Effects of Lactic Acid Bacteria and Yeasts on Growth Performance, Intestinal Health, and Organ Morphometry of Broiler Chickens

ABSTRACT This study evaluated the probiotic effects of lactic acid bacteria and yeasts on productive parameters, intestinal health, and morphometric changes in Cobb500 chickens during the first 21 days of life. A total of 450 chickens were randomly assigned to three groups ( n = 5 replicates of 30 birds): Ctrl, control; SlaLb, substrate fermented with Lactobacillus acidophilus and Lactobacillus bulgaricus ; SScKf, substrate fermented with Saccharomyces cerevisiae and Kluyveromyces fragilis . Various parameters were randomly evaluated: productive parameters, the relative weight of the digestive and lymphohematopoietic organs, and histomorphometric parameters (length and width of villi, depth of crypts, and villi/crypt ratio). The inclusion of microbial additives (SLaLb and SScKf) in the diet of broiler chickens significantly increased ( p = 0.041) the total weight (829.52 and 851.17 g), with no differences ( p > 0.05) in feed conversion. They also reduced the incidence of diarrhea (0.30% and 0.20%) and the relative weight of the gizzard and small intestine was higher. In addition, an improvement in histomorphological indicators was observed, suggesting better health and intestinal absorption capacity. Use of probiotics obtained from agro‐industrial waste improves intestinal health and weight gain and prevents mortality in chickens, making it a viable and promising alternative in poultry farming.