Influence of feeding thermally peroxidized lipids on the performance of growing pigs

Feeding pigs lipids containing high levels of lipid oxidation products (LOP) has been shown to reduce growth performance, but data is lacking on quantitative relationships between LOP and pig growth, feed intake, and feed efficiency. Four experiments (EXP) were conducted using soybean oil (SO) in EXP 1, 2, and 3, as well as SO, choice white grease and palm oil (PO) in EXP 4, to evaluate the impact of feeding diets containing different amounts of LOP on pig performance. Lipid peroxidation was carried out using variable heating temperatures and durations to generate lipids with a broad range of peroxide (PV, mEq) and anisidine value (AnV, unitless). Lipids were added to the diets at 10%, 10%, 8%, and 7.5% for EXP 1, 2, 3, and 4, respectively, with dietary PV and AnV calculated using lipid peroxidation concentrations of PV and AnV times the dietary lipid inclusion rate. Within each experiment, pig performance (6.2 to 13.4 kg, EXP 1; 13.5 to 23.7 kg, EXP 2; 20.3 to 36.9 kg, EXP 3; 29.6 to 44.1 kg, EXP 4) was affected differently depending on dietary PV and AnV concentrations. Using the control-fed pigs within each experiment as a baseline of 100%, correlations of pooled relative pig performance data (dependent variables of ADG, ADFI, and GF) from EXP 1, 2, 3, and 4 with their respective dietary LOP values (independent variables of dietary PV and AnV due their ability to be measured commercially) resulted in significant (P ≤ 0.01) regression equations for relative ADG [ADG, % = 101.2 - [(0.321 × PV) + (1.019 × AnV)], R2 = 0.81], ADFI [ADFI, % = 100.8 - [(0.320 × PV) + (0.629 × AnV)], R2 = 0.68], and GF [GF, % = 101.3 - [(0.016 × PV) + (0.525 × AnV)], R2 = 0.70], albeit PV was not a significant regression coefficient in the GF model (P = 0.90). This data shows that the values of primary and secondary LOP (i.e., PV and AnV, respectively) could be effectively used in predicting the effect of feeding oxidized lipids on growth, feed intake, and feed efficiency in growing pigs.