The quantitative effects of feed restriction in fattening pigs on weight gain, efficiency of feed utilisation and backfat thickness

Abstract

From the published data summarised in Table 1, it was calculated that, at an average degree of feed restriction of 15·8 %, daily weight gain decreased by 12·50% (or 0·78% for each 1% restriction), feed conversion efficiency improved by 3·96% (or 0·31% for each 1% restriction) and backfat thickness diminished by 7·63% (or 0·53% for each 1% restriction).Equations were calculated to show the degree to which daily weight gain, feed conversion efficiency and backfat thickness change with increasing feed restriction (Figures 1, 2 and 3).As the degree of feed restriction increases, the decrease in daily weight gain becomes relatively greater and the decrease in backfat thickness relatively smaller. Efficiency of feed utilisation, however, improves at first, but eventually decreases as restriction becomes more severe.It is thought that the equations found can be used, within certain limits, to calculate the average effects of feed restriction for different breeds of pigs, which when fed ad libitum consume 2·7 kg. meal ration (of normal composition) per day and have a growth rate of about 750 g. daily from 30 to 90 kg., and backfat thickness of about 37 mm. when kept under average environmental conditions.