1191
Relationship among efficiency measures, economic value and feedlot performance assessed in growing phase of Nellore cattle
Data from six-years of studies (2007-2012) were compiled using 357 Nellore bulls (212 + 38 kg BW; 279 + 29 days of age) to evaluate the relationship among efficiency measures, current economic value and feedlot performance. Dry matter intake (DMI) was recorded for two different ways: using a GrowSafe automated feeding system (GrowSafe Systems Ltd., Airdrie, Alberta, Canada) or individual pens. Efficiency measures evaluated were: residual feed intake (RFI), residual intake and BW gain (RIG) and residual BW gain (RG). Residual feed intake was calculated as the residuals from the regression of total DMI on BW0.75 and ADG. Residual gain was calculated as the residuals from the regression of total ADG on BW0.75 and DMI. Residual intake and BW gain was determined from linear combination into RFI and RG. Animals were classified for each efficiency measure as Low (<0.5 SD mean), Medium (within ± 0.5 SD), and High (>0.5 SD mean) groups. Economic value included was profit ($/steer.d-1), calculated from the economic data from 2006 to 2012. Feedlot performance variables were ADG (kg/d), DMI (kg/d), and final BW (kg). Profit for all groups differed (P < 0.05), with the exception between HighRIG and HighRG groups (P = 0.98) which had the highest profitability (Table 1). When the groups were analyzed separately, within each of efficiency measures, the profit increased (P < 0.0001). Final BW was similar among all groups of efficiency measures (P = 0.78). Body weight gain was not different between groups HighRFI and LowRFI (P = 0.64), Residual feed intake groups had lower gain only compare to HighRG group (P = 0.01). The HighRIG and HighRG increased approximately 8 % and 23 % (P < 0.0001 ) compared to LowRIG and LowRG, respectively. Among all the groups LowRFI and HighRIG had lower DMI (P < 0.01) and reduced by approximately 14 % compared to HighRFI and LowRIG, respectively. Therefore, residual intake and body weight gain is a recommended measure to increase profitability and reduce dry matter intake of Nellore cattle.
Table 1
|
RFI |
|
RIG |
|
RG |
|
|||
Variable |
Low |
High |
|
Low |
High |
|
Low |
High |
SEM |
Profit, $/steer.d-1 |
0.72b |
0.56c |
|
0.48d |
0.77a |
|
0.38e |
0.77a |
0.03 |
ADG, kg/d |
1.04bc |
1.05b |
|
1.00c |
1.08ab |
|
0.89d |
1.10a |
0.02 |
DMI, kg/d |
6.40 c |
7.46a |
|
7.49a |
6.46c |
|
7.00b |
6.75 b |
0.12 |
Final BW, kg |
330.39a |
333.88a |
|
335.63a |
329.91a |
|
334.66a |
328.39a |
59,39 |
ab P<0.05
Keywords: efficiency measures, Nellore cattle, profit