Effects of low levels of mango peels (Mangifera indica L.) and apple pectin on in vitro-fermentability, digestive-physiological, and microbiological parameters in piglet nutrition

• Innovative use of by-products: The study evaluates mango peel and apple pectin as cost-effective, sustainable feed ingredients for piglets, leveraging their dietary fiber and pectin content. • Dual methodology: In vitro batch fermentation and in vivo feeding trials assessed effects on fermentation, nutrient digestibility, and gut microbiota. • Enhanced fermentation potential: Mango peel and apple pectin stimulated short-chain fatty acid production and bacterial activity in vitro, with mango peel showing higher substrate utilization. • Digestive impact: Low levels (1–2%) of mango peel and apple pectin caused minor changes in piglet digestion and microbiota composition but maintained performance. • Future directions: Dose-response studies are recommended to optimize the inclusion levels of these by-products for practical application in pig nutrition. Food processing by-products such as mango peel and apple pectin present valuable sources of dietary fibre, pectins and various other beneficial compounds for pig nutrition. The study's objective was to explore the effects of incorporating mango peel and apple pectin into pig feed. Batch fermentations using sow faeces were conducted to assess the fermentability of the substrates over a 24-hour incubation period. Subsequently, a feeding experiment was conducted using post-weaning piglets to examine the impact of adding 1 % or 2 % (w/w) mango peel and apple pectin to their diet. The in vitro fermentation studies with sow faeces showed increasing lactate and short-chain fatty acid concentrations when apple and mango pectin were added as substrates. The feeding trial indicated no significant impact on piglets' performance, nor the apparent praecaecal digestibility of crude protein was altered, while the apparent praecaecal digestibility of crude fat decreased with the addition of 1 % apple pectin, but increased with 2 % mango peel. Concentrations of microbial metabolites in the digesta were similar, and only slight variations were observed in the bacterial levels as determined by qPCR. In the treatment groups, enhanced utilisation of mango peel and apple pectin by the faecal microbiota was noted compared to the control group (BIOLOG test). In summary, incorporating small quantities of mango peel and apple pectin resulted in only mild alterations within the piglets' digestive system. Additional research to determine the optimal levels for effective usage of mango peels and apple pectin in piglet diets is required.