Stephens T P, Loneragan G H, Karunasena E, Brashears M M
Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas 79409, USA.
J Food Prot. 2007 Oct;70(10):2386-91. doi: 10.4315/0362-028x-70.10.2386.
In this study, the effectiveness of direct-fed microbials at reducing Escherichia coli O157 and Salmonella in beef cattle was evaluated. Steers (n=240) received one of the following four treatment concentrations: control = lactose carrier only; low = 1 X 10(7) CFU per steer daily Lactobacillus acidophilus NP51; medium = 5 x 10(8) CFU per steer daily L. acidophilus NP51; and high = 1 x 10(9) CFU per steer daily L. acidophilus NP51. Low, medium, and high diets also included 1 x 10(9) CFU per steer Propionibacterium freudenreichii NP24. Feces were collected from each animal at allocation of treatment and found to have no variation (P = 0.54) between cohorts concerning E. coli O157 recovery. Feces and hide swabs were collected at harvest and analyzed for the presence of E. coli O157 by immunomagnetic separation and Salmonella by PCR. No significant dosing effects were detected for E. coli O157 recovery from feces at the medium dose or from hides at the medium and high doses. E. coli O157 was 74% (P < 0.01) and 69% (P < 0.01) less likely to be recovered in feces from animals receiving the high and low diets, respectively, compared with controls. Compared with controls, E. coli O157 was 74% (P = 0.05) less likely to be isolated on hides of cattle receiving the low dose. No significant dosing effects were detected for Salmonella recovery from feces at the medium and low doses or from hides at any doses. Compared with controls, Salmonella was 48% (P = 0.09) less likely to be shed in feces of cattle receiving the high dose. No obvious dose-response of L. acidophilus NP51 on recovery of E. coli O157 or Salmonella was detected in our study.
在本研究中,评估了直接投喂微生物对降低肉牛体内大肠杆菌O157和沙门氏菌的效果。阉牛(n = 240)接受以下四种处理浓度之一:对照组 = 仅乳糖载体;低剂量组 = 每头阉牛每天1×10⁷CFU嗜酸乳杆菌NP51;中剂量组 = 每头阉牛每天5×10⁸CFU嗜酸乳杆菌NP51;高剂量组 = 每头阉牛每天1×10⁹CFU嗜酸乳杆菌NP51。低、中、高剂量组日粮还包括每头阉牛每天1×10⁹CFU费氏丙酸杆菌NP24。在分配处理时从每只动物采集粪便,发现在大肠杆菌O157回收率方面各群组之间无差异(P = 0.54)。在屠宰时采集粪便和皮张拭子,通过免疫磁珠分离法分析大肠杆菌O157的存在情况,通过PCR分析沙门氏菌的存在情况。在中剂量组粪便中或中、高剂量组皮张上未检测到大肠杆菌O157回收率有显著的剂量效应。与对照组相比,接受高剂量和低剂量日粮的动物粪便中大肠杆菌O157的回收率分别低74%(P < 0.01)和69%(P < 0.01)。与对照组相比,接受低剂量的牛的皮张上大肠杆菌O157的分离率低74%(P = 0.05)。在中、低剂量组粪便中或任何剂量组皮张上均未检测到沙门氏菌回收率有显著的剂量效应。与对照组相比,接受高剂量的牛的粪便中沙门氏菌的排出率低48%(P = 0.09)。在我们的研究中未检测到嗜酸乳杆菌NP51对大肠杆菌O157或沙门氏菌回收率有明显的剂量反应。