Effects of peroxidized soybean oil on growth and energy digestibility in broilers

Peroxidized lipids have been shown to reduce broiler performance whereupon it was theorized that dietary peroxide value (PV) plus anisidine value (AnV) may be predictive of broiler performance. In experiment (EXP) 1, 64 pens (8 broilers/pen) were fed diets containing 8 levels of peroxidized soybean oil (SO). Broilers were fed diets from 7 to 35 d of age with 8 replications per dietary treatment. Broilers fed diets containing SO processed at 135°C resulted in a reduction in average daily gain (ADG) and average daily feed intake (ADFI, P ≤ 0.05) compared to birds fed diets containing the unheated SO while birds fed diets containing SO processed at 90°C resulted in a reduction in gain to feed (GF, P ≤ 0.05) compared to birds fed diets containing the unheated SO. Summarization of this data with published data resulted in significant (P ≤ 0.01) regression models for relative ADG [ADG, % = 101.9 - (0.05 × PV) - (0.30 × AnV), SE = 4.1, R² = 0.43], ADFI [ADFI, % = 101.7 - (0.09 × PV) - (0.19 × AnV), SE = 3.3, R² = 0.32], and GF [GF, % = 100.4 + (0.05 × PV) - (0.14 × AnV), SE = 2.6, R² = 0.27], albeit PV was not a significant regression parameter (P ≥ 0.36) for any equation. In EXP 2, the TME_n of four different SO was determined using the precision-fed rooster assay. Diets consisted of ground corn with SO added at 0, 7.5 or 15 % of the diet at the expense of ground corn with 4 roosters per treatment. Relative bioavailability (RBV) was determined using slope-ratio methodology where it was determined that the reduction in the RBV of peroxidized SO ranged from 12 to 29 percent compared to the unheated SO sample. These data suggests that bird performance relative to birds consuming unperoxidized lipids can be predicted based on dietary levels of PV and AnV, although the slopes for performance decline are relatively flat with the combination of PV and AnV accounting for 27 to 43 % of the response variable variance.