The growth-promoting effect of water extract of Chuanminshen violaceum stem and leaf on broilers.

Currently, developing nonantibiotic growth promoters is a broad consensus in broiler industry, which is one of the effective ways to reduce drug-resistant strains. Chuanminshen violaceum is a traditional Chinese medicinal herb that is commonly used for its roots, while the stems and leaves are often discarded, resulting in a huge amount of waste. This study optimized the preparation process of water extract of Chuanminshen violaceum stems and leaves (CVSLE) by response surface analysis based on the yields of polysaccharide and protein. The CVSLE and herbal powder (CVSL) were then processed into granules before being used as feed additives. The Macleaya cordata powder was used as positive control. The results showed that the addition of CVSLE (0.5% of the feed) showed the highest growth-promoting activity than other CVSLE groups (0.2% and 1%), 1% CVSL group and positive control (0.05%). CVSLE at the dosage of 0.5% could significantly increase the ADG and reduce the FCR from d 21 to 42, d 0 to 42. The HI antibody titers against Newcastle disease virus and avian influenza virus were significantly enhanced at 21, 28 and 42 d. CVSLE did not affect the slaughtering performances, but could significantly elevate the spleen, thymus and bursa of Fabricius indices and the transcriptional levels of IL-2, IL-4, IL-10 and IFN-γ in spleen. The intestinal barrier function of broilers was significantly enhanced by increased levels of immune barrier (sIgA), physical barrier (ZO-1, OCL and Muc-2) and flora barrier (Lactobacillus and Bifidobacterium). These results suggest that CVSLE was a promising herbal additive candidate for broilers.