Comparative feeding values of whole-shelled or whole steam-rolled corn and whole-shelled or whole steam-rolled barley for dairy cattle

Four Holstein dry cows were used to clarify the feeding value, nitrogen and energy utilization of whole-shelled or whole stream-rolled corn and whole-shelled or whole steam-rolled barley. All cows were fed control diet and 4 treatment diets consecutively in the order of 1) Italian ryegrass only (IRG), 2) IRG + whole-shelled corn (WC), 3) IRG + whole steam-rolled corn (RC), 4) IRG +whole-shelled barley (WB), and 5) IRG + whole steam-rolled barley (RB) for 2 weeks per treatment. They were offered to meet approximately 100% of total digestible nutrients (TDN) requirements according to Japanese Feeding Standard for dairy cattle (1994). The ratio of IRG to grain of 4 diets was 6:4. The results were as follows: 1) The nutrient digestibilities of RC and RB diets were higher than those of WC and WB diets respectively except for crude fiber, acid detergent fiber and neutral detergent fiber. 2) The dry matter digestibilities of corn and barley estimated by the difference method were 69% and 49% in whole-shelled type compared with 83% and 83% in the other type, respectively. Similarly, the starch digestibilities of corn and barley wee 73% and 48% in whole-shelled type compared with 100% and 100% in the other type, respectively. 3) The nitrogen retention in RC and RB diets tended to increase with the decrease in fecal nitrogen loss. 4) The digestibility and metabolizability of energy in corn and barley were markedly increased by steam-rolled processing. The extent of increase was greater in barley than that of corn. 5) The TDN, digestible energy (DE) and metabolizable energy (ME) contents, and net energy content for maintenance (MEm) of corn were 71%, 13.3, 10.5 and 6.0 MJ/kgDM for whole-shelled type, and 85%, 15.3, 14.0 and 9.0 MJ/kgDM for steam-rolled type, respectively. Those values of barley were 47%, 8.6, 7.8 and 3.5 MJ/kgDM for whole-shelled type, and 83%, 15.2, 12.6 and 7.1 MJ/kgDM for steam-rolled type, respectively