37. In vitro and Invivo Evaluation of Potato Protein as Alternative Protein Source for Weaning Piglets

Abstract Locally sourced protein ingredients and food industry by-products are increasingly considered sustainable alternatives to imported soybean meal (SBM) in pig nutrition. Potato protein concentrate (PPC), a by-product of starch extraction, exhibits variable nutritional and anti-nutritional profiles depending on processing methods and potato cultivar. This study aimed to evaluate four PPC sources with differing glycoalkaloid concentrations on growth performance and health parameters in post-weaning piglets, alongside in vitro protein digestibility kinetics. Protein digestibility of SBM and PPC was assessed using a two-phase in vitro digestion model simulating gastric and small intestinal conditions. Samples were incubated at 39 °C for 7.5 h, with pepsin added at pH 3.5 for 1.5 h followed by pancreatin and bile extract at pH 6.8 for 6 h. Dry matter and crude protein in supernatants were analyzed at 0, 0.5, 2, 4, and 6 h to classify fast (0–0.5 h), slow (0.5–4 h), and resistant ( >4 h) protein fractions. SBM exhibited significantly higher fast protein (69.9%) than PPC (37.5%), while PPC had greater slow (12.7%) and resistant (49.9%) fractions compared to SBM (2.3% and 27.7%, respectively). In vivo, 1,030 piglets (24 days old, 6.55 ± 0.39 kg) were allocated to five dietary treatments: a negative control (SBM-based) and four PPC diets (6% inclusion d0-14, 3% inclusion d14-42). Glycoalkaloid levels ranged from 80.9 to 3080 mg/kg, with α-solanine and α-chaconine varying across sources. Over 42 days, pigs were monitored for body weight (BW), feed intake (FI), average daily gain (ADG), feed conversion ratio (FCR), faecal consistency, and survivability. Data were analyzed using fixed effects of treatment and sex, with initial BW as covariate. No significant differences in BW were observed across treatments. SBM-fed pigs showed higher ADG from d28 onwards (P = 0.0542), likely due to greater fast protein availability and numerically higher FI. Despite the known bitter taste of glycoalkaloids, which can suppress feed intake, no linear correlation was found between increasing glycoalkaloid concentrations and ADFI across PPC treatments. Despite in vitro results indicating significantly higher levels of resistant protein in PPC compared to SBM—suggesting a potential for increased hindgut fermentation and diarrhoea—faecal scores observed in vivo did not reflect this expectation. SBM-fed piglets showed significantly higher faecal scores during the d14-28 period (P = 0.0075), and PPC treatments tending toward improved overall faecal scores (P = 0.0538). Moreover, mortality was significantly higher in SBM in comparison with 3 out of the 4 PPC (P < 0.05). In conclusion, while PPC showed lower in vitro digestibility and hence lower in vivo growth performance compared to SBM, it demonstrated improved health outcomes and may offer a viable sustainable alternative depending on glycoalkaloid content.