|Ono Yoshitaka, - KYUSHU UNIVERSITY, JAPAN|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 1995
Publication Date: N/A
Interpretive Summary: Increasing dietary health concerns of consumers have forced meat producers and packers to establish more efficient systems to produce leaner meat. In pork production, dietary supplementation with chromium (Cr) and exogenous administration of porcine somatotropin (pST) has received considerable attention because of its potential to increase lean accretion and decrease fat deposition. Therefore, this study was designed to determine cellular effects of Cr and pST on four hind limb muscles in barrows growing from 20 to 90 kg body weight. Dietary supplementation with Cr had no effect on either muscle fiber type distribution (percent) or fiber area (size). Exogenous administration of pST had no effect on fiber type distribution, but increased fiber area in the hind limb muscles. The simultaneous administration of Cr and pST also had no effect on fiber type distribution, but increased fiber area in all four muscles. This increase appeared to be a result of the pST. Thus, administration of pST seems to be the most effective way to produce more lean among the three types of treatments compared in this study and would benefit pork producers, packers and consumers. These results suggest that combining Cr and pST offered no additional benefits for hind limb muscles.
Technical Abstract: This research was conducted to evaluate the effects of dietary supplemental chromium tripicolinate (Cr = 300 ppb) and porcine somatotropin (pST) injection on the histochemistry of hind limb muscles (biceps femoris, semimembranosus, rectus femoris, gastrocnemius) from growing pigs (20 to 90 kg body weight). The administration of Cr had no effect on both the percentage of muscle fiber type distribution or fiber area. The administration of PST and the simultaneous administration of Cr and pST also had no effect on percentage fiber type distribution, but caused an increase of the fiber area of type W fibers from 17 to 27 percent and 21 to 28 percent, respectively, indicating no difference between the two treatments. In the course of growth (from 20 to 60 kg), the percentage distribution of I fibers decreased in biceps femoris and semimembranosus muscles, and W fibers increased in biceps femoris, semimembranosus and gastrocnemius muscles. R fibers did not change in percentage throughout the experimental period. Fiber area increased in all fiber types of all muscles with increasing body weight. The administration of pST resulted in an increase in the presence of giant fibers and the occurrence of giant fibers was associated with the type of muscle investigated.