Effects of Chinese Herbal Extract D against Escherchia coli and on Production Performance and Gut Health in White Carneau Squabs

With growing restrictions on antibiotic growth promoters (AGPs) in the animal production worldwide, there is a pressing need to develop safe and effective alternatives. Chinese herbal extracts, with their multiple functions, are promising candidates, though their efficacy depends on specific chemical composition. This study aimed to comprehensively evaluate a Chinese herbal extract D as a potential AGP alternative by characterizing the chemical profile, assessing in vitro antibacterial activity, and investigating in vivo safety and effects in White Carneau squabs. The extract was found to contain a blend of natural compounds and demonstrated strong antibacterial properties, compared to antibiotics. In the in vivo trial, a total of 240 healthy 10-day-old White Carneau squabs were randomly assigned to four groups, with 5 replicates per group and 12 squabs per replicate. The dietary treatments were basal diet only (Control), basal diet + 50 mg/kg ampicillin (AMP), basal diet + 313 mg/kg Chinese herbal extract D (D1), and basal diet + 625 mg/kg Chinese herbal extract D (D2). When added to feed, the extract showed no negative impact on animal health, indicating a favorable safety profile, with no significant differences in serum creatinine, urea nitrogen, uric acid, malondialdehyde, superoxide dismutase, catalase, and glutathione peroxidase levels compared with the control group ( P >0.05). During the in vivo trials, the higher dose (625 mg/kg) significantly improved key growth measures, including body weight, average daily gain, and feed conversion ratio, and significantly increased leg muscle percentage ( P <0.05), while most other carcass and meat quality traits showed no significant differences among four groups ( P >0.05). Moreover, the extract helped balance gut bacteria by significantly reducing Escherichia coli counts (both D1 and D2) and significantly increasing Bifidobacterium abundance (D2) ( P <0.05), with no significant change in Lactobacillus ( P >0.05). Overall, Chinese herbal extract D, particularly at the dose of 625 mg/kg, presents itself as a viable, natural feed additive that can enhance animal production performance and gut health without the use of antibiotics, offering a sustainable path forward for agriculture.