The effects of Grobiotic-P on growth performance, nutrient digestibilities, and cecal microbial populations in young...

This study was conducted to evaluate the effects of Grobiotic-P (GB), a prebiotic-type product that contains dairy and yeast fractions and dried fermentation extracts, on growth performance and nutrient digestibility at 4 and 21 d of age and cecal populations of Bifidobacterium, Lactobacillus, Escherichia coli, and Clostridium perfringens at 21 d of age. Two experiments were conducted using male New Hampshire x Columbian chicks. The first experiment evaluated GB at 2, 4, and 6% in a corn-soybean meal diet and compared these dietary treatments to a diet containing no GB (negative control) and a diet containing an antibiotic growth promoter (positive control), bacitracin methylene disalicylate. The second experiment used semi-purified dextrose-casein and dextrose-isolated soy protein diets to examine the effects of a 5% GB addition. In the first experiment, supplementing GB at 2, 4, and 6% in a corn-soybean meal diet had no effect on weight gain (P > 0.05). Feed efficiency and ME(n) were decreased (P < 0.05) by feeding 4 and 6% GB for some time periods, suggesting that the ME(n) value of GB used in diet formulation was too high. The GB had no consistent effect on apparent digestibility of amino acids. Cecal lactobacilli populations were linearly increased (P < 0.05) by GB in a corn-soybean meal diet in experiment 1. In the second experiment, the cecal populations of bifidobacteria were increased (P < 0.05) when 5% GB was supplemented to chicks fed a dextrose-casein diet, and the cecal populations of E. coli and C. perfringens were reduced (P < 0.05) when 5% GB was supplemented to chicks fed a dextrose-isolated soy protein diet. The results of this study indicate that feeding GB to chicks may promote the growth of beneficial bifidobacteria while reducing the growth of E. coli and C. perfringens in the ceca.