Accretion of Fat and Muscle in Growing Swine as Assessed by Ultrasonic Methods

Abstract

Body composition was measured sequentially with ultrasonic methods in growing swine at about 20, 55 and 90 kg body weight. Carcass chemical composition was determined at a body weight of about 96 kg. Growth of subcutaneous adipose tissue was mostly curvilinear over the weights studied, although it was linear at the midbody region. There were major differences in growth at contiguous adipose tissue sites. The amount of adipose tissue assessed by fat depth measurements or muscle assessed by longissimus area at 20 kg body weight (about feeder pig weight) was not highly correlated with similar measurements on the same animals at about 87 kg body weight or with carcass measurements at about 96 kg body weight. Prediction of market weight pig composition from measurements made on feeder pigs does not appear to be a viable option. Carcass chemical composition was predicted to a modest extent by live animal or carcass measurements in these animals with a relatively constant slaughter weight. Ultrasonic measurement in the live animal was as valuable as carcass measurements for these purposes. Furthermore, it was nondestructive and allowed the sequential or longitudinal assessment of the same animal.