Impacts of dietary forage and crude protein levels on the shedding of Escherichia coli O157:H7 and Listeria in dairy cattle feces

Abstract

A B S T R A C TThe shedding of Escherichia coli O157:H7 and Listeria monocytogenes in the feces of ruminants and the consequential risk to the public and environmental health is well reported. However, the influence of dietary manipulation on the shedding of fecal bacteria is not well understood. This study was conducted to improve understanding of the relationship between dietary feed composition and shedding of E. coli O157:H7 and Listeria spp. in dairy feces. Twelve cows were randomly assigned to four treatment diets of two dietary forage levels: low forage (37.4% dry matter, DM) vs. high forage (53.3% of DM) and two dietary crude protein (CP) levels: low protein (15.2% of DM) vs. high protein (18.5% of DM) in a 4×4 replicated Latin square design with four periods each including a 14 d adaptation and 3 d sample collection periods. Generic E. coli was detected in some of the feed ingredients, such as cotton seed, alfalfa hay, almond, and CaCO 3 , while Listeria was detected in the alfalfa hay and mineral mix. A significant interaction effect was observed between dietary forage and CP on the presence of fecal E. coli O157:H7 (P=0.01) but not with Listeria. On average, the greatest E. coli O157:H7 level (6.6 log 10 CFU/g of feces) was observed from the high forage and high protein diet and the lowest level was 6.1 log 10 CFU/g from the low forage and high protein diet. The average Listeria shedding rate was within the range of 1.7-2.3 log 10 CFU/g among the dietary forage and CP treatments. For the CP treatments, significantly low levels of Listeria were observed from cows fed the high protein (0.9−1.6 log 10 CFU/g) compared to the low protein (1.3-2.1 log 10 CFU/g) diet. Considering temporal fluctuations, no significant diurnal pattern was observed for either E.coli O157:H7 or Listeria. In addition, no time of sampling over day by dietary forage or CP content interaction on fecal E.coli O157:H7 or Listeria level was observed. This study showed that diets can influence the shedding of potentially pathogenic bacteria in dairy cow excreta.

Persistence of E. coli in Streambed Sediment Contaminated with Faeces from Dairy Cows, Geese, and Deer: Legacy Risks to Environment and Health

“…Differences in E. coli concentration in fresh faeces excreted by livestock, wildlife, and wildfowl are not unexpected, and studies have reported variability in E. coli shedding across different sources [ 30 ]. Differences in the initial concentration of E. coli likely reflect the diet associated with deer, dairy cows, and geese, and they also reflect the digestive tract characteristics and likely the cross-contamination from exposure to other animals in their habitats [ 31 , 32 ]. The dairy cow and deer faeces used in our study were collected from a working dairy farm and a deer park, respectively, where the animals were exposed to formulated feeds in addition to pasture.…”

Effect of Dairy Manure Storage Conditions on the Survival of E. coli O157:H7 and Listeria

“…The E. coli O157:H7 and Listeria spp. levels were determined using selective and differential agar media, as described by Biswas et al (2016).…”

Social and ecological analysis of commercial integrated crop livestock systems: Current knowledge and remaining uncertainty

“…Additional knowledge gaps include the survival of pathogens in animal manure in ICLS systems and subsequent infection or transmission to other individuals within the herd or potential implications for food safety. A recent study showed that pathogens in manure can survive for considerable amount of time under open-air conditions (Biswas et al, 2016).…”