Enzymatic digestion turns food waste into feed for growing pigs

Fruit, vegetable, meat, and dairy food waste were collected from supermarkets and enzymatically digested to generate food waste products, containing 90% smaller particles of food waste (SPFW) and 10% larger particles of food waste (LPFW). The objectives of this experiment were to determine the chemical composition of the enzymatically digested food waste products and to evaluate if these products may be used in diets for growing-finishing pigs. On average, SPFW contained 220.5 g/kg dry matter (DM), whereas LPFW contained 289.8 g/kg DM. On a DM basis, SPFW contained 220.5 g/kg crude protein, 365.8 g/kg crude fat, 4.8 g/kg Ca, and 3.3 g/kg P. Larger particle food waste contained 195.3 g/kg crude protein, 344.3 g/kg crude fat, 26.9 g/kg Ca, and 11.2 g/kg P. On a DM basis, total indispensable amino acids were 100.7 g/kg in SPFW and 79.9 g/kg in LPSF, whereas total dispensable amino acids were 117.6 g/kg in SPFW and 95.7 g/kg in LPSF, respectively. A relatively high variability was observed in concentrations of minerals and fiber among batches of LPFW than SPFW. Fifty-six crossbred pigs (approximately 32.99 kg initial body weight (BW)) were randomly allotted to one of 2 dietary treatments with 7 replicate pens per treatment and 4 pigs per pen (2 barrows and 2 gilts). A 3-phase feeding program was used with day 0 to 28 as phase 1, d 28 to 53 as phase 2, and d 53 to 79 as phase 3. The 2 dietary treatments were a control diet based on corn and soybean meal and a liquid diet with the mixture of SPFW and LPFW (90:10, vol:vol). In phases 1 and 2, pigs were fed control or liquid diets, whereas all pigs were fed the control diet in phase 3. Compared with the control diet, pigs fed the liquid diet had lower (P < 0.05) body weights throughout the experiment due to reduced (P < 0.05) DM intake. Pigs fed the liquid diet tended to have increased (P = 0.082) gain:feed in phase 3. In conclusion, the enzymatically digested food waste may provide nutrients on a DM basis that are close to the nutrient content in a corn-soybean meal diet fed to growing-finishing pigs.