The Case for Split Sex Feeding Gilts and Boars
Peadar Lawlor highlights how separating boars and gilts and tailoring diets to their unique needs can boost growth efficiency, reduce feed costs, and minimise environmental impact.
From around 30kg, male (boar) pigs grow faster and more efficiently than females (gilts). At a given slaughter age, male pigs will be heavier and will have consumed less feed to achieve their carcass weight compared to females. I previously discussed this, most recently in a 2020 newsletter piece. But why, when we know this, do so many units work with mixed-sex pen groups? Even on units where males and females are penned separately, why is the same diet fed to both groups? We are essentially wasting costly feed and nutrients, as we are over-supplying the females with nutrients and energy, particularly late in the finishing period.
The difference in growth and feed efficiency between males and females means that female pigs could be fed diets lower in energy by approximately 4% and lower in SID amino acids by around 7%. At the recent Teagasc Pig Farmers’ Conference, Elizabeth Ball (AFBI) gave an excellent presentation on ‘Lowering Nitrogen Excretion from Pig Production’. This work showed that substituting a 15% crude protein diet with a 13% crude protein diet for gilts from 60kg to slaughter did not negatively affect growth performance, but it did reduce nitrogen excretion and ammonia emissions by 18.5% and 20%, respectively. Feeding the reduced crude protein diet was also less costly. However, for males, reducing dietary crude protein from approximately 15% was more challenging, as this can negatively impact animal growth performance, thereby affecting economics, nitrogen excretion, and emissions. Therefore, the key message was that gilts and boars should be penned separately and fed diets tailored to their requirements, so that growth performance, feed cost, nitrogen excretion, and emissions are optimised.
Benefits of Split-Sex Feeding
- In Germany, where there is increasing production of entire male pigs, there is evidence that a proportion of females from mixed-sex pen groups are pregnant at the time of slaughter. This is seen as a welfare/ethical concern, as it could cause negative publicity for the pig industry. No one needs such negative publicity! For this reason, entire male and female pigs are always penned separately there.
- Penning males and females separately allows pens to be emptied over fewer weeks. It also allows males to be brought to a higher sale weight compared to females at a given slaughter age, or alternatively, if males and females are produced to the same target slaughter weight, it allows male pens to be emptied earlier.
- In continental Europe, as entire males and females are penned separately, they can be marketed separately. In some countries, this is important because meat from entire male pigs is leaner, less tender, and has a higher risk of boar taint. Separating the sexes allows males and females to be targeted towards the most suitable products for them.
Penning males and females separately is most easily done at weaning but is especially important during the finishing period, as it is only then that the sexes begin to grow differently. Feeding different diets to males and females will reduce feed costs, nitrogen excretion, and gaseous emissions on your farm. Is this something that you should be looking at now to future-proof your business?