Effect of feeding rice whole crop silage on growth rate, levels of vitamin A, β-carotene, vitamin E and IGF-1 in plasma and skeletal muscle protein degradation in Japanese black calves.

Abstract

This study evaluated the effects of rice whole crop silage (RWCS) on growth, plasma levels of vitamin A, β-carotene, vitamin E and IGF-1, and expression of genes involved in muscle protein degradation and synthesis in Japanese Black calves. Eleven calves were divided into RWCS (fed RWCS ad libitum and concentrate, n=5) and control groups (fed hay ad libitum and concentrate, n=6). Final body weight and dairy gain were significantly larger in the RWCS group compared with the control group. Plasma β-carotene and vitamin E concentrations were significantly higher in the RWCS group compared with control group. Although plasma vitamin E concentration in the RWCS group significantly increased from 4 to 9months of age, it did not increase in the control group. At 6months of age in the RWCS group, ubiquitin B (p<0.05) and calpain 1 (p=0.097) mRNA expression were lower than control group, but they were not different between groups at 9months of age. These results indicate that RWCS increases plasma β-carotene level and promotes muscle growth because of a decrease in the rate of protein degradation, but the effect is lost with the increase in plasma vitamin E level.