Effects of Dietary Supplementation of Quillaja Saponin or Phytase on the Growth Performance, Nutrient Digestibility, Faecal Gas Emissions, and Carcass Grade in Growing-Finishing Pigs

This experiment aimed to evaluate the effects of low doses of Quillaja saponin (QS) or phytase (PHY) on growth performance, nutrient digestibility, faecal gas emissions, and carcass grade in growing-finishing pigs. A total of 72 pigs (Landrace x Yorkshire x Duroc), each weighing 25.82 +/- 1.68 kg, were selected and randomly assigned to three treatment groups. Each group had six replicates, with four pigs per pen, and the allocation was based on the four initial body weight and sex of the pigs. They were randomly divided into the following three diet groups: the basal diet as a control (CON) group, the basal diet + 0.02% PHY; and the basal diet + 0.01% QS. The experiment period lasted for 110 days. The results of adding 0.01% QS to the basal diet of pigs show that it can significantly increase the body weight (BW) of growing-finishing pigs on the 110th day (p < 0.05). QS can significantly increase the average daily weight gain (ADG) on Days 80-110 of the experiment (p < 0.05). QS can significantly increase the total average daily weight gain (TADG) of growing-finishing pigs during the entire experimental period (p < 0.05) and has a tendency to improve the average daily feed intake and feed conversion rate during the entire experimental period. However, QS has no significant effect on pig nutrient digestibility and carcass grade. In addition, we also found that QS has a tendency to reduce carbon dioxide emissions. However, adding 0.02% PHY to the basal diet of growing-finishing pigs can only increase the TADG during the entire experimental period. Throughout the experiment, adding PHY to the diet had no significant impact on the nutrient digestibility, faecal gas emissions, and carcass grade of growing-finishing pigs. In summary, adding QS to feed can significantly improve the growth performance of growing-finishing pigs, and has a tendency to improve faecal gas emissions. PHY can only improve the growth performance of growing-finishing pigs.