Evaluation of the impact of the dietary inclusion of salty and sug-ary former food products on the liver and the plasma profile of pigs through OMICS approaches

Former food products (FFPs) are industrial bakery and confectionery food leftovers no longer intended for humans due to commercial or manufacturing defects, although being still suitable as feed. FFPs have more energy, fats and sugars than cereals and have been studied in mo-nogastric. Here, we replaced 30% cereals with FFPs in growing to finishing pig diets and eval-uated growth performance, meat quality, and impact on metabolism. Thirty-six Swiss Large White male pigs were assigned to three groups (12 animals/group): i) CTR, control diet (cere-als); ii) SA, 30% cereals replaced with salty FFPs; iii) SU, 30% cereals replaced with sugary FFP (SU). The trial lasted around 110 d from growing phase (22.4±1.7 kg, 60±3.8 d) to slaugh-ter (110±3 kg, 159±7.42 d), with growth performance monitored throughout. Liver tissue and blood samples were collected at the end and nano-LC HR-MS-MS was applied on liver proteo-me (6 samples/group, 18 samples in total) and plasma peptidome (1 sample/animal, 36 samples in total) to assess the potential metabolic impact of FFPs. Growth performance was analysed with MIXED procedure by SAS software. Meat quality, fatty acid profile and sensory data (1 sample/animal, 36 samples in total) were analysed by ANOVA after checking normality and homoscedasticity using R software. For omics data, MaxQuant software was used to process raw data and Perseus software for data interpretation. Results were statistically significant when P<0.05. FFP-fed pigs showed no difference in growth performance compared to CTR group. The SA and SU diets slightly modulated muscle and backfat fatty acid profile as well as meat sensory traits, but meat quality was not altered. The SA and SU diets significantly upregu-lated (log2 FC>0.57) and down-regulated (log2 FC<-0.57) a limited number of proteins (125 out of 2881) mostly related to lipid metabolism and cell structure with no metabolic interaction among them, indicating a limited impact of FFPs diets on liver function. Plasma peptidomes were not significantly different among groups, although three peptides related to vascular ho-meostasis and anti-hypertension were exclusively identified in the SA group, suggesting a po-tential self-regulating response to face the higher Na content of the SA diet. Overall, FFPs in-clusion was safe for pig welfare, with no unintended effect on metabolism, thus supporting the idea of a wider application of FFPs as feed ingredients to reduce feed-food competition and food waste.