The nutritional contributions from free-range foraging, growth, feed conversion and behaviour were investigated in 36 growing pigs foraging on Jerusalem artichokes (JA) and fed concentrates restrictedly (30% of energy recommendations) or ad libitum. Compared to the ad libitum fed pigs, the pigs fed restrictedly had a significant lower daily gain (560 vs. 1224 g pig−1), improved feed conversion ratio (17.6 vs. 42.8 MJ ME concentrate kg−1 live weight gain) and spent more time foraging JA tubers (7.9 vs. 1.1%). It is estimated that pigs fed restrictedly found approximately 60% of their energy requirement from foraging in the range.
Acta Agriculturae Scandinavica. Section A. Animal Science, 2013, Vol 63, Issue 2, p. 76-83