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The proximity of rail corridors to livestock production enterprises poses potential risks to welfare and production. The association between these factors and production have been extensively investigated. This review aims to assess the potential impact on the basis of existing data in a livestock production context. Due to expansion of freight rail networks through agricultural land, there is a need to investigate potential impacts of rail (including train and track) noise, vibration and visual disturbance on the physiology and behaviour of the livestock and subsequent production traits. Additionally, the factors influencing the impact on animals were characterised broadly as noise, vibration, and visual and spatial disturbance. This information was used to develop conceptual frameworks around the contribution of rail impact on allostatic load, animal welfare and production. Placing rail noise in the context of other, known, noise impacts showed that proximity to the rail line will determine the impact of noise on the behaviour and physiology of the animal. Thresholds for noise levels should be determined on the basis of known noise thresholds, taking into account the impact of noise on allostatic load. Further research is recommended to investigate the behavioural, physiological and production impacts on livestock from proximity to rail corridors. Current literature suggests that the allostatic load will vary depending on the proximity of the animal to the source of stimulus, the type, size or level of stimuli, habituation and the individual animal variation in response to the stimuli. [ABSTRACT FROM AUTHOR]

A dose-response experiment was designed to examine the effect of 3-nitrooxypropanol (3-NOP) on methane (CH4) emissions, rumen function and performance of feedlot cattle fed a tempered barley-based diet with canola oil. Twenty Angus steers of initial body weight (BW) of 356 ± 14.4 kg were allocated in a randomized complete block design. Initial BW was used as the blocking criterion. Cattle were housed in individual indoor pens for 112 d, including the first 21 d of adaptation followed by a 90-d finishing period when five different 3-NOP inclusion rates were compared: 0 mg/kg dry matter (DM; control), 50 mg/kg DM, 75 mg/kg DM, 100 mg/kg DM, and 125 mg/kg DM. Daily CH4 production was measured on day 7 (last day of starter diet), day 14 (last day of the first intermediate diet), and day 21 (last day of the second intermediate diet) of the adaptation period and on days 28, 49, 70, 91, and 112 of the finisher period using open circuit respiration chambers. Rumen digesta samples were collected from each steer on the day prior to chamber measurement postfeeding, and prefeeding on the day after the chamber measurement, for determination of rumen volatile fatty acids (VFA), ammonium-N, protozoa enumeration, pH, and reduction potential. Dry matter intake (DMI) was recorded daily and BW weekly. Data were analyzed in a mixed model including period, 3-NOP dose and their interaction as fixed effects, and block as a random effect. Our results demonstrated both a linear and quadratic (decreasing rate of change) effect on CH4 production (g/d) and CH4 yield (g/kg DMI) as 3-NOP dose increased (P < 0.01). The achieved mitigation for CH4 yield in our study ranged from approximately 65.5% up to 87.6% relative to control steers fed a finishing feedlot diet. Our results revealed that 3-NOP dose did not alter rumen fermentation parameters such as ammonium-N, VFA concentration nor VFA molar proportions. Although this experimental design was not focused on the effect of 3-NOP dose on feedlot performance, no negative effects of any 3-NOP dose were detected on animal production parameters. Ultimately, the knowledge on the CH4 suppression pattern of 3-NOP may facilitate sustainable pathways for the feedlot industry to lower its carbon footprint. [ABSTRACT FROM AUTHOR]

Stocking density may impact sheep welfare during live export voyages that occur under hot and humid conditions. The aim of this study was to assess the welfare implications for sheep housed at three allometric stocking densities (k = 0.030, 0.033, 0.042), while exposed to hot and humid climatic conditions. For 21 d, Merino wethers (n = 216) were housed in 12 pens of 18 wethers, in two climate-controlled rooms where wet-bulb temperature (TWB) mimicked the conditions of a live export voyage with high heat and humidity, and limited diurnal variation. Scan sampling of standing and lying behaviors was conducted on days 2, 5, 8, 11, 15, 18, and 20, at hourly intervals. Agonistic interactions were scored continuously on the same days between 1750 and 1800 h. Liveweights were recorded at the start and end of the study. For a subset of focal wethers (3 per pen), whole blood variables were assessed at the start and end of the experiment, along with fecal glucocorticoid metabolites (FGCM), which were also assessed on days 7 and 14. Rumen temperatures (TRUM) of focal wethers were recorded at 10-min intervals, and their respiration rates (RR) were measured every 2 h on days 1, 3, and from days 7 to 21. Focal wethers were slaughtered for necropsy after the study, and both adrenal glands were excised and weighed. The expression of some lying positions was impaired at high stocking densities, and lying with outstretched legs increased at high TWB. For respiration rates, there was an interaction between stocking density and TWB, such that RR was reduced by the provision of additional space at high TWB. TRUM was relatively unaffected by stocking density but increased at higher TWB, and any effects of stocking density on FGCM concentrations, liveweights (LW), adrenal gland weights or blood variables were minimal. Necropsy examination showed no indication that the wethers had experienced ongoing respiratory distress. These results suggest that the wethers were able to cope with these increases in stocking density under the conditions imposed. However, based on this evidence, the provision of additional space under hot conditions may be beneficial to facilitating the expression of some lying positions. Whilst the experiment was designed to emulate certain conditions relevant during live export voyages, other factors that may induce stress during this mode of transport were not present, and so the conclusions must be interpreted in the context of the experimental conditions. [ABSTRACT FROM AUTHOR]

Current Indonesian beef production only meets 45% of local demand. Increasing local beef production through integration of cattle production in pre-existing oil palm plantations is a possible solution to meeting this shortfall. The oil palm understorey provides feed, alleviating the need to convert additional land to agriculture. Smallholders are important contributors to both Indonesian cattle and palm oil production. This case study research seeks to understand key aspects of smallholder cattle management in palm oil production areas, to highlight opportunities and barriers to cattle integration. Thirty-nine smallholder cattle farmers from four villages in South Kalimantan were individually interviewed. The lack of alternative feed sources was the major driver towards the adoption of cattle production using oil palm understorey as feed. Cattle grazing was uncontrolled due to labour shortages and occurred in individually owned and 'plasma' plantations, with cattle penned at night where possible to avoid theft. Arrangements on land access and use between stakeholders are needed for systematic cattle grazing and to control cattle theft. [ABSTRACT FROM AUTHOR]

Wet winter conditions can create animal welfare issues in feedlots if the pen surface becomes a deep, wet, penetrable substrate. Feedlot pens with a clay and gravel base (N = 30) bedded with 150 mm (W15) and 300 mm (W30) depth of woodchips were compared to a control treatment with no bedding over a 109-day feeding period, while irrigated to supplement natural rainfall. The pad substrate was measured for variables which would affect cattle comfort and value of the substrate for composting. The penetrable depth of control pens was higher than both woodchip-bedded treatments from week 2, and increased until the end of the experiment. Meanwhile these scores were steady for W30 throughout the experiment, and increased for W15 only after week 10. Moisture content of the pad was higher throughout the experiment in the control pens than in the woodchip-bedded pens. In the control pens, the force required to pull a cattle leg analogue out of the pen substrate was three times that required in woodchip-bedded treatments. The W15 treatment increased C : N in the substrate to the upper limit of suitability for composting, and in W30, C : N was too high for composting after a 109-day feeding period. Overall, providing feedlot cattle with 150 or 300 mm of woodchip bedding during a 109-day feeding period improved the condition of the pad substrate for cattle comfort by reducing penetrable depth and moisture content of the substrate surface stratum, but composting value decreased in W30 over this feeding period duration. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Grasslands / Forrajes Tropicales is the property of International Centre for Tropical Agriculture - CIAT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: This study was conducted to investigate feedlot factors that influence the incidence of dark cutting in Australian grain-fed beef. Awareness of factors influencing dark cutting within the supply chain will enable the implementation of management strategies to manage dark cutting risk and reduce incidence. The reduction of dark cutting incidence will increase feedlot productivity as well as profitability across the entire supply chain. It has been well-established that dark cutting (DC) is a multifactorial issue that is associated with numerous animal and management factors. However, there is limited understanding of the feedlot-based factors that contribute to the influence of DC. The aim of this study was to evaluate the effect of climate, animal, and feedlot factors on the incidence of pH non-compliance in Australian grain-fed cattle. For this study, feedlot and abattoir records from 142,228 individual cattle over a 1-year period were investigated. These data incorporated records from seven feedlots that consigned cattle to three abattoirs. The average incidence of DC in these carcasses was 2.8%. The production factors that were associated with increased risk of DC included feedlot, sex, hormone growth promotants (HGP), cattle health, and days on feed (DOF). Additionally, DC also increased by reduced solar radiation (SR, W/m2), lower wind speeds (WS, m/s), increased ambient temperature (TA, °C), higher rainfall, a higher average temperature–humidity index (THI), and increased duration of time above heat-load-index threshold of 86 (HLI ≥ 86) during the 7 days prior to feedlot departure. This study identified the feedlot factors that increase the risk of DC from a feedlot-management perspective. [ABSTRACT FROM AUTHOR]

Population growth and improving living standards are leading to a growing demand for beef. The understorey in the 19 million hectares of oil palm plantation worldwide represent a source of cattle feed, while also sparing additional land conversion for grazing. Research on cattle grazing under oil palm is novel and knowledge is lacking on long-term profitability and sustainability of the system, a major deterrent to cattle–oil palm farming system adoption. Here we review the current literature on cattle grazing in oil palm plantations, to highlight the knowns and unknowns of grazing impacts on the understorey, cattle and oil palm productivity, as well as economic implications. This review’s major outcomes are the following: (i) although understorey utilization as feed is a major advantage of cattle–oil palm integrated farming systems, declining understorey productivity under ageing plantation indicates the need for alternative solutions for sustained cattle productivity over the plantation’s lifecycle; (ii) oil palm yields were reported to increase under cattle integration but evidence was weak, both oil palm yields and the pathways through which oil palm yields are impacted by cattle grazing should be further explored; (iii) economic analyses showed cattle grazing under oil palm plantations was profitable for large-scale oil palm producers due to cattle sales, and returns were further enhanced by reductions in weeding and fertilizer costs; (iv) sustainable cattle grazing was found to be difficult in smallholder oil palm plantations due to land constraints and the current practice of free-grazing; options for improving grazing sustainability and profitability in these systems should be explored. This systematic review concluded that cattle integration in oil palm plantations has great potential but further research is required to develop locally specific productive and sustainable systems of grazed cattle integration with oil palm plantations. [ABSTRACT FROM AUTHOR]

Context: In virtual fencing, where an animal learns to remain within a set area by responding to an audio cue in order to avoid receiving an aversive electrical stimulus, maternal learning may play a role in facilitating successful learning. Aims: This study aimed to investigate the effect of early observation of virtual fence engagement using a maternal demonstrator on the ability of lambs to later learn to respond correctly to a virtual fence. Method: Merino lambs (n = 114) were assigned to one of three treatments prior to being trained to a virtual fence: (1) lambs from experienced demonstrators, in which the lambs observed their mothers interacting with a virtual fence having been trained prior to lambing; (2) lambs from naïve demonstrators, in which lambs observed their mothers learning the virtual fence system; and (3) unexposed lambs, in which lambs had not encountered a virtual fence prior to being trained. Following weaning, lambs were trained to a virtual fence and responses to stimuli were recorded. Key results: The number of audio cue and electrical pulse stimuli received by the lambs did not differ across the three treatments (P > 0.05). There were no significant differences between the proportions of correct behavioural responses to the audio cue stimulus across the three treatment groups (P > 0.05). Logistic regression analysis of learning curves showed that lambs from naïve demonstrators displayed a change in behaviour and learned the correct response to the audio cue, while the unexposed lambs and lambs from pre-trained demonstrators did not. Conclusions: These results suggest that maternal influences may be influencing the ability of lambs to learn a virtual fence, although the training protocol was limited due to time, space, equipment and environmental constraints. Implications: This work may help to inform producers on management decisions for the application of the virtual fencing, such as enabling lambs to observe their mothers interacting with a virtual fence prior to weaning to enhance learning the virtual fence when applied later in life. Maternal learning (in which juveniles learn skills and behaviours from their mothers) has not been investigated in the context of virtual fencing in sheep. This study found that observing the mother learning the virtual fence, may influence the lamb's ability to learn the system when compared with control lambs who had not seen the fence, and lambs which had observed previously exposed mothers interacting with the system. Results suggest a possible role for maternal learning in virtual fence implementation. [ABSTRACT FROM AUTHOR]

Time spent feeding by grazing cattle is an important predictor of intake and feed efficiency. This study examined the use of automatic supplement weighing (ASW) units for monitoring voluntary access of breeding cows (n = 430) to mineral block supplements in an extensive rangeland of northern Australia. The ASW units (n = 10) were located within each of experimental sites (5 units per site; Bore and Eldons). Over the 62 days of data collection, 85%, 13%, and 2% of cows spent <600, 600-1200, >1200 min accessing supplements, respectively, with between-animal variation (CV) of 107%. A total of 133 cows visited both sites while 142 and 155 cows visited only Bore and Eldons, respectively. Most visits (80-90%) were recorded during the day (800-1700 h), 7-17% during the night (1800-2300 h), and 3% during the dawn (0-700 h). Time spent accessing supplements differed between ASW units across the two sites (p < 0.001) and varied according to the day of visits (p < 0.001). There was a significant relationship between time spent at the ASW units and supplement intake on a herd basis (p < 0.001; R²adj = 0.70). The results showed that the ASW units were capable of monitoring access to mineral block supplements that may reflect the supplement intake of rangeland cattle. [ABSTRACT FROM AUTHOR]

Context: Cassava bagasse is readily available in tropical countries as an energy source for ruminant diets, but previous research has shown low cattle performance at high inclusion rates. Aims: The nature of the dose–response relationship between increasing inclusion rate of cassava (Manihot esculenta Crantz) bagasse (CB), substituting for protein meals in diets of fattening cattle, was used to evaluate the reduced animal performance at high inclusion rates. Methods: Thirty growing Madura (Bos indicus × javanicus) bulls were fed concentrate-based diets with five levels of CB inclusion at 20 g dry matter (DM)/kg liveweight and elephant grass (Pennesetum purpureum) separately at 5 g DM/kg liveweight. The five tested CB inclusion rates into the offered diet were 30, 40, 50, 60 and 70% of total dry matter. Lines of best fit were used to describe the relationships between animal performance and CB inclusion rate. Key results: Intake of dry matter and concentrate both demonstrated a quadratic relationship with increasing CB inclusion, both maximised at 46–47% CB inclusion in the offered diet or a CB intake of ~9.7 g CB/kg liveweight. Liveweight gain and change in body condition score both demonstrated a quadratic dose–response relationship with increasing CB inclusion, with maximal performance achieved at 34–38% inclusion of CB. Although protein content at the highest level of CB inclusion was low (68 g/kg DM), modelling of predicted liveweight gain indicated that this was most constrained by energy intake (as a function of concentrate intake), rather than crude protein. Conclusions: Inclusion of CB up to ~45% of the diet, substituting for protein meals, does not improve, but has no detrimental effect, on liveweight gain. The plateauing of CB intake above 50% inclusion in in the offered diet suggests that cattle were eating to a maximal CB intake. Several hypotheses for reduced intake of concentrate at high levels of CB inclusion were proposed, including low protein content and hydrogen cyanide content of the CB, none of which satisfactorily explained why intake of concentrate was depressed above 50% CB inclusion of the diet on offer. Implications: Rations should be formulated to contain no more than 50% CB for maximal cattle performance. Further research is required to understand the causes of depressed intake at high inclusion rates of CB. Cassava bagasse is a by-product feedstuff with potential as a ruminant feed in tropical environments, but there is poor understanding regarding production responses from its inclusion in cattle diets. We found that when cassava bagasse inclusion in a concentrate mix was increased, cattle intake of the concentrate mix increased, but in a curvilinear fashion. We suggest that cattle will eat no more than a maximal limit of cassava bagasse intake, although the reasons why are not clear. [ABSTRACT FROM AUTHOR]

Livestock producers are facing increasing pressure to reduce the environmental and animal-welfare impacts of production, while also managing the challenge of an increasingly variable climate and diminishing resources. This perspective paper highlights the role for animal scientists to contribute to the sustainability of future livestock systems. We argue the need for a broader, more inclusive and more integrated concept of animal science, better connections among scientists, producers, consumers and policy makers, and more support for the next generation of animal scientists. Animal scientists have an important role to play in providing the evidence to support the social licence of livestock production and inform decisions made by policy makers and consumers regarding the production and consumption of livestock products. Animal scientists can also assist producers to adapt to social, environmental and political challenges that affect their livelihoods and the way they farm. Traditionally, animal science has focussed on species- and discipline-specific areas of research such as ruminant nutrition, genetics or reproductive physiology. While this fundamental research remains essential to understand the underlying biology of livestock production and improve production efficiency, it needs to be better integrated into research applied at and beyond the herd or flock level. Systems thinkers who can apply this knowledge across farm, regional and national scales also have an important role in providing information to key decision makers, from farmers to national government. Better engagement with the social and economic sciences can inform how animal scientists and extension services interact with producers to understand constraints to production as well as adoption of new technology and co-develop evidence-based solutions. Underlying this, the demographics of those who study and work in animal science are changing. Australian animal industries require the best and brightest minds to overcome future challenges and engaging these students as the new face of Australian animal science is an essential step towards sustainable future livestock systems. Livestock production is facing new challenges from consumers and operating environments, and, so, the role of animal science must also change to adequately solve these complex problems. The increasingly diverse next generation of animal science graduates has less traditional career pathways and links to primary industries, and will require new methods of mentoring and professional development to support the needs of livestock producers. Integrating other disciplines and systems approaches with species- and discipline-specific science will be essential to ensuring a sustainable future for livestock production in Australia. [ABSTRACT FROM AUTHOR]

Formulating diets conservatively for minimum crude-protein (CP) requirements and overfeeding nitrogen (N) is commonplace in grain finishing rations in USA, Canada and Australia. Overfeeding N is considered to be a low-cost and low-risk (to cattle production and health) strategy and is becoming more commonplace in the US with the use of high-N ethanol by-products in finishing diets. However, loss of N from feedlot manure in the form of volatilised ammonia and nitrous oxide, and nitrate contamination of water are of significant environmental concern. Thus, there is a need to improve N-use efficiency of beef cattle production and reduce losses of N to the environment. The most effective approach is to lower N intake of animals through precision feeding, and the application of the metabolisable protein system, including its recent updates to estimation of N supply and recycling. Precision feeding of protein needs to account for variations in the production system, e.g. grain type, liveweight, maturity, use of hormonal growth promotants and β agonists. Opportunities to reduce total N fed to finishing cattle include oscillating supply of dietary CP and reducing supply of CP to better meet cattle requirements (phase feeding). Overfeeding of nitrogen (N) to feedlot cattle is considered low risk (in terms of cost and effects on production), but excreted excess dietary N is of significant environmental concern. Our ability to formulate the protein content of grain-finishing rations is becoming more precise but there are still barriers to adoption on-farm. Precision feeding of protein needs to account for variations in production system, and will enable us to improve N-use efficiency, and reduce N intake and wastage in the feedlot. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Grasslands / Forrajes Tropicales is the property of International Centre for Tropical Agriculture - CIAT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Biennial Conference of Recent Advances in Animal Nutrition – Australia was held on 27–28 July 2023. The special issue contains latest research in the field of animal nutrition across the most economically significant animal species, including poultry, pigs, sheep, cattle, companion animals and aquaculture. [ABSTRACT FROM AUTHOR]

Livestock welfare and management could be greatly enhanced by the replacement of branding or ear tagging with less invasive visual biometric identification methods. Biometric identification of cattle from muzzle patterns has previously indicated promising results. Significant barriers exist in the translation of these initial findings into a practical precision livestock monitoring system, which can be deployed at scale for large herds. The objective of this study was to investigate and address key limitations to the autonomous biometric identification of cattle. The contributions of this work are fourfold: (1) provision of a large publicly-available dataset of cattle face images (300 individual cattle) to facilitate further research in this field, (2) development of a two-stage YOLOv3-ResNet50 algorithm that first detects and extracts the cattle muzzle region in images and then applies deep transfer learning for biometric identification, (3) evaluation of model performance across a range of cattle breeds, and (4) utilizing few-shot learning (five images per individual) to greatly reduce both the data collection requirements and duration of model training. Results indicated excellent model performance. Muzzle detection accuracy was 99.13% (1024 × 1024 image resolution) and biometric identification achieved 99.11% testing accuracy. Overall, the two-stage YOLOv3-ResNet50 algorithm proposed has substantial potential to form the foundation of a highly accurate automated cattle biometric identification system, which is applicable in livestock farming systems. The obtained results indicate that utilizing livestock biometric monitoring in an advanced manner for resource management at multiple scales of production is possible for future agriculture decision support systems, including providing useful information to forecast acceptable stocking rates of pastures. [ABSTRACT FROM AUTHOR]

Simple Summary: Quantifying mineral block supplement intake by individual beef cattle is a challenging task but may enable improved efficiency of supplement use particularly in a grazed system. Estimating time spent licking when cattle access the mineral block supplement can be useful for predicting intake on an individual basis. The advancement of sensor technology has facilitated collection of individual data associated with ingestive behaviours such as feeding and licking duration. This experiment was intended to investigate the effectiveness of wearable tri-axial accelerometers fitted on both neck-collar and ear-tag to identify the licking behaviour of beef cattle by distinguishing it from eating, standing and lying behaviours. The capability of tri-axial accelerometers to classify licking behaviour in beef cattle revealed in this study would offer the possibility of measuring time spent licking and further developing a practical method of estimating mineral block supplement intake by individual grazing cattle. Identifying the licking behaviour in beef cattle may provide a means to measure time spent licking for estimating individual block supplement intake. This study aimed to determine the effectiveness of tri-axial accelerometers deployed in a neck-collar and an ear-tag, to characterise the licking behaviour of beef cattle in individual pens. Four, 2-year-old Angus steers weighing 368 ± 9.3 kg (mean ± SD) were used in a 14-day study. Four machine learning (ML) algorithms (decision trees [DT], random forest [RF], support vector machine [SVM] and k-nearest neighbour [kNN]) were employed to develop behaviour classification models using three different ethograms: (1) licking vs. eating vs. standing vs. lying; (2) licking vs. eating vs. inactive; and (3) licking vs. non-licking. Activities were video-recorded from 1000 to 1600 h daily when access to supplement was provided. The RF algorithm exhibited a superior performance in all ethograms across the two deployment modes with an overall accuracy ranging from 88% to 98%. The neck-collar accelerometers had a better performance than the ear-tag accelerometers across all ethograms with sensitivity and positive predictive value (PPV) ranging from 95% to 99% and 91% to 96%, respectively. Overall, the tri-axial accelerometer was capable of identifying licking behaviour of beef cattle in a controlled environment. Further research is required to test the model under actual grazing conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: This study was conducted to generate a greater understanding of the abattoir factors that influence the incidence of dark cutting in Australian grain-fed beef. Elucidation of the factors that are associated with an increased risk of dark cutting will allow for the development of effective management strategies to be implemented to reduce dark cutting in feedlot cattle. This will increase profitability across the supply chain for both producers and abattoirs, whom need to collaborate for the minimization of dark cutting. The aim of this study was to evaluate the effect of carcass traits, lairage time and weather conditions during lairage and abattoir factors that impact the incidence of dark cutting in 142,228 grain-fed carcasses, as defined by Meat Standards Australia (MSA) guidelines. This study was conducted over a 12-month period analysing data from cattle that were supplied from seven feedlots and processed at three abattoirs. Abattoir data indicated that the average incidence of dark cutting within the study was 2.8%. Increased wind speeds (WSs) and rain during lairage at the abattoir was associated with an increased risk of dark cutting, whereas variation in ambient temperature and/or relative humidity did not influence dark cutting. Heavier carcasses with whiter fat, larger hump heights, more rib fat, higher marble scores and lower ossification had lower incidences of dark cutting. The factors abattoir, time in lairage, time to grading and grader within Abattoir had significant effects on the incidence of dark cutting. The results from this study suggest that reducing the time in lairage and increasing the time between slaughter and grading are the two major ways to reduce dark cutting in MSA carcasses. [ABSTRACT FROM AUTHOR]

Simple Summary: Virtual fencing is a new technology that uses audio signals and electrical stimuli to spatially control animals without the need for fixed fencing. It involves avoidance learning whereby the animals learn to respond to an audio cue (conditioning stimulus) to avoid receiving an aversive electrical stimulus (unconditioned stimulus). The audio cue is used to warn the animal that it is approaching the boundary and should be benign and not perceived as aversive to the animal. While a positive punishment stimulus is necessary for learning, it should not be so aversive to the animal that it impinges on its welfare. This study aimed to determine how the stimuli used in virtual fencing are perceived by the animal when they are first encountered. The audio and electrical stimuli were compared to other commonly encountered stimuli in normal sheep production systems, including a barking dog and a restraint procedure. The physiological and behavioral responses of sheep indicated that sheep were no more adversely impacted by virtual fencing stimuli than they were by other commonly encountered stimuli. The least to most aversive treatments were: Control < Beep < Barking Dog < Electrical stimulus < Restraint. To understand the animal welfare impact of virtual fencing stimuli (audio cue 'beep' and electrical stimulus) on naïve sheep, it is necessary to assess stress responses during the animal's first encounters with these stimuli. Eighty Merino ewes were exposed to one of the following treatments (n = 16 animals per treatment): Control (no stimuli), beep, dog bark, manual restraint, and electrical stimulus. Collars were used to apply the audio and electrical stimuli. The restraint treatment showed an elevated cortisol response compared with the control (p < 0.05), but there were no differences between the other treatments and the control. There were no differences between treatments in vaginal temperature (p > 0.05). For behaviors, the sheep receiving the bark and beep treatments were more vigilant compared to the control (p < 0.05), there were more aversive responses observed in the electrical stimulus treatment compared to the control. Together, the responses showed that the beep stimuli were largely benign, the bark stimuli was minimally aversive, the electrical stimuli was acutely aversive, and the restraint was moderately aversive. These data suggest that, for sheep, their first exposure to the virtual fencing stimuli should be perceived as less aversive than a commonly used restraint procedure. [ABSTRACT FROM AUTHOR]