Effects of varying proportions of crushed rice with hull in total mixed ration silage on feed intake, nutrient digestibility, feed particle passage rates, and nitrogen balance in Japanese Black cattle

The objective of this study was to evaluate the effects of varying proportions of crushed rice with hull (CR) in total mixed ration (TMR) silage on whole tract digestibility, feed particle passage rates, and nitrogen utilization in beef cattle. Four Japanese Black cows were fed TMR silage containing 0, 7, 14, or 21% CR. Dietary treatments did not affect dry matter intake, passage rate parameters of feed particles, or dry matter digestion. However, increased rice proportions in TMR silage linearly decreased the digestibility of crude protein and neutral detergent fiber. The ratio of urinary nitrogen (N) excretion to N intake decreased with increased rice proportions in TMR silage, and the ratio of N retention to N intake was the highest when cows were fed TMR containing 14% CR. These results suggest that the CR content in TMR silage does not affect feed intake at levels up to 21%. However, 14% was the most suitable CR content to optimize fiber digestibility and N utilization efficiency in cows.