Goat flock abortion: a retrospective study at Abergelle Agricultural Research Center, Tigray, Ethiopia.

BACKGROUND: Small ruminants are the principal component of livestock production in Tigray region, Ethiopia. But their productivity is affected by various factors. According to farmers and expert observation, goat abortion is among the leading causes of production losses in Tanqua-Abergelle district. However, study findings that examine the extent of distribution and economic impact of abortion cases in goats in the district are scarce. This retrospective study investigated the occurrence of abortion and its associated risk factors in three goat breed types at Abergelle Agricultural Research Center goat breeding site over a seven year period. The study included a total of does above one year old, and data were collected from a casebook that was specifically prepared for abortion cases. A thorough follow up was conducted to identify abortion cases. Additionally, a community survey was conducted in selected villages where the research center is located. RESULTS: The overall abortion proportion was 29.8% in the goat farm. Begait goat breeds had the highest abortion proportion (50.9%, CI 0.36-0.64) in 2015/16. Multivariate logistic regression analysis identified year, season, age and breed as major risk factors of abortion occurrence at flock level. Accordingly, the likelihood of goats experiencing abortion during the dry season (proportion = 34) was 1.87 times higher compared to those in the wet season (proportion = 22.8). Begait breeds had a higher incidence of abortion (proportion 37.5%, OR 4.87, CI 2.49-10.35) compared to other breeds. Age was negatively associated with abortion, suggesting that older goats (OR = 0.67) had a higher relative risk than younger goats (OR = 0.57). Moreover, the study noted a high incidence of abortion during the years 2014/15 to 2016/17 (proportion = 35.7-39.7). Within-breed analysis revealed that age and season were significant risk factors for Abergelle and Begait breeds, respectively by using a multivariate logistic regression analysis. A community survey indicated that 89.7% households responded their goats experienced abortion. CONCLUSIONS: This study highlighted the high prevalence of goat abortion at Abergelle and identifies important risk factors associated with its occurrence. The findings can inform targeted interventions to reduce abortion rates and improve goat productivity in the district.

Seroprevalence and risk factors of Toxoplasma gondii infection in goats from South Punjab Province, Pakistan.

Layyah District in South Punjab Province of Pakistan offers the most intensive caprine economy in the country; its Indus riverine and desert environment makes the area peculiar and worthy of specific investigations. This study aimed to investigate the prevalence of anti-Toxoplasma gondii (T. gondii) IgG-antibody in goats in serum samples and the potential risk factors. The prevalence of T. gondii infection was estimated using a two-stage sample design. All caprine farms in the study area were stratified by size, and from these 110 were randomly selected. Twelve goats (>1-year-old) were selected from each farm and a total of 1320 serum samples were collected and tested by ELISA. A questionnaire on the conditions and management practices of each farm was administered to 110 farmers. Four hundred and sixteen out of 1320 sera samples (31.5%) were found positive and 89% of the flock had at least one seropositive goat. The proportion of seropositive goats tested within each flock ranged from 8.3% to 83.3%. with several factors contributing to this heterogeneity. Goat age played a significant role in the presence of cats. Significant interactions were related to goat farms having floor of dirt and kitten presence. Moreover, age class, abortion history and water source supply were modulated by owner education levels. This is the first study to determine the prevalence of anti-T. gondii antibodies in goats sera in Layyah district and the largest carried out so far in Pakistan. The remarkable presence of T. gondii among goats in areas where goat farming plays a significant economic role may pose a production threat to the small-stock industry, as well as to public health and food safety. Therefore, investigations to identify high-risk goat populations are highly recommended in order to facilitate the implementation of local control strategies.

Technical note: utilization of various allotment strategies to evaluate variation and replications required to detect statistical significance in nursery pig research.

A total of 720 barrows (line 200 × 400, DNA genetics) were used in two 42-d nursery trials (initially 6.20 ±â€…0.12 kg and 5.63 ±â€…0.16 kg, respectively) to evaluate strategies for allotting pigs to pens in randomized controlled trials. At placement, the population was split into three cohorts with similar average weight and standard deviation and randomly assigned to one of the three allotment strategies. Strategy 1 (random) utilized a simple randomization strategy with each pig randomized to pens independent of all other pigs. Strategy 2 (body weight [BW] distribution) sorted each pig within the cohort into one of the five BW groups. One pig from each weight group was then randomly assigned to a pen such that distribution of BW within pen was uniform across pens. Strategy 3 (BW grouping) sorted pigs within the cohort into 3 BW categories: light, medium, and heavy. Within each BW category, pigs were randomized to pen to create pens of pigs from each BW category. Within each experiment, there were 72 pens with five pigs per pen and 24 pens per allotment strategy. For all strategies, once pigs were allotted to pens, pens were allotted to one of the two treatments for a concurrent trial. In experiment 1, environmental enrichment using ropes tied near the pan of the feeder was compared to a control with no enrichment. In experiment 2, treatment diets consisted of basal levels of Zn and Cu from the trace mineral premix for the duration of the study (110 and 17 mg/kg, respectively; control), or diets (supplemented control) with carbadox (50 g/ton; Mecadox, Phibro Animal Health, Teaneck, NJ) fed in phase 1 (days 0 to 22) and 2 (days 22 to 43), pharmacological levels of Zn and Cu (2,414 mg/kg Zn from ZnO; 168 mg/kg Cu from CuSO4) fed in phase 1, and only pharmacological levels of Cu (168 mg/kg Cu from CuSO4) fed in phase 2. These treatment designs were used to determine the impact on coefficient of variation (CV) and to estimate the number of replications required to find significant treatment differences based on allotment strategy. There were no meaningful allotment strategy × treatment interactions for either study. For between-pen CV, pigs allotted using BW distribution and BW grouping strategies had the lowest CV at allotment and final weight in both trials. For overall average daily gain in experiments 1 and 2 in experiment 2, the BW distribution strategy required the fewest replications to detect differences in performance. However, there is no meaningful difference between allotment strategies in replications required to detect significant differences for gain:feed ratio.

Decreasing variation between experimental units increases the likelihood of finding a statistically significant difference if one exists. Assignment of animals to experimental units (pens) may contribute to that variation. Therefore, the purpose of this trial was to investigate the effect that different methods of allotting pigs to pens (experimental unit) have on variation and in turn, the number of replications required to detect a significant difference of a given amount between treatments. The random strategy assigned pigs to pens in a completely random fashion. The body weight (BW) distribution strategy ordered pigs from lightest to heaviest and created five groups based on BW. Each pen was randomly assigned one pig from each of the five groups. The BW grouping strategy again ordered pigs from lightest to heaviest but split pigs into three groups based on BW and each pen was randomly assigned pigs from only one BW group such that there were pens of light pigs, pens of medium pigs, and pens of heavy pigs. Ultimately, the best allotment strategy depends on the parameter of interest. For final BW and overall ADG, the BW grouping method required the fewest pens to detect statistically significant differences.

Development strategies and application of antimicrobial peptides as future alternatives to in-feed antibiotics.

The use of in-feed antibiotics has been widely restricted due to the significant environmental pollution and food safety concerns they have caused. Antimicrobial peptides (AMPs) have attracted widespread attention as potential future alternatives to in-feed antibiotics owing to their demonstrated antimicrobial activity and environment friendly characteristics. However, the challenges of weak bioactivity, immature stability, and low production yields of natural AMPs impede practical application in the feed industry. To address these problems, efforts have been made to develop strategies for approaching the AMPs with enhanced properties. Herein, we summarize approaches to improving the properties of AMPs as potential alternatives to in-feed antibiotics, mainly including optimization of structural parameters, sequence modification, selection of microbial hosts, fusion expression, and industrially fermentation control. Additionally, the potential for application of AMPs in animal husbandry is discussed. This comprehensive review lays a strong theoretical foundation for the development of in-feed AMPs to achieve the public health globally.

Sow serenity: automatic long-term measurement of lying behavior in crates and free-farrowing pens using 3D accelerometers.

Accelerometers are useful in analyzing lying behavior in farm animals. The effect of the farrowing system on sow lying behavior has been studied around parturition, but not long-term. In a natural environment, sows increase activity 14 d post parturition, which we expected to be also evident in housed sows when they can move freely. The objective of this study was (1) to validate the methodology to automatically measure sow lying bouts and duration with accelerometers and (2) to apply it to crated and free-farrowing sows 24-h pre-parturition until weaning. We used videos with manual behavior coding as the gold standard for validation and calculated the agreement with an intraclass correlation coefficient (ICC), which was 0.30 (95% CI: -0.10 to 0.64) for the number of lying bouts. When transitional sitting bouts were excluded from the video dataset, the ICC for lying bouts increased to 0.86 (95% CI: 0.40 to 0.95). For lying duration, the ICC was 0.93 (95% CI: 0.26 to 0.98). We evaluated the effects of housing, day relative to parturition, and time of day on lying using the accelerometer data and linear mixed models. In crated sows, the number of lying bouts increased toward parturition, peaking at about five bouts per 6 h, and decreased to almost zero bouts after parturition. Then, it increased again (P = 0.001). In free-farrowing sows, the number of lying bouts gradually decreased from a high level towards parturition and was lowest after parturition. It remained constant, as in the crated sows, until day 15, when the number of bouts increased to eight bouts on day 20 (P = 0.001). Sows in both systems were lying almost all of the time between 18:00 and 00:00 hours and on all days (P = 0.001). The crated sows showed a very similar pattern in the other three-quarters of the day with a reduced lying time before parturition, a peak after parturition, reduced lying time from days 5 to 20, and an increase again towards weaning (P = 0.001). Free-farrowing sows had a similar pattern to the crated sows from 00:00 to 06:00 hours, but without the reduction in lying time from days 5 to 20. They showed an increase in lying time toward parturition, which remained constant with a final decrease toward weaning, especially during the day (P = 0.001). This study proves the accuracy of accelerometer-based sow lying behavior classification and shows that free-farrowing systems benefit lactating sows around parturition but also towards weaning in the nest-leaving phase by facilitating activity.

We analyzed lying behavior of sows using sensors, focusing on crated versus free-farrowing sows from pre-parturition to weaning. Lying behavior varies in this time following the needs of the sow and her litter. In a natural environment, sows increase activity 14 d post parturition, which we expected to be also evident in housed sows when they are allowed to move freely. Validation with video data showed excellent agreement for duration and frequency of lying. In crated sows, the number of lying bouts peaked around parturition, decreased after parturition, and then gradually increased. In free-farrowing sows, lying down occurred less often before parturition, but increased by day 20 compared to crated sows. Both housing systems showed prolonged lying periods from 18:00 to 00:00 hours. Crated sows had reduced lying times before parturition and lied longest post-parturition, which decreased until day 5 and then increased toward weaning. Free-farrowing sows had similar nocturnal patterns but persistent lying times that increased prior to parturition and decreased prior to weaning. Overall, the study highlighted the accuracy of accelerometer-based lying behavior classification and showed that free-farrowing systems benefit lactating sows not only around parturition but also toward weaning, facilitating activity during the nest-leaving phase.

Impact of diversified grazing systems on milk production, nutrient use and enteric methane emissions in dual-purpose cows.

This study evaluated three continuous grazing systems: Brachiaria Brizantha, Clitoria ternatea and naturalized pastures, complemented with commercial concentrate and C. ternatea silage on milk yield, nutrient use and enteric methane (CH4) emissions. Nine multiparous cows of local Zebu breeds, with an average weight of 448 ± 87 kg, were used. The chemical composition of the food was determined. Live weight, milk production, and quality were assessed. Furthermore, serum urea, urea nitrogen, creatinine and glucose in blood were monitored, and nitrogen use efficiency were calculated. Enteric methane (CH4) emissions were estimated using Tier-2 methodology. A 3 × 3 latin square experimental design was applied. The grazing systems of B. brizantha and C. ternatea had the greater live weights of 465.8 and 453.3 kg/cow, although the latter is similar to naturalized pasture. Milk production and quality were not affected by grazing system, with the exception of the non-fat solids, where the C. ternatea system was lower (102.2 g/kg) than the other grazing systems. The crude protein and N intake, and N excretion in feces and urine were lower in naturalized pasture systems (1139.0 g/day). N outputs in milk was high in the C. ternatea system (56.3 g/cow/day). The naturalized pastures systems showed the better feed use efficiency (25.7%) compared to others. Serum urea and blood urea nitrogen were greater in B. brizantha followed by C. ternatea. Enteric CH4 emissions were indifferent among grazing systems when expressed as a percentage of greenhouse gases (7.1%). In conclusion, the grazing C. ternatea supplemented with commercial concentrate and C. ternatea silage maintains milk production and quality, reduced cow/day emissions (by 2.5%) and lowered energy losses as methane.

A two-step Bayesian network approach to identify key SNPs associated to multiple phenotypic traits in four purebred laying hen lines.

When purebred laying hen chicks hatch, they remain at a rearing farm until approximately 17 weeks of age, after which they are transferred to a laying farm. Chicks or pullets are removed from the flocks during these 17 weeks if they display any rearing abnormality. The aim of this study was to investigate associations between single nucleotide polymorphisms (SNPs) and rearing success of 4 purebred White Leghorns layer lines by implementing a Bayesian network approach. Phenotypic traits and SNPs of four purebred genetic White Leghorn layer lines were available for 23,000 rearing batches obtained between 2010 and 2020. Associations between incubation traits (clutch size, embryo mortality), rearing traits (genetic line, first week mortality, rearing abnormalities, natural death, rearing success, pullet flock age, and season) and SNPs were analyzed, using a two-step Bayesian Network (BN) approach. Furthermore, the SNPs were connected to their corresponding genes, which were further explored in bioinformatics databases. BN analysis revealed a total of 28 SNPs associated with some of the traits: ten SNPs were associated with clutch size, another 10 with rearing abnormalities, a single SNP with natural death, and seven SNPs with first week mortality. Exploration via bioinformatics databases showed that one of the SNPs (ENAH) had a protein predicted network composed of 11 other proteins. The major hub of this SNP was CDC42 protein, which has a role in egg production and reproduction. The results highlight the power of BNs in knowledge discovery and how their application in complex biological systems can help getting a deeper understanding of functionality underlying genetic variation of rearing success in laying hens. Improved welfare and production might result from the identified SNPs. Selecting for these SNPs through breeding could reduce stress and increase livability during rearing.

Cohort profile: The FarmMERGE project-Merging human and animal databases to investigate the relationship between farmer and livestock health and welfare. The HUNT Study.

Stockmanship is an important determinant for good animal welfare and health. The goal of the FarmMERGE project is to investigate the associations between farmer health and work environment, and the health, productivity and welfare of their livestock. We merged several livestock industry databases with a major total population-based health study in Norway (The Trøndelag Health Study 2017-2019 (HUNT4)). This paper describes the project's collection and merging of data, and the cohort of farmers and farms that were identified as a result of our registry merge. There were 56,042 participants of HUNT4 (Nord-Trøndelag County participants only, participation rate: 54.0%). We merged a list of HUNT4 participants whose self-reported main occupation was "farmer" (n = 2,407) with agricultural databases containing production and health data from sheep, swine, dairy and beef cattle from 2017-2020. The Central Coordinating Register for Legal Entities was used as an intermediary step to achieve a link between the farmer and farming enterprise data. We identified 816 farmers (89.5% male, mean age 51.3 years) who had roles in 771 farming enterprises with documented animal production. The cohort included 675 unique farmer-farm combinations in cattle production, 139 in sheep, and 125 in swine. We linked at least one HUNT4 participant to approximately 63% of the dairy farms, 53% of the beef cattle farms, 30% of the sheep farms, and 38% of the swine farms in Nord-Trøndelag County in the 2017-2019 period. Using existing databases may be an efficient way of collecting large amounts of data for research, and using total population-based human health surveys may decrease response bias. However, the quality of the resulting research data will depend on the quality of the databases used, and thorough knowledge of the databases is required.

A review on the alternatives to antibiotics and the treatment of antibiotic pollution: Current development and future prospects.

Antibiotics, widely used in the fields of medicine, animal husbandry, aquaculture, and agriculture, pose a serious threat to the ecological environment and human health. To prevent antibiotic pollution, efforts have been made in recent years to explore alternative options for antibiotics in animal feed, but the effectiveness of these alternatives in replacing antibiotics is not thoroughly understood due to the variation from case to case. Furthermore, a systematic summary of the specific applications and limitations of antibiotic removal techniques in the environment is crucial for developing effective strategies to address antibiotic contamination. This comprehensive review summarized the current development and potential issues on different types of antibiotic substitutes, such as enzyme preparations, probiotics, and plant extracts. Meanwhile, the existing technologies for antibiotic residue removal were discussed under the scope of application and limitation. The present work aims to highlight the strategy of controlling antibiotics from the source and provide valuable insights for green and efficient antibiotic treatment.

Putting the cart before the horse: mixed-methods participatory investigation of working equid harnessing practices in three selected towns of the Oromia national regional state in Ethiopia.

BACKGROUND: Millions of working equids provide socio-economic support for many low-income communities worldwide. With the prevalence of harness-related wounds reported as higher than 60%, this study aims to describe the equipment used by working equids in three locations of the Ethiopian national regional state of Oromia (Fiche, Bishoftu and Shashamene), and the attitudes and practices of equid owners, users and harness makers regarding work equipment. This mixed-methods study consists of cross-sectional surveying of working equids used for taxi or transport of goods or water, as well as cart-driver questionnaires and focus groups (FG) with working equid stakeholders. Activities conducted with FG included participatory ranking of equipment attributes and equipment drawing exercises. Indicators of equipment design and assembly, as well as cart-driver attitudes and practices were described quantitatively. Associations between equipment characteristics and species, work-type and cart-driver indicators were investigated through univariable logistic regression models, whereas focus group discussions were transcribed and analysed thematically. RESULTS: In total, 368 working equid surveys and cart-driver questionnaires were completed and 87 participants took part in nine FG. Equipment composition and characteristics differed considerably from ideal animal draught and harnessing principles described in the literature, with none of the observed harnesses adhering to all principles and thus not considered fully adequate. Various harness compositions were used, with only saddles and breast collars present in all. Donkey equipment had fewer components than that of horses, such as swingle trees (OR 0.02; 95% CI 0.01-0.06; p < 0.001) or girths (OR 0.09; 95%CI 0.02-0.4; p = 0.002). Horse equipment was more likely to have functional elements such as breeching (OR 7.8; 95% CI 2.9-20.9; p < 0.001). Of all equipment attributes, FG participants ranked cost, design and impact on animal wellbeing as having the highest importance. Thematic analysis identified motivations and priorities regarding equipment; awareness and knowledge of design and function; barriers to using ideal equipment; and consequences of equipment design and practices as key themes. CONCLUSIONS: Various weaknesses of design, assembly and use of equid work equipment were identified. Promoting behavioural change through awareness and training could lead to a sustainable improvement of work equipment quality, access, and prevention of equipment-related problems.

Effect of prudent use of antimicrobials in the early phase of infection in pigs on the performance and meat quality of fattening pigs.

The presented study was a part of the ThermoEye project. The study examined the effect of prudent antibiotic treatment in response to illness on the fattening performance, slaughter traits, and meat quality of the pig fatteners. Pigs were divided into an experimental group - EXP and a control - CON. In both groups, the body temperature was monitored, and diseases were confirmed by a veterinarian. In the EXP group, metaphylaxis was used in each case of confirmed disease. The EXP fatteners had greater slaughter weight (by 4.7 kg) and meatiness (by 2.1 percentage points) compared to the CON pigs. The pH in pork was lower in EXP compared to CON pigs. The longissimus thoracis et lumborum of EXP pigs was characterised by a lower cooking loss (28.30 vs. 30.45%) and yellower colour compared to the CON group. Among the amino acids, only the content of histidine (by 5.2%; P < 0.01) and tyrosine (by 7.2%; P < 0.01) was significantly greater in the meat of the CON group compared to EXP, with no effect of sex noted. The content of SFA (by 14.6%; P < 0.05), UFA (by 15.6%; P < 0.05), MUFA (by 17.8%; P < 0.05), MCFA (by 14.1%; P < 0.05), and LCFA (by 15.6%; P < 0.05) was also greater in CON compared to EXP meat. In conclusion, automated monitoring of pig body temperature during the fattening period enables more precise, prudent treatment and effective animal health control while reducing costs due to disease losses and pharmacotherapy. It allows optimal production and affects meat quality.

Animal board invited review: Improving animal health and welfare in the transition of livestock farming systems: Towards social acceptability and sustainability.

The need to integrate more clearly societal expectations on livestock farming has led the authors of this article to consider that livestock farming systems must be redesigned to position health and welfare at the heart of their objectives. This article proposes a vision of the advances in knowledge required at different scales to contribute to this transformation. After defining health and welfare of animals, the article emphasises the need to consider health in a broader perspective, to deepen the question of positive emotional experiences regarding welfare, and raises the question of how to assess these two elements on farms. The positive interactions between health and welfare are presented. Some possible tensions between them are also discussed, in particular when improving welfare by providing a more stimulating and richer environment such as access to outdoor increases the risk of infectious diseases. Jointly improving health and welfare of animals poses a number of questions at various scales, from the animal level to the production chain. At the animal level, the authors highlight the need to explore: the long-term links between better welfare and physiological balance, the role of microbiota, the psycho-neuro-endocrine mechanisms linking positive mental state and health, and the trade-off between the physiological functions of production, reproduction and immunity. At the farm level, in addition to studying the relationships at the group level between welfare, health and production, the paper supports the idea of co-constructing innovative systems with livestock farmers, as well as analysing the cost, acceptability and impact of improved systems on their working conditions and well-being. At the production chain or territory levels, various questions are raised. These include studying the best strategies to improve animal health and welfare while preserving economic viability, the labelling of products and the consumers' willingness to pay, the consequences of heterogeneity in animal traits on the processing of animal products, and the spatial distribution of livestock farming and the organisation of the production and value chain. At the level of the citizen and consumer, one of the challenges is to better inter-relate sanitary and health perspectives on the one hand, and welfare concerns on the other hand. There is also a need to improve citizens' knowledge on livestock farming, and to develop more intense and constructive exchanges between livestock farmers, the livestock industry and citizens. These difficult issues plead for interdisciplinary and transdisciplinary research involving various scientific disciplines and the different stakeholders, including public policy makers through participatory research.

Synergies and trade-offs between provisioning and climate-regulating ecosystem services in reindeer herding ecosystems.

Reindeer (Rangifer tarandus) pastoralism utilizes vast boreo-arctic taiga and tundra as grazing land. Highly fluctuating population sizes pose major challenges to the economy and livelihood of indigenous herder communities. In this study we investigated the effect of population fluctuations on core provisioning and regulating ecosystem services in two Sámi reindeer herding districts with contrasting fluctuation trends. We compared 50-year long time series on herd size, meat production, forage productivity, carbon footprint, and CO2-equivalence metrics for surface albedo change based on the radiative forcing concept. Our results show, for both districts, that the economic benefits from the provisioning services were higher than the costs from the regulating services. Still, there were major contrasts; the district with moderate and stable reindeer density gained nearly the double on provisioning services per unit area. The costs from increasing heat absorption due to reduction in surface albedo caused by replacement of high-reflective lichens with low-reflective woody plants, was 10.5 times higher per unit area in the district with large fluctuations. Overall, the net economic benefits per unit area were 237 % higher in the district with stable reindeer density. These results demonstrate that it is possible to minimize trade-offs between economic benefits from reindeer herding locally and global economic costs in terms of climate-regulating services by minimizing fluctuations in herds that are managed at sustainable densities.

Porcine ear necrosis is associated with social behaviours in weaned piglets.

BACKGROUND: Porcine ear necrosis (PEN) is a worldwide health issue and its aetiology is still unclear. The aim of this study was to describe the prevalence and the severity of PEN in a commercial farm, associated with pig behaviour and health biomarkers measures. On two consecutive batches, PEN prevalence was determined at the pen level. PEN scores, blood haptoglobin concentration and oxidative status were measured on two pigs per pen (n = 48 pens) 9, 30 and 50 days (D) after arrival to the post-weaning unit. Social nosing, oral manipulation and aggression of pen mates and exploration of enrichment materials were observed on two to three pigs per pen twice a week from D9 to D50. RESULTS: At the pen level, the higher the time spent nosing pen mates, the lower the percentage of pigs affected by PEN during both the early and the late post-weaning periods (P < 0.002) and, in the opposite, the higher the time spent orally manipulating pen mates during the late post-weaning period, the higher the percentage of affected pigs (P = 0.03). At the pig level, the higher the increase in hydroperoxides and haptoglobin during the early post-weaning period, the higher the PEN scores on D30 (P < 0.001). CONCLUSIONS: This study suggests that a high incidence of social nosing, which can be an indicator of good social cohesion in a group, was significantly associated with less frequent lesions of PEN. In opposite, high incidence of oral manipulation of pen mates may increase the percentage of PEN-affected pigs. According to these observations, PEN is a multifactorial condition which may have social causes among others.

Working with cattle slurry on farms: emission and dispersion of hydrogen sulfide gas during stirring.

Over the past 15 years, there have been numerous fatalities related to working with animal slurry. Working with cattle slurry releases toxic gases, in particular, hydrogen sulphide (H2S), which can cause acute central nervous system toxicity, breathing difficulties, and death if exposed to high concentrations. Real-time measurements of H2S gas were taken over distance and time, during the stirring of cattle slurry on farms. Gas was measured at eight slurry stores with differing typical configurations of indoor or outdoor stores and with or without slatted flooring. Highest H2S gas levels were measured from indoor stores under slatted floors, and generally at positions closest to the stirrer or the point of maximum stirring, with levels decreasing with distance from source. Most of the data indicate H2S gas levels increase very rapidly after stirring starts, and mostly decline to baseline levels within 30 min post start of stirring. There were, however, circumstances where gas levels remained high and only started to decline once the stirrer had stopped. H2S gas levels at all farms, at all positions measured were consistently below 10 ppm within 30 min of the stirrer being stopped. The current data highlight areas of the farm and ways of working that have the potential for workers and others to be at risk of exposure to toxic slurry gases. The area should be left to ventilate naturally for at least 30 min after the stirrer has been stopped before re-entering buildings. Influencing the design of stirring equipment and future slurry stores would likely reduce the risk of worker exposure to slurry gases.