A Beef Production System and Meat Quality Using Grazing and Self-Sufficient Feed

Abstract

We investigated the possibility of a beef production system using year-round outdoor grazing and self-sufficient feed supplies such as corn silage for Japanese Brown (Kumamoto) (JB-K) (n = 3, 6-7 mo, 253±7 kg) and Japanese Black (JB) (n = 6, 6-7 mo, 230±17 kg) steers in southern Japan. JB-K and JB steers were grazed year-round outdoors on pasture, predominantly Italian ryegrass in the winter season and bahiagrass in summer. Cattle grazed until they reached a slaughter body weight of 751±15 kg (JB-K) and 613±15 kg (JB steers). Animals were fed corn silage in addition to their grazing of pasture from 24 months of age. JB-K steers achieved high (0.8-1.4 kg/day) daily weight gain during the grazing period compared with JB steers (0.4-0.9 kg/day). Plasma composition was affected by the chemical composition of the feed; in particular, the low crude protein of bahiagrass and corn silage. After slaughter, the carcass grade for JB-K and JB steers were A-2 and B-2, respectively. Both the shear-force value and collagen content of the longissimus thoracis muscle of JB-K steers were higher than those of JB steers. Both JB-K and JB steers showed high protein and low lipid contents in addition to high vitamin contents compared with those conventional beef. These results may have been affected by the vitamin composition of grass and the development of connective tissue in skeletal muscle as a result of grazing.