Decubital shoulder ulcers in sows: a review of classification, pain and welfare consequences

Effects of free farrowing system on the productive performance and welfare of sows and piglets

Regardless of international animal welfare regulations, most sows in production currently spend most of their lives and the peripartum period in caged housing systems. Although this type of management is intended to reduce neonatal mortality in piglets, several studies consider that there has been no significant reduction in its incidence over the last 30 years. On the contrary, cage housing has promoted the appearance of alterations during the farrowing process such as dystocia, as well as in maternal behavior and health, promoting stereotypes, skin lesions and other alterations, which not only impact the sows but also their progeny during the lactational period. Therefore, the aim of the present review is to compare the productive performance and welfare of sows and their piglets within the farrowing, lactation, and post-weaning period in both traditional and free-farrowing systems, highlighting the differences in these indicators in each of them.

Determining the Presence and Size of Shoulder Lesions in Sows Using Computer Vision

Shoulder sores predominantly arise in breeding sows and often result in untimely culling. Reported prevalence rates vary significantly, spanning between 5% and 50% depending upon the type of crate flooring inside a farm, the animal's body condition, or an existing injury that causes lameness. These lesions represent not only a welfare concern but also have an economic impact due to the labor needed for treatment and medication. The objective of this study was to evaluate the use of computer vision techniques in detecting and determining the size of shoulder lesions. A Microsoft Kinect V2 camera captured the top-down depth and RGB images of sows in farrowing crates. The RGB images were collected at a resolution of 1920 × 1080. To ensure the best view of the lesions, images were selected with sows lying on their right and left sides with all legs extended. A total of 824 RGB images from 70 sows with lesions at various stages of development were identified and annotated. Three deep learning-based object detection models, YOLOv5, YOLOv8, and Faster-RCNN, pre-trained with the COCO and ImageNet datasets, were implemented to localize the lesion area. YOLOv5 was the best predictor as it was able to detect lesions with an mAP@0.5 of 0.92. To estimate the lesion area, lesion pixel segmentation was carried out on the localized region using traditional image processing techniques like Otsu's binarization and adaptive thresholding alongside DL-based segmentation models based on U-Net architecture. In conclusion, this study demonstrates the potential of computer vision techniques in effectively detecting and assessing the size of shoulder lesions in breeding sows, providing a promising avenue for improving sow welfare and reducing economic losses.

Welfare of pigs during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of the animal welfare legislation. The present Opinion deals with protection of pigs during transport. The welfare of pigs during transport by road is the main focus, but other means of transport are also covered. Current practices related to transport of pigs during the different stages (preparation, loading/unloading, transit and journey breaks) are described. Overall, 10 welfare consequences were identified as highly relevant for the welfare of pigs during transport based on the severity, duration and frequency of occurrence: group stress, handling stress, heat stress, injuries, motion stress, prolonged hunger, prolonged thirst, restriction of movement, resting problems and sensory overstimulation. These welfare consequences and their animal‐based measures are described. A variety of hazards were identified, mainly relating to factors such as mixing of unfamiliar pigs, inappropriate handling methods and devices, the use of pick‐up pens, inexperienced/untrained handlers, structural deficiencies of vehicles and facilities, poor driving conditions, unfavourable microclimatic and environmental conditions and poor husbandry practices leading to these welfare consequences. The Opinion contains general and specific conclusions relating to the different stages of transport of pigs. Recommendations to prevent hazards and to correct or mitigate welfare consequences are made. Recommendations were also developed to define quantitative thresholds for microclimatic conditions and minimum space allowance within means of transport. The development of the welfare consequences over time was assessed in relation to maximum journey duration. The Opinion covers specific animal transport scenarios identified by the European Commission relating to transport of cull sows and ‘special health status animals’, and lists welfare concerns associated with these.

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.

Development and Progression of Shoulder Lesions and Their Influence on Sow Behavior

Simple Summary

Some sows are known to develop shoulder lesions after giving birth, yet the pattern of development and healing as well as the welfare implications of these lesions is not well-understood. This study found that the size of the lesion when first noticed was related to the duration that the lesion was present and to the maximum size of the lesion before healing. This information has the potential to help guide the treatment of these animals and reduce the severity of their lesions. We monitored these sows throughout lactation and during gestation and found that the only significant behavioral difference between the sows that did and did not have lesions was that the sows without lesions were more likely to change their posture more frequently. We believe this means that more frequent posture changes may have a protective effect against lesion development. Together, the results of this study have added to our understanding of how long it takes these lesions to heal and reveal insight into the lack of behavioral alterations in sows with such lesions.

Abstract

Shoulder lesions can develop in sows during lactation and vary in severity, potentially leading to euthanasia of the sow. There are questions about how these lesions affect the sow’s welfare. Here, sows that were loaded into farrowing pens were monitored prospectively to elucidate the risk for lesion development. To determine whether the presence of shoulder lesions affected behavior, 44 sows with shoulder lesions (LES) were matched to controls (CON) and observed during farrowing for postures and during nursing and gestation for posture and location. Lesions were measured daily. A low weaning body condition score (BCS) increased the possibility of lesion development (OR = 4.8 ± 2.8; p = 0.01). There was no difference in behavior between LES and CON with the exception of a higher frequency of postural changes in CON sows (p = 0.01). A larger maximum lesion size was associated with larger initial lesion (p < 0.01), higher weaning BCS (p < 0.001), low parity (p < 0.001), and lameness (p < 0.001). Median time to healing (24 ± 2.2 days) correlated with maximum lesion size. A low BCS during weaning increased the risk for lesion development and there were multiple factors found which influenced maximum lesion size; however, we did not find behavioral indications that lesions impacted welfare.

The Welfare of Cattle, Sheep, Goats and Pigs from the Perspective of Traumatic Injuries Detected at Slaughterhouse Postmortem Inspection

Simple Summary

The occurrence of traumatic injuries was assessed in cattle, sheep, goats and pigs reared and slaughtered in the Czech Republic. For the purposes of the study, the results of veterinary postmortem examinations at slaughterhouses in the period from 2010 to 2019 were analyzed. In the studied animal species, findings of traumatic lesions were detected at low frequency. The low frequency of traumatic lesions is favorable from the perspective of the welfare of slaughtered animals. In terms of further improvements to animal welfare, it would be desirable to focus on the prevention of trauma in cattle in particular, in which findings of trauma were more frequent than in the other species studied. The category most affected by trauma both to the limbs and body was cows.

Abstract

The welfare of cattle, pigs, sheep and goats was assessed by measuring trauma detected during veterinary postmortem inspection at slaughterhouses. The subject of this evaluation were all bovine, porcine, ovine and caprine animals slaughtered at Czech slaughterhouses in the monitored period, i.e., a total of 1,136,754 cows, 257,912 heifers, 1,015,541 bulls, 104,459 calves, 586,245 sows, 25,027,303 finisher pigs, 123,191 piglets, 22,815 ewes, 114,264 lambs, 1348 does and 5778 kids. The data on the numbers of traumatic findings were obtained retrospectively from a national veterinary database collecting data from slaughterhouse postmortem examinations. The results showed that findings of trauma were observed at a low frequency in the studied species. Injuries were detected most frequently in cows (1.71%). In contrast, no findings associated with the presence of trauma were recorded in does and kids. From the viewpoint of trauma localization, findings on the limbs were more frequent than findings on the body (p < 0.01). The only exceptions to this were lambs, does and kids, for which there was no statistically significant difference between findings on the limbs and the body (p = 1.00). The results show that housing system (bedding, the presence of slats, floor hardness), transport of animals to the slaughterhouse (moving animals to the vehicle, loading ramps, floors in transport vehicles and the transport of animals itself) and design of the slaughterhouse (unloading ramps, passageways and slaughterhouse floors) have a greater impact on the limbs than the bodies of animals in the majority of species. A difference was also demonstrated in the occurrence of findings of trauma in the limbs and body (p < 0.01) between culled adult animals and fattened animals, namely in cattle and pigs. A difference (p < 0.01) between ewes and lambs was found only in the occurrence of traumatic injury to the limbs. The results showed that fattened animals are affected by the risk of trauma to a lesser extent than both culled adult animals and young animals. Statistically significant differences (p < 0.01) were also found between the studied species and categories of animals. The category most affected from the viewpoint of injury both to the limbs and body was cows. In contrast to cows that are typically reared indoors, the low frequency of traumatic findings was found in small ruminants and in bulls, i.e., animals typically reared outdoors. Assumedly, access to pasture may be beneficial considering the risk of traumatic injury.

Iceberg Indicators for Sow and Piglet Welfare

This study identifies iceberg indicators for welfare assessment in sows and piglets to enhance feasibility and sustainability of available protocols. Indicators of the Welfare Quality® protocol and of a German protocol were collected over 65 farm visits to 13 farms in Germany between September 2016 and April 2018. Data were analysed using partial least square structural equation modelling (PLS-SEM). A hierarchical component model was built (animal welfare = higher-order, Welfare Quality® principles = lower-order components). In sows, welfare was revealed to be most influenced by the principles good housing, good health and appropriate behaviour (path coefficients = 0.77, 0.86, 0.91). High coefficients of determination R2 indicated a large amount of explained variance (good housing R2 = 0.59, good health R2 = 0.75, appropriate behaviour R2 = 0.83). Stereotypies was the indicator most valuable to assess sow welfare. Additionally, the final model included the indicators panting, shoulder sores, metritis, mortality and an indicator assessing stereotypies in resting animals (indicator reliabilities 0.54–0.88). However, the model did not include the indicators lameness and body condition, which may be due to the farm sample. Welfare of piglets was most explained by the indicators carpal joint lesions, mortality, sneezing and undersized animals (indicator reliabilities 0.48–0.86).

Characterisation of footpad lesions in organic and conventional broilers

Recent data suggest that organic broilers often score worse on footpad lesions than conventional broilers but also that the current scoring of organic broiler feet may be misleading. In order to characterise footpad lesions in organic broilers, this study assessed and compared footpad lesions in a sample of 2987 conventional and 3578 organic broiler feet obtained from a large Danish abattoir during summer and winter. The feet were scored according to two scoring systems: the modified Danish surveillance scoring system and a histopathology-based new scoring system specifically developed to target the ability to differentiate between broiler feet with hyperkeratosis and ulcers. For both systems, all broiler feet with visible lesions were cross-sectionally incised. Significant differences between the two production systems were found for both scoring systems (χ2 = 710; P < 0.001 and χ2 = 247; P < 0.001 for the new and the surveillance systems, respectively), showing that a larger proportion of the organic feet compared to conventional feet - summer and winter - exhibited signs of hyperkeratosis. In addition, a smaller fraction of the organic feet than of the conventional feet were given the outermost scores, that is, normal or ulcerated; 13.4% v. 25.3% broiler feet were given score 0 for organic v. conventional production systems, respectively (χ2 = 152; P < 0.001), and 18.4% v. 23.8% feet were given score 4 for organic v. conventional production systems, respectively (χ2 = 308; P < 0.001). Thus, the results suggest that surveillance scoring systems such as the one used in Denmark are useful for the examination of footpad lesions in broilers from both types of production systems. However, the results have also raised attention to a typical characteristic of the feet of organic broilers, that is, profound hyperkeratosis, which may underlie potential misclassifications in surveillance scoring systems like the one used in Denmark. Among the possible solutions to this challenge to the correctness and fairness of the scoring system are improved procedures (such as mandatory incision), training of technicians and calibration of results (especially for the organic footpads).

Transportation of Cull Sows-Deterioration of Clinical Condition From Departure and Until Arrival at the Slaughter Plant

Cull sows may be more vulnerable to transportation compared to other swine categories, as they are typically culled after several production cycles, and hence may be injured or weak. Until now, transportation of sows has received very little scientific attention. We aimed to investigate whether the clinical condition of the sows changed during transportation from commercial Danish farms to slaughter plants, and to initiate identification of potential risk factors for such deterioration. This observational study included 522 sows in 47 batches from 12 farms, varying according to transportation time from farm to slaughter plant. Standardized clinical examinations were conducted on-farm and on the slaughter plant. In addition, data on transportation duration, number and duration of stops, temperature during driving, and during waiting before unloading were collected. The sows' median parity was five (range 1-11) and close to 40% were lactating at the day of transportation. The mean duration of transportation was 232 ± 113 min, and the mean temperature in the trucks was 14.1 ± 5.3°C. Half of the clinical variables recorded before and after transportation changed significantly. Among these were injuries (e.g., superficial skin lesions, totally, P < 0.000; front, P < 0.001; wounds, P < 0.001; gait score, P < 0.001), and measures possibly related to heat stress (e.g. skin elasticity, P < 0.001). Three sows arrived in a condition as legally unfit for transport. The deterioration of the sows' condition was mainly related to transportation factors, such as temperature and duration-often in interaction-as well as duration of stops during the journey and while waiting before unloading. The changes in clinical condition were less dependent on the pre-transportation clinical condition of the sows, such as parity, body condition score and gait score. The results show that the clinical condition of the cull sows deteriorated from farm to slaughter plant, thereby adding data to the debate on fitness for transport of cull sows. The main risk factors were not related to characteristics of the sows, but of the journeys. Future studies should focus on identifying and distinguishing between risk factors in order to develop procedures that allow transportation of cull sows to slaughter without jeopardizing their welfare.

Scoring shoulder ulcers in breeding sows - is a distinction between substantial and insubstantial animal welfare-related lesions possible on clinical examination?

Background

Shoulder ulcers in breeding sows that are restricted to the superficial skin layers, epidermis and dermis are usually classified as insubstantial animal welfare-related lesions. These less-severe lesions need to be differentiated from more-severe wounds that also involve the subcutis and the underlying bone, commonly evaluated as substantial animal welfare-related lesions. Scoring schemes based on clinical or histopathological findings are available, but the consistency between both types of findings has not been definitively evaluated. The present study was designed to compare clinical findings for various stages of shoulder ulcers with accompanying histopathological evaluation. A validated histopathologic score (Score-H) classifying the tissues involved in the different stages of shoulder ulcers was set as the reference standard.

Results

Testing the histopathological scores for associations with various clinical findings resulted in a clinical score (Score-C) that could be segregated into four stages. Stage I is characterised by intact skin without any ulcerative lesions. Stage II, representing ulcerative lesions restricted to the superficial skin layers, can be predicted with a probability of 90% when a scab with diameter less than 1.2 cm is present. Stage III, representing ulcers involving the entire skin and sometimes the underlying bone, can be identified by the diameter of the scab (DOS) and/or proliferation of wound margins (powm) and/or increase of tissue volume (mass). To achieve a probability of 90%, the DOS needs to be 8.3 cm when mass and powm are absent. DOS, when accompanied by powm and mass, needs to be only a minimum of 1.9 cm for a correct classification with a 90% probability. Stage IV represents skin without open wounds but with scar tissue indicative of a former shoulder ulcer.

Conclusions

Based on the association with the histopathological findings as the reference standard a clinical score (Score-C) for the categorisation of shoulder ulcers in sows was developed. This score enables veterinarians and farmers to discriminate shoulder ulcers restricted to the superficial skin layers from ulcers involving all skin layers and sometimes even the underlying bone, which must be assessed as substantial animal welfare-related lesions.

Electronic supplementary material

The online version of this article (10.1186/s40813-018-0108-3) contains supplementary material, which is available to authorized users.

Does feeding frequency during lactation affect sows' body condition, reproduction and production performance?

The present study investigated whether a three-times compared to two-times feeding frequency during lactation affects sows' body condition, reproductive performance as well as growth performance of the piglets . In a commercial farm, eight groups (8-10 animals) with a total number of 68 sows were included in the study. During lactation, four groups received feed two times (treatment 2DF) and four groups three times daily (treatment 3DF). Within treatments, sows were classified into young (<2 parities) and old (≥3 parities). Body condition score (BCS), shoulder lesions, return to estrus rate and piglet's growth performance were recorded. The 3DF sows had a higher (p < 0.05) feed intake and less shoulder lesions (p < 0.05) than 2DF animals. Return to estrus rate in the 3DF treatment was 0% for young and 29% for old sows. In the 2DF treatment return to estrus rate was 20% for young and 5% for old sows. In conclusion, three-times versus two-times daily feeding frequency during lactation increased feed intake and had a positive effect on sows' BCS and the frequency of shoulder lesions, while it also reduced incidents of return to estrus rate in young sows.

Transportation of cull sows-a descriptive study of the clinical condition of cull sows before transportation to slaughter

Each year 500.000 sows, equal to 50% of Danish sows, are culled and transported to slaughter. However, the clinical condition, behavior, and welfare of cull sows have received almost no scientific attention. The aim of the current observational study was to describe the clinical condition of cull sows on the day of transportation to slaughter, including examination of possible differences between lactating and nonlactating sows. On the day of transportation, the participating farms were visited by trained technicians who conducted a thorough clinical examination of all sows selected by the farmer for slaughter. Four sows could not be transported because they were unfit according to the European Council Regulation regarding fitness for transportation, and they were not included in the present data. A total of 522 sows, with a median parity of 5 (range: 1-11), from 12 Danish farms were included in the study. Approximately, 10% showed signs of changed gait, and 0.8% were obvious lame. Wounds were observed in 54.6% of the sows, and 11% had decubital shoulder ulcers. Almost 40% of the cull sows were lactating. At culling, the lactating sows were of higher parity than the nonlactating sows, and lactating sows were at higher risk of having deviations from normal on clinical variables related to examination of the udder, such as udder swellings and inflammations. Nonlactating sows had 3.5 times more superficial skin lesions than lactating sows. Our findings warrant for further studies exploring different aspects of the life of cull sows in what is here defined as the The Cull Period, which is the interval from the culling decision is made until the sows are slaughtered.

The genetic correlation between scapula shape and shoulder lesions in sows

Shoulder lesions and body condition of sows at weaning have both environmental and genetic causes. The traits can be scored at farm level, and following recording, the traits can be included in the breeding goal and directional selection can be applied. However, to further increase the genetic progress of these traits, it is advantageous to develop indicator traits on the selection candidates (test boars or gilts, not yet exhibiting the phenotype themselves). It has previously been suggested that the scapula morphology and the spine of scapula might be a key factor for the sow to develop shoulder lesions. In this study, we developed 11 novel traits describing the morphology of the shoulder blade based on computed tomography images from scanned test boars. These traits include the area, length, width, height, and volume of the shoulder blade as well as 6 traits obtained from principal component analysis, describing 80% of the variation observed for the scapula spine profile. The analyzed traits have moderate to high heritability (h2 from 0.29 to 0.78, SE = 0.06), low to medium genetic correlations with shoulder lesions (up to 0.4, SE = 0.1), and body condition scoring at weaning (up to 0.25, SE = 0.1). These novel phenotypes can now be recorded automatically and accurately prior to selection of the AI boars. If such recordings are included in multivariate genomic selection models, it is expected to improve the genetic progress of shoulder lesions and body condition score by weaning.

Can a super sow be a robust sow? Consequences of litter investment in purebred and crossbred sows of different parities

The aim of this project was to study the consequences of litter investment on physical characteristics in primiparous and multiparous sows in 3 Norwegian breeds (Norsvin Duroc [ = 12], Norsvin Landrace [ = 12], and crossbreeds [Norsvin Landrace and Swedish Yorkshire { = 15}]). We predicted that the maternal sow line (Norsvin Landrace) would invest more in their litter in term of higher weight at birth, resulting in a higher litter weight of weaned piglets but with the consequence of greater loss in body condition and a higher prevalence of shoulder lesions. It was predicted that this should be more pronounced in primiparous sows than in multiparous sows. As predicted, the maternal pure line (Norsvin Landrace) had higher litter investment in terms of litter weight at birth ( = 0.003) and litter weight at weaning ( = 0.050) as well as higher total litter investment (litter weight at weaning plus weight of dead piglets [stillborn and mummified piglets and weight of piglets that died after farrowing but before weaning]; = 0.050) and suffered larger losses of body condition ( = 0.016) and had a higher prevalence of shoulder lesions ( = 0.008) during lactation than other breeds. Moreover, only in Norsvin Landrace was development of shoulder lesions related to inadequate feed consumption ( = 0.006). This has become a major welfare concern of modern pig breeding. Although primiparous and multiparous sows had similar litter sizes, primiparous sows had lower litter investment in terms of litter weight at birth ( = 0.032) and litter weight at weaning ( = 0.007) as well as total litter investment ( = 0.008). Primiparous sows suffered greater losses in body condition ( = 0.012) and developed more shoulder lesions ( = 0.026) due to lower total feed consumption ( < 0.001) during lactation than multiparous sows. Especially in the highly productive maternal line (Norsvin Landrace), development of shoulder lesions during the lactation period was more pronounced in primiparous sows than in multiparous sows ( < 0.001). The selection program has shifted the balance to greater investments in earlier life, when sows still need resources for their own growth and development. This has resulted in a larger number of weaned piglets but at a higher sow welfare cost in terms of higher losses in body condition and a higher prevalence of shoulder lesions. Our results pinpoint the importance of improving the balance between economic traits and traits that improve welfare and longevity of the sows.

A Review of Pain Assessment in Pigs

There is a moral obligation to minimize pain in pigs used for human benefit. In livestock production, pigs experience pain caused by management procedures, e.g., castration and tail docking, injuries from fighting or poor housing conditions, “management diseases” like mastitis or streptococcal meningitis, and at parturition. Pigs used in biomedical research undergo procedures that are regarded as painful in humans, but do not receive similar levels of analgesia, and pet pigs also experience potentially painful conditions. In all contexts, accurate pain assessment is a prerequisite in (a) the estimation of the welfare consequences of noxious interventions and (b) the development of more effective pain mitigation strategies. This narrative review identifies the sources of pain in pigs, discusses the various assessment measures currently available, and proposes directions for future investigation.

A retrospective study of forensic cases of skin ulcerations in Danish pigs from 2000 to 2014

BACKGROUND

Ulcerations in pigs, as in other farm animals, are considered to be painful and therefore hampering the welfare. Farmers are obliged to provide an intervention to protect animals against unnecessary suffering and failure to do so is considered negligence. Moreover, animals with severe open wounds are considered unfit for transportation and so are pigs with ulcerations located on hernias. This paper presents a retrospective study of forensic case files concerning ulcerations in Danish pigs from 2000 to 2014. The aim of the study was to clarify the number of cases, the number of pigs, the anatomical localization and size of ulcerations, evaluate changes during years and the age of the lesions.

RESULTS

A total of 209 case files concerning 283 pigs with 459 ulcerations were included. In 2004, 2005, 2007-2009 and 2011, sows with shoulder ulcerations were the most frequently submitted, while in 2014 pigs with ulcerations on umbilical outpouchings dominated. The change in pattern on body location most likely reflects specific national regulations enforced from 2003 to 2009. The ulcerations were estimated to be from 4 h to several months old and the median diameter of ulcerations was 4 cm.

CONCLUSIONS

Since 2004, the number of cases per year has declined. However, the number of affected pigs has remained almost constant from 2004 to 2014 (23.8 ± 8.5 pigs per year). The change in pattern on body parts with ulcerations likely reflected specific national regulations.

Genome-wide association study reveals novel loci for litter size and its variability in a Large White pig population

Background

In many traits, not only individual trait levels are under genetic control, but also the variation around that level. In other words, genotypes do not only differ in mean, but also in (residual) variation around the genotypic mean. New statistical methods facilitate gaining knowledge on the genetic architecture of complex traits such as phenotypic variability. Here we study litter size (total number born) and its variation in a Large White pig population using a Double Hierarchical Generalized Linear model, and perform a genome-wide association study using a Bayesian method.

Results

In total, 10 significant single nucleotide polymorphisms (SNPs) were detected for total number born (TNB) and 9 SNPs for variability of TNB (varTNB). Those SNPs explained 0.83 % of genetic variance in TNB and 1.44 % in varTNB. The most significant SNP for TNB was detected on Sus scrofa chromosome (SSC) 11. A possible candidate gene for TNB is ENOX1, which is involved in cell growth and survival. On SSC7, two possible candidate genes for varTNB are located. The first gene is coding a swine heat shock protein 90 (HSPCB = Hsp90), which is a well-studied gene stabilizing morphological traits in Drosophila and Arabidopsis. The second gene is VEGFA, which is activated in angiogenesis and vasculogenesis in the fetus. Furthermore, the genetic correlation between additive genetic effects on TNB and on its variation was 0.49. This indicates that the current selection to increase TNB will also increase the varTNB.

Conclusions

To the best of our knowledge, this is the first study reporting SNPs associated with variation of a trait in pigs. Detected genomic regions associated with varTNB can be used in genomic selection to decrease varTNB, which is highly desirable to avoid very small or very large litters in pigs. However, the percentage of variance explained by those regions was small. The SNPs detected in this study can be used as indication for regions in the Sus scrofa genome involved in maintaining low variability of litter size, but further studies are needed to identify the causative loci.

Infrared skin temperature measurements for monitoring health in pigs: a review

Infrared temperature measurement equipment (IRTME) is gaining popularity as a diagnostic tool for evaluating human and animal health. It has the prospect of reducing subject stress and disease spread by being implemented as an automatic surveillance system and by a quick assessment of skin temperatures without need for restraint or contact. This review evaluates studies and applications where IRTME has been used on pigs. These include investigations of relationships between skin, ambient and body temperatures and applications for detecting fever, inflammation, lesions, ovulation, and stress as well as for meat quality assessment. The best skin locations for high correlation between skin temperature and rectal temperature are most likely thermal windows such as ear base, eye region and udder. However, this may change with age, stressors, and biological state changes, for example, farrowing. The studies performed on pigs using IRTME have presented somewhat discrepant results, which could be caused by inadequate equipment, varying knowledge about reliable equipment operation, and site-specific factors not included in the assessment. Future focus areas in the field of IRTME are suggested for further development of new application areas and increased diagnostic value in the porcine and animal setting in general.

Does the presence of shoulder ulcers affect the behaviour of sows?

Shoulder ulcers are common in lactating sows. This case-control study compared behaviour of sows with shoulder ulcers (U-sows; N = 19) versus controls (C-sows; N = 19) and involved multiparous LxY sows, 14.7 ± 0.3 days post partum, kept in farrowing crates in a Danish herd. U-sows had at least one shoulder ulcer. Behavioural data were based on video recordings during a 24h period. U-sows spent less time lying (P = 0.04), tended to perform more postural changes (P = 0.096), spent more time standing still (P = 0.02), showed increased shoulder rubbing (P = 0.03) and reduced nursing frequency (P = 0.03) compared to the controls. These results show that the behaviour of sows with shoulder ulcers differ from healthy sows, suggesting that U-sows experienced discomfort or pain, and indicating that maternal behaviour can be sensitive to the presence of shoulder ulcers. Further studies - focussing on temporal development of shoulder ulcers combined with behaviour of sows and piglets - are needed to clarify animal welfare impact.

Grading of shoulder ulcerations in sows by biopsies

Shoulder ulcerations can be graded postmortem from 0 to 4 on a pathoanatomical scale. However, veterinarians and farmers express difficulties evaluating the grade of the lesions antemortem. Accurate grading is needed in order to comply with veterinary instruction in relation to the Danish legislation, stating that sows with shoulder ulcers grade 3 or 4 must be kept loose and have access to soft bedding. Thus, the aim of the present study was to evaluate if biopsies from the center of a shoulder ulcer can be used to point out animals for which an intervention must be initiated. Postmortem, a punch biopsy was sampled from the center of the ulceration or from the tissue overlaying the tuber spina scapula. Afterward, the shoulders were cross-sectioned and evaluated grossly and histologically ("gold standard"). In total, 121 shoulders were included in the study, and the diagnostic value of a punch biopsy in grading shoulder ulcerations was evaluated. The results showed a sensitivity of 0.78, a specificity of 0.98, a positive likelihood ratio of 38.36, and a negative likelihood ratio of 0.22. The agreement between the cross-section evaluation and the punch biopsy was found to be 0.90 by calculating the Cohen kappa value. In conclusion, a single punch biopsy from the center of an ulcer is useful for determining the grade of a shoulder ulcer and can be used to facilitate the identification of sows with ulcers requiring an intervention.

Identification of Treponema pedis as the predominant Treponema species in porcine skin ulcers by fluorescence in situ hybridization and high-throughput sequencing

Skin lesions often seen in pig production are of great animal welfare concern. To study the potential role of Treponema bacteria in porcine skin ulcers, we investigated the presence and distribution of these organisms in decubital shoulder ulcers (n=51) and ear necroses (n=54) by fluorescence in situ hybridization (FISH) and high-throughput sequencing. In addition, two cases of facial ulcers and five cases of other skin ulcers were included in the study. Samples from all 112 skin lesions and intact skin from pigs without skin ulcers (n=14) were screened by FISH. Three different oligonucleotide probes targeting 16S rRNA were used, specific for domain bacterium, Treponema spp. and species T. pedis. Screening showed that two cases each of facial and other ulcers, 35 (69%) of shoulder ulcers and 32 (59%) of ear necroses were positive for Treponema spp. T. pedis was the unequivocally, predominant species typically constituting more than 90% of the treponemes in a lesion, assessed visually by microscopy. Altogether, T. pedis was demonstrated in 69 of the 71 Treponema spp. positive lesions. We conclude that Treponema spp. are frequently present and abundant in various skin ulcers of pigs. The results from this study point toward an important role of T. pedis as a secondary bacterial infection in porcine skin ulcers, especially in severe and chronic lesions.