Nutrients content and in vitro digestibility of ex-food as feed ingredient for pig diets

Ex-food or Former Food Products (FFPs) represent a way by which losses from the food industry are converted into ingredients for the feed industry, thereby keeping food losses in the food chain. FFPs have been proposed as promising alternative feed ingredients. However, FFPs nutritional potential is not yet fully exploited. The aim of the present study was to perform a nutritional evaluation of selected FFPs. Six samples of mixed FFPs, all based on bakery products, were analysed for Dry matter (DM), Crude Protein (CP), Ether Extract (EE), Crude Fibre (CF), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), starch and ash. Nitrogen-Free Extractives (NFE) and Non-Structural Carbohydrate (NSC) were also calculated. Based on FFPs proximate analysis, Digestible Energy (DE) and Metabolizable Energy (ME) values for pigs were calculated. In vitro digestibility (IVD) of FFPs were evaluated using a multi-step enzymatic technique to predict the apparent total tract digestibility in pig. A wheat sample was included as control feed ingredient in the study. Data were analysed using IBM SPSS Statistics version 21 software (SPSS Inc.). In vitro digestibility values for FFPs samples were analysed using one-way analysis of variance in order to compare means. FFPs have shown a nutrient composition comparable to that of cereal grains. In the tested FFPs dry matter concentrations ranged from 912.8 g kg-1 to 937.6 g kg-1. The overall mean of CP content was 100 g kg-1 DM. Compared to wheat, FFPs were characterised by a relative high fat content (average EE 101.2 g kg-1 DM). The average starch content was 523.6 g kg-1 DM. Nitrogen-free extractives ranged from 611.7 g kg-1 DM to 746.8 g kg-1 DM, whereas NSC ranged from 585.4 g kg-1 DM to 792.7 g kg-1 DM. The relatively high NFE, NSC, starch and fat concentrations designated FFPs as valuable energy sources for pig. FFPs tested were characterized by valuable DE (17.2 MJ/kg) and ME (16.9 MJ/kg) values for pigs. However, DE and ME systems used may under/overestimate energy values due to the high lipid and starch content of FFPs. The average IVD value of FFPs samples (88.1 % ± 5.77) was comparable to IVD of wheat (90.6 % ± 1.62). In conclusion, FFPs can be considered a fat-fortified version of common cereals grains. The high-energy content and digestibility values elect FFPs as promising non-traditional ingredients for target animals as pig.