Effects of a partial to full replacement of soybean meal with <i>Arthrospira platensis</i> on apparent nutrient digestibility of diets for growing pigs

This study evaluated the effects of replacing soybean meal (SBM) with <i>Arthrospira platensis</i> (AP) on nutrient digestibility of diets for growing pigs and provided a preliminary estimation of AP <i>in vivo</i> digestibility and energy content. The digestibility trial involved 88 pigs during the growing phase of a feeding trial. Pigs were divided into four treatments (AP0, AP33, AP66, and AP100) differing in the progressive SBM replacement with a blend composed of AP, sugar beet pulp, wheat meal, L-lysine, and L-tryptophan at 0, 333, 666, and 1000 g/kg, respectively. Feeds were supplemented with silica (10 g/kg) to increase acid insoluble ash (AIA) content, and individual faecal samples were collected after 71 d on feed, when pigs averaged 117 ± 6 kg of BW. Nutrient digestibility was calculated based on changes in AIA concentration from feed to faeces, while AP digestibility was estimated using the difference method. The metabolisable energy (ME) and net energy (NE) contents of AP were derived from its digestible nutrient contents. Replacement of SBM with the AP-based nucleus did not affect growth rate or the apparent digestibility of dry matter (DM) and most nutrients, except for crude protein (CP), which showed a significant decrease (−3.6%) in the AP100. The digestibility coefficients of DM and CP for AP averaged 861 ± 35.5 and 848 ± 11.5 g/kg, respectively, whereas estimated ME and NE contents averaged 16.2 ± 0.573 and 10.3 ± 0.394 MJ/kg DM, respectively. Overall, replacing SBM with AP in growing pig diets appears feasible in terms of nutritional attributes. SBM replacement with a AP-based nucleus had minor effects on the DM and nutrients apparent digestibilityApparent digestibility of DM and CP of AP averaged 861 and 848 g/kg, respectively, while its ME and NE contents averaged 16.2 and 10.3 MJ/kg DM.SBM replacement with AP in growing pigs appears feasible in terms of nutritional attributes SBM replacement with a AP-based nucleus had minor effects on the DM and nutrients apparent digestibility Apparent digestibility of DM and CP of AP averaged 861 and 848 g/kg, respectively, while its ME and NE contents averaged 16.2 and 10.3 MJ/kg DM. SBM replacement with AP in growing pigs appears feasible in terms of nutritional attributes