Peer review

Two nitrogen balance trials and a growing-finishing experiment were conducted to compare opaque-2 and normal corn for the pig. Opaque-2 corn supported significantly (P<.01) greater nitrogen retention both on an absolute and a percentage basis than did normal corn when pigs were fed isonitrogenous diets of 11.2 or 8.2% protein. When an equivalent amount of corn protein was supplied by each diet, pigs fed opaque-2 corn absorbed significantly (P<.01) more nitrogen and retained a significantly (P<.01) greater percentage of that which was absorbed, indicating that the protein of opaque-2 corn is more digestible and has a higher biological value than normal corn protein. Apparent digestibility of dry matter in a diet containing 97% opaque-2 corn was significantly (P<.01) less than obtained with a similar diet based on normal corn. Similar gains and feed conversions resulted from feeding opaque-2 or normal corn in a corn-soybean meal diet at protein levels of 16% to 45 kg. and 13% thereafter to 92 kilograms. Reducing the protein level to 14 and 11.3% during the two periods did not significantly (P<.05) influence gains or feed/ gain ratios of pigs fed opaque-2 corn but resulted in significantly (P<.01) inferior gains and feed/gains when pigs were fed normal corn. Free-choice feeding of shelled opaque-2 or normal corn and a fortified soybean meal supplement resulted in slightly poorer gains and feed conversions as compared with those fed a complete mixed diet of 16 to 13% dietary protein. Pigs fed opaque-2 shelled corn consumed significantly (P<.05) less soybean meal supplement than those fed normal shelled corn.

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