Use of recycled co-products from the food industry: Effects on nutrient digestibility and growth performance in pigs from 7 to 23 kg

We studied the effects of the inclusion of recycled co-products from the food industry (yogurt, milk, cheese and baby foods) in diets for pigs weaned at 25 days of age. From day 1–21 of the experiment (Phase I), 8 treatments were organized as a 2 × 4 factorial with 2 levels of lactose (70 and 100 g/kg) and 4 diets differing in the food co-products used. The control diet was based on cooked wheat, fish meal, and dried whey, without any food co-product. Diets D2 and D3 included 150 g/kg lactal (yogurt and milk sprayed onto a cereal carrier) or 150 g/kg lactal-cheese (yogurt, milk and cheese sprayed onto the same carrier) in substitution of dried whey and fish meal of the control. Diet D4 was similar to D3 but in addition to 150 g lactal-cheese, included 200 g/kg of recycled baby foods (composed primarily of hydrolysed and processed cereals) in substitution of cooked wheat. From day 22–35 (phase II) all pigs received a common cereal-soybean meal diet. In phase I, an increase in the lactose content in the diet increased average daily feed intake (ADFI; P < 0.05) and average daily gain (ADG; P < 0.01). The inclusion of food co-products in the diet, however, did not affect ADG. At 14 days post-weaning, the total tract apparent digestibility of nutrients improved as the lactose content of the diet increased, and was greater in pigs fed D4 than in pigs fed any of the other diets (P < 0.05). In phase II, pig growth was not affected by previous dietary treatment. For the entire experiment, ADFI tended to increase (P = 0.065) in pigs fed the high lactose diets in phase I and was higher (P < 0.05) in pigs fed the D4 diet in phase I than in pigs fed the D2 diet, with pigs fed the other diets being intermediate. The ADG and the gain to feed ratio, however, were not affected. Cumulatively, post-weaning diarrhoea was not affected by the level of lactose or the type of diet used. In conclusion, increasing the lactose content of the diet after weaning from 70 to 100 g/kg improved pig performance. The food co-products tested can be used successfully in substitution of high quality ingredients, such as dried whey, fish meal and heat processed cereals, in diets for weanling pigs, without any negative effect on growth performance.