Dietary Chinese herbal extract mixture improves reproductive performance and external quality of fertilized eggs in Chinese soft-shelled turtle (Pelodiscus sinensis) broodstock

The reproductive performance of P. sinensis broodstock has gradually declined due to degenerated wild genetic resources, frequent extreme weathers and inbreeding in recent years. This study investigated the effect of Chinese herbal extract mixture (Herba Epimedii, Herba leonuri and Semen Vaccariae, termed as CHEM) on reproductive performance of turtle broodstock, external and internal quality traits of fertilized eggs. Six levels of CHEM at the rate of 0%, 0.1%, 0.2%, 0.4%, 0.8% and 1.6% were incorporated into the basal diet of turtle broodstock for six weeks. Each diet was randomly allocated into three greenhouse cement spawning ponds with 1000 turtles in each pond. The female-to-male ratio of the broodstock with about 8 years old was around 8: 1. The results revealed that dietary supplementation of 0.1% CHEM significantly improved daily feed consumption (DFC) and daily egg laying amounts (DELA) of turtles compared with that in control group (P < 0.05). The fertilization rate (FR) and hatching rate (HR) were significantly increased by more than 18% or 20% in CHEM supplemented groups compared with those in control group, respectively (P < 0.05). With regard to quality of fertilized egg, dietary CHEM addition elevated weight and size of fertilized eggs and shell weight, and the improved effect was most obvious in 0.8% CHEM group (P < 0.05). Interestingly, dietary CHEM also significantly improved eggshell quality, including compressive strength and calcium content (P < 0.05). Broken-line analysis based on repro-ductive parameters (DELA, FR and HR) against dietary CHEM indicated that the optimal dose range of CHEM in Chinese soft-shelled turtle broodstock was 0.063-0.186%.