Compensatory responses of swine following protein insufficiency in grower diets.

Four trials involving 426 crossbred pigs were conducted to determine the effect of protein restriction during early growth on subsequent performance and carcass characteristics at 100 kg. The experimental animals averaged 25 to 27 kg initial weight in trials 1, 2 and 3, and 18.2, 22.7 and 27.3 kg in three weight groups in trial 4. Pigs were fed corn-soybean meal supplemented diets of 12, 14 or 16% protein. Protein restriction (12 or 14% protein diets), to 52 kg in trial 1 and during the initial 4-wk period in trials 2, 3 and 4, reduced rate and efficiency of growth; performance was reduced more on 12% protein diets. In the subsequent growth period, early protein restriction improved gain and feed to gain ratio. Performance for the total period was similar for pigs fed a 14% protein diet continuously to that of pigs fed a 16 to 14% protein sequence when pigs had an initial weight of 25 kg or more. However, lighter weight pigs did not completely compensate for decreased performance during the early 4-wk period. Carcass characteristics were similar for all protein sequences.