Pig carcass tail lesions: the influence of record keeping through an advisory service and the relationship with farm performance parameters

Tail lesions are important pig welfare indicators that could be recorded during meat inspection as they are more visible on the carcass than on the live animal. Tail biting is associated with reduced performance in the bitten pig, but it is not clear whether problems with tail biting are reflected in general farm performance figures. Farm advisory services aim to improve farm productivity which could be associated with improvements in pig welfare. Record keeping forms an integral part of such advisory services. The aim of this study was to examine the influence of record keeping in the Teagasc eProfit Monitor (ePM herds) on the prevalence of tail lesion severity scores in Irish slaughter pigs. In addition, we investigated associations between the prevalence of tail lesion scores and production parameters at farm level in ePM herds. Pigs were observed after scalding/dehairing and tail lesion score (0 to 4), sex and farm identification were recorded. Tail lesion scores were collapsed into none/mild lesions (score ⩽1), moderate lesions (score 2) and severe lesions (score ⩾3). The effect of record keeping (ePM herd) on the different tail lesion outcomes was analysed at batch level using the events/trials structure in generalized linear mixed models (PROC GLIMMIX). Spearman’s rank correlations were calculated between average tail lesion score of a batch and production parameters. A total of 13 133 pigs were assessed from 73 batches coming from 61 farms. In all, 23 farms were identified as ePM herds. The average prevalence of moderate tail lesions was 26.8% and of severe tail lesions was 3.4% in a batch. Batches coming from ePM herds had a lower prevalence of moderate tail lesions than non-ePM herds (P<0.001). Average tail lesion score was negatively associated with age (P<0.05) and weight (P<0.05) at sale/transfer of weaners, and tended to be positively associated with the number of finishing days (P=0.06). In addition, the prevalence of severe tail lesions was negatively associated with average daily gain in weaners (P<0.05) and tended to do so with average daily gain in finishers (P=0.08). This study provides the first indication that record keeping through an advisory service may help to lower the risk of tail biting, which is associated with improved farm performance.     

‘Tailception’: using neural networks for assessing tail lesions on pictures of pig carcasses

Tail lesions caused by tail biting are a widespread welfare issue in pig husbandry. Determining their prevalence currently involves labour intensive, subjective scoring methods. Increased societal interest in tail lesions requires fast, reliable and cheap systems for assessing tail status. In the present study, we aimed to test the reliability of neural networks for assessing tail pictures from carcasses against trained human observers. Three trained observers scored tail lesions from automatically recorded pictures of 13 124 pigs. Nearly all pigs had been tail docked. Tail lesions were classified using a 4-point score (0=no lesion, to 3=severe lesion). In addition, total tail loss was recorded. Agreement between observers was tested prior and during the assessment in a total of seven inter-observer tests with 80 pictures each. We calculated agreement between observer pairs as exact agreement (%) and prevalence-adjusted bias-adjusted κ (PABAK; value 1=optimal agreement). Out of the 13 124 scored pictures, we used 80% for training and 20% for validating our neural networks. As the position of the tail in the pictures varied (high, low, left, right), we first trained a part detection network to find the tail in the picture and select a rectangular part of the picture which includes the tail. We then trained a classification network to categorise tail lesion severity using pictures scored by human observers whereby the classification network only analysed the selected picture parts. Median exact agreement between the three observers was 80% for tail lesions and 94% for tail loss. Median PABAK for tail lesions and loss were 0.75 and 0.87, respectively. The agreement between classification by the neural network and human observers was 74% for tail lesions and 95% for tail loss. In other words, the agreement between the networks and human observers were very similar to the agreement between human observers. The main reason for disagreement between observers and thereby higher variation in network training material were picture quality issues. Therefore, we expect even better results for neural network application to tail lesions if training is based on high quality pictures. Very reliable and repeatable tail lesion assessment from pictures would allow automated tail classification of all pigs slaughtered, which is something that some animal welfare labels would like to do.     

More tail lesions among undocked than tail docked pigs in a conventional herd

The vast majority of piglets reared in the European Union (EU) and worldwide is tail docked to reduce the risk of being tail bitten, even though EU animal welfare legislation bans routine tail docking. Many conventional herds experience low levels of tail biting among tail docked pigs, however it is not known, what the prevalence would have been had the pigs not been tail docked. The aim of this study was to compare the prevalence of tail lesions between docked and undocked pigs in a conventional piggery in Denmark with very low prevalence of tail biting among tail docked pigs. The study included 1922 DanAvl Duroc×(Landrace×Large White) female and castrated male pigs (962 docked and 960 undocked). Docked and undocked pigs were housed under the same conditions in the same room but in separate pens with 20 (±0.03) pigs/pen. Pigs had ad libitum access to commercial diets in a feed dispenser. Manipulable material in the form of chopped straw was provided daily on the floor (~10 g/pig per day), and each pen had two vertically placed soft wood boards. From weaning to slaughter, tail wounds (injury severity and freshness) were scored every 2^nd week. No clinical signs of injured tails were observed within the tail docked group, whereas 23.0% of the undocked pigs got a tail lesion. On average, 4.0% of the pigs with undocked tails had a tail lesion on tail inspection days. More pens with tail lesions were observed among pigs weighing 30 to 60 kg (34.3%; P<0.05) than in pens with pigs weighing 7 to 30 kg (13.0%) and 60 to 90 kg (12.8%). Removal of pigs to a hospital pen was more likely in undocked pens (P<0.05, 47.7% undocked pens and 22.9% docked pens). Finally, abattoir meat inspection data revealed more tail biting remarks in undocked pigs (P<0.001). In conclusion, this study suggests that housing pigs with intact tails in conventional herds with very low prevalence of tail biting among tail docked pigs, will increase the prevalence of pigs with tail lesions considerably, and pig producers will need more hospital pens. Abattoir data indicate that tail biting remarks from meat inspection data severely underestimate on-farm prevalence of tail lesions.     

Effect of pen design on tail biting and tail-directed behaviour of finishing pigs with intact tails

Tail biting is a welfare and economical concern in modern pig production. One common preventive measure used throughout the world is tail docking, which is generally considered one of the most effective methods for limiting tail biting. However, tail docking is a painful mutilation and systematic tail docking is not allowed in the EU. Therefore, the aim was to compare pig behaviour and the prevalence of tail biting in finishing pigs with intact tails housed in two different pen designs under Danish commercial conditions. PEN1 was a traditional Danish pen and PEN2 was inspired by Swedish finisher pen design and had a larger proportion of solid floor area (PEN1: 1/3 and PEN2: 2/3), reduced group size (PEN1: 15 and PEN2: 12), increased space allowance per head (PEN1: 0.7 m² and PEN2: 0.89 m²) and straw allocated on the floor (PEN2) whereas straw was provided in a straw rack in PEN1. Tail damage observations were carried out daily by the stockperson and every 2 weeks one trained research technician assessed tail damages according to a tail scoring system. Tail lesions were observed in 51% of PEN1 and in 11% of PEN2 (P < 0.001). PEN1 had higher prevalence of tail damages than PEN2 (23% v. 5%, P < 0.001). Behavioural observations were carried out by the use of video recordings. Pigs in PEN2 tended to spend more time on tail-directed behaviour than pigs in PEN1 (P = 0.07), whereas pigs in PEN1 tended to spend more time on ear-directed behaviour (P = 0.08). Pigs in PEN2 spent more time on straw-directed behaviour compared to pigs in PEN1 (P < 0.001). Pen design did not affect time spent on other penmate-directed behaviour. In addition, the level of welfare between the two pen designs was compared using the Welfare Quality® protocol. PEN2 received an overall score of ‘excellent’ while PEN1 scored ‘enhanced’. PEN2 scored higher on all principles besides ‘good health’, where PEN1 scored better on lameness and wounds. The main measurements accounting for the differences were water supply, huddling, tail biting, social behaviour and fear of humans. In conclusion, the combination of increased space allowance, increased area of solid flooring, straw allocated onto the floor and reduced group size (PEN2) resulted in fewer tail damaged pigs and a better overall welfare assessment, despite a tendency for more tail-directed behaviour.     

The effect of docking length on the risk of tail biting,tail-directed behaviour,aggression and activity level of growing pigs kept under commercial conditions

Tail biting in domestic pigs relates to a range of risk factors, primarily in the pigs’ environment. Preventive tail docking is widely used, and various experimental approaches suggest that docking reduces the risk of tail biting. However, whether the docking length affects the prevalence of tail biting outbreaks is less studied, as is how a shortened tail will affect pigs’ social behaviour. The aim of this study was to investigate how three different tail docking lengths, measured at docking, as well as retained intact tails (Short: 2.9 cm; Medium: 5.7 cm; Long: 7.5 cm; and Undocked) affected tail biting risk and behaviour directed at other finisher pigs with the same docking length treatment. Tail lesions were scored weekly, as was behaviour at pen level after introduction to finisher pens and until a potential outbreak of tail biting or slaughter. Pigs from four commercial herds (258 litters) entered the study. Before the pigs entered the finisher section and data collection started, some pigs were excluded, mainly due to tail biting outbreaks in the weaner section. The risk of a tail biting outbreak differed significantly between treatments (P=0.001), with a lowered risk of a tail biting outbreak in Short pens compared with Undocked (P<0.001) and Medium (P<0.05), and was affected by herd as well (P<0.001). Pens in the Long and Undocked treatments were pooled for the behavioural analysis due to low representation, especially in the Undocked treatment. The probability of tail contacts, where a pig interacted with a pen mate’s tail, differed between docking length treatments and was highest in the Long/Undocked compared with the Short treatment (P<0.01), but docking length did not affect aggressive behaviour. Docking length affected the risk of a tail biting outbreak and the frequency of tail-directed behaviour in our participating herds, of which three reported a high prevalence of tail biting problems. Only the shortest docking length treatment (Short) reduced the tail biting risk, but did not completely prevent tail biting outbreaks.     

A longitudinal study of pre- and post-weaning tail damage in non-docked pigs

Tail-biting occurs pre-weaning, but literature on tail damage during lactation and on the development of damage over time is sparse, especially for non-docked piglets. We assessed the prevalence of tail damage in non-docked piglets in a commercial Danish piggery during the lactation and weaning period, and investigated the within-animal association of tail lesions pre- and post-weaning. Non-docked piglets (n = 741) from 51 loose-housed sows were individually marked and tracked from birth to 9 weeks (w9) of age. Tail damage was scored during lactation at w1 and w4, and once a week post-weaning (average weaning age 30 days) at w6 to w9. The within-animal association of tail damage before and after weaning was investigated at pig level using generalized mixed models. Tail damage was prevalent already pre-weaning. During the lactation period, the prevalence of tail lesions was 5% at w1 and 42% at w4, with the most prevalent score being ‘superficial damages’ (66.7%, score 1; pre-weaning scheme: 0 = no damage, 3 = tail wound). Post-weaning, 45% of pigs had a tail lesion at least once over the four assessments, with 16.7% of pigs having a tail lesion at least at two assessments. The majority of lesions were ‘minor scratches’ (34.2%, score 1; post-weaning scheme: 0 = no damage, 4 = wound – necrotic tail end) and a ‘scabbed wound’ (19.9%, score 3). The number of pigs with lesions as well as wound severity increased over time. More pigs had a tail wound at w8 (15%, P < 0.001 and < 0.01) and w9 (19%, P < 0.001 and < 0.001) compared to w6 (2.7%) and w7 (5.6%). Pigs with tail lesions pre-weaning (w1: OR 3.0, 95% CI 0.9 to 10.2; w4: OR 3.4, 95% CI 2.0 to 5.8) had a significantly higher risk of having a wound post-weaning, and pigs with lesions at w4 additionally were at a higher risk (OR 3.0, 95% CI 1.8 to 5.1) of having a lesion over several assessments. Females compared to castrated males had a significantly lower risk of having tail lesions at w1 (OR 0.3, 95% CI 0.1 to 0.8). Similarly, females were at a significantly lower risk (OR 0.5, 95% CI 0.4 to 0.9) of having a wound post-weaning, and tended to have a lower risk of having lesions over several assessments (OR 0.7, 95% CI 0.5 to 1.2). Our study confirmed that tail damage is prevalent already during the lactation period, and that pre-weaning tail damage is predictive of tail wounds post-weaning.     

Prevalence of an inflammation and necrosis syndrome in suckling piglets

The current study describes the results obtained from clinical examination of over 4700 suckling piglets from 19 individual herds in Germany. In this cohort the prevalence of inflammation and necrosis in the tails, ears, claw coronary bands, heels and teats was determined using a pre-defined scoring system. Results show that already in the 1^st days of life, piglets were affected by inflammation and necrosis of the heels (80%), claw coronary bands (50%) and tail base (20%). The praevalences of these alterations in piglets were influenced by genetics (P <0.001) and age, decreasing gradually in the 2^nd week of life (P <0.001). Moreover, a correlation between tail length after tail docking and the prevalence of tail necrosis (P⩽0.04) was found. Tail and ear biting as a behavioural trait was not detected during this study. The early onset, appearance and multiple locations of clinical signs of inflammation and the positive correlation with the genetic background of the piglets may suggest an impairment of the innate immune system by infectious and non-infectious agents. This is in contrast to previously described behavioural abnormalities seen in fattening pigs. Considering the obvious reduction of animal welfare due to the described lesions, there is a need to create awareness among pig farmers and to understand the multifactorial causality involved in this inflammation and necrosis syndrome in piglets.     

Physiological indicators of stress and meat and carcass characteristics in tail bitten slaughter pigs

Background

Tail biting is a common welfare problem in pig production and in addition to being a sign of underlying welfare problems, tail biting reduces welfare in itself. The aim of this study was to evaluate the effects of tail biting on different pre and post mortem indicators of stress in slaughter pigs and on carcass and meat characteristics. A total of 12 tail bitten (TB) and 13 control (C) pigs from a farm with a long-term tail biting problem were selected for salivary cortisol analyses before and after transport to the slaughterhouse. After stunning, samples were taken for the analysis of serum cortisol, blood lactate, intestinal heat shock protein 70 (HSP70), and meat quality characteristics. In addition, body temperature immediately after and muscle temperature 35 min after stunning were measured, as well as lean meat percentage and carcass weight.

Results

TB pigs showed a lower cortisol response to the transport-induced stress than C pigs and also had a lower serum cortisol concentration after stunning. HSP70 content in the small intestine was higher in the TB pigs than in C pigs. TB pigs had a considerably lower carcass weight therefore produced a lower total amount of lean meat per carcass than C pigs.

Conclusions

This study suggests that prolonged or repeated stress in the form of tail biting causes a blunted stress response, possibly a sign of hypocortisolism. In addition, it underlines the importance of reducing tail biting, both from an animal welfare and an economic point-of-view.

     

Health parameters in tail biters and bitten pigs in a case–control study

Health in relation to tail-biting behaviour was investigated on a problem farm. Quartets (n = 16) of age- and gender-matched fattening pigs including a tail biter (TB, n = 16), a victim (V, n = 16), a control in the same pen (C_tb, n = 10) and a control in a pen where no tail biting was observed (C_no, n = 14) were chosen by direct behavioural observation. Haematological and clinicochemical analyses, autopsy and histological examination of 16 different tissues were carried out. Tail lesion severity was evaluated both macroscopically, on the basis of inspection, and histologically, in the sagittally cut tail. Category effects were tested using Friedman's ANOVA by Ranks, Cochran's Q or a repeated-measure GLM and, if significant, pair-wise tests were conducted using Wilcoxon Signed Ranks or McNemar's Test. The number of received tail bites correlated better with histological than with macroscopic tail lesion scoring because of deep inflammation beneath healthy skin in some cases. Most individuals had mild inflammatory lesions in internal organs suggestive of generalized activation of the immune system, and 30% of the animals were anaemic, possibly because of systemic spread of infectious agents. V had more severe respiratory organ lesions and higher serum protein concentrations than all other categories of pigs. Liver- and muscle-specific enzymes (alanine aminotransferase, alkaline phosphatase and creatine kinase) differed between categories. In conclusion, most animals had signs of generalized activation of the immune system, possibly because of systemic spread of infectious agents. V pigs suffered from more severe inflammatory lesions than TB, C_tb or C_no. Deep infections may exist under healthy skin in the tail of bitten pigs.     

Which is the most preventive measure against tail damage in finisher pigs: tail docking,straw provision or lowered stocking density?

One challenge of intensive pig production is tail damage caused by tail biting, and farmers often decrease the prevalence of tail damage through tail docking. However, tail docking is not an optimal preventive measure against tail damage and thus, it would be preferable to replace it. The aim of the current study was to investigate the relative effect of three possible preventive measures against tail damage. The study included 112 pens with 1624 finisher pigs divided between four batches. Pens were randomly assigned to one level of each of three treatments: (1) tail-docked (n=60 pens) v. undocked (n=52 pens), (2) 150 g of straw provided per pig per day on the solid floor (n=56 pens) v. no straw provided (n=56 pens), (3) stocking density of 1.21 m²/pig (11 pig/pen; n=56 pens) v. 0.73 m²/pig (18 pigs/pen; n=56 pens). Tail damage was recorded three times per week throughout the finisher period by scoring the tail of each individual pig. A pen was recorded as a tail damage pen and no longer included in the study if at least one pig in a pen had a bleeding tail wound; thus, only the first incidence of tail damage on pen level was recorded. Data were analysed by a Cox regression for survival analysis assuming proportional hazards. Results are presented as hazards, and a higher hazard means that a pen has a higher risk of tail damage and of it happening earlier in the finisher period. Pens with undocked pigs had a 4.32-fold higher hazard of tail damage compared with pens with docked pigs (P<0.001). Pens with no straw provided had a 2.22-fold higher hazard of tail damage compared with pens with straw provided (P<0.01). No interactions was seen between the treatments, but the effect of tail docking was higher than the effect of straw provision (P<0.001). Stocking density did not have a significant effect on the hazard of tail damage (hazard rate ratios (HRR)=1.67; P=0.064). However, a combination of straw provision and lowered stocking density showed a similar hazard of tail damage as seen with only tail docking (HRR=1.58; P=0.39). In conclusion, tail docking and straw provision were preventive measures against tail damage, and tail docking reduced the risk more than straw provision. A combination of other preventive measures is necessary to reduce the risk of tail damage in undocked pigs to the same level as in docked pigs.     

Effects of scalding and dehairing of pig carcasses at abattoirs on the visibility of welfare-related lesions

There is increasing interest in developing abattoir-based measures to assist in determining the welfare status of pigs. The primary aim of this study was to determine the most appropriate place on the slaughter line to conduct assessments of welfare-related lesions, namely apparent aggression-related skin lesions (hereafter referred to as ‘skin lesions’), loin bruising and apparent tail biting damage. The study also lent itself to an assessment of the prevalence of these lesions, and the extent to which they were linked with production variables. Finishing pigs processed at two abattoirs on the Island of Ireland (n=1950 in abattoir A, and n=1939 in abattoir B) were used. Data were collected over 6 days in each abattoir in July 2014. Lesion scoring took place at two points on the slaughter line: (1) at exsanguination (slaughter stage 1 (SS1)), and (2) following scalding and dehairing of carcasses (slaughter stage 2 (SS2)). At both points, each carcass was assigned a skin and tail lesion score ranging from 0 (lesion absent) to 3 or 4 (severe lesions), respectively. Loin bruising was recorded as present or absent. Differences in the percentage of pigs with observable lesions of each type were compared between SS1 and SS2 using McNemar/McNemar-Bowker tests. The associations between each lesion type, and both cold carcass weight and condemnations, were examined at batch level using Pearson’s correlations. Batch was defined as the group of animals with a particular farm identification code on a given day. The overall percentage of pigs with a visible skin lesion (i.e. score>0) decreased between SS1 and SS2 (P<0.001). However, the percentage of pigs with a severe skin lesion increased numerically from SS1 to SS2. The percentage of pigs with a visible tail lesion and with loin bruising also increased between SS1 and SS2 (P<0.001). There was a positive correlation between the percentage of carcasses that were partially condemned, and the percentage of pigs with skin lesions, tail lesions and loin bruising (P<0.05). In addition, as the batch-level frequency of each lesion type increased, average cold carcass weight decreased (P<0.001). These findings suggest that severe skin lesions, tail lesions and loin bruising are more visible on pig carcasses after they have been scalded and dehaired, and that this is when abattoir-based lesion scoring should take place. The high prevalence of all three lesion types, and the links with economically important production parameters, suggests that more research into identifying key risk factors is warranted.     

Olfactory evaluation of boar taint: effect of factors measured at slaughter and link with boar taint compounds

There is a commitment by the European pig sector to ban surgical castration of male piglets in the European Union in 2018. One alternative to castration is to raise entire male pigs, with an increased risk of boar taint. A field study was performed to: (1) evaluate inter- and intra-farm variation in boar taint prevalence, (2) investigate factors measured at slaughter influencing boar taint and (3) evaluate the relationship between sensorial scoring by a trained panel and the concentration of boar taint components. From 34 farms, neck fat samples were collected from all entire male pigs in at least two slaughter batches per farm (78 batches; 9167 animals). In addition to olfactory boar taint analysis, data were also collected on fresh skin lesions (score 0 to 3) at the slaughter line, slaughter weight, lean meat percentage, duration of transport, time spent in lairage, total delivery duration, day length, shortening of days and outdoor mean temperature. Using the hot iron method, neck fat samples were scored (eight-point scale) for boar taint. Average boar taint prevalence (score ≥3) was 5.6±2.5% and the mean difference between the maximum and minimum prevalence per farm was 4.3±3.2%. Androstenone (AND), skatole (SKA) and indole concentrations were measured for a subset (n=254) of the samples. According to binomial univariate mixed models, entire male pigs with a higher skin lesion score had higher odds of having boar taint (P=0.031), as did fatter entire male pigs (P<0.001). In the binomial multivariate mixed model lean meat percentage (P<0.001) and outdoor mean temperature (P=0.005) remained as only significant factors. Based on our results, we can conclude that these statistically significant at least partially influence the prevalence of boar taint. According to the binomial univariate mixed models SKA concentration in liquid fat seems a better predictor for boar taint than AND. There were no significant synergetic effects between boar taint compounds.     

Tail posture and motion in relation to natural behaviour in juvenile and adult pigs

The tail of pigs has been suggested as a welfare indicator as it can provide insight into a pig’s behavioural and emotional states. Tail posture and motion have so far mainly been studied in the context of tail biting behaviour. The aim of this study was to investigate the relationship between pigs’ natural behaviour and their tail posture and tail motion. This was studied in a free-range farm in which tail biting is absent. In total 214 pigs of different age categories were observed individually (sows, gilts, boars, and 6-month old pigs) or by group (6-month and 1-year old pigs) for their tail posture, tail motion and behaviour, using live observations and videos obtained by drone. Results showed that a fully curled tail occurred most during locomotion (P < 0.001); and an actively hanging tail occurred more during foraging (P < 0.001), excavation (P = 0.006), feeding (P = 0.017), receipt of agonistic behaviour (P = 0.036), and non-agonistic social interactions (P = 0.046). A fully curled tail (P < 0.001) and a half curled tail (P < 0.005) occurred least in the group of sows. Tail motion was infrequent (6.7% of observations), and involved mainly loosely wagging, which occurred more during locomotion (P = 0.006) and non-agonistic social interactions (P = 0.006). A higher temperature-humidity index increased the probability of half curled tails (P < 0.001) and loose wagging (P < 0.001), while reducing the probability of active (P < 0.001) and passive hanging tails (P = 0.013). These results provide insight into tail posture and tail motion in pigs under semi-natural conditions, showing especially that hanging tails are not primarily associated with tail biting, and that the use of tail postures for welfare assessment should be in consideration with the context in which the animals are kept.     

Does group size have an impact on welfare indicators in fattening pigs?

Production systems for fattening pigs have been characterized over the last 2 decades by rising farm sizes coupled with increasing group sizes. These developments resulted in a serious public discussion regarding animal welfare and health in these intensive production systems. Even though large farm and group sizes came under severe criticism, it is still unknown whether these factors indeed negatively affect animal welfare. Therefore, the aim of this study was to assess the effect of group size (<15 v. 15 to 30 v. >30 pigs/pen) on various animal-based measures of the Welfare Quality® protocol for growing pigs under conventional fattening conditions. A total of 60 conventional pig fattening farms with different group sizes in Germany were included. Moderate bursitis (35%) was found as the most prevalent indicator of welfare-related problems, while its prevalence increased with age during the fattening period. However, differences between group sizes were not detected (P>0.05). The prevalence of moderately soiled bodies increased from 9.7% at the start to 14.2% at the end of the fattening period, whereas large pens showed a higher prevalence (15.8%) than small pens (10.4%; P<0.05). With increasing group size, the incidence of moderate wounds with 8.5% and 11.3% in small- and medium-sized pens, respectively, was lower (P<0.05) than in large-sized ones (16.3%). Contrary to bursitis and dirtiness, its prevalence decreased during the fattening period. Moderate manure was less often found in pigs fed by a dry feeder than in those fed by a liquid feeding system (P<0.05). The human–animal relationship was improved in large in comparison to small groups. On the contrary, negative social behaviour was found more often in large groups. Exploration of enrichment material decreased with increasing live weight. Given that all animals were tail-docked, tail biting was observed at a very low rate of 1.9%. In conclusion, the results indicate that BW and feeding system are determining factors for the welfare status, while group size was not proved to affect the welfare level under the studied conditions of pig fattening.     

Old breeds,new solutions? Effects of two different traditional sire breeds on skin lesions,tail lesions,tail losses,performance and behaviour of rearing pigs

Some studies indicated a relationship between modern, fast-growing, lean-meat-producing hybrid pigs and the occurrence of tail-biting, one of the major issues of conventional pig husbandry. Therefore, this study investigated the effects of different local, traditional sire breeds on the behaviour and performance of rearing pigs. Between December 2019 and November 2020, a total of 1 561 piglets were weaned from hybrid sows (Bundes Hybrid Zucht Programm (BHZP) Landrace × BHZP Large White) that were paired with either Swabian-Hall (SH), Bentheim Black Pied (BB) or BHZP-Piétrain (Pi) boars. Tails of the piglets were left intact (43.5%) or docked (56.5%), and male piglets were castrated. Piglets were conventionally reared on fully slatted plastic flooring in mixed-sex groups. Starting one day after weaning, skin lesions were scored once per pig, and tail lesions and losses were scored weekly until the end of rearing. The average daily gain was documented for the suckling and rearing period. The activity behaviour of eight focal pens was analysed using video recordings. Differences between modern and traditional breeds were found in this study for so-called aggressive and non-aggressive biting pronounced by skin and tail lesions and tail losses. Significantly fewer BB pigs had severe skin lesions on the front body than SH or Pi pigs (P < 0.05). Additionally, piglets that were classified as light (<5.6 kg) at weaning showed skin lesion scores of 0 more often than piglets that were classified with a medium (≥5.6–≤8.3 kg) or heavy (>8.3 kg) weaning weight (P < 0.05). In the first half of the rearing period, significantly more BB pigs were assessed as having no tail lesions and tail losses than SH and Pi pigs (P < 0.01). However, these differences disappeared in the second half of rearing. Either docked or undocked Pi pigs had significantly higher average daily gains than SH and BB pigs (P < 0.05). The activity of the focal pens was not influenced by the sire breed or tail lesion class, which might be due to the limited sample size of eight pens. To conclude, the use of the traditional sire breed BB has the potential to reduce injurious behaviour in the offspring. However, adjustments to the housing and feeding should be taken to further reduce the incidence of tail lesions and losses and to enhance performance.     

Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs

In pig production, piglets are tail docked at birth in order to prevent tail biting later in life. In order to examine the effects of tail docking and docking length on the formation of neuromas, we used 65 pigs and the following four treatments: intact tails (n=18); leaving 75% (n=17); leaving 50% (n=19); or leaving 25% (n=11) of the tail length on the pigs. The piglets were docked between day 2 and 4 after birth using a gas-heated apparatus, and were kept under conventional conditions until slaughter at 22 weeks of age, where tails were removed and examined macroscopically and histologically. The tail lengths and diameters differed at slaughter (lengths: 30.6±0.6; 24.9±0.4; 19.8±0.6; 8.7±0.6 cm; P<0.001; tail diameter: 0.5±0.03; 0.8±0.02; 1.0±0.03; 1.4±0.04 cm; P<0.001, respectively). Docking resulted in a higher proportion of tails with neuromas (64 v. 0%; P<0.001), number of neuromas per tail (1.0±0.2 v. 0; P<0.001) and size of neuromas (1023±592 v. 0 μm; P<0.001). The results show that tail docking piglets using hot-iron cautery causes formation of neuromas in the outermost part of the tail tip. The presence of neuromas might lead to altered nociceptive thresholds, which need to be confirmed in future studies.     

Changes in activity and object manipulation before tail damage in finisher pigs as an early detector of tail biting

Tail damage within the production of finisher pigs is an animal welfare problem. Recent research suggests that removal of known risk factors may not be enough to eliminate tail biting, especially in undocked pigs, thus a different strategy is worth investigating. This could be early detection of tail biting, using behavioural changes observed before tail damage. If these early stages of tail biting can be detected before tail damage occurs, then tail damage could be prevented by early interventions. The first step in developing such a strategy is to identify the types of behaviour changes that emerge during early stages of tail biting. Thus, the aim of the current study was to investigate whether pen level activity and object manipulation evolved differently during the last 7 days before the scoring of tail damage (day 0) for pens scored with tail damage (tail damage pens) and pens not scored with tail damage (matched control pens). The study included video recordings for twenty-four tail damage pens and thirty-two matched control pens. Activity level and object manipulation were observed the last 7 days before day 0 during the morning (0600 to 0800 h), afternoon (1600 to 1800 h) and evening (2200 to 2400 h, only activity level). Both activity level and object manipulation were analysed using generalised linear mixed effects models with a binomial distribution for activity level and a negative binomial distribution for object manipulation. The probability of being active was higher in tail damage pens compared to control pens during the afternoon the last 5 days before day 0 (P<0.001). This was seen due to a decrease in activity level in the control pens, which makes it difficult to identify future tail damage pens from this difference. Object manipulation was lower in tail damage pens compared to the control pens on all 7 days before day 0, but only in pens with undocked pigs (P<0.01). Thus, it is still unknown when this difference in object manipulation initiated. It was concluded that both activity level and object manipulation seemed related to ongoing tail biting and should be investigated through more detailed observations and for a longer time to establish the normal behaviour pattern for a particular pen. Thus, it is suggested that future research focusses on developing automatic monitoring methods for pen level activity and object manipulation and applies algorithms that establish and detect deviations from the normal behaviour pattern of the pen before tail damage.     

Interdependence of welfare outcome measures and potential confounding factors on finishing pig farms

The factors influencing the observed prevalence of some welfare outcome measures were investigated as part of a larger project examining the feasibility and benefits of incorporating on-farm welfare outcome assessments into UK Pig Farm Assurance Schemes. All finishing pigs (>40 kg) on six farms that had pens containing 25 pigs or less were assessed for dirtiness, body lesions, tail lesions, bursitis, lameness, oral behaviour and pigs requiring hospitalisation. The overall small number of significant correlations between the measures across all farms (29 out of a possible 120) and the lack of a significant correlation between any pair of measures on all six or even five farms suggests that no measure can be reliably replaced by another. On the three farms with the highest farm prevalence of dirtiness there were significant negative correlations between pen prevalences of dirtiness and recorded tail and/or body lesions (p < 0.02). The prevalence of pigs requiring hospitalisation was positively correlated with lameness on four farms (p < 0.001) and tail lesions on three farms (p < 0.005). Using a univariate general linear model the time of observation was only found to correlate with one measure, the dirtiness of the pigs (p = 0.004), with the prevalence of dirtiness in pens on the three ‘dirtiest’ farms increasing as the day progressed. There was no effect of the stocking density, group size, time since feeding and time since straw provision on the prevalence of any of the outcome measures. It is recommended that to prevent bias in the recording of tail and body lesions farm assurance assessments are conducted on pigs with a prevalence for dirtiness of less than 17%. Lower prevalences of dirtiness are more likely to occur on some farms first thing in the morning.     

Divergent selection for residual feed intake in group-housed growing pigs: characteristics of physical and behavioural activity according to line and sex

The aim of the study was to assess the impact of selection for residual feed intake (RFI) on the behavioural activity of lines divergently selected for RFI during seven generations. In all, six successive batches from the seventh generation of selection were raised in collective pens equipped with a single-place electronic feeder (SEF) from 10 weeks of age to 100 kg BW. Each batch included four groups of 12 pigs: high RFI (RFI⁺) castrated males, RFI⁺ females, low RFI (RFI⁻) castrated males, RFI⁻ females. At 17 weeks of age, health criteria were evaluated using a gradient scale for increased severity of lameness, body lesions, bursae and tail biting. Individual behavioural activities were recorded by 24-h video tape on the day after health evaluation. The investigative motivation towards unfamiliar objects was quantified at 18 weeks of age. The daily individual feeding patterns were computed from SEF records during the 4 weeks surrounding 12, 17 and 22 weeks of age. All pigs spent significantly most of their time lying in diurnal (80% of total scan) and nocturnal (>89%) periods. The RFI⁻ pigs showed a lower proportion of health problems (P<0.01) than RFI⁺ pigs. The RFI⁻ pigs used the SEF less than the RFI⁺ pigs, in diurnal (5.3% v. 6.4% of video scans, P<0.05) and nocturnal periods (3.6% v. 4.5% of video scans, P<0.05). This was confirmed by a significantly lower daily number and duration of visits to the SEF computed from the SEF data. The feeding activity measured from the video recording was significantly correlated (R>0.34; P<0.05) with feeding patterns computed from the SEF. The RFI⁻ pigs spent less time standing over the 24-h period (9.7% v. 12.2% of scans, i.e. 35 min/day, P<0.05). In terms of energy costs, this amounted to 14% of the line difference in terms of daily metabolizable energy intake. The castrated males used the SEF more than females, especially at night (4.7% v. 3.4% of total scans, P<0.05), whereas females displayed greater investigation of their environment (7.7±0.3% v. 6.6±0.2% of total scans, P<0.05) and the novel objects (10.7% v. 4.9% of total scans, P<0.05). In conclusion, the lower physical activity associated with reduced energy expenditure in RFI⁻ pigs compared with RFI⁺ pigs contributed significantly to their improved efficiency and was not related to worsened health scores.