PS7-5. Understanding the Impact of Oxidized Chicken Meal on Product Acceptance Through Metabolomics, E-nose, and Palatability Trials with Working Labrador Retrievers.

Abstract Palatability is essential for successful pet food; however, the oxidation state of high-protein ingredients poses a major challenge to large-scale producers. To better understand how oxidation impacts quality of canine diets, this study assessed palatability, digestibility, and odor profiles of extruded kibble produced with varying levels of oxidized chicken meal in working Labrador Retrievers. Oxidation of rendered chicken meal was induced through heating at 100 °C in an oven and incorporated into 4 different complete and balanced extruded diets based on length of oxidation: 0hr (control), 24hr, 72hr, or 120hr. Oral and aromatic palatability were assessed using the two-pan preference test with a panel of 20-dogs. ATTD of each diet was determined using the indicator method using twenty-four dogs (n = 8 per diet). Odor profiles of the meal and diets were assessed using gas chromatography mass spectrometry (GC-MS), GC-MS solid phase microextraction (SPME), and electronic nose (E-nose) technology. In oral palatability trials, there was a decrease in first-bite preference for the 72 and 120-hour oxidized diets (P < 0.05) and decreased intake ratio for the 24 and 120-hour oxidized diets compared to control diet (P < 0.05). Percent consumed decreased for the 120-hour oxidized diet (P < 0.05). There was no preference over control based on first-approach for any diet (P ≥ 0.34). In aromatic palatability trials, there were no differences in percent interaction time (P ≥ 0.24) or rate of first approach (P ≥ 0.26). ATTD for dry matter and metabolizable energy were decreased in diets containing chicken meal oxidized for 120 hours compared to 72 hours (P < 0.05). Oxidation tended to affect crude protein (P = 0.07) and nitrogen-free extract digestibility (P = 0.05), but post-hoc analysis showed no differences among diets. Crude fat digestibility did not differ among diets (P = 0.34). GC-MS analysis revealed differences in non-polar and polar metabolites between the raw chicken meal and extruded diets. Differences were observed for the same metabolites across different oxidation levels. Nearly all non-polar metabolites were found to be significantly more abundant in the raw chicken meal. GC-MS SPME analysis revealed differences in non-polar metabolite profiles between the raw chicken meal and the extruded kibble, with 1-undecanol significantly higher in the chicken meal. 1-undecanol increased with increasing oxidation in both meal and kibble (P < 0.05). E-nose analysis showed that overall flavor intensity increased with oxidation: raw chicken meal exhibited greater flavor intensity at each oxidation level than the respective diet. Our findings suggest that even minimal oxidation of rendered meat meals negatively impacts the oral palatability of pet food and alters odor profiles. Furthermore, we found that the changes induced by oxidation of raw ingredients can negatively impact the oral palatability of the extruded product.