1751-0147-48-S1-S3

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Bio Med Central Page 1 of 3 (page number not for citation purposes) Acta Veterinaria Scandinavica Open Access Oral presentation Animal Welfare Aspects of Preventing Boar Taint MetteGiersing*, JanLadewig and BjörnForkman Address: Royal Veterinary and Ag ricultural University, Denmark * Corresponding author Introduction Since boar taint is connected to testicular hormones and sexual maturity, surgical castration has for centuries been the method employed to prevent taint in meat from male pigs, as well as to obtain more docile pigs. However, since the castration is performed without anaesthesia, it is pain- ful for the pig and therefore poses a serious welfare prob- lem. With growing focus on animal welfare in animal production, surgical castration without anaesthesia and some form of analgesia is now increasingly regarded as unacceptable. The options, singly or combined, are: - castrating the pigs by methods that do not entail suffer- ing, either surgically or non-surgically - raising entire male pigs by methods that limit the devel- opment of boar taint - selecting pigs with low levels of taint - producing only female pigs for consumption. This presentation focuses on the animal welfare concerns of these different ways of preventing or reducing boar taint. The welfare aspects of castration have recently been reviewed by a working group under European Food Safety Authority [1], by Bonneau & Prunier [2] and by Prunier et al.[3]. We wish to acknowledge the many involved authors, as these reviews provide a significant basis and the references for this presentation – supplemented by ref- erences that have since come to light. Surgical castration Surgical castration without anaesthesia is painful, as shown by the acute physiological responses (increased

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since come to light. Surgical castration Surgical castration without anaesthesia is painful, as shown by the acute physiological responses (increased Hypothalamic-Pituitary-Adrenal-responses and protein c- fos expression in spinal neurons), as well as by vocalisa- tion and behaviour during and immediately after the operation. The frequency and duration of high-frequency calls points towards the extraction of the testes and the severing of the spermatic cords as being the most painful in the procedure. Behavioural changes include disturbed massaging/suckling, activity, play and behavioural syn- chronisation. Some behavioural changes may persist for more than 24 hours after the operation, e.g. tail-wagging and rump-scratching, behaviours that may be related to wound-healing. It appears that the assumption, that pigs under the age of 7 days experience castration as less pain- ful than older pigs, is not substantiated. The incomplete neural development of young animals may render them more, rather than less, sensitive to painful stimuli. The effect of surgical castration on immune response var- ies with the type of challenge, with the age at castration, and is modified by the use of anaesthesia [4]. The different results are, however, open to interpretation in terms of pig welfare. Reports that castration compromises the health of the pigs in that the prevalence of pneumonia and other diseases was higher in castrates compared to gilts, and castrates compared to boars and gilts, are not confirmed by a review of data from Danish abattoirs. Here the opposite was found with regard to Mycoplasma hyopneumoniae infection, with boars having the highest risk, females the lowest and castrates intermediate [5]. from Prevention of Boar Taint in Pig Production : The 19th Symposium of

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rs having the highest risk, females the lowest and castrates intermediate [5]. from Prevention of Boar Taint in Pig Production : The 19th Symposium of the Nordic Committ ee for Veterinary Scientific Cooperation Gardermoen, Norway. 21–22 November 2005 Published: 7 August 2006 Acta Veterinaria Scandinavica 2006, 48 (Suppl 1):S3doi:10.1186/1751-0147-48-S1-S3 <supplement> <title> <p>Prevention of Boar Taint in Pig Production: The 19th Symposium of the Nordic Committee for Veterinary S cientific Cooperation</p> </title> <note>Meeting abstracts</note> <url>http://www.biomedcentral.com/content/files/pdf/1751-0147 -48-S1-full.pdf</url> </supplement> © 2006 Giersing et al.; licensee BioMed Central Ltd.

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Acta Veterinaria Scandinavica 2006, 48 (Suppl 1):S3 Page 2 of 3 (page number not for citation purposes) Possible long-term effects on disease susceptibility need further investigation – with regard to effects of the castra- tion procedure as well as the absence of male steroids. Local anaesthesia (commonly lidocaine plus adrenalin in a pH-buffered vehicle) effectively reduces the pain and stress symptoms of castration- most effectively when injected both into the testes and in the funicular area of the scrotum [1]. This happens in spite of the additional handling involved, as the response to intratesticular injec- tion is much lower than to castration without anaesthesia. Prunier [6] recently confirmed the effect of anaesthesia, but found no further effect of pre-emptive analgesia with flunixine. General anaesthesia of piglets, both injection and inhala- tion, has been regarded as unrealistic (time, cost and forced veterinary assistance) under practical conditions. It has moreover been associated with high piglet mortality as well as risks in the post-operative period of sedation. Although CO 2 inhalation has been regarded as too averse to pigs, new research indicates that CO 2 anaesthesia, in the right gas proportions and with the right equipment, may be effective and practicable at farm level [7]. The whole procedure is very fast: 15 seconds to unconscious- ness, 1–2 minutes to total anaesthesia, 15 seconds for cas- tration and 30–40 seconds for full recovery. Anaesthetic as well as analgesic properties of the procedure are under fur- ther investigation, as is the significance of the pig's initial aversion responses to the gas in relation to welfare. How- ever, more recent results concerning anæsthesia of piglets prior to castration are discussed in another

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ponses to the gas in relation to welfare. How- ever, more recent results concerning anæsthesia of piglets prior to castration are discussed in another paper of this volume. Non-surgical castration Methods of non-surgical castration include immunocas- tration, by which male pigs are actively immunised against GnRH, thus inhibiting testicular development. Currently this method is used in Australia and New Zea- land. When effective, the behaviour, production and boar taint level of the immunocastrates are similar to surgically castrated pigs. The procedure must be repeated twice to be effective, which means twice capture, restraint and injec- tion of relatively large pigs because, in order to retain the production advantages of entire males, the pigs are immu- nocastrated as late as possible (14 and 18 weeks of age). Stress or trauma from capture, restraint and injection could probably be minimised by correct handling proce- dures. Lesions in the hypothalamus, the target site of the vaccine, were initially reported, but a subsequent report by the same group of scientists concludes that immunisa- tion against GnRH does not induce either morphological or pathological abnormalities in the brain [8]. The welfare consequences of this vaccination still need further investi- gation. Another method of non-surgical castration is local destruction of testicular tissue by chemical compounds such as formaldehyde, acetic acid, or salt from silver or zinc. No thorough welfare evaluation has been made. Swelling of the testes or scrotum has been observed which indicates inflammation and, although not proven, is likely to cause pain. The use of exogenous steroid hormones or steroid ago- nists, to down-regulate the HPG axis, is not a method which would be acceptable to EU-consumers.

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The use of exogenous steroid hormones or steroid ago- nists, to down-regulate the HPG axis, is not a method which would be acceptable to EU-consumers. Raising entire male pigs Producing entire males for meat consumption calls for particular management procedures to minimise boar taint and to promote pig welfare. The one main boar taint sub- stance, skatole, can to a large extent be controlled by feed- ing and by keeping the pigs clean. The latter may lead to extensive use of slatted floors, which is not conducive to pig welfare. An alternative, and more welfare friendly approach, is to control the climatic environment and pro- vide pigs with possibilities for thermoregulation, e.g. showers, instead of leaving them to wallow in their own excreta. To reduce skatole development it is moreover rec- ommended that feed be withheld from entire males from 26 hours before slaughter. This may be a welfare problem, as modern pigs have large appetites, but the harm to the welfare this might cause has not been investigated. The remainder of this section is devoted to effects of – and on – androstenone. Entire males are more aggressive than females and cas- trates – this applies also to play fighting behaviour in young pigs. Both aggression/fighting and sexual behav- iour/mounting which takes place in groups with male pigs, compromise animal welfare as well as meat and car- cass quality through skin damage and leg injuries. Recently, agonistic behaviour at feeding and sexual (mounting) behaviour was found to be significantly higher in entire male groups and mixed male and female groups compared to females alone [9]. In earlier studies [1] it has been shown that boars in mixed sex groups had higher fat androstenone levels and were more sexually mature than those in single sex

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studies [1] it has been shown that boars in mixed sex groups had higher fat androstenone levels and were more sexually mature than those in single sex groups when slaughtered at over 100 kg live weight. Dominance and aggression are related to increased levels of androstenone, with dominant animals having the high- est levels. High level of androstenone in a group has an enhancing effect on androstenone levels of that group. Salmon [10] found the highest level of aggression, sexual (mounting) behaviour and the highest testes weight in a male-only environment, compared to rooms with both male and female groups, which could confirm that strong

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Publish with Bio Med Central and every scientist can read your work free of charge "BioMed Central will be the most significant development for disseminating the results of biomedical research in our lifetime." Sir Paul Nurse, Cancer Research UK Your research papers will be: available free of charge to the entire biomedical community peer reviewed and published immediately upon acceptance cited in PubMed and archived on PubMed Central yours — you keep the copyright Submit your manuscript here: http://www.biomedcentral.com/info/publishing_adv.asp Bio Med central Acta Veterinaria Scandinavica 2006, 48 (Suppl 1):S3 Page 3 of 3 (page number not for citation purposes) boar pheromone odour has a stimulating effect on other boars. This is perhaps not surprising, considering that boars in nature live in bachelor groups when reaching sex- ual maturity. Aggressive behaviour as well as sexual behaviour has been shown to be associated with increases in testosterone and androstenone levels in plasma, whereas corresponding increases in fat levels have only been measured after HCG challenge. Mixing unacquainted pigs will always lead to aggression/ fighting until a new dominance order has been estab- lished. Mixing entire males will therefore not only be stressful and injurious, but increase the risk of higher androstenone levels. 'Birth to slaughter' systems, where litters of pigs are kept together from birth to slaughter, including transport and preslaughter lairage, not only minimises skin damage (fighting), but also reduces the level of androstenone in entire males [11]. Whether litter rearing and minimal mixing influences the development of sexual maturity and mounting behaviour is not yet clear. It is likely that mixing of strangers and establish- ment of new hierarchies will

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elopment of sexual maturity and mounting behaviour is not yet clear. It is likely that mixing of strangers and establish- ment of new hierarchies will provoke testicular activity and accelerate the initiation of puberty, whereas the initi- ation of puberty may be inhibited in stable sibling groups Because of increased aggressiveness and activity levels, it is likely that rearing environments and handling facilities for entire males should contain more resources (space, facilities, including devices for thermoregulatory behav- iour) than normally provided for castrates in order to minimise competition and aggression. If adequate facili- ties are not given, effects of behaviour on skin and leg injuries, as well as the general stress level, may be increased if pigs cannot escape or avoid harassment from particularly active males. Effects of these factors on boar taint are not documented. High levels of received aggres- sion or levels of cortisol have not been associated with either skatole or androstenone levels. Genetic selection It is not known whether selecting or breeding animals for low skatole and androstenone production or for high ska- tole and androstenone metabolism has any consequences for animal welfare, but this seems unlikely. Sperm sorting The current technique for sperm sorting in pigs, in order to produce only female pigs for meat consumption, neces- sitates intrauterine insemination of the sows, which could increase the risk of discomfort, injury and pain and thus compromise the welfare of the sows. This may change with the development of new techniques. References 1.EFSA: Welfare Aspects of the Castration of Piglets. Scientific Report of the Scientific Panel for Animal Health and Welfare, European Food Safety Authority 2004

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are Aspects of the Castration of Piglets. Scientific Report of the Scientific Panel for Animal Health and Welfare, European Food Safety Authority 2004 [http://www.efsa.eu.int/science/ahaw/ ahaw_opinions/512_en.html ]. Accessed Sept 28 2005 2.Bonneau M, Prunier A: Alternatives to piglet castration. 56th Annual Meeting of the EAAP, Uppsala. June 5–8,2005 Session 27 (PNPh5.1) . 3.Prunier A, Bonneau M, von Borrell EH, Cinotti S, Gunn M, Fredriksen B, Giersing M, Morton DB, Tuyttens F, Velarde A: A review of the welfare consequences of surgical castration in piglets and evaluation of non-surgical methods. Animal Welfare in press. 4.Merlot E, Prunier : A Long term consequences of castration on the inflammatory response in piglets. Meeting of the Working Group on the Utilisation of Meat from Entire Male Pigs, Uppsala, June 8– 9,2005 . 5.Nielsen JP, Jensen SC, Bækbo P, Jorsal SE, Sørensen V, Houe H: Myc- oplasma hyopneumoniae infectio n. A review of pathogene- sis, diagnosis, risk factors and biological effects as input for economical modelling. CEPROS report no.5. Research Centre for the Management of Animal Production and Health, Foulum, Denmark 2000. 6.Prunier A, Moriez R, Mounier AM: Effects of local anaesthesia and preemptive analgesia on pl asma profiles of cortisol and ACTH in piglets undergoing surgical castration. Meeting of the Working Group on the Utilisation of Me at from Entire Male Pigs, Uppsala, June 8–9,2005 . 7.Svendsen O, Strøbech L, Forkman B: CO 2 /O 2 as an anaesthetic agent during castration of piglets. Meeting of the Working Group on the Utilisation of Meat from Entire Male Pigs, Uppsala, June 8–9 2005 . 8.Oonk HA, Turkstra JA, Sc haaper WMM, Meloen RH: Further expe- rience with anti-GnRH vaccines in male pigs. Proc. EAAP Work- ing Group on

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8–9 2005 . 8.Oonk HA, Turkstra JA, Sc haaper WMM, Meloen RH: Further expe- rience with anti-GnRH vaccines in male pigs. Proc. EAAP Work- ing Group on Production and Utilisation of Meat from Entire Male Pigs. Milton Keynes, U.K. September 27–29 1995 . 9.Boyle L, Björklund L: Effects of finishing en tire males in single or mixed sex groups and split marketing on behaviour, wel- fare and performance. 3rd Int. Workshop: Assessment of Animal Welfare at Farm and Group Level (WAFL-05) Sept. 22–24, 2005 Vienna. Abstract . 10.Salmon L: The effects of gender sepa ration on behaviour and performance of entire boars and gilts from 60 kg to 130 kg live weight. Meeting of the Working Grou p on the Utilisation of Meat from Entire Male Pigs, Uppsala, June 8–9, 2005 . 11.Fredriksen B, Nafstad O, Lium BM, Marka CH, Heier BT, Dahl E, Choinski JU: Entire male pigs in a farrow-to-finish-system. Effects on androste none and skatole. Livestock Science in press.