Injecting to delay the onslaught of puberty
As animal welfare campaigners in Europe continue to push for a ban on boar castration, Liz Shankland considers a vaccination which some producers believe could be the answer to boar taint
However you feel about the castration of piglets reared for meat, those who do it routinely know that sometime in the future they will have to consider the alternatives. As reported in last month’s Country Smallholding, the target date for an end to the practice of physically castrating without anaesthesia or analgesia in Europe has been extended to the end of 2018. Welfare campaigners have long argued that this type of castration — carried out in the first week of life to guard against any risk of boar taint ( See box, right) — is painful, inhumane and medically risky. Major producers in several countries across Europe have already made voluntary changes in the way they operate, either abandoning physical castration altogether, or carrying out the procedure with the aid of local anaesthetic and/or painkillers.
The first part of this two-part feature ( Country Smallholding, October) looked at ways in which the risk of taint could be minimised by better husbandry and careful stock selection, but, for an increasing number of producers, vaccination seems to be a practical answer.
As already discussed, not all boars will produce tainted meat; some breeds — and some bloodlines within certain breeds — will be more susceptible than others. Husbandry and environmental issues can also be factors. However, to reduce the risk of customer dissatisfaction, the majority of butchers still prefer meat from gilts (young females) or from physically-castrated boars.
Physical castration can only be carried out within the first week of life by a breeder; any later and it must be done by a veterinarian using a local anaesthetic and analgesia. Castration performed in this way can reduce the risk of taint, but there is growing opposition to castration, which not only carries welfare concerns and health risks, but can also have a detrimental effect on growth ( Country Smallholding, October).
One alternative approach which is being used with excellent results is immunocastration. At the moment, there is only one vaccine licensed for use for immunocastration — Improvac®. It is important to stress that this vaccine is not a form of chemical castration — a phrase which often sets alarm bells ringing. Improvac® works by temporarily suppressing testicular function (including testosterone production). In effect, it delays puberty, while allowing the pig to grow as normal in all other respects.
Take up in the UK has been relatively slow, but in the United States, where more than 95% of pigs are castrated because producers take their pigs to much higher weights, interest is increasing.
Larry Rueff, a vet from Greensburg, Indiana, who owns his own pig farm and uses it as a teaching facility, has been a pioneer in persuading others to use immunocastration instead of physical castration. He has been using Improvac® for more than four years and has carried out detailed trials with numerous batches of pigs — with impressive results. Central to his research is his long-held belief (backed by scientific studies) that entire boars produce better, leaner carcasses and better value for money than those who have been physically castrated.
“Immunocastration lets boars be boars,” he insists. “The reality is that we sometimes forget that performance in uncastrated boars is so much better, from a feed conversion and growth rate point of view, than when they are castrated.”
Although Improvac® is now being used extensively in some parts of Europe, its usage in the United States is still limited, largely because of concerns over food safety.
“We have become very concerned about our food,” Larry explains. “Here in the US we have the safest food in the world, but some of the general public are still suspicious about what they’re buying.”
Larry believes that concerns about genetically-modified products are partly to blame for confusing consumers; there is a general misconception, he says, that anything which involves scientific intervention must be bad.
“When you say immunocastration, people think hormones,” he says. “They think it’s something that will make the pork unsafe. That’s just not true. Quite simply, androstenone and skatole, which are the compounds that the male pig naturally produces when it is intact, are the things which can give the pig’s meat taint. All that immunocastration does is to block the physiological process that allows those products to be made. It makes the body shut the process off, just as your immune system reacts when you vaccinate for something, such as, in the pig industry, mycoplasma or circovirus. It just uses the body’s natural immune system to turn things off.”
According to studies carried out, while the main reason for using immunocastration is to delay puberty and reduce the risk of boar taint, it also helps to reduce aggression when boars are reared together. Larry Rueff says he routinely keeps 25 young boars in a pen — often boars mixed from different litters — without any problems, right up to slaughter weight. When finished, the pigs’ carcasses are leaner than their castrated counterparts and they have consumed less food.
According to studies carried out, while the main reason for using immunocastration is to delay puberty and reduce the risk of boar taint, it also helps to reduce aggression when boars are reared together
The risk of taint could be minimised by better husbandry and careful stock selection, but vaccination is also a practical answer