Effect of Different Dietary Energy Levels in Early and Middle Fattening Periods on Fattening Performance of Holstein Steers

抄録

Thirty-six Holstein steers (8 months of age) were allocated to three different dietary programs with low, medium, and high energy levels (LE, ME, and HE, respectively) in early (18 weeks) and middle (16 weeks) fattening periods. The TDN (% of DM) of LE, ME, and HE were 73, 75, and 77 in the early period, and 79, 81, and 84 in the middle period, respectively. All the steers were fed the same finishing diet with 85% TDN for 16 weeks. Lower DM intake and lower weight gain were observed in the HE in early period as compared with the LE. Although TDN intake was not different among the diets, the HE showed lower TDN efficiency than the LE in the early period, presumably caused by a restriction of metabolizable protein. There were tendencies towards lower final body weight in the HE and larger reduction in DM intake in the LE in the finishing period, whereas no statistical difference in carcass traits was seen among the diets except for the occurrence of high contents of C 16: 1, C 18: 2, and/or C 18: 3 in the HE. These results suggest that dietary TDN level of 75% or slightly less for the early period and a gradual change in dietary energy level would be commendable for successfully fattening Holstein steers.