Forty-eight individually-fed Large White pigs, initially 10 weeks of age, were used to test the effects of growth checks induced by severe restriction of feed intake. The checks were imposed at 50 lb. or 100 lb. live-weight and lasted for 5 weeks, during which live-weight gains averaged only 1·6 lb. and 4·1 lb. per pig, respectively. The daily feed allowances of the unchecked controls and of other pigs while not on check were according to a fixed scale based on live-weight. All pigs were slaughtered as their individual weights reached 200 lb. and a number of measurements were made on the carcasses.

Excluding the period of the check, efficiency of feed conversion and rate of gain were better for pigs checked at 50 lb. than for the controls. The difference in age at a given weight caused by the check was narrowed by about 6 days at the end of the experiment. Indications of a similar compensation in growth of pigs checked at 100 lb. were mostly explained by the rapid growth of these pigs before 100 lb. and by the sudden increase i n their weight at the end of the check period which was probably due to increased gut fill.

A check at 50 lb. or 100 lb. did not affect either the specific gravity of the carcass, which was taken as an indication of the overall proportion of lean to fat, the area of ‘eye’ muscle, the depth of backfat over the shoulder, the thickness of streak or the Danish ‘slight of lean’ measurement, but the check at 50 lb. increased the thickness of fat at position (1) over the ‘eye’ muscle. Both checks increased the minimum thickness of back fat in females but not in castrates and reduced the average rump fat in castrates but not in females. It was concluded that the checks did not affect carcass composition although they probably caused changes in the distribution of the backfat.