Entire Male Pigs

Table of Contents

1. Introduction
   1. Objectives
   2. Learning goals
   3. Teacher page
2. Entire Male Pigs
3. Castration of male pigs
   1. Statistics
4. Legislation and enforcement
5. Origin of boar taint
   1. Androstenone
   2. Skatole
6. Reasons for castration
   1. Increase the proportion of fat
   2. Increase consumer acceptance
   3. Reduce aggression
   4. Prevent unplanned breeding
7. Surgical castration
   1. Traditional surgical castration
   2. Anaesthesia combined with castration
   3. Gas analgesics
8. Problems related to surgical castration
   1. Animal welfare
   2. Pain and behaviour - the acute response
   3. Reduced growth rate and changed behaviour after surgery
   4. Health consequences
   5. Effect of age
   6. Consumer awareness
   7. Labour cost
9. Alternatives to castration
   1. Slaughter at lower weight
   2. On-line sorting
   3. Management
   4. Breeding and sperm sexing
   5. Perceptual masking of boar taint
   6. Immunocastration
   7. Immunocastration - physiology
   8. Immunocastration - practical implications
10. Completion
    1. Comments
    2. Self-assessment
    3. Key messages
    4. Further reading
    5. Evaluation
11. Acknowledgement

Breeding and sperm sexing

There are indications of genetic influence on skatole levels in pigs and there are also large differences in androstenone levels between breeds (EFAS, 2004). Some producers are trying to breed out the taint by avoiding the few breeds of pigs that are high in taint, such as Duroc (Hortos et al., 2000; Doran et al., 2002), whereas Yorkshire, Hampshire and other lightercoloured pigs are known to be particularly low in androstenonebased taint. Selection experiments for high or low levels of androstenone have not been fully successful because of the association with delayed puberty in litter-mate gilts (Willeke et al., 1987; Sellier and Bonneau, 1988). Selection against skatole will not have such an effect.

Sorting of semen according to sex is possible, but not yet available for routine use in pigs. This method of predetermining the sex of offspring can be the future of pig production, leading to pork production being entirely based on the production of female pigs.

The present technique (sorting by sex chromosome) is based on flow cytometry but it is time-consuming: it takes 10 hours to produce a 150 mill sperm semen dose).

To reduce the number of sperm cells needed per dose, insemination with sexed semen will also introduce the need for new insemination methods. By depositing the sperm directly into the uterus, the required number of sperm cells can be reduced. This technique needs to be developed further.