Intestinal mucosa development in broiler chickens fed natural growth promoters

ABSTRACTThis study evaluated the use of probiotics and prebiotics on thehistological and morphological indexes of the intestinal mucosa of broilersat 21 days of age. Thirty-six birds were randomly distributed in a 3 x 3factorial arrangement, considering 3 probiotics and prebiotics sourcesin the diet. There were 9 treatments with 4 repetitions. Diet treatmentswere: 1 - Control (without growth promoters); 2 - Bacillus subtilis -basedprobiotic (Pro 1); 3 - Probiotic (Pool) based on Lactobacillus acidophilusand casei, Streptococcus lactis and faecium, Bifidobacterium bifidumand Aspergillus oryzae (Pro 2); 4 - Prebiotic based on PhosphorylatedMannanoligosaccharide (MOS) and Organic Acidifier (OA) (Pre 1); 5 -MOS-based prebiotic (Pre 2); 6 - Pro 1 + Pre 1; 7 - Pro 1 + Pre 2; 8 - Pro 2+ Pre 1; 9 - Pro 2 + Pre 2. Higher villus height (VH) (p<0.01) were seen inthe duodenum of birds fed diets without prebiotics, whereas birds fedBacillus subtilis-based probiotic and birds fed prebiotic based on MOS andOA showed higher VH (p<0.01) in jejunum and ileum. Greater crypt depths(CD) (p<0.01) were observed in the duodenum, jejunum and ileum of birdsreceiving B. subtilis, and in the duodenum and jejunum of birds fed dietswithout prebiotics. Significant interaction (p<0.01) between the evaluatedfactors was seen for both, VH and CD, in the three intestinal portions.Greater VH was obtained in duodenum, jejunum and ileum with the use ofprobiotics and prebiotics and greater CD with the use of probiotics, in relationto the control group. There was no difference in villus density (VD) betweenbirds fed diets without additives or diets containing probiotics and prebiotics.Nevertheless, there was a significant interaction (p<0.05) between theevaluated factors for VD in the duodenum. Concluding, beneficial effectswere seen in histological indexes of the intestinal mucosa with the useof probiotics and prebiotics at 21 days of age.INTRODUCTIONThe intestinal epithelium acts as a natural barrier against pathogenicbacteria and toxic substances that are present in the intestinal lumen.Stressors, pathogens, and chemical substances, among others, causedisturbances in the normal microflora or in the intestinal epitheliumthat may alter the permeability of this natural barrier, facilitating theinvasion of pathogens and prejudicial substances, modifying themetabolism, the ability to digest and absorb nutrients, and leading tochronic inflammatory processes at the intestinal mucosa (Hofstad, 1972;Podolsky, 1993; Oliveira, 1998). Consequently, there is decrease in thevillus, increase in the cell turnover and decrease in the digestive andabsorptive activities (Visek, 1978).Since absorption is totally dependent on the mechanisms that occurin the intestinal mucosa, the manipulation of probiotics (microbialsupplements comprised of specific bacteria or fungi) together with