Ability of unsterilized recycled manure solids bedding to support growth of Klebsiella pneumoniae and Escherichia coli.

Although recycled manure solids (RMS) bedding is used on dairy farms, it could allow bacterial growth when contaminated by feces and thus increase the incidence of clinical mastitis in cows. The objective of this study was to describe bacterial growth in three different types of RMS bedding, as well as in sand, when samples were experimentally inoculated with Escherichia coli and Klebsiella pneumoniae. Two 3-day trials were conducted, during which treatments included inoculating bedding samples with E. coli and K. pneumoniae, as well as no inoculation. The trial was repeated 3 times for each bedding sample on each day. Samples were incubated at 15°C for 3 d and bacterial counts were measured every day. After inoculation, there was no significant K. pneumoniae or E. coli growth phase during the trial in those RMS samples that were prepared either in a container or in a heap. Recycled manure solids and sand samples prepared in a rotary drum, however, showed a similar active growth phase of K. pneumoniae during the first 24 h of the trial. Moreover, a significant E. coli growth phase was observed in the samples of sand bedding in the first 24 h. The 3 different types of RMS bedding samples did not react in a similar manner to coliform inoculation. No active growth phase was observed in bedding samples already containing a high bacterial concentration following inoculation with coliforms.

Bien que la litière de fumier recyclé (LFR) soit utilisée dans les fermes laitières, elle pourrait permettre la croissance bactérienne lorsqu'elle est contaminée par des matières fécales et augmenter ainsi l'incidence de mammite clinique chez les vaches. L'objectif de cette étude était de décrire la croissance bactérienne dans trois types de LFR, ainsi que dans du sable, lorsque des échantillons étaient inoculés expérimentalement avec Escherichia coli et Klebsiella pneumoniae. Deux essais de trois jours ont été réalisés, au cours desquels les échantillons de litière ont été inoculés ou non avec E. coli et K. pneumoniae. L'essai a été répété trois fois pour chaque échantillon de litière, chaque jour. Les échantillons ont été incubés à 15 °C pendant 3 jours et la numération bactérienne a été mesurée chaque jour. Après inoculation, il n'y a pas eu de phase de croissance significative de K. pneumoniae ou d'E. coli au cours de l'essai dans les échantillons de LFR préparés dans un conteneur ou en tas. Les échantillons de sable et de LFR préparés dans un tambour rotatif ont cependant montré une phase de croissance active similaire de K. pneumoniae pendant les premières 24 heures de l'essai. En outre, une phase de croissance significative d'E. coli a été observée dans les échantillons de litière de sable au cours des premières 24 h. Les trois différents types d'échantillons de LFR n'ont pas réagi de la même manière à l'inoculation de coliformes. Aucune phase de croissance active n'a été observée dans les échantillons de litière contenant déjà une concentration bactérienne élevée après l'inoculation de coliformes.(Traduit par Docteur Simon Dufour).

Treatment of cow manure from exercise pens: A laboratory-scale study of the effect of air injection on conventional and alternative biofilters.

Woodchips in stand-off pads for wintering cows have been applied in countries like Ireland and New Zealand. Their primary role is to protect soils by effectively filtering nutrients during wet conditions, while ensuring a healthy and comfortable environment for the cows. The stand-off pad concept has the potential to be adopted in Canada to provide year-long outdoor access to tie-stall dairy cows. The objective of this study was to evaluate the effect of alternative filtering materials and bed aeration under controlled laboratory conditions. Twelve biofilter columns (0.3 m in diameter and 1-m high) were installed in 12 environmentally-controlled chambers (1.2-m wide by 2.4-m long), and divided into four treatments: a bed of conventional woodchips or an alternative mix of organic materials (sphagnum peat moss, woodchips and biochar) with and without aeration (flux rate set at 0.6 m3/min/m2). Approximately 0.6 L of semi-synthetic dairy manure and 1 L of tap water were poured on the biofilters during two experimental periods of 4 weeks, simulating the effect of either winter or summer conditions (room temperature below or over 10 °C) on the retention of nutrients and fecal bacteria. Results showed that the alternative biofilters under both summer and winter conditions were more efficient in removing COD, SS, TN, and NO3-N than conventional biofilters (maximum efficiencies of 97.6%, 99.7%, 96.4%, and 98.4%, respectively). Similarly for E. coli, they achieved a minimum concentration of 1.8 Log10 CFU/100 ml. Conventional biofilters were more efficient for PO4-P removal with a maximum efficiency of 88.2%. Aeration did not have any significant effect under the tested temperature conditions. Additional factors such as media adaptation time as well as aeration flow during this period should be considered.

Impact of liquid hog manure applications on antibiotic resistance genes concentration in soil and drainage water in field crops.

Agricultural practices such as manure applications could contribute to the spread of antibiotic resistance genes (ARGs) within the environment. Our objective was to assess the impact of certain fertilization methods (mineral or manure) and tillage practices (reduced or conventional) on the presence of ARGs and bacteria in soil and drainage water under wheat and grain corn crops. Targeted ARGs tet(T), sul1, and blaCTX-M-1 in liquid hog manure, soil, and water samples were quantified by qPCR. Conventional PCR was used to detect mcr-1 and mcr-2. ARGs in control plots were detected despite the absence of manure, representing an environmental reservoir of resistant microorganisms. The manure application rate higher than 39 m3/ha increased tet(T) and sul1 gene concentrations in soil for more than 180 days. Tillage practices had no impact on ARG concentrations in soil and water samples. The blaCTX-M-1 gene was only detected in seven water samples in 2016, but no link was established with the treatments. The mcr-1 and mcr-2 genes were not detected in all tested samples. This study demonstrated that tet(T) and sul1 gene concentrations increased in soil after liquid hog manure application as well as in drainage water in the next weeks.

Irrigation Water Sources and Time Intervals as Variables on the Presence of Campylobacter spp. and Listeria monocytogenes on Romaine Lettuce Grown in Muck Soil.

Irrigation water has been identified as a possible source of vegetable contamination by foodborne pathogens. Risk management for pathogens such as Campylobacter spp. and Listeria monocytogenes in fields can be influenced by the source of the irrigation water and the time interval between last irrigation and harvest. Plots of romaine lettuce were irrigated with manure-contaminated water or aerated pond water 21, 7, or 3 days prior to harvesting, and water and muck soil samples were collected at each irrigation treatment. Lettuce samples were collected at the end of the trials. The samples were tested for the presence of Campylobacter spp. and L. monocytogenes. Campylobacter coli was isolated from 33% of hog manure samples (n = 9) and from 11% of the contaminated water samples (n = 27), but no lettuce samples were positive (n = 288). L. monocytogenes was not found in manure, and only one sample of manure-contaminated irrigation water (n = 27) and one lettuce sample (n = 288) were positive. No Campylobacter or L. monocytogenes was recovered from the soil samples (n = 288). Because of the low incidence of pathogens, it was not possible to link the contamination of either soil or lettuce with the type of irrigation water. Nevertheless, experimental field trials mimicking real conditions provide new insights into the survival of two significant foodborne pathogens on romaine lettuce.

Fractionation and analysis of veterinary antibiotics and their related degradation products in agricultural soils and drainage waters following swine manure amendment.

The fate of antimicrobial active compound residues in the environment, and especially antibiotics used in swine husbandry are of particular interest for their potential toxicity and contribution to antibiotic resistance. The presence of relatively high concentrations of bioactive compounds has been reported in agricultural areas but few information is available on their degradation products. Veterinary antibiotics reach terrestrial environments through many routes, including application of swine manure to soils. The objectives of this project were first, to develop an analytical method able to quantify and identify veterinary antibiotics and their degradation products in manure, soil and water samples; and second, to study the distribution of these target compounds in soils and drainage waters. A brief evaluation of their potential toxicity in the environment was also made. In order to achieve these objectives, liquid chromatography coupled to high-resolution mass spectrometry was used for its ability to quantify contaminants with sensitivity and selectivity, and its capacity to identify degradation products. Samples of manure, soil and water came from a long-term experimental site where swine manure containing veterinary antibiotics has been applied for many years. In this study, tetracycline antibiotics were found at several hundred µg L(-1) in the swine manure slurry used for fertilization, several hundred of ng L(-1) in drainage waters and several ng g(-1) in soils, while degradation products were sometimes found at concentrations higher than the parent compounds.

Persistence of Indicator and Pathogenic Microorganisms in Broccoli following Manure Spreading and Irrigation with Fecally Contaminated Water: Field Experiment.

In 2011 and 2012, trials consisting of experimental plots were carried out to evaluate the presence of pathogenic (Listeria monocytogenes, Salmonella) and prevalence of indicator (Escherichia coli) microorganisms in broccoli fertilized with liquid hog manure or mineral fertilizers and irrigated zero, one, or two times with E. coli-contaminated water. In 2011, results showed that E. coli contamination in broccoli heads was affected by the interval between irrigation and sampling (P = 0.0236), with a significant decrease between the first and third day following irrigation (P = 0.0064). In 2012, irrigation frequency significantly increased E. coli prevalence in broccoli samples (P = 0.0499). In 2012, E. coli counts in the soil were significantly influenced by the type of fertilizer applied, as plots receiving liquid hog manure showed higher bacterial counts (P = 0.0006). L. monocytogenes was recovered in one broccoli sample, but geno-serogrouping differentiated the isolate from those recovered in manure and irrigation water. The L. monocytogenes serogroup IIA, pulsotype 188 strain was found in six soil samples and in irrigation water applied 5 days before soil sampling. This study highlights the link between E. coli levels in irrigation water, irrigation frequency, and interval between irrigation and harvest on produce contamination. It also demonstrates that L. monocytogenes introduced into the soil following irrigation can persist for up to 5 days.

Detection of human food-borne and zoonotic viruses on irrigated, field-grown strawberries.

This study evaluated the presence of pathogenic human and zoonotic viruses on irrigated, field-grown strawberries. Norovirus genogroup I, rotavirus, and swine hepatitis E virus genogroup 3 were detected on strawberries, and irrigation water is suspected as the contamination origin.

Total and infectious Cryptosporidium oocyst and total Giardia cyst concentrations from distinct agricultural and urban contamination sources in Eastern Canada.

Cryptosporidium and Giardia (oo)cyst concentrations are frequently used for assessing drinking water safety. The widely used USEPA Method 1623 provides total counts of (oo)cysts, but may not be accurate for human health risk characterization, since it does not provide infectivity information. The total counts and infectious fraction of Cryptosporidium oocysts and the total counts of Giardia cysts were assessed in major fecal pollution sources. Fresh calf and cow feces, their manure, and the discharge point were sampled in a small rural sub-watershed (n = 20, 21, 10, 10). Median concentrations for total (oo)cysts were higher in calves (333 oocysts g(-1); 111 cysts g(-1)) than in cows (52 oocysts g(-1); 7 cysts g(-1)). Infectious oocysts were found in 17 (7%) of the samples and none were found in manure or at the discharge point. Urban sources were sampled in the influent and effluent (n = 19, 18) of two wastewater treatment plants. Peak concentrations were 533 oocysts L(-1) and 9,010 cysts L(-1) for influents and 89 oocysts L(-1) and 472 cysts L(-1) for effluents. Infectious oocyst fractions varied from below the detection limit to 7-22% in the effluent and influent respectively. These infectious fractions are significantly lower than those currently used for quantitative microbial risk assessment estimates.