Evaluation of fruit–vegetable and fish wastes as alternative feedstuffs in pig diets

Fruit–vegetable and fish wastes were evaluated as potential feedstuffs for growing-finishing pigs. Wastes were collected from shops in the city of Salamanca (Spain) and their nutritional composition, mineral content and digestibility were determined. The dry matter of the wastes under study was relatively low (12% for fruit–vegetable waste and 26% for fish waste), but they presented all of the nutrient requirements for swine diets. The fish waste contained 58% crude protein, 22% ash, 19% ether extract and 1% crude fibre, whereas the fruit–vegetable waste contained 65% nitrogen free extract, 13% crude fibre, 12% crude protein, 8% ash and 2% ether extract. Waste digestibility decreased with temperature, and hence temperatures over 65 °C for fruit–vegetable waste and 105 °C for fish waste should not be used in the treatment to reduce the moisture and to ensure the microbiology quality. Therefore, two diets were formulated using linear programming. The analysed waste was included in approximately 20% of one of the diets, while another diet was formulated without any type of waste. These data showed that this part of biodegradable municipal waste could be managed as alternative feedstuffs in swine diets, reducing the amount of biodegradable municipal waste going to landfills.