摘要
Three experiments were conducted to evaluate direct-fed microbial (<strong>DFM</strong>) supplementation on live performance, carcass characteristics, and fecal shedding of <em>E. coli</em> in feedlot steers. In Exp. 1, 400 steers (BW = 348 kg) were assigned to treatments: <strong>CON</strong> = lactose carrier only, <strong>BOV</strong> =<em> P. freudenreichii </em>(NP24) +<em> L. acidophilus</em> (NP51), <strong>BOVD</strong> = <em>P. freudenreichii</em> (NP24) +<em> L. acidophilus</em> (NP51), and <strong>COMB</strong> = BOV fed for the first 101 d on feed, followed by BOVD for the final 28 d prior to harvest. In Exp. 2 (n = 1800;BW = 354 kg) and Exp. 3 (n = 112;BW = 397 kg), steers were utilized in a randomized complete block design and assigned to DFM treatments using low dose and high dose, respectively. Fecal samples were collected prior to harvest and analyzed for <em>E. coli</em> serogroups. In Exp. 1, DFM reduced (P < 0.01) the concentration of<em> E. coli</em> O157. Prevalence of O157 was reduced by BOVD supplementation in Exp. 2 and 3 (P < 0.01 and P = 0.08, respectively), and concentration of <em>E. coli</em> O157 in positive samples was reduced in both experiments where enumeration was performed (P ≤ 0.02). Weighted mean differences across the three experiments were equal to a 33% reduction in the prevalence of E. coli O157:H7 in BOVD treated cattle. A significant reduction in prevalence of O26, O45, O103, and O121 was observed in Exp. 2 (P ≤ 0.03). These results indicate that high levels of <em>L. acidophilus</em> (NP51) may represent an effective pre-harvest food safety intervention to reduce fecal shedding of several <em>E. coli</em> serogroups.
Three experiments were conducted to evaluate direct-fed microbial (<strong>DFM</strong>) supplementation on live performance, carcass characteristics, and fecal shedding of <em>E. coli</em> in feedlot steers. In Exp. 1, 400 steers (BW = 348 kg) were assigned to treatments: <strong>CON</strong> = lactose carrier only, <strong>BOV</strong> =<em> P. freudenreichii </em>(NP24) +<em> L. acidophilus</em> (NP51), <strong>BOVD</strong> = <em>P. freudenreichii</em> (NP24) +<em> L. acidophilus</em> (NP51), and <strong>COMB</strong> = BOV fed for the first 101 d on feed, followed by BOVD for the final 28 d prior to harvest. In Exp. 2 (n = 1800;BW = 354 kg) and Exp. 3 (n = 112;BW = 397 kg), steers were utilized in a randomized complete block design and assigned to DFM treatments using low dose and high dose, respectively. Fecal samples were collected prior to harvest and analyzed for <em>E. coli</em> serogroups. In Exp. 1, DFM reduced (P < 0.01) the concentration of<em> E. coli</em> O157. Prevalence of O157 was reduced by BOVD supplementation in Exp. 2 and 3 (P < 0.01 and P = 0.08, respectively), and concentration of <em>E. coli</em> O157 in positive samples was reduced in both experiments where enumeration was performed (P ≤ 0.02). Weighted mean differences across the three experiments were equal to a 33% reduction in the prevalence of E. coli O157:H7 in BOVD treated cattle. A significant reduction in prevalence of O26, O45, O103, and O121 was observed in Exp. 2 (P ≤ 0.03). These results indicate that high levels of <em>L. acidophilus</em> (NP51) may represent an effective pre-harvest food safety intervention to reduce fecal shedding of several <em>E. coli</em> serogroups.
作者
Alex Thompson
M. Alexandra Calle
Flavio R. Ribeiro
Ansen R. Pond
Wanda M. Kreikemeier
Allen McDonald
Edward G. Johnson
Matthew D. Edmonds
Guy H. Loneragan
Mindy M. Brashears
Bradley J. Johnson
Alex Thompson;M. Alexandra Calle;Flavio R. Ribeiro;Ansen R. Pond;Wanda M. Kreikemeier;Allen McDonald;Edward G. Johnson;Matthew D. Edmonds;Guy H. Loneragan;Mindy M. Brashears;Bradley J. Johnson(Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, USA;School of Veterinary Medicine, Texas Tech University, Amarillo, TX, USA;Darling International Inc., Des Moines, IA, USA;Nutrition Physiology Company, LLC, Overland Park, KS, USA;Johnson Research Center, Parma, Italy)