ 34 ].…”

“… 1 Supporting sources: Canelli et al [ 23 ]; Sucu [ 24 ]; Cabrita et al [ 26 ]; Shaaban [ 27 ]; Madhubalaji et al [ 28 ]; Tokuşoglu and üUnal [ 29 ]; Prabakaran et al [ 31 ]; Ferreira et al [ 32 ]; Coelho et al [ 35 ]; Panahi et al [ 39 ]; Edelmann et al [ 40 ]; Gonzalez and Bashan [ 41 ]; Janczyk et al [ 42 ]; Khoeyi et al [ 43 ]; Batista et al [ 44 ]; Safi et al [ 45 ]; Kholif et al [ 46 ]; Jalilian et al [ 47 ]. 2 Contains trace amounts of other 16:1 isomers.…”

Body Weight Development in Adult Dogs Fed a High Level Resistant Starch Diet

“…Grains are an important carbohydrate source in dog diets, with most extruded pet foods containing 20–50% carbohydrates [ 31 ]. Nutritionally, carbohydrates are not essential nutrients [ 32 ]; yet, when compared to animal protein or fats, carbohydrates are an extremely economical energy source for use in pet foods [ 33 ]. Although grains are a widely used carbohydrate source within the pet food industry, many companion animal owners are concerned about feeding their pets grains, and studies on the safety of carbohydrate sources available in dog foods are limited [ 34 ].…”