Quercetin from Sophora japonica alleviates growth retardation of broilers on a low protein diet

Abstract

Abstract The aim of this experiment was to study the effects of low dietary crude protein (CP) content and supplementation with quercetin on growth performance and further production parameters of broiler chicks. A total of 360 1-day-old broiler chicks were randomly assigned to one of 4 dietary treatments for a 35-day trial (starter, days 1–7; grower, days 8–21; finisher, days 22–35). There were 5 replicate cages and 18 birds per cage in each dietary treatment. Dietary treatments included standard CP content (SCP) diet, low CP content (LCP) diet, and LCP diet supplemented with 0.025 or 0.050% quercetin. The CP content of the diet was the same in the LCP group as in the SCP group on days 1–7, while it was lower than in the SCP group on days 8–21 (20.96 vs. 21.50% CP) and 22–35 (19.50 vs. 20.00% CP). Broiler chicks given the LCP diet had lower body weight gain (BWG) during days 8–21 and 1–35 and higher relative weight of abdominal fat than those given the SCP diet. Moreover, the addition of quercetin to the LCP diet resulted in a positive linear response in BWG during days 8–21 and 1–35 and a negative linear response in relative abdominal fat weight with the increase in quercetin dose. However, the nutrient digestibility, caecal microbiota, and excreta gas emission did not differ among the dietary groups. Therefore, supplementing quercetin ameliorated the growth deterioration and abdominal fat enhancement caused by reducing dietary CP content.