This review of sow welfare addresses all aspects of housing for adult female pigs, including the issue of piglet welfare during lactation. It puts the issue of sow welfare in perspective by briefly outlining different approaches to the scientific assessment of welfare, the ‘feelings, preference, nature, and the functional or homeostasis’ approaches. We believe the last approach currently offers science the best assessment of welfare and is the approach that is utilised in this review. It involves comparing housing or husbandry systems and risks to welfare on the basis of relative changes in biological (behavioural and physiological) responses and corresponding decreases in fitness (growth rate, reproductive performance, or health/injury/immunology). The review discusses the following areas: ( i ) housing of individually housed pregnant pigs, with subsections on tethers, stalls, reproductive performance, exercise, and new stall designs; conventional, alternative, and outdoor group housing with subsections on aggression, electronic feeding stations, ecoshelters, and other alternative group housing designs; and other issues, such as lameness, culling, straw and other substrates, diet and hunger, quality of stockpeople, and housing around mating including oestrus detection and mating; and ( ii ) farrowing and lactating pigs with subsections on farrowing crates and alternative farrowing systems, stress around farrowing and during lactation, maternal behaviour and piglet survival, and sow and piglet injury and lameness. Conclusions and recommendations arising from the review include the need for public education to provide an informed consumer base that will result in some consensus on welfare issues among diverse interest groups and the need for industry education that results in better animal welfare and a sustainable industry. Some specific research recommendations include space allowance and the duration of housing for individually housed pigs, welfare issues of breeding sows in ecoshelters, piglet mortality in alternative systems, aggression in conventional and large groups, bedding, and hunger.

Factors that have been shown to impact the welfare of group-housed sows are discussed in this review. Floor space allowance markedly affects sow welfare. In addition to quantity of floor space, the quality of space is important: spatial separation between sows can be provided with visual or physical barriers and stalls. Whereas 1.4 m²/sow is insufficient, further research is required to examine space effects in the range of 1.8 to 2.4 m²/sow in more detail. The period immediately after mixing has the most pronounced effects on aggression and stress, and therefore, well-designed mixing pens offer the opportunity to reduce aggression, injury, and stress while allowing the social hierarchy to quickly form. Because hunger is likely to lead to competition for feed or access to feeding areas, strategies to reduce hunger between meals through higher feeding levels, dietary fiber, or foraging substrate should be examined. However, feeding systems, such as full-body feeding stalls, can also affect aggression and stress by providing protection at feeding, but deriving conclusions on this topic is difficult because research directly comparing floor feeding, feeding stalls, and electronic sow feeder systems has not been conducted. Familiar sows engage in less aggression, so mixing sows that have been housed together in the previous gestation may reduce aggression. Although there is evidence in other species that early experience may affect social skills later in life, there are few studies on the effects of early “socialization” on aggressive behavior of adult sows. Genetic selection has the potential to reduce aggression, and therefore, continued research on the opportunity to genetically select against aggressiveness and its broader implications is required. Most research to date has examined mixing sows after insemination and knowledge on grouping after weaning is limited.

Precision livestock farming has emerged with the aim of providing detailed information to detect and reduce problems related to animal management. This study aimed to develop and validate computer vision techniques to track required features of cattle face and to remotely assess eye temperature, ear-base temperature, respiration rate, and heart rate in cattle. Ten dairy cows were recorded during six handling procedures across two consecutive days using thermal infrared cameras and RGB (red, green, blue) video cameras. Simultaneously, core body temperature, respiration rate and heart rate were measured using more conventional ‘invasive’ methods to be compared with the data obtained with the proposed algorithms. The feature tracking algorithm, developed to improve image processing, showed an accuracy between 92% and 95% when tracking different areas of the face of cows. The results of this study also show correlation coefficients up to 0.99 between temperature measures obtained invasively and those obtained remotely, with the highest values achieved when the analysis was performed within individual cows. In the case of respiration rate, a positive correlation (r = 0.87) was found between visual observations and the analysis of non-radiometric infrared videos. Low to high correlation coefficients were found between the heart rates (0.09–0.99) obtained from attached monitors and from the proposed method. Furthermore, camera location and the area analysed appear to have a relevant impact on the performance of the proposed techniques. This study shows positive outcomes from the proposed computer vision techniques when measuring physiological parameters. Further research is needed to automate and improve these techniques to measure physiological changes in farm animals considering their individual characteristics.

The transport of young calves is a welfare concern. Young calves aged ≤3 mo are particularly vulnerable to compromised welfare, and are at a relatively high risk of morbidity and mortality compared with adult cattle. Calves face several potential challenges to welfare during and after transport, including food and water deprivation, disease, injury, and stress from handling, social mixing, and new environments. The key risk factors identified for poor calf welfare associated with transport include long transport and fasting durations, young age at transport, poor colostral immunity, timing within the calving season, lack of bedding in trucks, and high stocking density. Maximizing calf welfare thus requires a multifaceted approach, such as minimizing transport and fasting durations, transporting at an appropriate stocking density with comfortable bedding, only transporting calves that are healthy and fit, and optimizing pre-transport calf management. More research is needed to understand the effect of transport on the mental or affective state of calves.