Valorisation of grape stem as an alternative ingredient in rabbit feed.

Grape stem is a winery by-product that it is currently disposed as waste or at best as soil conditioner. However, it is rich in fibres and polyphenols which makes it interesting for animal feeding. In this regard, rabbit farming emerges as a target livestock farming since fibre content is essential in rabbit's diets for preventing digestive troubles and polyphenols are associated with improved performances in animals due to their antimicrobial and antioxidant activities. This study aims to assess the suitability of a grape stem-based ingredient for rabbit feeding. The stem was dried using flash drying technology to prevent rapid spoilage and stabilise the ingredient. Then, its nutritional value was evaluated resulting in a high fibre (>40%) and polyphenol (>6%) content ingredient with antioxidant and antimicrobial activity against Staphylococcus aureus. A feed efficiency trial was conducted and inclusion rates of up to 10% of grape stem-based ingredient did not affect animals' mortality, average daily feed intake, daily gain or feed conversion ratio. In conclusion, grape stem-based ingredient arises as a secondary feedstuff for cuniculture reducing the dependence on other fibre sources, such as cereals or sunflower hulls. This could also contribute to reduce the environmental footprint of the wine sector by giving a second life to an existing waste, while generating a new activity based on circular economy.

Production of Bioactive Peptides from Hake By-Catches: Optimization and Scale-Up of Enzymatic Hydrolysis Process.

Fish by-catches, along with other fish side-streams, were previously used as raw material for the production of fishmeal and fish oil but appropriate handling allows their use in more valuable options. The aim of this research was to valorize undersized hake (Merluccius merluccius) as a model of using fish by-catch from the Bay of Biscay to produce protein hydrolysates with bioactivities. Six enzymes, with different proteolytic activities (endo- or exoproteases) and specificities, were tested to produce protein hydrolysates. Products obtained with an endoprotease of serine resulted in the most promising results in terms of protein extraction yield (68%), with an average molecular weight of 2.5 kDa, and bioactivity yield (antioxidant activity = 88.5 mg TE antioxidant capacity/g fish protein; antihypertensive activity = 47% inhibition at 1 mg/mL). Then, process conditions for the use of this enzyme to produce bioactive products were optimized using Box-Behnken design. The most favorable process conditions (time = 2 h, solids = 50% and enzyme/substrate = 2% with respect to protein) were scaled up (from 0.5 L to 150 L reactor) to confirm laboratory scale and model forecasts. The results obtained in the pilot-scale testing matched the outcomes predicted by the model, confirming the technical viability of the proposed process.

Evaluation of Valorisation Strategies to Improve Spent Coffee Grounds' Nutritional Value as an Ingredient for Ruminants' Diets.

Lignin in animal diets is a limiting factor due to its low digestibility. This study assessed the effects of thermal or mechanical pre-treatments and enzymatic hydrolysis on spent coffee grounds' (SCG) nutritional value and digestibility. A first trial studied the effect of thermal pre-treatment and hydrolysis with removal of the liquid part and a second trial studied mechanical pre-treatment and hydrolysis with and without removal of the liquid part. Autoclaving did not improve the enzymatic performance nor the nutritional value. Hydrolysis reduced the digestibility of the solid phase and impaired its ruminal fermentation efficiency. Hydrolysates without removing the liquid part improved its nutritional value, but not compared with unprocessed SCG. Grinding increased crude protein and reduced crude fibre and protein, which led to greater fermentation and in vitro digestibility. Thus, grinding emerges as the most promising valorisation strategy to improve SCG nutritional characteristics and their use for animal feed, contributing to the circular economy.

Multi-criteria assessment of the viability of valorising vegetable by-products from the distribution as secondary raw material for animal feed.

Approximately 33% of food produced around the world is wasted. In the distribution sector, erroneous orders or demand predictions result in products that cannot be sold before the expiration date. Despite its enormous potential, a low percentage of this food wastage is valorised causing negative social, economic and environmental impacts. Vegetable food waste has potential as raw material for animal feed. However, the profitability of its valorisation depends on several key factors and there is a risk of underestimating any of them making this valorisation technically, economically or environmentally unfeasible. Moreover, the geographical dispersion requires selecting the appropriate location for the processing plant and optimising the logistics routes to collect and transport them from the origin points to the processing plant. GISWASTE tool, which combines Analytic Hierarchy Process (AHP) method with ArcGIS, has been used to simulate the viability of this valorisation alternative from a holistic point of view. In addition, a sensitivity analysis in the economic modelling has been carried out to determine the economic viability factors with more influence in the global profitability. The valorisation of vegetable food waste from distribution and retailing sector for animal feed has been considered feasible in the case study region: Basque Country (Spain). However, there are some economic uncertainties for the return of the investment. The variable with more influence over the profitability is by far the incomes from waste management (81.4%).

Spent Coffee Grounds Alter Bacterial Communities in Latxa Dairy Ewes.

Antimicrobial and antioxidant properties of spent coffee grounds (SCG) make them a potential ingredient in a diet for ruminants. This study investigated the effects of SCG on rumen microbiota. For 51 days, 36 dairy ewes were assigned to the experimental treatments (0, 30, 50, and 100 g SCG/kg). Ruminal samples were collected on day 50. DNA was extracted and subjected to paired-end Illumina sequencing of the V3-V4 hypervariable region of the 16S rRNA genes. Bioinformatic analyses were performed using QIIME (v.1.9.0). SCG increased dose-dependently bacterial diversity and altered bacterial structure. Further, 60, 78, and 449 operational taxonomic unit (OUT) were different between control and 30, 50 and 100 g/kg SCG groups, respectively. Higher differences were observed between the control and 100 g/kg SCG group, where OTU of the genera Treponema, CF231, Butyrivibrio, BF331, Anaeroplasma, Blautia, Fibrobacter, and Clostridium were enriched with SCG. Correlations between volatile fatty acids (VFA) and bacterial taxa were sparser in the SCG groups and had little overlap. Certain bacterial taxa presented different signs of the correlation with VFA in SCG and control groups, but Butyrivibrio and Blautia consistently correlated with branched-chain VFA in all groups. SCG induced shifts in the ruminal bacterial community and altered the correlation networks among bacterial taxa and ruminal VFA.