Southern Plains Agricultural Research Center, Agricultural Research Service, US Department of Agriculture, College Station, Texas 77845, USA.
Foodborne Pathog Dis. 2010 May;7(5):605-8. doi: 10.1089/fpd.2009.0417.
The current research examined the inclusion of 20% wet distiller's grains (WDG) fed with steam-flaked corn (SFC) or dry-rolled corn (DRC) in diets fed to feedlot cattle on fecal prevalence of Escherichia coli O157:H7 and Salmonella. Crossbred beef heifers (n = 272; average initial body weight (BW) = 354 kg) were blocked by BW and pen size and randomly assigned to treatment. Fecal samples from freshly voided fecal pats were collected from each pen on the day cattle shipped for slaughter (237 fecal samples: 72, 125, and 40 from cattle 132, 160, and 181 days on feed, respectively). Fecal samples were cultured quantitatively and qualitatively for the above pathogens. Populations of E. coli O157:H7 and Salmonella were generally low with very few samples containing quantifiable populations. Similarly, after enrichment, few samples were E. coli O157:H7 positive in any collection with no treatment differences (p > 0.10). More samples were Salmonella positive during the first collection with an increased (p < 0.05) prevalence observed in the SFC and DRC treatments compared with DRC + WDG treatment. No other treatment differences were observed for Salmonella. Putative fecal coliform isolates (18 per treatment; first collection) were examined for antimicrobial susceptibility, and the majority were susceptible to all of the antibiotics examined. Most of the resistance was observed in the SFC (n = 3) and DRC (n = 4) treatments, and only one isolate in each of the two WDG treatments demonstrated resistance (one antibiotic each, streptomycin and tetracycline). All multidrug resistance (2-4 antibiotics) was observed in isolates cultured from the DRC and SFC treatments (n = 2 isolates in each treatment). Results of the current research found no significant effect of feeding WDG to feedlot cattle on fecal prevalence, at time of shipment for slaughter, of E. coli O157:H7, and only modest differences (decreases) in Salmonella prevalence with no apparent affect on antimicrobial susceptibility of fecal coliform isolates.
当前的研究调查了在饲养育肥牛的日粮中添加 20%湿酒糟（WDG）与蒸汽压片玉米（SFC）或干压玉米（DRC）对粪便中大肠杆菌 O157:H7 和沙门氏菌流行率的影响。杂交肉牛小母牛（n = 272；平均初始体重（BW）= 354kg）按 BW 和栏大小分组，并随机分配到处理组。在运往屠宰场的当天，从每个栏的新鲜粪便垫上采集粪便样本（237 个粪便样本：分别来自 132、160 和 181 天饲养的牛的 72、125 和 40 个）。对上述病原体进行定量和定性的粪便培养。大肠杆菌 O157:H7 和沙门氏菌的数量通常较低，很少有样本含有可量化的数量。同样，经过富集后，很少有样本在任何一个采集样本中呈大肠杆菌 O157:H7 阳性，且处理之间没有差异（p > 0.10）。在第一次采集时，更多的样本呈沙门氏菌阳性，与 DRC + WDG 处理相比，SFC 和 DRC 处理的阳性率增加（p < 0.05）。沙门氏菌没有观察到其他处理差异。对每处理组的 18 个假定粪便大肠菌群分离株（第一次采集）进行了抗生素敏感性检测，大多数分离株对所有检测的抗生素均敏感。大多数耐药性仅在 SFC（n = 3）和 DRC（n = 4）处理中观察到，而在两个 WDG 处理中，每个处理中只有一个分离株显示出耐药性（各有 1 种抗生素，链霉素和四环素）。在 DRC 和 SFC 处理中培养的分离株中均观察到所有多药耐药性（2-4 种抗生素）（每个处理中有 2 个分离株）。当前研究的结果发现，在运往屠宰场的时间点，向育肥牛日粮中添加 WDG 对粪便中大肠杆菌 O157:H7 的流行率没有显著影响，仅对沙门氏菌的流行率有适度影响（降低），但对粪便大肠菌群分离株的抗生素敏感性没有明显影响。
