Biofumigation to Reduce Swine Parasite Contamination on Organic Pastures

Abstract Parasite infection is a common problem in organic pig production. Pastures grazed by infected pigs can become sources of parasite transmission because parasite eggs can survive in soil for several years. Biofumigation is a method used by farmers to reduce plant pathogens and nematodes in soil by incorporating plant residues into the soil that rapidly release toxic isothiocyanates. This study explored whether grazing crops with biofumigation properties affects parasite fecal egg counts of pigs managed organically, and subsequent parasite eggs in organic pasture soil after biofumigation. A study was conducted using 66 pigs (BW = 72.6 kg ± 21.2 SD) that were raised organically in two blocks. Within each block, pigs were housed in four pens (8 to 9 pigs/pen) and provided feed ad libitum in a hoop barn. Each pen had access to a pasture (0.5 acres). Each pasture was subjected to one of four management treatments: control pastures (Ladino clover) or biofumigation pastures (Rapeseed), each with or without incorporating plant residues. Each pasture was split into four paddocks (9.1m × 10.7m) and pigs were given access to each paddock for one week. Fecal samples (n = 198) were collected from each pig before, two and four weeks after grazing. Triple soil samples (n = 480) were collected from each paddock before grazing, immediately after pigs were removed from pasture paddocks, and weekly thereafter for three weeks. Fecal and soil samples were analyzed for Ascaris suum, Trichuris suis, and Oesphagostomum spp. eggs. Data were analyzed using a mixed model with pen or paddock as the experimental unit. Fecal egg counts of the three parasite species did not differ between pigs that grazed on pastures with different management treatments. All pigs had drecreased Ascaris suum (P < 0.01) and Trichuris suis (P < 0.01) fecal egg counts after four weeks of grazing compared with before grazing. Both clover and rapeseed pastures without incorporating plant residue had decreased Ascaris suum egg counts in the soil compared with incorporating plant residue (both P < 0.05). Rapeseed pastures without incorporating plant residue had reduced (P < 0.05) Trichuris suis egg counts in the soil compared with clover pastures but did not differ from rapeseed pasture with incorporated plant residue. Across pasture management treatments, Ascaris suum and Trichuris suis eggs in the soil were reduced (P < 0.05) two and three weeks after pigs were removed from pastures compared with before, immediately after, and one week after pigs were removed. These results suggest that grazing pastures crops with biofumigation properties did not affect fecal egg counts of pigs. While the number of parasite eggs decreased overtime in pasture soil, biofumigation may not be an effective way to reduce swine parasite eggs in organic pastures.