Salmonella heidelberg prevalence is reduced in Original XPC-fed broilers

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1 As published in Salmonella heidelberg prevalence is reduced in Original XPC-fed broilers By Don McIntyre, Ph.D., PAS Director, North American Poultry Research & Technical Service Diamond V Diamond V has amassed a large portfolio of research demonstrating that Original XPC can help suppress Salmonella colonization in poultry. Published reports include: a) in vitro testing, b) in vivo challenges, c) controlled pen studies and d) paired house field trials. Work has been conducted with caged layers, breeding stock and commercial broiler chickens or turkeys. Current research has shown suppression of several Salmonella serotypes including: S. enteritidis, S. typhimurium, S. kentucky, S. heidelberg and S. arizonae in both live birds and environmental samples. In-depth studies have shown that Original XPC can help reduce pathogens by enabling the immune system of birds to suppress challenges, improving intestinal morphology and supporting gut microflora to reduce ph and increase volatile fatty acid (VFA) production. The combination of events coordinated by fermentation metabolites within Original XPC consistently limits both the prevalence and load of food born pathogens like Salmonella. Recently, another study was completed as commercial broiler chickens were challenged with a marked strain of Salmonella heidelberg. The study design and results are summarized below. Diamond V 1

2 Experimental design This study was conducted in cooperation with Southern Poultry Research Group in Nicholson, GA. Cobb male chicks were obtained for this challenge trial and assigned to one of three (3) feed treatments identified in Table 1. All birds were sprayed with Coccivac-B at the hatchery and no antibiotic growth promoter (AGP) was included in the feed. Table 1. Dietary treatments Dietary Starter Grower Finisher Salmonella Challenge (-21d) (21-35d) (35-42d) d T1 No XPC No XPC No XPC Yes T2 XPC lb/t XPC 1.25 lb/t XPC 1.25 lb/t Yes T3 XPC 2.5 lb/t XPC 2.5 lb/t XPC 2.5 lb/t Yes Dietary Nutrients: ME (kcal/kg) 3,67 3,13 3,165 C. Protein (%) Three feed treatments; 8 pens each Fifty males per pen; chickens per treatment; 1, birds total Birds grown to 42d of age Performance criteria: Body weight gain, feed conversion and livability Salmonella isolation and enumeration Salmonella challenge Twenty-five (25) tagged birds per pen were orally gavaged at d of age with a nalidixic acid resistant strain of S. heidelberg ( CFU/ml). The other 25 birds per pen were not challenged directly to measure horizontal spread of Salmonella within each pen. Drag swabs were taken from each pen at 14d and 42d to measure environmental Salmonella prevalence. On 42d, 5 challenged birds and 5 nonchallenged birds per pen were harvested to evaluate Salmonella from cecal samples. Results No differences were observed between treatments for livability (%) or body weight (BW) gain at 35d or at 42d of age. Statistical differences (P.5) were observed for feed conversion as shown in Table 2. Diamond V 2

3 Table 2. Feed conversion results at 35 & 42d of age T1 No XPC T lb/t XPC* T3 2.5 lb/t XPC* 35d Feed Conversion 42d Feed Conversion 1.68 a 1.79a 1.66 ab 1.77b 1.64 b 1.75b ab Column values with different superscripts are statistically different (P.5) Of the sample population tested (5 out of 25 birds/pen/challenge group) ), the prevalence of Salmonella (independent of dietary treatment) was similar between challenged birds and non-challenged birds (28.3% and 3.4% positives, respectively). These resultss indicate that the non-challenged birds were exposed to Salmonella through horizontal transmission. By 42d, Salmonella was isolated from the fecal swabs in % of pens (8 of 8) for T1 and T2 while only 88% of pens (7 of 8) in T3 were confirmed positive (Figure 1). Figure 1. Salmonella prevalence 42d fecal swab lb/t XPC lb/t XPC* 2.5 lb/t XPC* Salmonella heidelberg recovery in cecal samples at 42d is shown in Figure 2. Control birds (not fed Original XPC) had the highest incidence of Salmonella recovery (38.3%) and broilers fed 2.5 lb/t XPC (during grower/finisher phase) were significantly lower (17.5%). Birds fed 1.25 lb/t XPC (during grower/finisher phase) were intermediate (33.3%) for Salmonella recovery in ceca. Diamond V 3

4 Figure 2. Salmonella prevalence 42d cecal samples a 33.3 ab 17.5 b lb/t XPC 1.25 lb/t XPC* 2.5 lb/t XPC* ab Values with different superscripts are statistically different (P.5) In addition to the treatmentt averages (shown in Figure 2), individual pen average results for Salmonella incidence in cecal samples were plotted by treatment in Figure 3. The graph furtherr demonstrates the significant reduction in Salmonella cecal recovery in the birds fed T3 (2.5 lb/t XPC in grower/finisher phase) as compared to T1 (no XPC). Figure 3. Cecal Salmonellaa recovery Individual 42d pen averages T1 = no XPC fed T2 & T3 = 2.5 lb/t XPC starter and 1.25 or 2.5 lb/t XPC grow/finisher, respectively Diamond V 4

5 Conclusions 1. Feeding Original XPC at either the standard inclusion rate (T2; 2.5 lb/t Starter, then 1.25 lb/t Grow & Finish) or the higher dose (T3; 2.5 lb/t continuously) resulted in significantly improved feed conversion compared to controls. 2. Feeding 2.5 lb/t XPC continuously (T3) significantly reduced Salmonella prevalence compared to controls (T1), with standard Original XPC inclusion rate (T2) being intermediate. Copyright 13 Diamond V All rights reserved Diamond V 5