The Use of Arsanilic Acid in the Production of Market Pigs

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Abstract
In one experiment 40 pigs were fed in 4 lots to study the value of 3 different levels of arsanilic acid when added to a mixed ration. From the start of the experiment to an average weight per pig of 125 lb. the pigs fed arsanilic acid gained at an average rate approximately 5 percent greater than the controls. This difference was not significant (P>.05). There was no difference in feed efficiency due to the feeding of the arsonic acid. Growth and feed efficiency data beyond 125 lb. were confused by a problem not associated with the treatments. In a second experiment 40 pigs were fed in 4 lots. Three of these were fed different predetermined levels of protein in mixed rations which contained 60 gm. arsanilic acid per ton of feed. The fourth lot was allowed to select its own protein level; they were fed ground corn and a mixed supplement free-choice. The supplement was composed of the same ingredients as were used to balance the corn in the mixed rations fed to the other 3 lots. For the free-choice fed pigs 240 gm. of arsanilic acid was added per ton of supplement. The differences between the lots in rate of gain and feed efficiency could not be related to the protein level of the rations fed, and differences in the liveweight gains were not significant at the 5 percent level. There were no significant differences in carcass quality which could be attributed to the feeding of arsanilic acid (Experiment 1) or to the protein level of the ration (Experiment 2). The pigs fed arsanilic acid retained small amounts of arsenic in the tissues and the amount retained was related to the level fed. Arsenic in the liver was approximately 1.5 to 2.0 times as great as the storage in the kidneys. The amount retained in the muscle, fat or skin was low at all levels of arsanilic acid fed. Removal of arsanilic acid from the ration prior to slaughter resulted in rapid excretion of arsenic from the liver and kidney. The rate of excretion from the muscle was less rapid. There was no evidence of toxicity in any of the pigs, in either experiment, due to the feeding of arsanilic acid.