Host associated probiotics Lactobacillus reuteri and Enterococcus faecium Mitigate multidrug resistant Salmonella enterica in broiler chicks.

Probiotics can provide an eco-friendly alternative solution to improve poultry production and disease resistance. Considering safer and more effective probiotic strains from cultured species, this study included three host-associated probiotics (HAPs): Limosilactobacillus reuteri PFS4, Enterococcus faecium PFS13, and PFS14, previously isolated from poultry gut. This study evaluated the effects of three HAPs blend and a commercial probiotic blend (ProtexinR) on broiler growth, intestinal morphology, serum immunoglobulins, and cecal microflora challenged with two fluoroquinolone-resistant Salmonella Typhimurium (ST) and Salmonella Enteritidis (SE). A total of 240-day-old broiler chicks were randomly assigned to six treatment groups (n = 40 in each group): negative control (NC), positive control (PC), HAPs control blend (IPRO-) without ST and SE challenge, HAPs blend with ST and SE challenge (IPRO+), Commercial probiotic (ProtexinR) blend with ST and SE challenge (CM+), Commercial probiotic (ProtexinR) control (CM-) blend without ST and SE challenge. Growth parameters, including body weight gain (BWG), average feed intake (AFI), and feed conversion ratio (FCR), along with microbial populations, were assessed weekly. Meanwhile, gut morphology, relative organ weight, and serum immunoglobulin levels were evaluated on days 7 and 28. The chicks infected with ST and SE were depressed, had high mortality (20 %), and reduced BWG. The growth performance parameters were significantly improved (p ≤ 0.005) in all groups administered probiotics, with the IPRO- group exhibiting the highest results. Similarly, light microscopy findings showed that all probiotic-fed groups significantly (p ≤ 0.005) improved their gut morphology compared to the positive control group. Both HAPs and commercial probiotic blend treatments increased serum IgA and IgG compared with the PC (p ≤ 0.001). IPRO+ treatment significantly (p ≤ 0.001) increased cecal populations of total Lactobacillus and total Enterococcus, while reducing cecal and liver populations of Salmonella. In conclusion, the use of HAPs showed better growth performance and enhanced MDR Salmonella control, suggesting that the poultry sector should prioritize the development and application of probiotics derived from host-specific strains rather than other sources.