Estimating backfat depth, loin depth, and intramuscular fat percentage from ultrasound images in swine

Fast, accurate, and reliable estimates of backfat depth, loin depth, and intramuscular fat percentage in swine breeding stock are used to increase genetic improvement and farm profitability. The objective of this study was to develop an equation-based model for the estimation of swine backfat depth, loin depth, and intramuscular fat percentage estimates obtained from longitudinal ultrasound images. Images were collected from purebred Duroc (n = 230), purebred Large White (n = 154), and commercial (n = 190) pigs born in January 2021 at three farms located in North Carolina. An Exapad ultrasound machine captured longitudinal images across the 10th to 13th ribs at 182 (±12.8 SD) days of pig age. The total number of images processed for Duroc, Large White, and commercial pigs was 1 385, 928, and 1 168 images, respectively. To establish a standard measurement for model comparison, trained personnel following standard company procedures using the BioSoft Toolbox (v4.0.1.2; Biotronics Inc., Ames, IA) obtained backfat and loin depth measurements from the images. Longissimus muscle intramuscular fat percentage was predicted using near-infrared spectroscopy at approximately 22 h postmortem. Backfat and loin depth estimation were conducted only for commercial pigs (n = 190) while intramuscular fat estimation was conducted on all pigs (n = 574). Average backfat depth, loin depth, and intramuscular fat percentage were 14.6 (±2.6 SD) mm, 63.7 (±5.5 SD) mm, and 2.21 (±0.82 SD) %. Image analysis and estimation model development were conducted in MATLAB R2021a. Edge detection via the image gradient was applied to segment ultrasound images into backfat, loin, and rib regions. Segmented images were used to estimate backfat depth, loin depth, and loin intramuscular fat percentage. After image quality control and filtering, the image inclusion rate for each breed-trait combination ranged from 76 to 97%. All Duroc and commercial pigs and 97% of Large White pigs were represented by at least one image for trait estimation. Coefficient of determination of models for the estimation of backfat depth, loin depth, and intramuscular fat percentage were 0.58, 0.57, and 0.56, respectively. Root mean square error of backfat depth, loin depth, and intramuscular fat estimation were 1.65 mm, 3.58 mm, and 0.54%, respectively. Results demonstrate the feasibility of using ultrasound image gradient and an equation-based approach to estimate swine backfat and loin depth, and intramuscular fat percentage. This equation-based approach to estimate carcass traits in live swine can enhance genetic improvement.

Impact of an abbreviated adenosine protocol incorporating adjunctive treadmill exercise on adverse effects and image quality in patients undergoing stress myocardial perfusion imaging

BACKGROUND

Limited data are available about the effects of adjunctive treadmill exercise on adverse effects and the image quality of adenosine perfusion imaging. This study compared the incidence of adverse effects and image quality between standard 6-minute adenosine perfusion imaging and a stress test incorporating a 4-minute adenosine infusion with low-level treadmill exercise.

METHODS AND RESULTS

Nineteen patients underwent both a 6-minute adenosine technetium-99m sestamibi single photon emission computed tomography (SPECT) imaging study and a 4-minute adenosine Tc-99m sestamibi SPECT study with 6 minutes of simultaneous low-level treadmill exercise. Symptoms were recorded at 1-minute intervals during the stress and recovery periods. Heart-to-liver and heart-to-lung count ratios were determined from anterior planar images. More adverse effects were experienced during the standard adenosine study than during the adenosine study with low-level exercise (2.7+/-1.4 vs. 1.4+/-1.1, P = .0003). The duration adverse effects were experienced was longer during the standard 6-minute adenosine protocol (6.6+/-2.1 minutes vs 3.2+/-2.8 minutes, P<.0001). Additionally, the symptom-severity scores were higher with the standard adenosine study (15.5+/-9.8 vs 4.5+/-5.1, P<.0001). The heart-to-liver ratios were noted to be higher in the 4-minute adenosine protocol with low-level exercise (1.0+/-0.3 vs. 0.6+/-0.2, P = .0003).

CONCLUSIONS

In comparison with standard 6-minute adenosine perfusion imaging, a protocol incorporating a 4-minute adenosine infusion with low-level treadmill exercise results in a marked reduction in the quantity and severity of adverse effects and an improvement in image quality.

A low-molecular weight chick brain-derived growth factor is mitogenic for cultured astroglia from the chick embryo

Immunohistochemically defined astrocytes from the 10-day chick embryo were stimulated to incorporate increased levels of [3H]thymidine when a low-molecular weight peptide growth factor, chick brain-derived growth factor (CBGF), was added to the cultures. Treatment of these GFAP-positive astrocytes with 10 ng/ml CBGF in medium supplemented with 1% fetal bovine serum resulted in a 3.5-4-fold increase in [3H]thymidine incorporation when compared to astrocytes cultured in defined medium supplemented with 1% serum alone. CBGF had no effect on the survival, proliferation or differentiation of a number of other cell types from the 10-day chick embryo brain, including neurons and meningeal fibroblasts. CBGF was also ineffective as a mitogen for chick embryo skeletal muscle myoblasts, primary mouse embryo fibroblasts and one murine teratocarcinoma-derived cell line (STO). We suggest that CBGF might act as a mitogenic signal for astroglia during central nervous system development and repair.