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Thermal Death Kinetics of Three Representative Salmonella enterica Strains in Toasted Oats Cereal
Get PDFpeer-reviewedSeveral reports have indicated that the thermal tolerance of Salmonella at low-water activity increases significantly, but information on the impact of diverse food matrices is still scarce. The goal of this research was to determine the kinetic parameters (decimal reduction time, D; time required for the first decimal reduction, δ) of thermal resistance of Salmonella in a previously cooked low water activity food. Commercial toasted oats cereal (TOC) was used as the food model, with or without sucrose (25%) addition. TOC samples were inoculated with 108 CFU/mL of a single strain of one of three Salmonella serovars (Agona, Tennessee, Typhimurium). TOC samples were ground and equilibrated to aw values of 0.11, 0.33 and 0.53, respectively. Ground TOC was heated at temperatures between 65 °C and 105 °C and viable counts were determined over time (depending on the temperature for up to 6 h). Death kinetic parameters were determined using linear and Weibull regression models. More than 70% of Weibull’s adjusted regression coefficients (R2adj) and only 38% of the linear model’s R2adj had values greater than 0.8. For all serovars, both D and δ values increased consistently at a 0.11 aw compared to 0.33 and 0.53. At 0.33 aw, the δ values for Typhimurium, Tennessee and Agona were 0.55, 1.01 and 2.87, respectively, at 85 °C, but these values increased to 65, 105 and 64 min, respectively, at 0.11 aw. At 100 °C, δ values were 0.9, 5.5 and 2.3 min, respectively, at 0.11 aw. The addition of sucrose resulted in a consistent reduction of eight out of nine δ values determined at 0.11 aw at 85, 95 and 100 °C, but this trend was not consistent at 0.33 and 0.53 aw. The Z values (increase of temperature required to decrease δ-value one log) were determined with modified δ values for a fixed β (a fitting parameter that describes the shape of the curve), and ranged between 8.9 °C and 13.4 °C; they were not influenced by aw, strain or sugar content. These findings indicated that in TOC, high thermal tolerance was consistent among serovars and thermal tolerance was inversely dependent on aw
Where to grow the Giant Kelp? “Nutritional composition of wild harvested giant kelp compared"
No full textThe giant Kelp (Macrocystis pyrifera) is one of the fastest growing seaweeds globally with growth rates
of up to 60 cm per day. It is a positively buoyant species enabling the creation of kelp forests - a critical
ecosystem in the ocean. Macrocystis pyrifera communities have been lost in recent decades off the coast
of Australia, and since 2012 this species is listed as a threatened ecological community. It is also a native
species to New Zealand and found on the west coast of the US, South America, and South Africa.
The protein content of Macrocystis pyrifera ranges from 9-17% dry weight and depends on factors
including, location, environmental factors and harvest season. Protein obtained from seaweed contain all
the essential amino acids, and the protein profile of seaweeds is similar to egg protein. Initial nutritional
analysis using AOAC standard protocols of wild harvested fronds of Macrocystis pyrifera from Tory Channel,
South Island, New Zealand, found 12.2% dry weight (DW) crude protein. Macrocystis pyrifera from Tower
Bay, Tasmania, Australia contained only 6.5% protein based on DW. Total fat values were similar at both
sites with 1.9% DW from New Zealand, and 1.2% and 1.4% DW from Australia. Macrocystis pyrifera
usually has <2% fat content year-round therefore these values are in the expected range. Interestingly,
total polysaccharides varied between sites with the New Zealand kelp found to contain 21.6 mg / 100 g
polysaccharides and the Australian samples 21.8 mg / 100 g, and 35.3 mg / 100 g, respectively. Previous
studies have found higher growth rates for this species on wave-exposed sites that can impact positively
nutrient uptake specifically in low nitrogen environments. This data suggests that such wave-exposed
locations are worth investigating for aquaculture-based seaweed farms, to enable optimal conditions for
seaweed production and quality, within a changing climate
Mycobacterium avium subspecies paratuberculosis infection in cattle – a review in the context of seasonal pasture-based dairy herds
Get PDFpeer-reviewedJohne’s disease is an infectious disease affecting cattle, other ruminants and non-ruminant wildlife worldwide, caused by Mycobacterium avium subspecies paratuberculosis (MAP). This review provides an up-to-date concise overview of the pathogenesis of MAP, the significance of Johne’s disease in cattle and the use of diagnostic testing at both animal and herd level in the context of seasonal pasture-based herds. While MAP can only replicate intracellularly, the bacterium is sufficiently robust to survive for months in the environment. Transmission of MAP is mostly via the faecal-oral route, however in-utero transmission in also possible. The bacteria evade the immune system by persisting in macrophages in the small intestine submucosa, with this latent stage of infection lasting, in most cases, for at least two years before bacterial shedding and clinical signs begin. The slowly progressive nature of MAP infection, poor performance of diagnostic tests and management systems that expose susceptible calves to infection make control of Johne’s disease challenging, particularly in seasonal calving herds. Testing of individual animals provides little assurance for farmers and vets due to the poor sensitivity and, in the case of ELISA, imperfect specificity of the available tests. Repeated herd-level testing is utilised by the IJCP to detect infected herds, identify high risk animals, and provide increasing confidence that test-negative herds are free of infection. The IJCP aims to control the spread of Johne’s disease in cattle in Ireland, in order to protect non-infected herds, limit the economic and animal health impact of the disease, improve calf health and reassure markets of Johne’s disease control in Ireland
Lameness prevalence and management practices on Irish pasture-based dairy farms
Get PDFpeer-reviewedBackground
Lameness is a painful disease, which negatively impacts dairy cow production and welfare. The aim of this observational study was to determine herd lameness prevalence, describe current lameness management practices and identify the presence of established risk factors for lameness on Irish pasture-based dairy farms. Farms were visited once during grazing (99 farms) and again during housing (85 farms). Lameness scoring was carried out at each visit (AHDB 0–3 scale); cows were classified as lame if they scored two or three. Farm management practices and infrastructure characteristics were evaluated via farmer questionnaires and direct measurements of farm infrastructure.
Results
Median herd-level lameness prevalence was 7.9% (interquartile range = 5.6 – 13.0) during grazing and 9.1% (interquartile range = 4.9 – 12.0) during housing; 10.9% of cows were lame at a single visit and 3.5% were lame at both visits (chronically lame or had a repeat episode of lameness). Fifty-seven percent of farmers were not familiar with lameness scoring and only one farm carried out lameness scoring. Only 22% of farmers kept records of lame cows detected, and 15% had a lameness herd health plan. Twenty-eight percent of farmers waited more than 48 h to treat a lame cow, and 21% waited for more than one cow to be identified as lame before treating. Six percent of farmers carried out routine trimming and 31% regularly footbathed (> 12 times per year). Twelve percent put severely lame cows in a closer paddock and 8% stated that they used pain relief to treat severely lame cows. Over 50% of farms had at least one cow track measurement that was classified as rough or very rough, and cow tracks were commonly narrow for the herd size. On 6% of farms, all cubicle beds were bare concrete (no matting or bedding) and on a further 6% of farms, there was a combination of cubicles with and without matting or bedding. On 56% of farms, all pens contained less than 1.1 cubicles per cow and on 28% of farms, a proportion of pens contained less than 1.1 cubicles per cow.
Conclusions
Overall, this study identified infrastructure and management practices which could be improved upon. The comparatively low lameness prevalence demonstrated, compared to fully housed systems, also highlights the benefits of a pasture-based system for animal welfare; however, there remains scope for improvement
Exploring adolescents’ perceptions of dairy farming careers in Ireland: views of students studying agricultural science in secondary school
Get PDFpeer-reviewedA global challenge for dairy farmers is the attraction and retention of people to careers in primary agriculture. This study aimed to explore the perceptions of Irish secondary-level students studying agricultural science towards careers in dairy farming. Quantitative data were collected via a national survey (n = 976) prior to collection of qualitative data via two focus groups. Descriptive statistics including frequencies, percentages and means were used to analyse the quantitative data. Data analysis of the survey results identified general themes, which contributed to a deductive assessment of the overarching hypothesis, supplemented by inductive reasoning based on the analysis of the data from the focus groups. From the survey, adolescents perceived dairy farming as a physically demanding job with a poor work–life balance without any extra financial reward compared to other careers. In the focus groups, participants expressed concerns about environmental sustainability and economic viability. They also identified the ageing farming population as making it a less attractive career for young people. The paper supports arguments for greater integration of actual labour market opportunities into the secondary school curriculum to raise aspirations for 21st century careers in dairy farming, among other careers. There is an opportunity within the agricultural science curriculum to encourage students to explore the wide spectrum of emerging careers in food systems including dairy farming through classroom discussion, ideally with a variety of role models employed in the agricultural sector
The role of colloids and other fractions in the below-ground delivery of phosphorus from agricultural hillslopes to streams
Get PDFpeer-reviewedColloids can be important for facilitated transfer of phosphorus (P) to groundwater (GW) and contribute to elevated P concentrations later delivered to surface water. To assess the role of colloidal P and other P fractions in delivery processes via below-ground pathways, this study investigated the influence of catchment and flow event characteristics on particulate (>450 nm), medium-sized colloidal (200–450 nm) and fine (<200 nm) P fractions in two agricultural hillslopes (TG, TA). Total and dissolved P fractions and their derivatives were also monitored. Samples in both stream and GW were taken weekly during baseflow conditions and every 2 h during storm conditions. Higher frequency monitoring of streamflow was also conducted to delineate hydrological flowpaths and determine P loads and hysteresis processes. Results indicated that during baseflow fine P was dominant in the streams (80 to 100 % of total P) and in shallow GW in TA (83 to 96 %) whereas in TG shallow GW was dominated by PP (55 to 96 %) possibly due to colloidal Fe-P complexes. Similarly, in TG shallow GW was dominated by PP (79 to 81 %) during high flow events. During a larger flow event (within the period of land fertilization) the quickflow pathway (24 % of total flow) delivered 3.2 g ha−1 of PP which was dominant in the stream (44 to 68 %). A smaller flow event (within the period of prohibited land fertilization) facilitated delivery of P via deeper baseflow pathways (87 % of total flow) as fine reactive P (1.3 g ha−1), also dominant in the stream (73 to 78 %). The research indicated a very limited presence of medium-sized colloidal P but a large presence of fine P that may contribute to elevating P concentrations above environmental thresholds. Further work should constrain the controlling factors for colloidal P presence/absence and also on the extent and speciation of coarser and finer fractions in the hillslope to stream continuum
Evaluating the timing of insecticide application to manage barley yellow dwarf virus and yield in winter barley
Get PDFpeer-reviewedBarley yellow dwarf virus (BYDV) is an important viral disease of grain crops worldwide and a major cause of yield loss. The risk periods for BYDV infection coincide with milder temperature that prolongs aphid flight and facilitates viral transmission through primary and secondary aphid movement in the crop. Secondary aphid movement is associated with greater BYDV spread in winter cereals. A critical component of BYDV management is therefore delaying sowing of winter cereals and correctly timing insecticide application to maximise crop protection. Previous research in Ireland considered insecticide timing in early (September) and late (October onwards) sown cereals. Early research did not consider action thresholds around temperature, aphid flight and risk of secondary spread. This research set out to understand the optimal timing of insecticide application in October sown winter barley to reduce BYDV infection and yield impact. A critical temperature of 3°C was used as a threshold for aphid development that leads to movement and BYDV spread, and insecticide treatments were applied to the crop at predictable intervals in relation to temperature. Results show that BYDV symptoms and yield are affected by spray time, location and year, although only significant with regard to the reduction of BYDV symptoms. For both BYDV symptoms and yield, there was a significant difference between untreated (control) plots and “early” and “late” applications of insecticide, again more notable for BYDV symptoms than yield. This work indicates the value of optimising a single insecticide spray for control of October sown cereals and supports decision-making in the management of cereal crops
Biofunctional, structural, and tribological attributes of GABA-enriched probiotic yoghurts containing Lacticaseibacillus paracasei alone or in combination with prebiotics
No full textpeer-reviewedThis study investigated some biofunctional, structural, and tribological attributes of synbiotic yoghurts produced using Lacticaseibacillus paracasei as probiotic, and galactofructose, inulin, soy protein isolate, and spirulina as prebiotics. The highest gamma-aminobutyric acid (GABA) production (99.63 μg mL−1) and glutamic acid consumption (98.39 μg mL−1) was found in spirulina-supplemented probiotic yoghurts (YSP), followed by galactofructose-supplemented probiotic yoghurts (YGF). However, YSP exhibited the lowest probiotic viability and the greatest pH drop. The biological activity of YSP, in terms of total phenolics, antioxidant potential, antihypertensive activity, and degree of hydrolysis was significantly higher than the other yoghurts. YSP showed lower friction coefficient in the high sliding velocities compared with other yoghurt samples. The best appearance and mouthfeel was rated by panellists for YSP, while the taste, texture, and overall acceptance of other yoghurts were preferred. Overall, the synbiotic yoghurts containing spirulina, and galactofructose represent a promising strategy for development of functional dairy products.Enterprise Irelan
Yield response of field beans (Vicia faba) to plant population and sowing date in a temperate climate
Get PDFpeer-reviewedSowing date and seed rate influence crop establishment, growth, yield and profitability. The growth and yield of field beans (Vicia faba) in response to sowing date and seed rate was examined over three seasons, 2016–2019, in Teagasc, Oak Park, Carlow, Ireland. Early winter sowings (October) established better than late winter sowings in November and January. No significant difference was found in establishment from mid-February to mid-March. Yield was generally highest from October sowings for the winter cultivar. Yields were similar from February, March and April sowings for the spring cultivar, with March generally yielding higher across the three seasons. Yield was also found to increase significantly with seed rate for both winter and spring cultivars. The economic optimum plant population was estimated for the October and March sowing dates, by fitting a standard (linear + exponential) curve. There is no published information on the optimum plant populations for field beans in Ireland and we believe we are the first to report these findings. The estimated economic optimum plant populations varied between 13 and 38 plants/m2 for both varieties, with an average optimum of 25.5 plants/m2. This range falls within the current recommendations for sowing field beans in Ireland, demonstrating that increasing plant populations above the current commercial practice for field beans in Ireland, will not increase yield or profitability
Inactivation of Listeria monocytogenes and Salmonella Typhimurium in beef broth and on diced beef using an ultraviolet light emitting diode (UV-LED) system
Get PDFpeer-reviewedUltraviolet Light-Emitting Diode (UV-LED) is a potential decontamination technology for reducing bacterial loads on meat. This study investigated the efficacy of UV-LED technology to reduce Listeria monocytogenes, Salmonella Typhimurium, total viable counts (mesophiles (TVCm) and psychrophiles (TVCp)) and total Enterobacteriaceae counts (TEC) when suspended in beef broth and after inoculation onto diced beef. Inoculated samples (107 CFU/mL) were treated with UV light using single (255, 265, 285 nm) and combined (255 and 265 nm, 255 and 285 nm, 265 and 285 nm) wavelengths, exposed for 2, 30 or 60 min. Significant (p < 0.05) reductions in all of the target bacteria were achieved after 2 min with almost complete elimination after 60 min for all the individual and combinations of wavelengths tested, with the exception of 255 nm. On the diced beef, significant (p < 0.05) reductions in L. monocytogenes, TVCm and TEC were achieved using 285 nm and all of the combined wavelength treatments after 60 min. It was concluded that UV-LED technologies have potential application for the decontamination of beef products and validation in a commercial plant should be undertaken to facilitate the transfer of this technology to the meat sector