Characterization and anaerobic digestion of manure from pigs submitted to feed restriction or supplemented with ractopamine or chromium

Abstract The aim of this study was to characterize the production and anaerobic digestion of manure from finishing pigs subjected to feed restriction or supplemented with ractopamine or chromium (Cr). The waste came from 50 barrows in the finishing phase, aged ± 154 days, with a starting weight of 99.0 ± 4.4 kg and a final weight of 117.2 ± 5.8 kg. The experimental diets were as follows: control (conventional diet), qualitative restriction (7.5% reduction in net energy compared to the control diet), quantitative restriction (15% reduction in feed supply), Cr (0.8 mg), and ractopamine (10 ppm). The data were subjected to an analysis of variance using a randomized block design, in which the weeks of analysis were considered blocks (cofactors). There were no differences in manure production between the diets regarding natural matter (NM), dry matter (DM), mineral matter (MM), or organic matter (OM). Animals fed the control diet had the highest residue coefficient, and there was no difference among the other diets. No differences were observed among the diets regarding total solids, pH, or total nitrogen in the tributaries or effluents. The highest biogas yield (574 mL g-1) of added volatile solids (VS) was obtained in the digesters supplied with manure from animals fed a qualitatively restricted diet. It can be concluded that a qualitatively restricted diet results in higher manure production but with lower nitrogen and phosphorus excretion and higher biogas yields. Resumo Realizou-se este estudo com o objetivo de caracterizar a produção e a digestão anaeróbia de dejetos de suínos em terminação submetidos a restrição alimentar ou suplementados com ractopamina ou cromo. Os dejetos foram provenientes de 50 suínos machos castrados, em fase de terminação, com ± 154 dias de idade, com peso inicial de 99,0 ± 4,4 kg e final de 117,2 ± 5,8 kg. As dietas experimentais foram: controle (dieta convencional); restrição qualitativa (redução de 7,5% de energia líquida em relação à dieta controle); restrição quantitativa (redução de 15% no fornecimento de ração); cromo (0,8 mg); e ractopamina (10 ppm). Os dados foram submetidos à análise de variância por meio do delineamento em blocos ao acaso, no qual as semanas de análises foram consideradas como blocos (cofator). Não foram observadas diferenças entre as dietas nas produções de dejetos na matéria natural (MN), matéria seca (MS), matéria mineral (MM) e matéria orgânica (MO). Animais que receberam a dieta controle apresentar