Comparative of probiotics reveals cecal microbial component associated with performance parameters in broilers

Abstract

29 Probiotics have become increasingly popular in poultry industry as a promising nutritional 30 intervention to promote modulation of intestinal microbiota as a means of improving health and 31 performance. This study aimed to determine the effects of different probiotic formulations on the 32 cecal microbial communities and performance in 21 and 42 day-old-broilers, as well as to define 33 associations between ceca microbial profile and growth parameters. Probiotics investigated 34 included a synbiotic (SYNBIO), a yeast-based probiotic (YEAST), and three single-strain 35 formulations of spore-forming Bacillus amyloliquefaciens (SINGLE1), B. subtilis (SINGLE2) 36 and B. licheniformis (SINGLE3). Dietary inclusion of SYNBIO, YEAST, and SINGLE2 37 increased body weight (BW) by 7, 14, and 21d (p<0.05) compared to a basal diet without 38 probiotics (CON). The treatments SYNBIO, and YEAST decreased mortality by 21d, while 39 SYNBIO reduced the overall mortality rate by 42d (p<0.05). Bifidobacteriales had the highest 40 (p<0.05) population in SINGLE2, whereas Clostridiales was reduced compared to CON, 41 SINGLE1, and SINGLE3. The addition of SYNBIO into diet mainly stimulated (p<0.05) the 42 cecal relative abundance of Lactobacillales by 21d. Besides, Spearman's correlation analyses 43 revealed that population of Lactobacillales was associated with lower Enterobacteriales, higher 44 BW, and lower mortality of growing broilers. These results suggest that the modulation of ceca 45 microbiota and the greatest productive parameters were achieved by supplementation of specific 46 probiotic mixture. The selection of probiotics by their ability to drive cecal microbiota towards 47 lactic acid bacteria colonization may be a strategic approach to improve the indicators of 48 performance in broilers. 49 3 50 51 Introduction 52 Worldwide, the decreased percentage of chickens treated with sub-therapeutic levels of 53 antibiotics has attracted attention towards a better understanding of dietary alternatives as growth 54 and health promoters. Among them, probiotics have been indicated as a promising nutritional 55 intervention to manipulate the avian microbiome [1-4]. Beneficial bacteria colonization of 56 intestinal microbiota is essential for favoring host growth and performance, while an unfavorable 57 alteration of the commensal structure may promote enteric infections, thereby deteriorating 58 welfare and the performance indicators of poultry production [5]. 59 Probiotics have become increasingly popular across human medicine and livestock 60 industry due to the following benefits in the host: stimulation of beneficial microbiota, reduction, 61 and prevention of pathogen colonization, development of immune system, improvement in 62 digestive efficiency, and maturation of intestinal microbiota [3,5-9]. Although several bacterial 63 species and yeasts have been described as potential probiotic for broiler chickens; Bacillus, 64 Lactobacillus, Enterococcus, Bifidobacterium, Pediococcus, and Escherichia are the most 65 common bacte...