Responses in production and body composition traits in ad libitum fed pigs from lines selected for high and low growth rate on a fixed ration

Compared with low growth selection, the correlated genetic responses to high growth selection on restricted feeding measured in these ad libitum fed pigs were economically desirable for both performance and carcass composition traits. The increase in growth and decrease in fatness, associated with a reduction in voluntary food intake in the high line pigs, suggested a reduced energy cost of the gain relative to the low growth line. It is concluded that selection for high growth rate on restricted feeding will produce pigs which perform more profitably on ad libitum individual feeding.