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Peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) as indicators of dietary lipid peroxidation, reduced growth performance, and metabolic oxidation status when feeding peroxidized lipids to pigs and broilers
To evaluate the impacts of dietary peroxidized lipids on the growth and metabolic oxidation status of nonruminants, data were summarized from studies that measured growth performance of pigs (n = 16 comparisons) and broilers (n = 26 comparisons) fed diets containing peroxidized lipids. Only studies evaluating supplemental lipid sources when feeding isocaloric diets within each comparison were included. Dietary TBARS and PV were obtained from each study, along with response variables including ADG, ADFI, G:F, and serum or plasma concentrations of vitamin E and TBARS. Data were evaluated using UNIVARIATE and CORR procedures of SAS. Overall responses for swine and broilers fed diets with peroxidized lipids showed that ADG was 88.8 ± 12.5% (range = 49.8 to 104.6%), ADFI was 92.5 ± 9.0% (range = 67.8 to 109.8%), and G:F was 95.7 ± 7.2% (range = 70.4 to 106.3%) relative to animals fed diets with unperoxidized lipids. The magnitude of reduction from feeding diets with peroxidized lipids relative to diets with unperoxidized lipids for ADG (11.4 vs. 11.1 %) and ADFI (8.8 vs. 6.6 %) were similar for swine and poultry, respectively. This finding suggests that the growth performance of both species is reduced to a similar extent when feeding peroxidized lipids. For swine, ADG was negatively correlated with dietary TBARS content (r = - 0.63, P = 0.05), but not PV. Conversely, dietary PV was negatively correlated with ADG in broilers (r = - 0.78, P < 0.01), but dietary TBARS concentrations were not reported in any of the 26 broiler studies. The difference in magnitude of change for ADG (11.2%) compared to ADFI (7.5%) suggests that factors in addition to caloric intake contribute to reduced ADG when feeding peroxidized lipids. For swine and broilers fed peroxidized lipids, serum content of vitamin E was 53.7 ± 26.3% (range = 15.2 to 105.8%, n = 18) and TBARS was 119.7 ± 23.3% (range = 97.0 to 174.8%, n = 12) relative to animals fed unperoxidized lipids, indicating that inclusion of peroxidized lipids in diets contributes to changes in metabolic oxidation status. Historically, PV has been used to assess lipid peroxidation, but TBARS may be a better measure for predicting the effects of lipid peroxidation on growth in swine. Future research is necessary to develop an accurate model for predicting reductions in growth performance and metabolic oxidation status when feeding diets containing peroxidized lipids.
Keywords: broiler, swine, lipid peroxidation