Indirect Genetic Effects for Growth Rate in Domestic Pigs Alter Aggressive and Manipulative Biting Behaviour

Indirect Genetic Effects for Growth Rate in Domestic Pigs Alter Aggressive and Manipulative Biting Behaviour
By Irene Camerlink, Winanda W. Ursinus, Piter Bijma, Bas Kemp, J. Elizabeth Bolhuis. 2015. Behavior Genetics 45: 117–126.

Indirect genetic effects (IGEs) are heritable effects of an individual on phenotypic values of others, and may result from social interactions. We determined the behavioural consequences of selection for IGEs for growth (IGEg) in pigs in a G × E treatment design. Pigs (n = 480) were selected for high versus low IGEg with a contrast of 14 g average daily gain and were housed in either barren or straw-enriched pens (n = 80). High IGEg pigs showed from 8 to 23 weeks age 40 % less aggressive biting (P = 0.006), 27 % less ear biting (P = 0.03), and 40 % less biting on enrichment material (P = 0.005). High IGEg pigs had a lower tail damage score (high 2.0; low 2.2; P = 0.004), and consumed 30 % less jute sacks (P = 0.002). Selection on high IGEg reduced biting behaviours additive to the, generally much larger, effects of straw-bedding (P < 0.01), with no G × E interactions. These results show opportunities to reduce harmful biting behaviours in pigs.

Two-level pen may be feasible option to increase space allowance and to create functional areas in a piglet pen

Use of space and behavior of weaned piglets kept in enriched two-level housing system
By Michaela Fels, Franziska Lüthje, Alice Faux-Nightingale & Nicole Kemper. 2018 Journal of Applied Animal Welfare Science

In this study, the possibility of introducing an elevated platform to a piglet pen was explored as a way of increasing available space and creating functional areas. On the platform, nine different manipulable materials were offered. In four batches, 40 weaned piglets were kept for five weeks in the two-level pen. Video recordings were taken two days per week. In the afternoon, more piglets were on the platform than in the morning or at night (7.2 ± 0.1 vs. 4.9 ± 0.1 vs. 0.6 ± 0.1 piglets/5 minutes; p < .05). The area under the platform was preferred more in the morning and at night than in the afternoon (18.5 ± 0.1 vs. 21.6 ± 0.2 vs. 12.5 ± 0.1 piglets/5 minutes; p < .05). Up to 36 piglets were counted there simultaneously, mainly in the recumbent position. On and under the platform, air velocity and ammonia concentration were within the recommended ranges. The study concluded that a two-level pen is a feasible option to increase space allowance and to create functional areas in a piglet pen.

Weaned littermate piglets seem less socially connected and prone to becoming tail-biting victims

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.

Curly pig tail farming in Finland and Italy (two EC videos)

EU legislation on the welfare of pigs (Council Directive 2008/120/EC laying down minimum standards for the protection of pigs) does not allow routine tail-docking and requires farmers to provide to their pigs “manipulable material” such as straw, hay or sawdust.
To better inform farmers how to prevent routine tail docking, the Commission developed educational materials. The two videos present success stories in achieving the goal of rearing not-tailed pigs.

A Finnish farming with an intensive system rearing piglets with intact, curly tails.

An Italian farmer proud of rearing curly tails on straw

Chains as enrichment for pigs (Book chapter with supplement)

Chains as proper enrichment for pigs (incl. supplement) (Book chapter in Advances in Pig Welfare, M Spinka (Editor), Elsevier).

Rearing pigs in barren conditions reduces their welfare. Enrichment of pig pens is needed to allow the performance of species-specific natural behaviour like rooting. A metal chain provides rather limited enrichment, but when presented in an optimized way, may substantially improve the welfare of conventionally reared pigs in a most feasible way. The short metal chain can be optimize into the branched chain design. This is a long anchor-chain type chain reaching til floor level, with 2 or 3 shorter chain branches at nose height, and 1 such a branched chain being provided for every 5 pigs in the pen.

The underlying ideas are described in this book chapter:

Bracke MBM. Chains as proper enrichment for pigs (incl. supplement). In: Spinka M, editor. Advances in Pig Welfare: Elsevier (2017). The chapter (without supplement) can also be downloaded here.


This chapter primarily compiles work in which the author (Marc Bracke) has been involved with providing science-based decision support on the question of what is proper enrichment material for intensively-farmed pigs as required by EC Directive 2001/93/EC. Proper manipulable material should primarily provide occupation (i.e. reduce boredom), and preferably reduce tail biting.

The RICHPIG model was built expressing enrichment value as a score on a scale from 0 to 10. Metal objects like short metal chains had the lowest score. Subsequently, the Dutch government banned the use of metal chains, and most Dutch pig farmers attached a hard plastic ball or pipe to the prevalent, short metal chain. Unfortunately, our on-farm observations repeatedly suggested that this ‘enrichment’ may have reduced pig welfare, rather than improving it as intended by the Directive.

So-called AMI (animal-material interaction) sensors can be used to (semi-)automatically record object manipulation by attaching a motion sensor to hanging objects. Exploratory data are presented to, directly and indirectly, record enrichment value. AMI-sensors may provide objective, flexible and feasible registration tools of enrichment value, but their application is still rather demanding.

That the enrichment value of short metal chains can be improved upon, e.g. by providing branched chains. Essentially, this entails making chains longer, preferably reaching until the floor, and making them more readily available in a pig pen. To facilitate the process towards proper enrichment the principle of intelligent natural design (IND) is proposed. IND entails organising a repeated selection process of the (currently) best-available enrichment material so as to gradually reduce pig boredom and enhance the opportunities for the rearing of pigs with intact tails. IND should start with basically all pig farmers implementing promising enrichment like the branched-chain design on their farms as soon as possible, followed by conducting small-scale on-farm experiments to compare and improve enrichment through sharing of available knowledge. Suggestions are given as to how and why this novel approach can be implemented to solve persistent animal-welfare problems like providing proper enrichment for intensively-farmed pigs.

Related posts:

Chains as enrichment for pigs (Book chapter with supplement)
Ketting als hokverrijking voor varkens (incl. link naar het supplement)
Pig animation – Improved, branched chain design as proper enrichment for pigs
Branched chains as enrichment for pigs (technical description, pictures and video)
Proper enrichment for intensively-farmed pigs – From review to preview
A collection of pictures of other enrichment materials for pigs can be found here: Prize contest (Prijsvraag) 2011.
Do pigs play with chains? Science versus society

The video below shows the value of a branched chain provided in the outdoor run of organic pigs. This prototype branched was called ‘enriched chain’ because it was having various branches and reaching till the floor. The prototype was not yet made of stainless steel anchor chain links, but of relatively large c-chain links (2.5 cm wide, 5.5 cm long). It also shows that pigs show signs of frustration when trying to manipulate the hockey-type ball hanging on a short chain.

Tool for scoring tail, ear and skin lesions in pigs

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).

New book: Advances in Pig Welfare

New book: Advances in Pig Welfare
1st Edition
Editors: Marek Špinka
Hardcover ISBN: 9780081010129
Imprint: Woodhead Publishing (Elsevier)
Published Date: 10th November 2017
Page Count: 506

Table of Contents

Part One: Pig Welfare Hotspots
1. Overview of commercial pig production systems and their main welfare challenges* – Lene Juul Pedersen
2. Sow welfare in the farrowing crate and alternatives*
3. Piglet mortality and morbidity: inevitable or unacceptable?*
4. Lifetime consequences of the early physical and social environment of piglets* – Helena Telkänranta, Sandra Edwards
5. Tail biting* – Anna Valros
6. Manipulable materials* – Marc Bracke
7. Mitigating hunger in pregnant sows*
8. Aggression in group housed sows and fattening pigs
9. Handling and transport of pigs
10. Slaughter of pigs

Part Two: Pig Welfare Emerging Topics
11. The pain-sensitive pig* – Mette S Herskin, Pierpaolo Di Giminiani
12. On-farm and post-mortem pig health status assessment
13. Pig-human interactions: Pig-human interactions: creating a positive perception of humans to ensure pig welfare*
14. Breeding for pig welfare; opportunities and challenges*
15. Positive pig welfare
16. Pigs as laboratory animals* – Jeremy Marchant-Forde, Mette S. Herskin

Chapters marked with * have (co-)authors involved in FareWellDock. Chapters with stated authors only have FareWellDock partners as (co-)authors.


Advances in Pig Welfare analyzes current topical issues in the key areas of pig welfare assessment and improvement. With coverage of both recent developments and reviews of historical welfare issues, the volume provides a comprehensive survey of the field.
The book is divided into two sections. Part One opens with an overview of main welfare challenges in commercial pig production systems and then reviews pig welfare hot spots from birth to slaughter. Part Two highlights emerging topics in pig welfare, such as pain and health assessment, early socialization and environmental enrichment, pig-human interactions, breeding for welfare, positive pig welfare and pigs as laboratory animals.
This book is an essential part of the wider ranging series Advances in Farm Animal Welfare, with coverage of cattle, sheep, pigs and poultry.
With its expert editor and international team of contributors, Advances in Pig Welfare is a key reference tool for welfare research scientists and students, veterinarians involved in welfare assessment, and indeed anyone with a professional interest in the welfare of pig. View less >

Key Features
•Provides in-depth reviews of emerging topics, research, and applications in pig welfare
•Analyzes on-farm assessment of pig welfare, an extremely important marker for the monitoring of real welfare impacts of any changes in husbandry systems
•Edited by a leader in the field of pig welfare, with contributing experts from veterinary science, welfare academia, and practitioners in industry

Animal Welfare research scientists, Postgraduate students, Policy makers and stakeholders, R&D managers

The book may be ordered here.

Pig enrichment affects immune response to disease

Effect of enriched housing on levels of natural (auto-)antibodies in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae.
Lu Luo, Ingrid Daniëlle Ellen van Dixhoorn, Inonge Reimert, Bas Kemp, Jantina Elizabeth Bolhuis and Hendrik Karel Parmentier 2017. Vet Res (2017) 48:75.


Housing of pigs in barren, stimulus-poor housing conditions may influence their immune status, including antibody
responses to (auto-)antigens, and thus affect immune protection, which will influence the onset and outcome of
infection. In the present study, we investigated the effects of environmental enrichment versus barren housing on the
level of natural (auto-)antibodies (NA(A)b) and their isotypes (IgM and IgG) binding keyhole limpet hemocyanin (KLH),
myelin basic protein (MBP), and phosphorycholine conjugated to bovine serum albumin (PC-BSA) in pigs co-infected
with porcine reproductive and respiratory syndrome virus (PRRSV ) and Actinobacillus pleuropneumoniae (A. pleuro-pneumoniae). Pigs (n= 56) were housed in either barren or enriched pens from birth to 54 days of age. They were infected with PRRSV on 44 days of age, and with A. pleuropneumoniae 8 days later. Blood samples were taken on 7 dif-ferent sampling days. Housing significantly affected the overall serum levels of NA(A)b binding KLH, MBP and PC-BSA, and before infection barren housed pigs had significantly higher levels of NA(A)b than enriched housed pigs, except for KLH-IgM and PC-BSA-IgG. Infection only affected the IgM, but not the IgG isotype. Moreover, changes in MBP-IgM and PC-BSA-IgM following infection were different for enriched and barren housed pigs. These results suggest that the effect of infection on NA(A)b is influenced by housing conditions and that NA(A)b, especially IgM may be affected by infection.

Docking piglet tails: How much does it hurt and for how long?

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.