What can carcass-based assessments tell us about the lifetime welfare status of pigs?
Carroll et al. 2018. Livestock Science
• The use of carcass measures to understand lifetime pig welfare status was explored.
• Tail and skin lesions acquired in early life remain visible on the carcass.
• These lesions were not necessarily visible on the live animal in later life.
• Carcass weight was negatively associated with persistent tail injuries.
• Therefore carcass lesions and weight provide useful lifetime welfare information.
There is increasing interest in developing abattoir-based measures of farm animal welfare. It is important to understand the extent to which these measures reflect lifetime welfare status. The study aim was to determine whether lesions acquired during different production stages remain visible on the carcass, and the degree to which carcass-based measures may reflect broader health and welfare issues. 532 animals were assessed at 7, 9 and 10 weeks of age (early life, EL), and at 15 and 20 weeks of age (later life, LL) for tail lesions (TL), skin lesions (SL) and a number of health issues (HI) including lameness and coughing. Pigs were categorised according to when individual welfare issues occurred in the production process; ‘early life’ [EL], ‘later life’ [LL], ‘whole life’ [WL], or ‘uninjured’ (U) if showing no signs of a specific welfare issue on-farm. Following slaughter, carcasses were scored for tail length, tail lesions, and skin lesions and cold carcass weights (CCW) were obtained. Generalised linear, ordinal logistic and binary logistic fixed model procedures were carried out to examine the ability of TL, SL and HI lifetime categories to predict carcass traits. Pigs with TL in EL, LL and WL had higher carcass tail lesion scores than U pigs (P < 0.001). Pigs with TL in LL (P < 0.05) and WL (P < 0.001), but not in EL (P > 0.05), also had shorter tails at slaughter than U pigs. In relation to TL scores, U pigs also had a higher cold carcass weight compared to LL and WL (P < 0.001), but not EL pigs (P > 0.05). Pigs with SL in EL, LL and WL had higher healed skin lesion scores on the carcass than U pigs (P < 0.001). Health issues recorded during lifetime were not reflected in carcass measures used (P > 0.05). The current study shows that tail lesions and skin lesions, acquired at least 10 weeks before slaughter, remain evident on the carcass and consequently, may be useful as tools to assist in determining the lifetime welfare status of pigs. Low CCW was associated with tail lesions, supporting previous research suggesting that tail lesions have a negative impact on growth performance in pigs.
Early intervention with enrichment can prevent tail biting outbreaks in weaner pigs
Lahrmann et al. 2018. Livestock Science.
• Providing extra enrichment as an early intervention reduced tail biting outbreaks.
• Tail damage was observed among weaner pigs with intact tails in 58 of 60 pens.
• Solitary tail damage did occur without escalating into tail biting outbreaks.
Tail biting is a serious animal welfare problem in the modern pig production. A frequently studied preventive measure is enrichment materials, and increasing levels of enrichment materials, especially litter materials, reduces the risk of tail biting. However, permanent access to litter materials, can cause blockage of the slurry system and increase production cost. The aim of the present study was, therefore, to investigate if providing extra enrichment material, when observing the first tail damage could reduce the prevalence of tail biting outbreaks. The study included 1804 weaner pigs from 7 to 30 kg distributed in 60 pens with intact tails. As basic enrichment material, pens were equipped with two wooden sticks and daily provided with approximately 400 g of fine chopped straw. From outside the pen pigs were checked for tail damages three times weekly. When the first tail damage (fresh or scabbed) was recorded, the pen was assigned to one of four treatments; chopped straw (approximately 200 g/pen) on the floor (straw), haylage in a spherical cage (haylage), hanging rope with a sweet block (rope) or no extra material (control). From first treatment day and until a tail biting outbreak, tails were scored three times weekly. A tail biting outbreak occurred when four pigs in a pen had a tail damage, irrespective of wound freshness. The experiment was designed to compare the prevalence of tail biting outbreaks in each of the extra material group with the control group. A treatment was carried out in 44 of the 60 pens: 10 pens with straw, 8 pens with haylage, 7 pens with rope and 19 control pens. The risk of a tail biting outbreak was significantly lower in pens with haylage and straw compared with control pens (P < 0.05), and there tended to be fewer tail biting outbreaks in rope-pens compared with control pens (P = 0.08). The results should, though, be interpreted with caution due to the relatively small sample size. In control pens with no intervention, a tail biting outbreak developed in 42% of the pens within two to five days after the first tail damage was observed, whereas a tail biting outbreak did not occur in 32% of the control pens. In conclusion, a regular tail inspection and the use of extra enrichment material, when the first minor tail damage occur, could be one way to reduce the prevalence of tail biting outbreaks.
Do weaner pigs need in-feed antibiotics to ensure good health and welfare?
By Alessia Diana, Edgar G. Manzanilla, Julia A. Calderon Diaz, Finola C. Leonard,
Laura A. Boyle. 2017. PlosOne.
Antibiotics (AB) are used in intensive pig production systems to control infectious diseases
and they are suspected to be a major source of antibiotic resistance. Following the ban on
AB use as growth promoters in the EU, their prophylactic use in-feed is now under review.
The aim of this study was to evaluate the effect of removing prophylactic in-feed AB on pig
health and welfare indicators. Every Monday for six weeks, a subset of 70 pigs were
weaned, tagged and sorted into two groups of 35 pigs according to weight (9.2 ± 0.6 kg). AB
were removed from the diet of one group (NO, n = 6) and maintained in the other group (AB,
n = 6) for nine weeks. Ten focal pigs were chosen per group. After c. five weeks each group
was split into two pens of c.17 pigs for the following 4 weeks. Data were recorded weekly.
Skin, tail, ear, flank and limb lesions of focal pigs were scored according to severity. The
number of animals per group affected by health deviations was also recorded. The number
of fights and harmful behaviours (ear, tail bites) per group was counted during 3×5min
observations once per week. Data were analysed using mixed model equations and binomial
logistic regression. At group level, AB pigs were more likely to have tail (OR = 1.70; P =
0.05) but less likely to have ear lesions than NO pigs (OR = 0.46; P<0.05). The number of
ear bites (21.4±2.15 vs. 17.3±1.61; P<0.05) and fights (6.91±0.91 vs. 5.58±0.72; P = 0.09)
was higher in AB than in NO pigs. There was no effect of treatment on health deviations and
the frequency of these was low. Removing AB from the feed of weaner pigs had minimal
effects on health and welfare indicators.
Understanding Tail-Biting in Pigs through Social Network Analysis
By Yuzhi Li, Haifeng Zhang, Lee. Johnston and Wayne Martin 2018. Animals 2018, 8(1), 13
The objective of this study was to investigate the association between social structure and incidence of tail-biting in pigs. Pigs (n = 144, initial weight = 7.2 ± 1.57 kg, 4 weeks of age) were grouped based on their litter origin: littermates, non-littermates, and half-group of littermates. Six pens (8 pigs/pen) of each litter origin were studied for 6 weeks. Incidence of tail injury and growth performance were monitored. Behavior of pigs was video recorded for 6 h at 6 and 8 weeks of age. Video recordings were scanned at 10 min intervals to register pigs that were lying together (1) or not (0) in binary matrices. Half weight association index was used for social network construction. Social network analysis was performed using the UCINET software. Littermates had lower network density (0.119 vs. 0.174; p < 0.05), more absent social ties (20 vs. 12; p < 0.05), and fewer weak social ties (6 vs. 14, p < 0.05) than non-littermates, indicating that littermates might be less socially connected. Fifteen percent of littermates were identified as victimized pigs by tail-biting, and no victimized pigs were observed in other treatment groups. These results suggest that littermates might be less socially connected among themselves which may predispose them to development of tail-biting.
Deutscher Schweine Bonitur Schlüssel (Geman pig evaluation key, in English)
The ‘key’ provides a standardised classification for recording skin lesions.
In the course of numerous recent tail biting projects, German investigators developed a common tail and ear lesion scoring key in order to make results more comparable. The key now has a composite nature. Depending on the background of the study, lesions can be scored in different levels of detail which can be combined in order to allow analyses across projects. The provided documents include a summary key, descriptions of scores and exemplary pictures (follow this link for the document in English).
PS German guidelines for the on-farm assessment of farm animal welfare (cattle, pigs and poultry) can be found here (in German).
Docking piglet tails: How much does it hurt and for how long?
By Pierpaolo Di Giminiani, Abozar Nasirahmadi, Emma M. Malcolm, Matthew C. Leach, Sandra A. Edwards. 2017. Physiology & Behavior 182: 69-76.
• Short and long-term behavioural changes due to tail docking in pigs are described.
• Vocalisations suggested the procedure to be painful for piglets.
• The behaviour sampling adopted detected no changes up to 2 days post-tail docking.
• Long-term effects of tail injury on mechanical nociceptive thresholds were absent.
Tail docking in pigs has the potential for evoking short- as well as long-term physiological and behavioural changes indicative of pain. Nonetheless, the existing scientific literature has thus far provided somewhat inconsistent data on the intensity and the duration of pain based on varying assessment methodologies and different post-procedural observation times. In this report we describe three response stages (immediate, short- and long-term) through the application of vocalisation, behavioural and nociceptive assessments in order to identify changes indicative of potential pain experienced by the piglets. Furthermore, we evaluated the following procedural differences: (1) cautery vs. non-cautery docking; (2) length of tail removal. Sound parameters showed a significantly greater call energy and intensity exhibited by docked vs. sham-docked piglets (P < 0.05). Observations of general activity of the animals in a test situation failed to detect a difference among treatments (P > 0.05) up to 48 h post-tail docking. Similarly, no difference in mechanical nociceptive thresholds indicative of long term pain was observed at 17 weeks following neonatal tail docking (P > 0.05). The present results highlight the potential for the use of measures of vocalisation to detect peri-procedural changes possibly associated with evoked pain. Nonetheless, activity and nociceptive measures failed to identify post-docking anomalies, suggesting that alternative methodologies need to be implemented to clarify whether tail docking is associated with short- and long-term changes attributable to pain experienced by the piglets.
Determination of stable reference genes for RT-qPCR expression data in mechanistic pain studies on pig dorsal root ganglia and spinal cord.
By Sandercock DA, Coe JE, Di Giminiani P, Edwards SA. 2017. Res Vet Sci. 2017 Sep 28;114:493-501.
RNA expression levels for genes of interest must be normalised with appropriate reference or “housekeeping” genes that are stably expressed across samples and treatments. This study determined the most stable reference genes from a panel of 6 porcine candidate genes: beta actin (ACTB), beta-2-microglobulin (B2M), eukaryotic elongation factor 1 gamma-like protein (eEF-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), succinate dehydrogenase complex subunit A (SDHA), Ubiquitin C (UBC) in sacral dorsal root ganglia and spinal cord samples collected from 16 tail docked pigs (2/3rds of tail amputated) 1, 4, 8 and 16weeks after tail injury (4 pigs/time point). Total RNA from pooled samples was measured by SYBRgreen real-time quantitative PCR. Cycle threshold values were analysed using geNorm, BestKeeper and NormFinder PCR analysis software. Average expression stability and pairwise variation values were calculated for each candidate reference gene. GeNorm analysis identified the most stable genes for normalisation of gene expression data to be GAPDH>eEF-1>UBC>B2M>ACTB>SDHA for dorsal root ganglia and ACTB>SDHA>UBC>B2M>GAPDH>eEF-1 for spinal cord samples. Expression stability estimates were verified by BestKeeper and NormFinder analysis. Expression stability varied between genes within and between tissues. Validation of most stably expressed reference genes was performed by normalisation of calcitonin gene related polypeptide beta (CALCB). The results show similar patterns of CALCB expression when the best reference genes selected by all three programs were used. GAPDH, eEF-1 and UBC are suitable reference genes for porcine dorsal root ganglia samples, whereas ACTB, SDHA and UBC are more appropriate for spinal cord samples.
Characterization of short- and long-term mechanical sensitisation following surgical tail amputation in pigs. By Pierpaolo Di Giminiani, Sandra A. Edwards, Emma M. Malcolm, Matthew C. Leach, Mette S. Herskin & Dale A. Sandercock. 2017. Nature Scientific Reports.
Commercial pigs are frequently exposed to tail mutilations in the form of preventive husbandry procedures (tail docking) or as a result of abnormal behaviour (tail biting). Although tissue and nerve injuries are well-described causes of pain hypersensitivity in humans and in rodent animal models, there is no information on the changes in local pain sensitivity induced by tail injuries in pigs. To determine the temporal profile of sensitisation, pigs were exposed to surgical tail resections and mechanical nociceptive thresholds (MNT) were measured in the acute (one week post-operatively) and in the long-term (either eight or sixteen weeks post-surgery) phase of recovery. The influence of the degree of amputation on MNTs was also evaluated by comparing three different tail-resection treatments (intact, ‘short tail’, ‘long tail’). A significant reduction in MNTs one week following surgery suggests the occurrence of acute sensitisation. Long-term hypersensitivity was also observed in tail-resected pigs at either two or four months following surgery. Tail amputation in pigs appears to evoke acute and sustained changes in peripheral mechanical sensitivity, which resemble features of neuropathic pain reported in humans and other species and provides new information on implications for the welfare of animals subjected to this type of injury.
See also our article in PigProgreess.
The effect of mixing piglets after weaning on the occurrence of tail-biting during rearing
By Christina Veit, Kathrin Büttner, Imke Traulsen, Marvin Gertz, Mario Hasler, Onno Burfeind, Elisabeth grosse Beilage, Joachim Krieter, 2017. Livestock Science 201: 70–73.
The aim of this study was to investigate the effects on tail-biting during rearing of housing piglets of the same litter compared to piglets from different litters. The treatments “litter-wise” (LW, n =240) and “mixed litters” (ML, n =238) were housed in five identical units. Each tail was scored regarding tail lesions and tail losses once per week with a four-point score (0= no damage/original length to 3= severe damage/total loss). The effect of week after weaning had highly significant influences on tail lesions (p<0.001). Tail-biting started in the second week after weaning, with an increasing severity during rearing. First tail losses were observed in the fourth week after weaning. The batch and the interaction between treatment and batch had highly significant influences on tail losses at the end of rearing (p<0.001). Depending on batch, piglets in the LW or ML treatment were more affected by tail-biting.
The Tail Biting “WebHAT” (Web based Husbandry Advisory Tool) is a website designed to be an interactive resource providing information about the key risks for tail biting in pigs and practical suggestions to help reduce these risks on-farm.
Taking information from evidence-based sources and scientific literature, this WebHAT identifies a number of risks associated with tail biting (a key pig behaviour), and can be used to generate a report of prioritised, key tail-biting risks found on a farm and obtain suggestions to address the specific risks identified
You can access the WebHAT tool here.