In commercial situations dry sows are fed a relatively small amount of food once or twice a day. In group feeding systems this can cause a lot of aggression at feeding time and result in an unequal distribution of food between sows when dominant sows prevent subdominant sows from eating. Ad libitum feeding of a suitable diet may be one way to overcome these problems.

Four groups of 12 multiparous sows were housed in deep straw pens (2.9 m2/sow). They were allocated to one of two feeding treatments involving high or low competition for food. Groups on the high competition (HC) treatment were floor-fed once a day 3.0 kg/sow of a barley-soyabean meal diet in pelleted (8 mm) form. Groups on the low competition (LC) treatment received ad libitum a diet containing 60% unmolassed sugarbeet pulp from a 3-space hopper. The composition of the diets is shown in table 1.

Groups were allocated to treatment after service. Feed intake was recorded regularly, liveweight and backfat thickness were measured every fortnight over a 10 week period.