The grade assigned to a pork carcass is influenced by the thickness of the backfat on the carcass. Although objective quantification of backfat thickness in pigs using an ultrasonic measuring device is recommended, the use of ultrasonic devices has been avoided as removing body hair and applying gel to the skin is labor intensive. We focused on the bioimpedance method, which measures body fat in dogs and monkeys without the need for removing body hair. The relationship between the impedance value ratio (100 kHz/50 kHz) of impedance values (frequency 50 kHz and 100 kHz) measured with a handheld impedance meter and backfat thickness values measured with an ultrasonic meter was examined in this study. We also studied how the carcass thickness ratings (thin, normal, thick) after shipment compared to the impedance value ratios at 20 weeks of age. The results showed a well-fitting regression equation with a coefficient of determination over 0.7 between the impedance value ratio and backfat thickness value with body hair at 20 weeks of age and on the day before shipment without body hair. Although the coefficient of determination was slightly lower without body hair at 20 weeks of age and with body hair on the day before shipment, the regression equation was still a good fit. A significant difference (p<0.05) between thin and thick fat ratings was observed either with or without body hair. These results suggest that it is possible to estimate the backfat thickness of 20-week-old fattening pigs without removing body hair by using the bioimpedance method, and that the ratio of impedance values at the same age can be used to estimate the carcass backfat thickness ratings after shipment.

The present study aimed to evaluate the relationship between plasma L-carnitine levels and sperm parameters in young boars. Blood and spermatozoa were collected from 53 healthy young Duroc boars between 189 and 394 days of age (mean age, ca. 300 days). Correlation analysis was made on plasma L-carnitine level versus sperm total motility and progressive motility. Among them, weak positive correlation was found in the relationship between the sperm progressive motility and plasma free L-carnitine concentration (r＝0.253, p＝0.068). It was suggested that examining plasma L-carnitine level might be a practical method for predicting the sperm quality. With a larger population of young boars, further investigations are needed to elucidate the causal relationship between those two parameters.