PSVII-18 Standardization method for ultrasound device measurements of pig loin area: Compatibility study between A-mode and B-mode devices.

Abstract Accurate evaluation of pig loin area is essential for swine breeding programs. Currently, A-mode and B-mode ultrasound devices are widely used to measure backfat thickness, loin eye area, and intramuscular fat, but differences between device measurements have raised standardization concerns. This study aimed to scientifically verify compatibility between the two devices and develop a standardized measurement system. The study utilized 87 pigs (16 Duroc, 12 Landrace, and 59 Yorkshire) and compared actual measurements from hot carcass, cold carcass, and VCS2000 with ultrasound measurements from both types of devices. Measurement direction (parallel/perpendicular to the spine) and analysis programs (ImageJ/Python) were also evaluated. Results showed consistent differences of 1.04-1.25cm between B-mode measurements and actual values, with high explanatory power (R² > 0.93) across all measurement methods. Python analysis of perpendicular spine measurements demonstrated the highest coefficient of determination (R² = 0.97-0.99), establishing it as the most reliable measurement method. A relationship equation between A-mode and B-mode was derived: “B-mode backfat thickness (parallel to the spine) = 1.08 × A-mode posterior measurement.” Based on this, an integrated prediction equation was developed: “Hot carcass backfat thickness = (1.08/0.56) × A-mode posterior measurement.” This equation showed high explanatory power (R² = 0.9471), empirically proving compatibility between the two devices. The posterior measurement provided the most reliable prediction results among A-mode measurement positions, establishing a foundation for using A-mode as a standard measurement position. Backfat thickness and intramuscular fat showed no significant correlation, while loin depth accurately predicted loin eye area. Both devices showed high regression line concordance for breeds with genetically reduced backfat. At the same time, B-mode provided more stable measurements in animals with thicker backfat thickness, suggesting selective application based on breed characteristics. The standardization method developed through this research provides a scientific basis for potential implementation in swine breeding programs. Further validation with larger sample sizes across diverse environmental conditions and refinement of image analysis techniques are recommended before wide-scale adoption. The conversion system between devices and identification of optimal measurement conditions contribute valuable groundwork for improving the consistency of pig production trait measurements.