Performance of feeder pigs of various grades

Production of feeder pigs has become a major swine enterprise in Tennessee. An increasing number of these pigs are being marketed through organized feeder pig sales where they are sorted according to weight and grade. The grade of a feeder pig is determined by evaluating its logical slaughter potential and its thriftiness. The logical slaughter potential of a thrifty feeder pig is its expected slaughter grade at a market weight of about 220 pounds after a normal feeding period. Therefore, the objective of this experiment was to measure the performance, feed efficiency and carcass characteristics of pigs of various feeder grades. Twenty pigs, weighing 40 to 50 pounds, were randomly selected from each of three graded pens; mixed U.S. No. 1 and U.S. No. 2, U.S. No. 3 and U.S. No. 4; at the Lawrence County Feeder Pig Sale, Lawrenceburg, Tennessee. They were wormed, sprayed for external parasites and fed a 16% protein wheat-supplement ration for 105 days. Average daily gain, during the 105-day finishing period, of pigs graded U.S. No. 1-2, U.S. No. 3, and U.S. No. 4 at weaning (40 to 50 pounds) was 1.67, 1.68 and 1.74 pounds per head per day, respectively. The pigs which were graded U.S. No. 4 as feeders were fatter, slightly shorter, less muscular and graded lower at slaughter than the pigs graded higher, U.S. No. 1 through 3. Average back probe for the three feeder grade groups, U.S. No. 1-2, U.S. No. 3, and U.S. No. 4 was 1.30, 1.33 and 1.53 inches, respectively. The leaner, U.S. No. 1 through No. 3 pigs were more efficient feed converters than the fatter U.S. No. 4 pigs. Pigs graded U.S. No. 4 as feeders tended to grade higher at slaughter. Ten percent of the pigs in this feeder grade were graded U.S. No. 1 at slaughter, 35% were graded U.S. No. 2, 50% graded U.S. No. 3 and only 5% were graded U.S. No. 4. These results indicate that many Tennessee feeder pigs are being place in feeder grades below their potential slaughter grade and genetic potential at feeder pig sales due to poor pre-sale management and nutrition. The response of the No. 4 pigs, especially during the 12-day adjustment period, shows the Tennessee producers have an opportunity, through improved management and nutritional practices, to have a greater percentage of their pigs graded higher as feeders.