Performance, carcass characteristics, and ultrasonic estimates of muscle development and fat deposition of boars, barrows, and gilts

In recent years a marked improvement has been made in the type of hogs going to market. Much of this success can be attributed to the use of swine improvement programs. Testing stations are used (1) to test progeny; (2) as a guide in selecting full or half-sibs of animals being tested; and (3) as an indicator of the tested pig's merit as a potential breeding animal where slaughter is not a requirement of the testing procedure. Ultrasonic evaluation techniques have been introduced in recent years and serve as a tool to measure depth of backfat and loin eye area. This process eliminates the sacrificing of potential breeding animals to determine the loin eye area. Accumulation of more fundamental knowledge of growth and development in swine is needed before effective control of the pig as a meat-producing animal can be achieved by the breeder and feeder. It is fitting that swine producers encourage development of new and improved methods of live animal evaluation which will result in a superior market product. It should be recognized, however, that market hogs of different sex should not be directly compared in performance and carcass traits. For example, boars generally make more efficient gains and have less backfat than do littermate barrows or gilts. Although there is sound evidence that sex differences exist in many traits, few adjustments are currently being made among the sexes. Research work has demonstrated that boars can be fed to market weight more economically than barrows or gilts. The possibility of marketing boars for slaughter at 190-220 lb. could well be one of the major steps forward for the swine industry in the foreseeable future. The objectives of this experiment were to expand existing knowledge on growth and development of the pig, to determine the effect of sex on performance and carcass characteristics, and to measure the reliability of the somascope for improving accuracy in selection for superior performance and carcass traits in swine.