Comparative Evaluation of the Effectiveness of Using Quinoa Grain (<i>Chenopodium quinoa</i> Willd.) with High and Low Saponin Content in Broiler Chicken Feeding

The aim of this study was to conduct a comparative analysis of the effects of native quinoa grain with a high saponin content and quinoa grain subjected to preliminary saponin removal with low saponin content on growth, meat quality, biochemical blood composition, and the expression of genes related to muscle growth, gut health, and nutrient transport in broiler chickens. The control group of chickens received a standard diet. The SAP group feed contained quinoa grain without saponin removal (saponin level—5.20%) at 3% of the “Starter” feed mass and 5% of the “Grower” and “Finisher” feeds, maintaining the same nutritional values as the control group. The SAP-FREE group feed contained quinoa grain that was pre-treated to remove saponins by washing with water for 60 min at a temperature of 50 °C (saponin level—0.24%) in the same amount as the SAP group. The research results indicated certain advantages of unprocessed quinoa grain in relation to saponin content. Specifically, in the SAP group, the broiler performance index was at the same level as the control, while the SAP-FREE group had a high mortality rate (10%), resulting in a performance index that was 23.82 units lower than the control. The use of quinoa grain with high saponin content promoted better development of thigh muscles by 9.6% compared to the control (<i>p</i> = 0.008) and increased yields of wing, neck, and back muscles by 2.9 abs.% (<i>p</i> = 0.007) compared to the use of purified quinoa grain. The fat yield decreased by 1.7 abs.% (<i>p</i> = 0.015) with saponin-free quinoa compared to the control and by 2% (<i>p</i> = 0.008) compared to the high saponin group, making this feeding system viable for producing dietary meat. Upon stopping the feeding of purified quinoa, chickens showed a 34.0% increase in AST activity (<i>p</i> = 0.019) and a 15.7% increase in creatinine levels (<i>p</i> = 0.008), likely indicating intensified protein metabolism upon cessation of the inhibiting factor of purified quinoa. Molecular genetic studies revealed a 1.6-fold increase in IGF1 gene expression (<i>p</i> = 0.014) in breast muscle and a 69.12-fold increase (<i>p</i> = 0.010) in AvBD9 in the cecum due to high-saponin quinoa grain, while purified quinoa increased GHR gene expression by 3.29 times (<i>p</i> = 0.039) in breast muscle and decreased IRF7 activity to 2^−ΔΔCT = 0.54 (<i>p</i> = 0.017). The expression of transporter protein genes decreased to low or undetectable levels, indicating the presence of anti-nutritional factors and the need for further research on feeding quinoa with the addition of proteases. Thus, high-saponin quinoa grain, unlike purified quinoa, positively influences gut health and bird survival, maintaining performance levels similar to the control, suggesting the feasibility of using unprocessed quinoa in poultry nutrition, thus avoiding additional costs in feed preparation.