Review of Temporary Crating of Farrowing and Lactating Sows

Salivary oxytocin changes and effect of the season in sows kept in different farrowing systems: Farrowing crate and farrowing pen with temporary crating

Alternative farrowing systems that have been developed in recent years could have a positive effect on the welfare of sows during farrowing and lactation. Oxytocin measurements in saliva may provide information about positive animal welfare status. The purpose of this study was to evaluate the changes in salivary oxytocin concentrations in sows during the lactation period in three different farrowing systems and in two different seasons. Crossbred Duroc sows (n = 34, average parity = 3.6 ± 1.80) were housed in conventional farrowing crates (FC) (n = 10) or in farrowing pens with temporary crating (TC), including SWAP (n = 12) and JFL15 (n = 12) in two different seasons: summer and winter. Saliva samples were collected for six days during lactation: days 2, 4, 12, 23, 25 (i.e., 1-day post-weaning) and 26 (i.e., 2-day post-weaning) after farrowing. Moreover, behavioral data from sows was recorded on days 2, 4, 12 and 23 after farrowing, using a 30-s scan sampling method for 3 min per pen to record the behaviors which were assessed by the same observer. The results showed that the salivary oxytocin concentrations were 472.5 pg/mL and 399.4 pg/mL higher in both TC (SWAP and JLF15, respectively) than in the FC in early-lactation period, and these differences were more pronounced in summer and at the end of lactation in winter. In terms of behavior, higher number of mother-young interactions were observed in TC than FC in early- and mid-lactation period. In conclusion, TC is associated to a higher salivary oxytocin concentration that could indicated an increased mother-young interaction, although oxytocin concentration can be influenced by other factors, such as season or day of lactation.

Sow dimensions and loose-housed farrowing pen sizes on commercial piglet-producing farms in Sweden

International interest in loose-housed farrowing is growing and there are ongoing discussions within the European Union (EU) on new legal requirements. However, there is a lack of empirical data on loose-housed farrowing pen sizes and sow dimensions in commercial production. The aim of this study was to map and describe sow size and loose-housing farrowing pen size on commercial piglet-producing farms in Sweden. The study included 146 sows and 51 pen types on 35 medium sized to large Swedish piglet-producing farms (ranging from 106 to 1300 sows in production). Sow length ranged from 129 to 238 cm (mean ± SD 191.3 ± 19.3 cm) and sow height from 74 to 133 cm (86.7 ± 7.7 cm). Floor space occupied by the sow when lying down (length x height) ranged from 1.0 to 3.2 m2 (1.7 ± 0.3 m2). Pen length ranged from 259 to 415 cm (315.1 ± 24.3 cm), pen width from 188 to 245 cm (207.0 ± 10.7 cm), total pen area from 5.7 to 8.9 m2 (6.5 ± 0.5 m2), piglet corner area from 0.5 to 1.8 m2 (1.1 ± 0.4 m2) and area available for the sow (total area - piglet corner area) from 3.9 to 6.4 m2 (5.4 ± 0.6 m2). These results show that there is substantial variation in sow, pen and piglet corner size on commercial piglet-producing farms in Sweden. This poses a risk of mismatches between sow and pen size (pens too short in relation to sow dimensions), especially for older sows. These findings are of practical significance for animal welfare and production and emphasise the importance of designing loose-housed pens adapted to future sow, litter and piglet size.

Review: Early life piglet experiences and impacts on immediate and longer-term adaptability

Pigs in production systems are routinely exposed to challenging situations including abrupt weaning, painful husbandry procedures, intense contact with stockpeople, and exposure to novel social and physical environments. The resilience of pigs to these stressors has implications for animal welfare and productivity and can be affected by early life experiences. In rodents and primates, early experiences with stressors that the animal can adequately cope with confers future stress adaptability, leading to less abnormal behaviour, lower behavioural and physiological responses to stressors, and faster recovery after stress exposure. Early experiences that can affect the ability of pigs to overcome challenge include interactions with the dam, conspecifics, humans, and the overall complexity of the environment. Farrowing crates limit the sow's ability to show maternal behaviour towards piglets, and negatively affect piglet social behaviour during lactation, with less play and more manipulation of pen mates in crates than in large pens. Rearing in pens has been proposed to improve the ability of pigs to cope with routine stressors, but the evidence for this is conflicting. The early housing environment can affect general fearfulness and fear of humans, and surprisingly, most studies have shown fear responses to be greater in pigs reared pens than in crates. Given the potential for fear to affect animal welfare and productivity, more detailed research on early housing effects is needed. While there is limited evidence that early housing influences fear in the longer term, human contact early in life appears to have a more profound and sustained effect, with regular positive human interaction early in life having an enduring effect on reducing pigs' fear of humans. The practicality of positive human-pig interaction in a commercial environment needs to be examined further, but only a small amount of positive human contact early in life can improve the resilience of pigs to routine husbandry stressors. Early social experience with non-littermates reduces stress at weaning and mixing, while early weaning before 3-4 weeks of age increases abnormal behaviours. Environmental enrichment, such as foraging substrates and increased floor space, reduces abnormal behaviour in piglets, but housing in an enriched environment early in life and subsequently in a non-enriched environment can increase abnormal behaviour if these environments are dramatically different. Although the later environment can modify the influence of the early environment, overall, early life experiences can be important in shaping how pigs cope with stress in both an immediate and longer-term capacity.

Impact of farrowing system and prepartum nest-building material on nest-building behaviour and farrowing in sows

Farrowing crates are widely used as the main housing system for farrowing and lactating sows on commercial farms although they have a negative impact on sow welfare and behaviour. One of the main reasons for using farrowing crates is to reduce piglet mortality during farrowing and lactation. We compared the effects of temporary crating (TC) versus free farrowing (FF) with different nest-building materials on production and welfare measures. Sows were investigated using a 2 × 3 factorial design. Sows were allocated to two farrowing treatments: FF sows were not crated around farrowing, and TC sows were crated from 2 days before expected farrowing until 3 days after farrowing, when the crate was opened. In both farrowing treatments, the nest-building material was given from 7 days prior to farrowing as follows: (1) 1 L of straw twice per day, (2) 1 sheet of newspaper twice per day or (3) fastened jute fabric to the farrowing crate. The study consisted of two parts; part 1 included a total of 87 sows for data on piglet mortality and growth, and part 2 included data on nest-building and farrowing behaviour from a subset of these sows (n = 34). Farrowing treatment affected piglet mortality; FF sows had a lower number of stillborn piglets than TC sows (P = 0.04), but the number of crushed piglets was higher (P < 0.01). Nest-building material tended to have an impact on total number of crushed piglets (P = 0.08) and piglets that died during 3 days of lactation (P = 0.09). Litter growth was better in the FF group than in the TC group from piglet age of 1 day to 3 weeks (P = 0.04). Overall, little nest-building-related behaviour occurred, probably due to the small amount of nest-building material. The usability of the nest-building material varied with farrowing treatment; FF sows used newspaper most for nest-building, while TC sows used straw and jute fabric (P = 0.01). There were no differences in the piglet birth intervals or the farrowing duration. In conclusion, free farrowing can have positive effects on piglet growth but negative effects on piglet survival in early lactation. Different nest-building materials have different effects depending on the type of farrowing system.

Factors contributing to high performance of sows in free farrowing systems

BACKGROUND

Pressure to abolish farrowing crates is increasing, and producers are faced with decisions about which alternative system to adopt. For sow welfare, well designed free farrowing systems without close confinement are considered optimal but producers have concerns about increased piglet mortality, particularly crushing by the sow. Reporting accurate performance figures from commercial farms newly operating such systems could inform the transition process. This study investigated performance on three commercial farms operating four different zero-confinement systems, three of which were newly installed. A total of 3212 litters from 2920 sows were followed from farrowing to weaning over a three-year period with key performance indicators (KPIs) recorded. Mixed Models (LMMs, GLMMs) determined the influence of different factors (e.g. farrowing system, sow parity, management aspects) and litter characteristics on performance, including levels and causes of piglet mortality.

RESULTS

Piglet mortality was significantly influenced by farm/system. Live-born mortality ranged from 10.3 to 20.6% with stillbirths ranging from 2.5 to 5.9%. A larger litter size and higher parity resulted in higher levels of mortality regardless of system. In all systems, crushing was the main cause of piglet mortality (59%), but 31% of sows did not crush any piglets, whilst 26% crushed only one piglet and the remaining sows (43%) crushed two or more piglets. System significantly influenced crushing as a percentage of all deaths, with the system with the smallest spatial footprint (m2) compared to the other systems, recording the highest levels of crushing. Time from the start of the study influenced mortality, with significant reductions in crushing mortality (by ~ 4%) over the course of the three-year study. There was a highly significant effect of length of time (days) between moving sows into the farrowing accommodation and sows farrowing on piglet mortality (P < 0.001). The less time between sows moving in and farrowing, the higher the levels of piglet mortality, with ~ 3% increase in total mortality every five days. System effects were highly significant after adjusting for parity, litter size, and days pre-farrowing.

CONCLUSION

These results from commercial farms demonstrate that even sows that have not been specifically selected for free farrowing are able, in many cases, to perform well in these zero-confinement systems, but that a period of adaptation is to be expected for overall farm performance. There are performance differences between the farms/systems which can be attributed to individual farm/system characteristics (e.g. pen design and management, staff expertise, pig genotypes, etc.). Higher parity sows and those producing very large litters provide a greater challenge to piglet mortality in these free farrowing systems (just as they do in crate systems). Management significantly influences performance, and ensuring sows have plenty of time to acclimatise between moving in to farrowing accommodation and giving birth is a critical aspect of improving piglet survival.

Animal board invited review: The need to consider emissions, economics and pig welfare in the transition from farrowing crates to pens with loose lactating sows

In the development and implementation of housing systems for pigs, there has been a significant focus on pig welfare including loose housing of lactating sows either indoors or outdoors. However, it is equally important to consider the environmental and economic aspects of housing systems to ensure sustainability in livestock production. The aim of this work was to review the sustainability (societal and animal welfare, environmental and economic impact) of different approaches for housing farrowing and lactating sows in indoor environments. The review illustrates that like outdoor systems, indoor housing systems are challenged in meeting the three pillars of sustainability when changing the housing of lactating sows from conventional crates with permanent confinement to systems with temporary or zero-confinement. Increased space allowance increases sow welfare, but in addition, pen designs with increased space increase ammonia emission, investment and running costs. Furthermore, indoor loose lactation systems come with an increased risk for piglet mortality, which unless effectively managed, reduces animal welfare and the economic sustainability of the system. If farms retrofit existing buildings, the larger space per loose farrowing pen leads to a reduction in pen numbers and therefore herd size, reducing the farm profitability. If farmers choose to reduce herd size to meet requirements, welfare will be reduced while emissions will be increased as more sows are brought into production again in other countries, often in conventional systems with fully slatted flooring, to meet the demand for animal protein to feed the growing global population. The review indicates there are ways to house lactating sows loose indoors with increased opportunity to perform highly motivated species-specific behaviours compared to the conventional crates with continuous confinement. These systems can offer a lower risk for environmental impact and economic risk through reducing piglet mortality. Nevertheless, a trade-off for continual freedom of sow movement may be required as zero-confinement increases the risk of piglet mortality and increased emissions. It is important to raise awareness among citizens and policy makers that loose farrowing and lactating systems if applied today, come with a higher production cost and the risk of increased environmental impact. More research and development is needed in relation to the environmental and economic impact of these systems in order to give farmers the best information to invest in new and more sustainable production systems.

Implementation of Computer-Vision-Based Farrowing Prediction in Pens with Temporary Sow Confinement

The adoption of temporary sow confinement could improve animal welfare during farrowing for both the sow and the piglets. An important challenge related to the implementation of temporary sow confinement is the optimal timing of confinement in crates, considering sow welfare and piglet survival. The objective of this study was to predict farrowing with computer vision techniques to optimize the timing of sow confinement. In total, 71 Austrian Large White and Landrace × Large White crossbred sows and four types of farrowing pens were included in the observational study. We applied computer vision model You Only Look Once X to detect sow locations, the calculated activity level of sows based on detected locations and detected changes in sow activity trends with Kalman filtering and the fixed interval smoothing algorithm. The results indicated the beginning of nest-building behavior with a median of 12 h 51 min and ending with a median of 2 h 38 min before the beginning of farrowing with the YOLOX-large object detection model. It was possible to predict farrowing for 29 out of 44 sows. The developed method could reduce labor costs otherwise required for the regular control of sows in farrowing compartments.

Risk factors differ for viable and low viable crushed piglets in free farrowing pens

Newborn piglets have a high risk of being crushed by the sow, and this risk implies welfare and economic consequences. The aim of this study was to investigate the importance of differentiating between low viable (secondary crushing losses) and viable crushed (primary crushing losses) piglets for the evaluation of risk factors for crushing related to characteristics of the sow, the litter, and the environment. Eleven Swiss farmers recorded sows' production data (parity class, gestation length, numbers of live-born and stillborn piglets), data (age, sex, weight, cause of death, and signs of weakness) for every live-born piglet that died in the first week after birth (piglet loss), and ambient temperature. Piglet losses were assigned to five categorical events: piglet loss, subdivided into not crushed and crushed, the latter being further subdivided into low viable crushed and viable crushed. Piglets recorded by the farmer as crushed were assigned to the events low viable crushed and viable crushed based on the piglet's body weight and signs of weakness (diseases, malformations). Data of 9,543 live-born piglets from 740 litters were eventually used to statistically model the hazard of dying at any given time in the first week after birth due to one of these events (mixed-effects Cox model). Five potential risk factors were analyzed as co-variates: parity class, gestation length, number of live-born piglets, number of stillborn piglets, and daily number of hours with ambient temperature >30°C. We identified two risk factors for dying from the event viable crushed that were not identified as risk factors for low viable crushed, namely shorter gestation length and higher daily number of hours with ambient temperature  > 30°C. Vice-versa, we identified additional live-born piglets in the litter as risk factor for low viable crushed, but not for viable crushed. Our results show the importance of differentiating between low viable and viable crushed piglets for the interpretation of risk factors for crushing losses. Therefore, we suggest that for breeding purposes and in research, this differentiation should be made.

Transitioning from crates to free farrowing: A roadmap to navigate key decisions

There are animal welfare concerns about the continued use of permanent crating systems for farrowing and lactating sows, which is the most prevalent maternity system in global pig production. Greater societal attention in recent years has culminated in changes (or proposed changes) to regulations as well as market-driven initiatives to move away from crated systems. Transitioning from farrowing crates to systems that allow the sow greater freedom of movement and behavioral expression requires a number of key decisions, with various trade-offs apparent when trying to balance the needs of different stakeholders. This review discusses these decisions based on common questions asked by farmers, policy makers and other stakeholders when deciding on a new system to build/approve. Based on the latest scientific evidence and practical insight, decisions such as: whether to retrofit an existing barn or build a new one, what spatial dimensions are necessary per sow place, whether to adopt free farrowing or temporary crating, how to provide substrate/enrichment and be hygienic and environmentally friendly, and how to optimize the human inputs and transition between systems are considered. The aim of this paper is to provide a roadmap for those interested in uptake of higher welfare systems and practices, as well as to highlight areas requiring further optimization and research.

Welfare of pigs on farm

This scientific opinion focuses on the welfare of pigs on farm, and is based on literature and expert opinion. All pig categories were assessed: gilts and dry sows, farrowing and lactating sows, suckling piglets, weaners, rearing pigs and boars. The most relevant husbandry systems used in Europe are described. For each system, highly relevant welfare consequences were identified, as well as related animal-based measures (ABMs), and hazards leading to the welfare consequences. Moreover, measures to prevent or correct the hazards and/or mitigate the welfare consequences are recommended. Recommendations are also provided on quantitative or qualitative criteria to answer specific questions on the welfare of pigs related to tail biting and related to the European Citizen's Initiative 'End the Cage Age'. For example, the AHAW Panel recommends how to mitigate group stress when dry sows and gilts are grouped immediately after weaning or in early pregnancy. Results of a comparative qualitative assessment suggested that long-stemmed or long-cut straw, hay or haylage is the most suitable material for nest-building. A period of time will be needed for staff and animals to adapt to housing lactating sows and their piglets in farrowing pens (as opposed to crates) before achieving stable welfare outcomes. The panel recommends a minimum available space to the lactating sow to ensure piglet welfare (measured by live-born piglet mortality). Among the main risk factors for tail biting are space allowance, types of flooring, air quality, health status and diet composition, while weaning age was not associated directly with tail biting in later life. The relationship between the availability of space and growth rate, lying behaviour and tail biting in rearing pigs is quantified and presented. Finally, the panel suggests a set of ABMs to use at slaughter for monitoring on-farm welfare of cull sows and rearing pigs.

Improving young pig welfare on-farm: The Five Domains Model

Considering welfare through the "neonatal and nursery pig perspective" is an exciting approach, and one that resonates with consumers. Overlaying this with the Five Domains Model, as we suggest in this review, points to practical on-farm improvements that provide each pig the opportunity to experience positive mental states. The Five Domains Model is broken into physical and functional states, that includes Domain 1 Nutrition, Domain 2 Physical Environment, Domain 3 Health and, Domain 4 Behavioral Interaction, and Domain 5 Mental State. The Five Domains Model can build on the breadth and depth of swine welfare science to highlight opportunities to improve welfare on-farm. In Domain 1 management of increasingly large litters is considered, with examples of sow vs. artificial rearing, colostrum quality and quantity, and creep feed management strategies. Efforts can result in positive mental states such as feeling full and content and the ability to experience pleasure of drinking and food tastes/smells. Domain 2 considers space complexity and access to key resources, along with thermal and physical amenities, to promote feelings of physical comfort. Domain 3 considers pig health in three broad, yet inter-linking categories, (a) congenital and hereditary health, (b) environmental pathogen load and, (c) colostrum quality and quantity, and its effect on the microbiome. Improvements can result in a pig that displays vitality and feels healthy. Domain 4 provides the pig opportunities to express its rich behavioral repertoire, specifically positive social interactions, play, and exploration. These efforts can result in pigs feeling calm, safe, comfortable, having companionship, engaged, interested and rewarded. In conclusion, using the Five Domains Model can highlight numerous opportunities to improve current and future housing and management through the "neonatal and nursery pig perspective" with a focus on inducing positive mental states that can result in improved quality of life and welfare state.