A set of Dutch trials aimed at finding ways to overcome certain problems when finishing boars, has not yielded any new management options so far.
Research, carried out at the Swine Innovation Centre Sterksel, part of Wageningen University and Research Centre, focused on influencing mounting behaviour in finisher boars as well as adjusting the feeding management to reduce chances of boar taint. Both trials, however, proved not to have any effect. In both fields of study additional research is required.
The research is relevant as stakeholders throughout the European Union aims move away from physical castration by 2018. To achieve this goal, however, solutions need to be found for the problems that raising boars brings about, like tainted carcasses as well as mounting behaviour in the pens.
Boars are known to be more difficult to manage than gilts or barrows as they display restless behaviour and are inclined to mount each other. One hypothesis would be that this behaviour can be reduced by housing them together with their litter mates throughout the finishing phase and by feeding them at the same time. Some measures were assumed to even positively influence boar taint.
Tests compared the keeping of complete litters versus mixing boars from several litters; feeding simultaneously versus non-simultaneously; and feeding a special feed, aimed at having lower boar taint.
The trials showed, however, that keeping litters together does not reduce mounting behaviour. The percentage of boars displaying mounting behaviour in pens with only boars was comparable to that of pens with litters.
In earlier Swedish and French research, a reduced percentage of mounting behaviour was seen in boars kept with their litter mates, when compared to ‘mixed’ boars with boars or gilts from other litters. The Dutch test, however, showed a low percentage of animals displaying mounting behaviour – possibly the reason no real effects could be discovered.
The boars did show a stronger tendency to mounting behaviour. More skin lesions and more lame animals were observed than in gilts.
Feeding simultaneously did not reduce the boars’ mounting behaviour in comparison to consecutive feeding. The trials, however, revealed that the percentage of boars mounting is higher in the afternoon than in the morning.
Feeding a special feed, aimed at reducing boar taint, in the last two weeks before slaughter, did not affect the animals’ technical results.
Percentages of boars having boar taint did not differ significantly when boars were kept in groups with only boars – and in groups with only litter mates.
The feeding system did not appear to have any influence on boar taint and the androstenone level, one of two major hormones associated with boar taint. Levels of the other hormone, skatole, however, came down clearly in boars fed using a long trough (simultaneous feeding) in comparison to a consecutive, dry feeding trough.
No clear effects could be seen of the special feed on the percentage of boars having boar taint – as well as on the levels of androstenone and skatole.
Next research at the test farm will focus on the effects of light colour (normal versus green light) and light regimes; group sizes; a hiding wall in the pen.
The research was carried out by By order of the Dutch Ministry of Economic Affairs, Agriculture and Innovation and the Dutch Product Board for Livestock and Meat.