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

The increased fish consumption by the growing human population in the world translates into an increase in fish waste. The reintroduction of these fish by-products into food and feed chains presents economic benefits and contributes to counteracting their negative environmental impact. Under this context, the present study aimed to evaluate the effects of the dietary inclusion of fish hydrolysate and oil obtained from fish waste (experimental diet) in substitution of shrimp hydrolysate and salmon oil (control diet) mainly imported from third countries on palatability, apparent total tract digestibility, fecal characteristics and metabolites, blood fatty acid profile, flatulence, and coat quality of adult dogs. A two-bowl test was performed to evaluate palatability by the pairwise comparison between the two diets. A feeding trial was conducted according to a crossover design with two diets (control and experimental diets), six adult Beagle dogs per diet, and two periods of 6 weeks each. The replacement of shrimp hydrolysate and salmon oil with fish hydrolysate and oil did not affect the first diet approach and taste, as well as the intake ratio. Generally, the digestibility of dry matter, nutrients, and energy was not affected by diet, but the intake of digestible crude protein (CP) and ether extract was higher, respectively, with the control and the experimental diet. The higher intake of eicosapentaenoic acid and docosahexaenoic acid with the experimental diet was reflected in a higher content of these long-chain polyunsaturated fatty acids and the omega-3 index of red blood cells, but it did not affect coat quality. The significantly higher intake of digestible CP with the control diet might have contributed to the higher fecal ammonia-N and valerate concentrations. Daily fecal output and characteristics were similar between diets. Overall, results suggest that fish hydrolysate and oil from the agrifood industry might constitute sustainable functional ingredients for dog feeding while adding value for wild fisheries, aquaculture, and fish farming under a circular economy approach and reducing dependence on imports from third countries with a high carbon footprint.

Gastric epithelial response to milk fat using the semi-dynamic INFOGEST digestion model coupled with NCI-N87 cells.

The stomach is a relevant spot of lipolysis for milk fat, but research on the effect of digested milk fat in the gastric epithelium is scarce and difficult to evaluate. In the present study, we implemented the semi-dynamic in vitro digestion model of INFOGEST, combined with gastric NCI-N87 cells, to study the effect of fat-free, whole conventional, and whole pasture-based milk on gastric epithelium. Cellular messenger ribonucleic acid (mRNA) expression of membrane fatty acids receptors (GPR41, GPR84), antioxidant enzymes (CAT, SOD, GPX), and inflammatory molecules (NF-κB p65, IL-1ß, IL-6, IL-8 and TNF-α) was assessed. No significant differences were observed in mRNA expression of GPR41, GPR84, SOD, GPX, IL-6, IL-8, and TNF-α, after exposure of the NCI-N87 cells to milk digesta samples (p > 0.05). An increase of CAT mRNA expression was observed (p < 0.05), at a similar level, for all milk types. Whole milk digested samples induced higher mRNA expression of NF-κB p65 and IL-1ß than fat-free milk (p < 0.05); while no differences were observed between whole conventional and whole pasture-based milk (p > 0.05). Moreover, the effect of milk digesta on gastric mRNA expression was studied in a scenario of subsequent stimulation of NCI-N87 monolayer with the pro-inflammatory cytokine IFN-γ. In these conditions, milk digesta samples increased CAT mRNA expression (p < 0.05), but had no effect in the expression of NF-κB p65 and IL-1ß (p > 0.05). The increase of CAT mRNA expression suggests that milk fatty acids are used for energy production by gastric epithelial cells. Cellular antioxidant response to higher milk fatty acids availability could be associated to gastric epithelial inflammation, but did not contribute to increased inflammation in case of an external contact with IFN-γ. Besides, a conventional or a pasture-based origin did not affect the impact of whole milk in the NCI-N87 monolayer. The combined model responded to differences in milk fat content, which indicates its usefulness to study effects of foods at the gastric level.

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

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.

A Novel Approach for Monitoring the Volatile Metabolome in Biological Samples from Ruminants through Miniaturized Liquid-Liquid Extraction and Multiclass Gas Chromatography Analysis.

A straightforward and versatile methodology for the extraction of volatile metabolites in biological samples from ruminants for gas chromatography analysis is proposed. The methodology was applied in the determination of multiclass metabolites (short-chain fatty acids, aldehydes, alcohols, ketones, esters, phenols, and sulfides) in different analytical matrices (rumen fluid, urine, and feces) collected from Holstein cows. The 24 multiclass volatile metabolites reported in the different biological samples and their respective concentrations were critically discussed in the context of digestive physiology. Most detected compounds are derived from the rumen and lower gut fermentation of carbohydrates, proteins, and lipids or their metabolism, being consistent with the prior state of the art. The proposed method also takes advantage of the already existing tools in animal nutrition laboratories, providing a novel methodological ground that can generate relevant bioanalytical information with a significant impact on ruminant's nutritional studies.

Unravelling the phytonutrients and antioxidant properties of European Vicia faba L. seeds.

For the first time, seven European varieties of Vicia faba L. seeds were investigated for (1) their phytonutrients profile by HPLC-DAD-MS/MS, (2) total phenolic content (TPC), and (3) antioxidant capacity (DPPH and FRAP assays). A wide range of compounds were identified, namely alkaloids, organic acids, terpenoids, jasmonates, and phenolics; these two latter being the most abundant. TPC ranged between 2.62 and 4.3 mg (gallic acid equivalent) g-1 dry weight, for V. faba major variety Belshi and V. faba minor variety Bauska, respectively. The DPPH radical scavenging capacity showed poor correlation (r = 0.550, P = .041) with TPC, suggesting the presence of other antioxidant sources than phenolics. Still, FRAP was positively correlated with TPC (r = 0.709, P < .01) and DPPH (r = 0.819, P < .01). These results elucidated the phytonutrients and antioxidant properties of V. faba L. seeds as functional food sources.

Profiling of phenolic compounds and antioxidant properties of European varieties and cultivars of Vicia faba L. pods.

Vicia faba L. pods are a by-product generated from the industrial processing of beans for human and animal consumption. As phenolic compounds may play important roles in health, the present work envisaged the phenolic characterization of seven European varieties and cultivars of V. faba (major and minor) pods and the assessment of their antioxidant activity. The V. faba methanolic extracts were characterized by HPLC-DAD-MS/MS for identification of polyphenolic compounds. The total phenolic content and antioxidant capacity of the extracts were evaluated by colorimetric methods (Folin-Ciocalteu, DPPH scavenging capacity assay, and FRAP assay). Main compounds identified by HPLC-DAD-MS/MS were derivatives of caffeic acid, coumaric acid and kaempferol. The broad bean Jögeva variety presented the highest content of free and esterified phenolics (26.3 and 26.7 mg 100 g-1 dry weight, respectively), followed by the horse bean varieties Bauska and Lielplatones. These results were corroborated by the analysis of total phenolic content, DPPH scavenging capacity and FRAP. This study confirmed the rich phenolic content of V. faba pods suggesting to be an interesting novel source for animal nutrition, promoting product quality and consumers' health.

Determination of ammonia nitrogen in solid and liquid high-complex matrices using one-step gas-diffusion microextraction and fluorimetric detection.

This paper introduces a new method for a one-step determination of ammonia nitrogen (NH3) in high complex solid and liquid samples from the agricultural and livestock sectors. To this end, we developed a simultaneous extraction and fluorimetric labeling of NH3, using gas diffusion microextraction (GDME), followed by the fluorescence measurement under 96-well microplate format. The GDME ensured a selective diffusion of NH3 through a commercial hydrophobic membrane, and confined the acceptor solution, which included the fluorimetric labeling reagent o-phthalaldehyde (OPA). The OPA-NH3 labeling reaction was optimized resorting to a full factorial experimental design, which showed that the reducing agent (Na2SO3) concentration was critical to achieve the highest sensitivity. A similar optimization approach for GDME showed that time and temperature significantly influenced the sensitivity of the assay, and also that the modifications in these two factors could be used to adjust the sensitivity according to the concentrations present in the samples. In our final conditions, it was possible to quantify NH3 in the range between 0.38 and 6.27mgL-1 using a 10min extraction at 25°C in different samples (e.g., corn and grass silages, feces, urine). The developed method showed a high repeatability and reproducibility (intraday and interday relative standard deviations values of 4.5% and 9.5%, respectively) and an adequate limit of detection (0.22mgL-1). This new methodology also highlighted the simplicity and versatility of GDME for the determination of volatile components of high-complex matrices, which will certainly drive future developments in the analysis of environmental and biological samples.

Detailed dimethylacetal and fatty acid composition of rumen content from lambs fed lucerne or concentrate supplemented with soybean oil.

Lipid metabolism in the rumen is responsible for the complex fatty acid profile of rumen outflow compared with the dietary fatty acid composition, contributing to the lipid profile of ruminant products. A method for the detailed dimethylacetal and fatty acid analysis of rumen contents was developed and applied to rumen content collected from lambs fed lucerne or concentrate based diets supplemented with soybean oil. The methodological approach developed consisted on a basic/acid direct transesterification followed by thin-layer chromatography to isolate fatty acid methyl esters from dimethylacetal, oxo- fatty acid and fatty acid dimethylesters. The dimethylacetal composition was quite similar to the fatty acid composition, presenting even-, odd- and branched-chain structures. Total and individual odd- and branched-chain dimethylacetals were mostly affected by basal diet. The presence of 18:1 dimethylacetals indicates that biohydrogenation intermediates might be incorporated in structural microbial lipids. Moreover, medium-chain fatty acid dimethylesters were identified for the first time in the rumen content despite their concentration being relatively low. The fatty acids containing 18 carbon-chain lengths comprise the majority of the fatty acids present in the rumen content, most of them being biohydrogenation intermediates of 18:2n-6 and 18:3n-3. Additionally, three oxo- fatty acids were identified in rumen samples, and 16-O-18:0 might be produced during biohydrogenation of the 18:3n-3.