Increase the proportion of fat
One of the reasons why farmers castrated male piglets for meat production was to increase the proportion of fat in the carcass. Like many other mammals, pigs that have been castrated have a higher propensity to deposit fat. Nowadays it is well documented that consumer preference has drastically changed to require mainly lean meat.
Measuring the thickness of fat and muscle using a Hennessy Grading System (HGS) electronic instrument named. Source: Danish Meat Research Institute.