The influence of grade and body type on the performance of purchased feeder pigs

Two trials involving 480 pigs were conducted to determine the influence of grade and body type on the performance of purchased feeder pigs.

Ninety U.S. No. 1, 90 U.S. No. 2 and 60 U.S. No. 3 pigs were purchased in each trial. The No. 1 and No. 2 grades were divided into three body types: type 3–longer, taller pigs; type 2–average for the grade; and type 1–shorter, compact pigs. The U.S. No. 3 grade pigs were divided only into the type 2 and type 1 categories.

The addition of 10% oats to the basal diet increased (P<.05) average daily gain of pigs after 7 days while additions of 10% alfalfa meal resulted in more feed (P<.05) consumed per pound of gain after 21 days on experiment.

The addition of .3% potassium to the basal diet reduced (P<.05) average daily gain after 7 and 21 days and increased feed required per pound of gain (P<.05) when compared to feed per gain for pigs receiving 250 ppm copper during the first 21 days. The addition of 250 ppm copper to the diet improved performance during the first 21 days. Measurements from a life size projection of each pig and carcass measurements were obtained. Pig height from the floor perpendicular through the flank to the top of the animal accounted for 23% of the variability in grade.

Initially and at slaughter, grade 3 type 1 pigs and grade 2 type 1 pigs had higher (P<.05) backfat measurements than any other grade-body type combinations.

Grade 2 type 3 and grade 1 type 3 pigs were longer (P<.05) at slaughter than all other grade-body type combinations. All grade 1 pigs had higher (P<.05) muscling scores than grades 2 and 3 type 1 pigs.

Type 1 pigs were (P<.05) fatter than all other pigs. The simple correlation between final ultrasonic fat and actual carcass backfat for both trials was .74 suggesting that backfat accounted for 55% of the variability among the grades.

Ultrasonic measurement of fat only over the last lumbar vertebra accounted for 61% of the variability among grades in carcass backfat postslaughter.