Abstract
Eleven Japanese Black steers were used to evaluate the effects of feeding whole crop rice silage (Rice-WCS) on growth, blood profiles and carcass quality. Nine of the 11 steers were the sons of Sire-J. These steers were fed hay and concentrate from 10 to 18.5 months of age and then each was assigned to one of the following three experimental groups : one group fed rice straw and concentrate (n=4, Straw/C), one group fed rice-WCS and concentrate (n=4, R-WCS/C) and one group fed rice-WCS and concentrate containing raw rice bran and ground hulled rice (n=3, R-WCS/Rice/C). Rice-WCS was harvested at the yellow maturing stage or late yellow maturing stage. The steers were slaughtered at 28 to 30 months of age after an experimental fattening period of 9 to 11 months. Daily intake of rice straw on a fresh basis was 0.70kg for steers fed Straw/C, and daily intakes of silage were 6.23kg for steers fed R-WCS/C and 6.96kg for steers fed R-WCS/Rice/C. Daily intakes of concentrate were 6.93kg for steers fed Straw/C, 6.15kg for steers fed R-WCS/C and 5.72kg for steers fed R-WCS/Rice/C. Daily body weight gains were 0.52kg for steers fed Straw/C, 0.60kg for steers fed R-WCS/C and 0.61kg for steers fed R-WCS/Rice/C. Plasma retinol concentration in steers fed Straw/C declined from 72μg/dL in month 0 to 19μg/dL in month 8, whereas the concentrations in steers fed R-WCS/C and in steers fed R-WCS/Rice/C remained at the normal level of 50-65μg/dL. The average slaughter weights of steers fed Straw/C, R-WCS/C and R-WCS/Rice/C were 608, 656 and 646kg, respectively. As for carcass traits of Sire-J's nine sons, except for one steer for which concentrate consumption was insufficient, all Beef Qualities of the carcasses (n=3) of steers fed Straw/C were ranked Grade 4 (Good) under the Japanese Beef Carcass Grading Standard, two were Grade 3 (Average) and two were Grade 5 (Excellent) for steers fed R-WCS/C, and two were Grade 4 for steers fed R-WCS/Rice/C. Fat color of one carcass of a steer fed Straw/C was judged as BFS No. 2 (Beef Fat Standard number) and fat color of eight carcasses of steers fed Straw/C, R-WCS/C and R-WCS/Rice/C were judged as BFS No. 3. There were significant differences between fatty acids compositions of kidney fat in steers fed R-WCS/C and those in steers fed R-WCS/Rice/C, but there was no significant differences in subcutaneous fat. There appeared to be no differences in growth and other carcass traits between steers fed R-WCS/C and steers fed R-WCS/Rice/C. The results indicate that it is possible to feed rice-WCS to steers at the later fattening stage without adversely affecting carcass grade and fat quality.
