Producing Leaner Market Hogs by Different Feed Combinations and Controlled Corn Intake

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Abstract
Leaner market hog carcasses were produced when the energy level of the rations was appreciably reduced. This was accomplished by eliminating grain from the ration at 50 and 125 lb.; limiting the corn intake by hand feeding various percentages of a full feed; and mixing high levels of minerals with ground corn. The elimination of grain from the ration resulted in an extremely long feeding period and inferior carcasses due to a lack of finish. Oats fed throughout the feeding period or during the last 100 lb. of gain did not significantly reduce the fat content of the carcasses when protein supplement was fed free choice. Indications were that a level of 50 to 70% of a full feed of corn was desirable to increase the proportion of lean to fat in carcasses without seriously reducing rate of gain and lengthening the feeding period. Apparently the actual energy available to the pig was lowered by the inclusion of high levels of a mineral mixture with ground shelled corn. The high intake of calcium or the imbalance of the calcium:phosphorus ratio may have reduced the digestibility of corn in the ration thus resulting in the lowering of available energy. A significant increase in the lean content of carcasses was not reached until 12% minerals was included in the ration. As the available energy was reduced by all three methods, average daily gain was decreased and the feeding period increased. Feed efficiency was decreased in all cases except by limited feeding of corn on pasture where it was increased. A study of correlation data obtained from 198 carcasses in this series of trials was made. It was indicated that the yield of the four lean cuts as a percentage of the chilled carcass weight was a more accurate estimate of the leanness of carcasses than the average backfat thickness. The true fat percentage of the carcasses was determined by chemical analysis of a sample of the meat of the entire right half of each carcass studied. Copyright © . .