The evaluation of next-generation probiotics on broiler growth performance, gut morphology, gut microbiome, nutrient digestibility, in addition to enzyme production of spp. in vitro.

Considerable research has been conducted into the efficacy of individual probiotics in broiler production, however information on the most effective combinations of synergistic probiotic is lacking. This study investigated the impact of different strain combinations in broiler chickens, as well as in vitro enzyme production. In experiment one, a total of 576 Ross 308 broilers at 1 d old were grown for 21 d across 6 treatments of maize-soybean diets ( = 12 pens per treatment) to compare three different strain combinations (formulation 1 [F1]: 3 strains ; F2: and 2 strains ; F3: and 2 strains ; F5: and 2 strains ), positive control (PC), and a negative control antibiotic treatment group (NC). In Exp. 2, a total of 360 one-day-old ROSS308 broilers were used to test five treatments ( = 9) including PC, NC, F1 and F5 (selected from Exp. 1), and F4 ( and 2 strains ) in a maize-soybean diet. F1 demonstrated a significant improvement in feed conversion ratio (FCR) compared to F2 at d 14 (1.49 vs 2.10;  = 0.038) and the body weight (BW) at d 21 (847.0 g vs 787.4 g) compared to other combinations ( = 0.027). The FCR at d 21 tended to be lower in birds fed F1 (1.46 vs 1.66) compared to the control ( = 0.068). Probiotic treatments had significantly improved nutrient digestibility compared to the PC and NC. Also, probiotic treatments supported the growth of , a common commensal genus and reduced the abundance of genera that correlated with low weight gain such as . Experiment two revealed that F4 improved FCR ( < 0.001) and BW at 28 d ( = 0.014). In vitro testing showed a high production of protease and amylase by . Thus, the addition of probiotics, particularly containing strains and , into the diet of broiler chickens improves production performance, nutrient digestibility, and allows the proliferation of beneficial gut microbiota.