Evaluating machine and technician effects on ultrasonic measures of backfat and longissimus muscle depth in swine
Miles Todd See, MS, PhD
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Objective: To compare the accuracy of A-mode versus B-mode ultrasoundin measuring last-rib backfat, tenth-rib backfat, and tenth-rib longissimusmuscle depth.
Procedure: Twenty-seven market pigs were measured by three differenttechnicians using five different A-mode ultrasonic machines. Measures includedtenth-rib fat depth, tenth-rib longissimus muscle depth, and last-rib fatdepth measured at the C and K positions. B-mode measures were collectedby a National Swine Improvement Federation-certified technician as the standardfor comparison.
Results: For last-rib fat depth, the effects of machine and pigwere highly significant (P<=.001). However, the interaction betweenmachine x pig was also significant (P<=.01). Pig and machine xpig interactions may be explained by overestimating C and K for leaner pigsand underestimating C and K for fatter pigs. At the tenth rib only, theeffect of machine was significant (P<=.001). For longissimus muscledepth, machine was highly significant (P<=.001) and a tendency(P<=.1) for the effects of technician and technician x machineinteraction was observed.
Implications: The accuracy of the estimation of both fat and longissimusmuscle depth varies among ultrasound machines, which should be consideredwhen making the decision to purchase ultrasonic equipment.
Keywords: ultrasound, carcass
Cite as: See MT. Evaluating machine and technician effects on ultrasonic measures of backfat and longissimus muscle depth in swine. J Swine Health Prod 1998;6(2):61-66.
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