Effects of feeding whole crop rice [Oryza sativa] silage during the later fattening stage on growth, blood profiles and carcass traits of Japanese black steers

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-WCSIC) and one group fed rice-WCS and concentrate containing raw rice bran and ground hulled rice (n=3, R-WCS/Rice/C). Rice-WCS were 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 6.23 kg 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, 0.60 kg for steers fed R-WCS/C and 0.61 kg for steers fed R-WCS/Rice/C. Plasma retinol concentration in steers fed Straw/C declined from 72microg/dL in month 0 to 19microg/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 50-65mcirog/dL. The average slaughter weights of steers fed Straw/C, R-WCS/C and R-WCS/Rice/C were 608, 656 and 646 kg, 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 difference 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.