The Influence of Arsanilic Acid on Protein Requirements of Growing Pigs

Abstract

Six lots of 5 pigs each were fed in each of 2 trials to compare 3 mixed rations containing different levels of protein fed with and without arsanilic acid fortification. Two additonal lots of 5 pigs each, in each trial, were allowed to balance their own rations. One lot of each “protein-level“ pair was fed arsanilic acid in the supplement. The free-choice-fed pigs and those fed the mixed rations with 18 percent protein gained slightly faster during the period immediately following weaning. However, the pigs fed the lower-protein levels caught up later and reached market weight at essentially the same time as those fed the higher-protein mixed rations or those fed by the free-choice method. The addition of 60 gm. of arsanilic acid per ton of mixed feed or of 240 gm. per ton of supplement (fed free-choice with ground yellow corn) produced small increases in rate of gain, at all levels of protein fed, from weaning to approximately 125 lb. live weight. These differences were not significant at the 5 percent level. The feeding of arsanilic acid produced a consistent increase of approximately 4 percent in feed efficiency. Arsanilic acid did not appear to have a “protein-sparing” effect under the conditions of this experiment. There was no evidence of toxicity in any of the pigs fed arsanilic acid. From the practical standpoint, the 14–11 percent protein mixed rations were as satisfactory as the mixed rations which were higher in protein.