The effect of Grobiotic-P combined with yeast cell wall and gluconic acid on growth performance, nutrient digestibilities, and cecal microbial populations in young chicks

Two experiments were conducted with New Hampshire × Columbian chicks fed a corn-soy-bean meal diet to examine the efficacy of varying levels and combinations of Grobiotic P (GB), a prebiotic-type product that contains dairy and yeast fractions and dried fermentation extracts, gluconic acid, and yeast cell wall (YCW) on growth performance, nutrient di-gestibility, and cecal microbial populations. In experi-ment 1, chicks were allowed ad libitum access to a corn-soybean meal basal diet or the basal diet supplemented with 2 or 4% GB, 1.5 or 3% gluconic acid, 0.2% YCW, or various 2-way combinations of the supplements in place of dextrose and arenaceous flour. In experiment 2, the same supplement combinations were used as in experiment 1; however, the 3% gluconic acid supple-ment was eliminated. In both experiments, supplement-ing GB, YCW, or 1.5% gluconic acid to the diet had no consistent effect on growth performance except that the weight gain was depressed (P < 0.05) when the chicks were fed a diet containing 3% gluconic acid. Chicks fed diets containing 2 or 4% GB combinations showed a significant increase (P < 0.05) in ME_n at 21 d when compared with chicks fed the basal diet. For amino acid (AA) digestibility, 2% GB combined with 0.2% YCW or 1.5% gluconic acid resulted in a reduction (P < 0.05) in AA digestibility at 7 d; however, at 21 d, these com-binations increased (P < 0.05) digestibility of all AA. There was no consistent effect of dietary treatment on cecal bifidobacteria, lactobacilli, Escherichia coli, or Clostridium perfringens populations or cecal pH. These experiments indicated that diets containing GB gener-ally increased ME_n and AA digestibility at 21 d and that the prebiotic combinations had no consistent ef-fects on cecal microbial populations.