Comparison of supplementary concentrate levels with grass silage, separate or total mixed ration feeding, and duration of finishing in beef steers |
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| Authors: | MG Keane MJ Drennan AP Moloney |
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| Institution: | aTeagasc, Grange Beef Research Centre, Dunsany, Co. Meath, Ireland |
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| Abstract: | Winter finishing of beef cattle is expensive so feed costs per kg carcass gain must be minimised. The objectives of this study with finishing beef steers were (1) to determine the production responses to varying levels of supplementary concentrates with grass silage, (2) to compare the effects of feeding silage and concentrates separately or as a total mixed ration (TMR), and (3) to compare short (S) and long (L) finishing periods. A total of 117 finishing steers were blocked on weight and assigned to 13 groups of 9 animals each comprising a pre-experimental slaughter group and 12 finishing groups arranged in a 6 (feeding treatments) × 2 (durations of finishing) factorial experiment. The 6 feeding treatments were: (1) silage only offered ad libitum (SO), (2) SO plus a low level of concentrates offered separately (LS), (3) SO plus a low level of concentrates offered as a TMR (LM), (4) SO plus a high level of concentrates offered separately (HS), (5) SO plus a high level of concentrates offered as a TMR (HM), and (6) concentrates ad libitum plus restricted silage (AL). Target low and high concentrate levels were proportionately 0.375 and 0.750 of daily dry matter (DM) intake, respectively. S and L finishing periods were 105 and 175 days, respectively. Silage DM intake decreased (P < 0.001) and total DM intake increased (P < 0.001) with increasing concentrate level. Maximum DM intake occurred at the high concentrate level but maximum net energy intake occurred on ad libitum concentrates. Live weight gains for SO, LS, LM, HS, HM and AL were 212, 900, 929, 1111, 1089 and 1207 (S.E. 46.2) g/day, respectively. Corresponding carcass weight gains were 119, 506, 540, 662, 633 and 746 (S.E. 25.4) g/day. Kill-out proportion, carcass conformation score and all measures of fatness increased significantly with increasing concentrate level. Feeding a TMR increased silage intake at the low concentrate level but otherwise had no effect on overall animal performance or carcass traits. Extending the finishing period reduced (P < 0.001) daily live weight gain, but the associated reduction in carcass weight gain was not statistically significant. It is concluded that the response to supplementary concentrates decreased with increasing level, there was no animal production advantage to a TMR over separate feeding of the dietary constituents, and extending the duration of the finishing period reduced mean daily live weight gain and increased fatness. |
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| Keywords: | Beef cattle Concentrate supplementation Total mixed ration Winter finishing |
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