In several species breeders want to increase the body weight to obtain more efficient animals. Often animals are fed ad libitum to give the opportunity to animals to show their growth (as well as obesity) to a maximal extent. However, Danish scientist reported that this might not be sustainable - at least for minks. They conducted the experiment with restricted and ad libitum feeding regime and found out that minks from the restricted group were more fertile and had better utilization of feed. I wonder how does this relate to pigs, rabbits, etc.