Abstract
The influence of close-up feed strategies on growth performance and dietary NE in light-weight feedlot steers during a 56 d receiving period was evaluated. Dietary treatments were formulated to meet the average metabolizable amino acid requirements of calves during 1) the initial 7 d; 2) the initial 14 d; and 3) the initial 21 d following arrival into the feedlot, assuming average interval DMI of 2.8, 3.0, and 3.6 kg/d, respectively. Thereafter, all steers received dietary treatment 3. Fish meal was the source of supplemental protein. One hundred eight medium-framed crossbred steers (168.4 ± 5.0 kg) were blocked by weight and assigned to 18 pen groups (6 steers per pen). P-value (≤0.10) was considered as statistically significant. Daily weight gain (linear effect, P = 0.09) and gain efficiency (linear effect, P = 0.08) decreased as the close-up interval increased. DMI was not influenced by feeding program (P = 0.46). The ratio of observed to expected dietary NEm (linear effect P = 0.06) and NEg (linear effect, P = 0.05) decreased as length of close-up interval increased. Morbidity was low (18%) and not affected (P > 0.40) by dietary treatments. It is concluded that the addition of a close-up diet formulated to meet the metabolizable amino acid requirements of shipping stressed calves during the initial 7 d in the feedlot, when feed intakes are comparatively low, will have long-term beneficial effect on cattle growth performance and dietary NE.
Highlights
Receiving diets are typically formulated to meet the average protein requirements of calves during the course of the receiving period; feed intake during the first few weeks, when cattle are adapting to the feedlot environment, is characteristically low [1] [2]
The objective of the present study is to examine the influence of close-up feed strategies, matching metabolizable protein supply to expected DMI during the initial 7, 14, or 21 d of the receiving period, on 56 d growth performance and dietary NE in light-weight feedlot steers
Dietary treatments (Table 1) were formulatedto meet the average metabolizable amino acid requirements of calves [9] during: 1) the initial 7 d; 2) the initial 14 d; and 3) the initial 21 d following their arrival into the feedlot, assuming average interval DMI of 2.8, 3.0, and 3.6 kg/d, which correspond to 1.66%, 1.78% and 2.14% of BW, respectively
Summary
Receiving diets are typically formulated to meet the average protein requirements of calves during the course of the receiving period; feed intake during the first few weeks, when cattle are adapting to the feedlot environment, is characteristically low [1] [2]. During this period protein nutrition may be grossly inadequate [3]-[5]. The objective of the present study is to examine the influence of close-up feed strategies, matching metabolizable protein supply to expected DMI during the initial 7, 14, or 21 d of the receiving period, on 56 d growth performance and dietary NE in light-weight feedlot steers
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