94 Effect of Litter Salmonella Status on Growth Performance and Bacterial Status of Small Intestine Mucosa of Broiler Chickens and Litter

Although Salmonella is a major problem in poultry food safety, it is believed to be of minor concern for broiler production in regard to animal performance. To determine the effect of Salmonella challenge in broiler chickens, 2880 male Cobb 500 birds derived from a commer­ cial hatchery were evenly distributed over 48 floor pens resulting in 60 birds per pen. Litter was 50% new wood shavings and 50% litter from a previous study. Pens were tested for Salmonella status at d 0 and 42 of trial. One pen tested positive for Salmonella on d 0 but negative on d 42 and was therefore excluded from analysis. From the remaining 47 pens, litter from 11 pens tested positive for Salmonella on d 42. Animal performance was compared between birds raised in Salmonella positive (Sal+) versus Salmonella negative (Sal−) pens. In addition, gut micro­ biota analysis of selected bacterial groups of small intestine mucosa, averaged over 2 randomly selected birds per pen, and bacterial analysis within litter, collected from the center of each pen, was determined on d 42 of the study. Feed intake and body weight gain were reduced (P < 0.05 and P = 0.06, respectively) in birds up to 28 d of age from pens that tested Sal+ compared with animals from Sal− pens. However, there was no impact of d 42 Salmonella status on animal growth per­ formance between d 28 and 42 (P > 0.10). The reduced performance coincided with a trend toward increased (P = 0.06) avian pathogenic E. coli (APEC) in small intestine mucosa of birds and high (P = 0.01) total gram-negative bacteria counts of litter from pens that tested Sal+ compared with Salpens. Although there was no difference (P > 0.10) in litter total Clostridium and C. perfringens counts, and C. septicum was below detection level in all samples, other Clostridium species were reduced (P < 0.05) in litter from pens with Sal+ compared with pens with Salstatus. These results indicate that broiler chickens from Sal+ pens were slowed in their growth up to 28 d, but animal growth performance was not affected between d 28 and 42.