The following research report provides information regarding the bacterial contamination that exists in feed ingredients and mixed animal feeds collected from 4 commercial feed mills and the research feed mill from Auburn University. The experiment was conducted to establish if feed ingredients or commercial animal feeds serve as sources of contamination of Salmonella, Escherichia coli (EC), and Clostridium perfringens. During microbiological isolation, an unknown group of bacteria belonging to the Clostridium genus was identified. Therefore, the second aim of this research was to characterize the unknown group of bacteria. No Salmonella serovars were detected on ingredients or feed samples collected; however, the presence of C. perfringens was confirmed in some mixed animal feeds. Peanut meal and corn gluten meal were the ingredients with highest contamination of Clostridium spp. (CS), and peanut meal and corn meal for EC. Soybean meal and distillers dried grains with solubles had the lowest contamination with CS and EC. The stage of feed processing (postmixing, postpelleting, postcooling, and loadout) did not influence the degree of contamination with CS. However, contamination with EC was higher at the postmixing stage, but it was significantly reduced after the pelleting process (9/10 times), which suggests low stability of EC during thermal processing. Recontamination of mixed feed with EC after the pelleting process was observed in 2 of 5 feed mills studied; therefore, strategies must be developed by feed mills to prevent feed recontamination after thermal processing and thus guarantee EC–free animal feed. The unknown bacteria found in mixed feeds were identified as Bacillus proteolyticus or Clostridium argentinense, the latter representing a potential risk for farm animals because of its ability to produce a neuroparalytic toxin that can cause botulism. The present research report underscores the importance of evaluating alternatives to control bacterial pathogens such as EC, C. perfringens, and C. argentinense that may be present on animal feeds.

以下研究报告提供了有关从4家商业饲料厂和奥本大学研究饲料厂收集的饲料成分和混合动物饲料中存在的细菌污染的信息。进行该实验以确定饲料成分或市售动物饲料是否可作为沙门氏菌，大肠埃希氏菌（EC）和产气荚膜梭菌的污染源。在微生物分离过程中，鉴定出了一个属于梭菌属的未知细菌。因此，这项研究的第二个目的是表征未知细菌群。没有沙门氏菌在收集的原料或饲料样品中检测到血清型；但是，在某些混合动物饲料中证实了产气荚膜梭菌的存在。花生粉和玉米面筋粉是梭状芽胞杆菌污染最高的成分。（CS），以及EC的花生粉和玉米粉。豆粕和酒糟含可溶物的干粮中CS和EC的污染最低。饲料加工阶段（后混合，后造粒，后冷却和上料量）不影响CS的污染程度。但是，EC的污染在后混合阶段较高，但在制粒过程后显着减少（9/10次），这表明EC在热处理过程中的稳定性较低。在所研究的5家饲料厂中，有2家在制粒过程后用EC对混合饲料进行了重新污染。因此，饲料厂必须制定策略，以防止热处理后的饲料再污染，从而保证不含EC的动物饲料。混合饲料中发现的未知细菌被鉴定为蛋白水解芽孢杆菌或阿根廷梭菌（Clostridium argentinense），后者代表了家畜的潜在风险，因为它具有产生可引起肉毒杆菌中毒的神经麻痹毒素的能力。本研究报告强调评估替代品来控制动物饲料中可能存在的控制细菌病原体（如EC，产气荚膜梭菌和阿根廷梭状芽胞杆菌）的重要性。