Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs
By M. S. Herskin, K. Thodberg and H. E. Jensen. 2015. Animal 9: 677-681.
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.
Behavioural differences between weaner pigs with intact and docked tails
By Paoli, MA; Lahrmann, HP; Jensen, T; D’Eath, RB, 2016. Animal Welfare 25: 287-296.
Tail-biting in pigs (Sus scrofa) reduces welfare and production. Tail-docking reduces (but does not eliminate) tail-biting damage. The reason tail-docking reduces tail damage is unknown. It may reduce pigs attraction to tails (H1), or increase tails’ sensitivity to investigation (H2). To investigate these hypotheses, behavioural differences between 472 individually marked grower pigs with intact tails (nine groups of 25–34 pigs) or docked tails (nine groups of 22–24 pigs) were observed from 5–8 weeks of age on a commercial farm in Denmark. Pens had part-slatted floors, dry feeding and two handfuls of straw per day, and enrichment objects were provided. Behavioural sampling recorded actor and recipient for tail-directed (tail interest, tail in mouth, tail reaction) and investigatory behaviours (belly-nosing, ear-chewing, interaction with enrichment). Scan sampling recorded pig posture/activity and tail posture. Intact-tail pigs performed more overall investigatory behaviours but tail type did not affect the amount of tail-directed behaviours. Larger pigs performed more investigatory and tail-directed behaviours than smaller pigs and females performed slightly more tail investigation. Tail-directed behaviours were not consistent over time at the individual or group level. However, ear-chewing was consistent at the group level. One group with intact tails was affected by a tail-biting outbreak in the final week of the study (evidenced by tail-damage scores) and showed an increase over time in tail posture (tail down) and tail-directed behaviour but not activity. Overall, there were few behavioural differences between docked and undocked pigs: no evidence of reduced tail investigation (H1) or an increased reaction to tail investigation (H2) in docked pigs, and yet docked pigs had less tail damage. We propose that docking might be effective because longer tails are more easily damaged as pigs are able to bite them with their cheek teeth.
Improving Welfare, Health and Productivity in Pigs by Optimizing Adaptation
By J.E. Bolhuis and B. Kemp, 2016. Journal of Animal Science (conference paper, March 14-16, 2016, Des Moines, USA).
Welfare problems in pigs often arise from an imbalance between the challenges they are exposed to and their adaptive capacity. A major challenge for pigs is the weaning transition. Weaning often results in reduced growth, intestinal problems and damaging behaviors. The natural behavior of pigs and their adaptive strategies can inspire us to reduce weaning-related problems. We found that early ingestion of feed can be stimulated by facilitating information transfer from sow to piglet, both through flavor learning in utero and social learning. This early feeding, in turn, seems vital for a good post-weaning performance. Also enrichment substrates that stimulate early sampling of feed positively affect piglet performance around weaning. We are developing a multi-litter group housing system for lactating sows and their piglets in which both opportunities for sow-piglet information transfer and enrichment substrates are provided. Piglets raised in this system and kept in large groups post-weaning show improved performance until at least 9 weeks of age. Measures that facilitate the weaning transition in pigs typically also reduce the occurrence of damaging behaviors directed at pen mates, such as tail biting and ear biting. These behaviors both reflect and generate welfare problems, and are influenced by multiple factors. Apart from the impact of early life conditions, we studied the contribution of (genetic) characteristics of pigs and of their environment to the tendency of displaying damaging behaviors. Tail biting seems associated with fearfulness, serotonin metabolism and with (genetic and phenotypic) production characteristics. Excessive levels of damaging behaviors lead to reduced growth in the victims, and we therefore investigated the impact of a novel breeding strategy, targeting indirect genetic effects on growth. Pigs with high indirect genetic effects on growth inflicted less tail damage and showed less ear biting. They also seemed less fearful and showed lower leukocyte, lymphocyte and haptoglobin levels. Enrichment with straw bedding had similar beneficial effects additive to those of the new genetic strategy. On most farms it is, however, not feasible to provide pigs with straw, and we therefore studied the effectiveness of a simple enrichment material – a burlap sack – and found a twofold reduction in damaging behaviours and a five-fold reduction in the proportion of animals with a tail wound. In conclusion, – small and large – changes in genetic background, early life conditions and quality of the environment that contribute to the adaptive capacity of pigs, and reduce their stress load, can be used to improve pig welfare and performance in concert.
Understanding tail biters and victimized pigs during outbreaks of tail biting
By Y. Li, J. Anderson, A. Holten, A.M. Hilbrands, J. Holen and L.J. Johnston, 2016. Jounal of Animal Science 94, suppl 2: 2, p. 8-9.
Tail biting is a common problem in growing–finishing pigs, which can compromise health, growth, and welfare of pigs. Because tail biting is an abnormal behavior performed by tail biters toward victimized pigs, understanding these pigs may help us solve the problem. This study was conducted to evaluate immune function of tail biters and victimized pigs. Pigs (n = 240; 25.7 ± 2.9 kg initial weight) were housed in 8 pens of 30 pigs for 16 wk. Once visible blood on a tail appeared, pigs in that pen were assessed daily for tail score (0 = no damage, 1 = healed lesions, 2 = visible blood without swelling, 3 = swelling and signs of infection, and 4 = partial or total loss of the tail). Victimized pigs were defined as pigs with tail scores equal to or greater than 2. Meanwhile, a 2-h observation was conducted for 2 consecutive days to identify tail biters. In each pen in which tail biting occurred, blood samples were collected from victimized pigs on the day that tail biting was first observed as well as from tail biters and 2 control pigs with no sign of tail damage. Fourteen biters (6 barrows and 8 gilts), 30 victimized pigs (21 barrows and 9 gilts), and 28 control pigs (14 barrows and 14 gilts) were identified for blood sampling. Total serum protein and IgG concentrations were analyzed using the spectrophotometric method. Data were analyzed using the Glimmix model of SAS (SAS Inst. Inc., Cary, NC). Compared with control and victimized pigs, tail biters had lower total serum protein (P = 0.01; Table 018) and IgG concentrations (P = 0.01), suggesting poor immunity. There were no differences in total serum protein or IgG concentrations between control and victimized pigs. These preliminary results suggest that tail biters may experience compromised immunity.