Effect of salty or sweet food leftover based diets on serum metabolites in piglets

Nowadays, agriculture and livestock production face several challenges for what concerns sustainability. In particular, animal feed production competes with human food production for the use of lands and natural resources. The use of alternative feed ingredients could thus increase the sustainability of livestock production. In this study, conventional cereal grains have been partially replaced by confectionery or bakery former food products (FFPs) in pigs’ diets to evaluate their effect on pig serum metabolites. FFPs are safe and healthy ingredients produced for human consumption, but no longer intended for this purpose. Specifically, 36 post-weaning female piglets were fed with three different diets: (1) control diet (CTR), 0% FFPs; (2) FFP-C diet, (30% cereals replaced by 30% confectionery FFPs); (3) FFP-B diet, (30% cereals replaced by 30% bakery FFPs). The diets were formulated to meet the NRC requirements and to be iso-energetic (15.3MJ/kg DM) and iso-nitrogenous (19% CP DM). During the 42 days of trial, blood samples were collected on days 0 (t0), 21 (t1) and 42 (t2). The serum metabolites, measured using a standard enzymatic colorimetric analysis, were: total proteins, albumin, globulin, albumin/globulin (A/G), urea, alanine aminotransferase (ALT-GPT), aspartate aminotransferase (AST-GOT), alkaline phosphatase (ALP), total bilirubin, glucose, triglycerides (TG), non-esterified fatty acids (NEFA), α-amylase, total cholesterol, calcium, phosphorus, magnesium. Data were analyzed using one-way analysis of variance (one-way ANOVA) and further explored by principal component analysis (PCA). The results showed that the levels of serum metabolites were similar across the three experimental groups in the three different time points. The only exceptions were observed for α-amylase and TG. In particular, α-amylase tended to be lower in both experimental groups (FFP-C and FFP-B) in comparison with CRT group throughout the experiment, whereas TG were lower in the FFP-C experimental group only at t1. In conclusion, the inclusion of FFPs (up to a level of 30%) in post-weaning piglets’ diet does not lead to a significant perturbation of the level of several serum metabolites, thereby enhancing the hypothesis of their reuse in animal nutrition. However, further studies are needed to strengthen these results and increase the knowledge. Acknowledgements This study was performed as part of the SUSFEED project funded by Cariplo Foundation (SusFEED-Rif. Pratica: 2018-0887).