Effects of probiotics on blood metabolites, enterocytes, growth, and carcass characteristics of broilers challenged with Salmonella Serovar Heidelberg

This study was aimed to evaluate the use of probiotics (B. amyloliquefaciens, B. subtilis, B. thuringiensis, and S. cerevisiae) both in the litter and diets of broiler chickens challenged with Salmonella Serovar Heidelberg (SH) on performance, carcass, and cut yield, relative liver and fat weight, blood biochemistry parameters, intestinal morphometry, caecal contamination by SH and litter quality. A total of 640 one-day-old male broiler chickens (Cobb 500) were randomly assigned to 5 treatments: NC -negative control feed (no antibiotics); PC -positive control feed (antibiotics); NCPF-NC + 1 kg ton(-1) of probiotic in the feed; NCPL-NC + 20 g m(-2) of probiotic in the litter; NCPFL-NC + 1 kg ton(-1) of probiotic in the feed and application of 20 g m(-2) of probiotic in the litter. Each treatment consisted of 8 replicated pens with 16 broiler chickens per pen. The poultry received bran feed and water ad libitum throughout the experimental period. Probiotic application to litter was performed 5 days before housing of chicks, later the litter was collected for evaluation of dry matter, pH, and ammonia. At 3 days of age, 4 chicks per experimental unit received a culture inoculum solution with SH (106 CFU chick-1). Data were sub-mitted to analysis of variance and Tukey's test at 5% probability. In the initial phase (1 to 21 days), it was observed that poultry receiving the treatments PC (1.393), NCPF (1.396) and NCPFL (1.383) had better feed conversion rate results (P < 0.05). In the same period, the same treatments, PC (916), NCPF (865) and NCPFL (914) provided better weight gain results (P < 0.05). At the end of the experiment (42 days), the treatments NCPF (5.023) and NCPFL (5.005) showed lower feed intake (P < 0.05). In the same period, NCPF (1.564) and NCPFL (1.544) showed better feed conversion ratio results (P < 0.05). Probiotic was not influenced (P > 0.05) on the characteristics of carcass yield, cutting yields, relative liver weight, and fat. Probiotic was not influenced (P > 0.05) on the blood biochemistry and the cecum. Probiotic in the diets and litter promoted an improvement in litter quality at 28 days, with lower concentration of ammonia and lower humidity. In conclusion, probiotic improved growth performance, without altering intestinal morphometric, serum metabolites, liver, and kidney metabolites in poultry.