The re-use of water in agricultural settings

Agriculture offers considerable opportunities for the safe and sustainable re-use of water, be that water sourced from humans or animals. A key point is understanding the differences in pathogen profiles between wastewater from humans as compared with that derived from animals. Agricultural re-use also offers the opportunity to appropriately match the treatment level of the used water with the planned end-use. There is no doubt that the reuse of water in agriculture will be an increasing focus as Australian agriculture adapts to the challenges of food security in a changing world

Are point of management assays relevant for food safety in the poultry industries?

The current pandemic has ensured considerable attention has been paid to the role of the approach termed ‘Point of Care’ diagnostics. Indeed, the term ‘RAT’ (Rapid Antigen Test) and RAT hunting now have totally different meaning to that widely understood before 2020. In the veterinary field, including food safety, the term used for these types of rapid in situ assays is ‘Point of Management’ (POM) assays. In this article, we describe our recent research on low cost, low technology, in-house style POM assays in the field of food safety as applied to the poultry industries. We then discuss what are the advantages and disadvantages of these low cost, low technology POM assays

Antibiotic resistance in Campylobacter jejuni and Campylobacter coli isolated from poultry in the South-East Queensland region

Objectives: The aim of this study was to determine the antimicrobial resistance patterns of 125 Campylobacter jejuni and 27 Campylobacter coli isolates from 39 Queensland broiler farms. Methods: Two methods, a disc diffusion assay and an agar-based MIC assay, were used. The disc diffusion was performed and interpreted as previously described (Huysmans MB, Turnidge JD. Disc susceptibility testing for thermophilic campylobacters. Pathology 1997; 29: 209–16), whereas the MIC assay was performed according to CLSI (formerly NCCLS) methods and interpreted using DANMAP criteria. Results: In both assays, no C. jejuni or C. coli isolates were resistant to ciprofloxacin or chloramphenicol, no C. coli were resistant to nalidixic acid, and no C. jejuni were resistant to erythromycin. In the MIC assay, no C. jejuni isolate was resistant to nalidixic acid, whereas three isolates (2.4%) were resistant in the disc assay. The highest levels of resistance of the C. jejuni isolates were recorded for tetracycline (19.2% by MIC and 18.4% by disc) and ampicillin (19.2% by MIC and 17.6% by disc). The C. coli isolates gave very similar results (tetracycline resistance 14.8% by both MIC and disc; ampicillin resistance 7.4% by MIC and 14.8% by disc). Conclusions: This work has shown that the majority of C. jejuni and C. coli isolates were susceptible to the six antibiotics tested by both disc diffusion and MIC methods. Disc diffusion represents a suitable alternative methodology to agar-based MIC methods for poultry Campylobacter isolates

Water addition, evaporation and water holding capacity of poultry litter

Litter moisture content has been related to ammonia, dust and odour emissions as well as bird health and welfare. Improved understanding of the water holding properties of poultry litter as well as water additions to litter and evaporation from litter will contribute to improved litter moisture management during the meat chicken grow-out. The purpose of this paper is to demonstrate how management and environmental conditions over the course of a grow-out affect the volume of water A) applied to litter, B) able to be stored in litter, and C) evaporated from litter on a daily basis. The same unit of measurement has been used to enable direct comparison—litres of water per square metre of poultry shed floor area, L/m2, assuming a litter depth of 5 cm. An equation was developed to estimate the amount of water added to litter from bird excretion and drinking spillage, which are sources of regular water application to the litter. Using this equation showed that water applied to litter from these sources changes over the course of a grow-out, and can be as much as 3.2 L/m2/day. Over a 56 day grow-out, the total quantity of water added to the litter was estimated to be 104 L/m2. Litter porosity, water holding capacity and water evaporation rates from litter were measured experimentally. Litter porosity decreased and water holding capacity increased over the course of a grow-out due to manure addition. Water evaporation rates at 25 °C and 50% relative humidity ranged from 0.5 to 10 L/m2/day. Evaporation rates increased with litter moisture content and air speed. Maintaining dry litter at the peak of a grow-out is likely to be challenging because evaporation rates from dry litter may be insufficient to remove the quantity of water added to the litter on a daily basis

Water addition, evaporation and water holding capacity of poultry litter

Litter moisture content has been related to ammonia, dust and odour emissions as well as bird health and welfare. Improved understanding of the water holding properties of poultry litter as well as water additions to litter and evaporation from litter will contribute to improved litter moisture management during the meat chicken grow-out. The purpose of this paper is to demonstrate how management and environmental conditions over the course of a grow-out affect the volume of water A) applied to litter, B) able to be stored in litter, and C) evaporated from litter on a daily basis. The same unit of measurement has been used to enable direct comparison—litres of water per square metre of poultry shed floor area, L/m2, assuming a litter depth of 5 cm. An equation was developed to estimate the amount of water added to litter from bird excretion and drinking spillage, which are sources of regular water application to the litter. Using this equation showed that water applied to litter from these sources changes over the course of a grow-out, and can be as much as 3.2 L/m2/day. Over a 56 day grow-out, the total quantity of water added to the litter was estimated to be 104 L/m2. Litter porosity, water holding capacity and water evaporation rates from litter were measured experimentally. Litter porosity decreased and water holding capacity increased over the course of a grow-out due to manure addition. Water evaporation rates at 25 °C and 50% relative humidity ranged from 0.5 to 10 L/m2/day. Evaporation rates increased with litter moisture content and air speed. Maintaining dry litter at the peak of a grow-out is likely to be challenging because evaporation rates from dry litter may be insufficient to remove the quantity of water added to the litter on a daily basis

Water activity of poultry litter: Relationship to moisture content during a grow-out

Poultry grown on litter floors are in contact with their own waste products. The waste material needs to be carefully managed to reduce food safety risks and to provide conditions that are comfortable and safe for the birds. Water activity (Aw) is an important thermodynamic property that has been shown to be more closely related to microbial, chemical and physical properties of natural products than moisture content. In poultry litter, Aw is relevant for understanding microbial activity; litter handling and rheological properties; and relationships between in-shed relative humidity and litter moisture content. We measured the Aw of poultry litter collected throughout a meat chicken grow-out (from fresh pine shavings bedding material to day 52) and over a range of litter moisture content (10–60%). The Aw increased non-linearly from 0.71 to 1.0, and reached a value of 0.95 when litter moisture content was only 22–33%. Accumulation of manure during the grow-out reduced Aw for the same moisture content. These results are relevant for making decisions regarding litter re-use in multiple grow-outs as well as setting targets for litter moisture content to minimise odour, microbial risks and to ensure necessary litter physical conditions are maintained during a grow-out. Methods to predict Aw in poultry litter from moisture content are proposed

An easy-to-perform, culture-free Campylobacter point-of-management assay for processing plant applications

Aims Current culture-based methods for detection and determination of Campylobacter levels on processed chickens takes at least two days. Here, we sought to develop a new complete, low-cost and rapid (approximately 2·5 hours) detection system requiring minimal operator input. Methods and Results We observed a strong correlation between culture-based cell counts and our ability to detect either Campylobacter jejuni or Campylobacter coli by Loop mediated isothermal amplification (LAMP) from the same samples. This knowledge was used to develop a rapid and simple five-step assay to quantify Campylobacter, which was subsequently assessed for its specificity, reproducibility and accuracy in quantifying Campylobacter levels from processed chickens. The assay was found to be highly specific for C. jejuni and C. coli and was capable of distinguishing between samples that are either within or exceeding the industry set target of 6,000 Campylobacter colony forming units (cfu) per carcass (equivalent to 12 cfu ml-1 of chicken rinse) with> 90% accuracy relative to culture-based methods. Conclusions Our method can reliably quantify Campylobacter counts of processed chickens with an accuracy comparable to culture-based assays but provides results within hours as opposed to days. Significance and Impact of the Study The research presented here will help improve food safety by providing fast Campylobacter detection that will enable the implementation of real-time risk management strategies in poultry processing plants to rapidly test processed chickens and identify effective intervention strategies. This technology is a powerful tool that can be easily adapted for other organisms and thus could be highly beneficial for a broad range of industries

Antimicrobial resistance in bacteria associated with porcine respiratory disease in Australia

The porcine respiratory disease complex greatly affects the health and production of pigs. While antimicrobial agents are used to treat the respiratory infections caused by bacterial pathogens, there is no current information on antimicrobial resistance in Australian pig respiratory bacterial isolates. The aim of this study was to determine the antimicrobial resistance profiles, by determining the minimum inhibitory concentration of nine antimicrobial agents for 71 Actinobacillus pleuropneumoniae, 51 Pasteurella multocida and 18 Bordetella bronchiseptica cultured from Australian pigs. The majority of A. pleuropneumoniae isolates were resistant to erythromycin (89%) and tetracycline (75%). Resistance to ampicillin (8.5%), penicillin (8.5%) and tilmicosin (25%) was also identified. The P. multocida isolates exhibited resistance to co-trimoxazole (2%), florfenicol (2%), ampicillin (4%), penicillin (4%), erythromycin (14%) and tetracycline (28%). While all the B. bronchiseptica isolates showed resistance to beta-lactams (ampicillin, ceftiofur and penicillin), some were resistant to erythromycin (94%), florfenicol (6%), tilmicosin (22%) and tetracycline (39%). The incidence of multiple drug resistance (MDR) varied across the species - in B. bronchiseptica, 27.8% of resistant isolates showed MDR, while 9.1% of the resistant isolates in A. pleuropneumoniae, and 4.8% in P. multocida showed MDR. This study illustrated that Australian pig strains of bacterial respiratory pathogens exhibited low levels of resistance to antimicrobial agents commonly used in the pig industry

Use of a proposed antimicrobial susceptibility testing method for Haemophilus parasuis

The aim of this study was to examine the antimicrobial susceptibility of 97 Haemophilus parasuis cultured from Australian pigs. As there is no existing standard antimicrobial susceptibility technique available for H. parasuis, methods utilising the supplemented media, BA/SN for disc diffusion and test medium broth (TMB) for a microdilution technique, were initially evaluated with the reference strains recommended by the Clinical and Laboratory Standards Institute. The results of the media evaluation suggested that BA/SN and TMB can be used as suitable media for susceptibility testing of H. parasuis. The proposed microdilution technique was then used with 97 H. parasuis isolates and nine antimicrobial agents. The study found that Australian isolates showed elevated minimum inhibitory concentrations (MICs) for ampicillin (1%), penicillin (2%), erythromycin (7%), tulathromycin (9%), tilmicosin (22%), tetracycline (31%) and trimethoprim-sulfamethoxazole (40%). This study has described potential antimicrobial susceptibility methods for H. parasuis and has detected a low percentage of Australian H. parasuis isolates with elevated antimicrobial MICs