Effect on pig performance of feed restriction during the growth period

Two experiments were conducted to determine the compensatory responses of pig to feed restriction during the growth period. Eighty Dalland pigs (40 boars and 40 gilts) and 60 Large White × (Large White × Landrace) barrows were used in two different experiments. They were slaughtered at 97 and 122 kg. During the restriction period, the animals were restricted by 46% and 25% of their ad libitum consumptions in experiment 1 and 2 respectively. The restriction periods lasted 28 and 35 days respectively. Considering the whole study period, in experiment 1 the average daily weight gain and food intake were lower for restricted pigs compared to those fed ad libitum: 762 vs 856 g (P < 0.03) and 2147 vs 2396 g (P < 0.08). However, the feed conversion ratio was no different: 2.83 vs 2.80 g g-1 (P < 0.81). In this experiment, the interaction treatment x sex was not significant in either test. When performance over the total period was examined in experiment 2 (moderate restriction), a stronger trend was seen towards a greater average daily weight gain in groups with restricted access to feed (853 vs 821 g in those fed ad libitum, P < 0.11). No significant differences were observed for average daily feed intake, feed conversion ratio and dorsal fat thickness (measured at the 14th rib by ultrasound) (2638 vs 2635 g, 3.09 vs 3.2 g g-1 and 16,9 vs 16.2 mm respectively).