Lipid Peroxidation Decreases Performance and Viability of Nursery Pigs

The objective of this study was to investigate the impact of lipid peroxidation in a dose-dependent manner on performance, health, medical treatment, viability and oxidative status of nursery pigs. Pigs (n=2,200; BW=5.95±0.2 kg) were housed in 100 pens with 22 pigs/pen in a RCBD based on initial BW and sex and assigned to 5 dietary treatments. Treatments consisted of corn-soybean meal based diets supplemented with 5% of either control corn oil (FFA=0.06%, anisidine value=2.5, peroxide value=4.8 mEq/kg oil) or corn oil peroxidized with air at 20 L/min at 60°C for 12 days (FFA=0.35%, anisidine value=30.4, peroxide value=162.6 mEq/kg oil). Diets were blended to obtain 0, 25, 50, 75, and 100% degrees of peroxidation. Pigs were fed a 3-phase nursery diet program (7, 13, and 23 d, respectively). Pigs were vaccinated with PRRS and Mycoplasma hyopneumoniae (Mhyo) mixed vaccine at placement and PCV2 and Mhyo combination vaccine at 9 weeks of age. Blood samples were collected from 10 light- and 10 heavy-weight pigs per treatment prior to and 14 d after the second vaccine dose to determine serum antibody titers, oxidative stress and vitamin E concentrations. There were no differences in ADG and ADFI among treatments. Gain:feed decreased linearly with increasing peroxidation (P=0.02) during the first 20 d and overall (665, 669, 664, 659, 652 g/kg for 0, 25, 50, 75 and 100% peroxidation). Pigs pulled, culled, treated and mortality increased linearly (P<0.05), while percentage of full-value pigs (98.9, 97.8, 96.6, 95.2 and 95.9%, for 0, 25, 50, 75 and 100% level) decreased linearly (P<0.05) with increasing peroxidation. Final pen gain, which considers mortality and culls, decreased linearly (P<0.01) with increasing peroxidation (341, 317, 311, 303 and 305 kg, for 0, 25, 50, 75 and 100% level). Antibody titers to Mhyo and PCV2 increased post-vaccination (P<0.01), but were not affected by peroxidation. Serum MDA was 19% higher in heavy pigs than light weight pigs (P<0.01), but was not affected by peroxidation. Total antioxidant capacity and vitamin E concentrations were 10% higher (P<0.04) in heavy weight pigs (P<0.03) than light weight pigs and decreased (P=0.05) linearly (1.24, 1.32, 1.23, 0.99, 1.15 ppm serum vitamin E for 0, 25, 50, 75 and 100% peroxidation) as peroxidation increased. Data indicate a progressively negative impact of lipid peroxidation on pig productivity measured under field population conditions, which was primarily related to increased mortality, number of pigs medicated, and number of pigs that were excessively light.