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Performance of Nellore beef cattle fed with whole corn diet
Higher amounts of whole grain in the diet increase the risk of ruminal acidosis due abrupt changes that happen in the rumen. Metabolic disorders that happen during adaptation to new high grain diets often times causes decreased feedlot performance. The objective was to evaluate effects of virginiamycin (VM) and monensin sodium (MON) in whole corn diet, with or without the use of roughage during adaptation on performance of feedlot cattle. The animals were kept in the feedlot in group pens (5 pens/treatment) for 106-d with a 21-d adaptation period. One hundred Nellore bulls were used in a randomized complete block design with a 2x2 factorial arrangement, being two kinds of additives (VM and MON) and two adaptation strategies, 4 treatments and 5 replicates. Treatments were defined by VM (25 mg/kg of DM) and MON (30 mg/kg of DM), with or without sugarcane bagasse (SB) during adaptation period as follows: VM 10% SB; VM 0% SB; MON 10% SB e MON 0% SB. After the adaptation period, animals were fed ad libitumonce daily with a diet containing 85% whole corn, 15% pelleted feed (soybean, minerals and the additive). Dry matter intake (DMI) was higher (p<0.05) for the VM compared to MON, however, the roughage in diet did not affect the DMI (Table 1). The relationship between DMI and BW was higher (p<0.05) to VM treatments. Differences were not observed between treatments for final BW (FBW) and average daily gain (ADG). There was no interaction between the additives and roughage source for any variables studied. In contrast, animals fed with SB at adaptation period tended (p<0.10) to have higher FBW, ADG and feed efficiency (FE) than treatments without bagasse, independent of the additive used. VM and MON had a similar effect on gain, however, MON decrease DMI compared to VM. The use of roughage source may increase the performance due to a greater adaptation of the Nellore bulls to whole corn diet.
Table 1 – Performance of Nellore bull feedlot fed with whole corn diet
Variables |
MON |
VM |
SEM |
P-value |
||||
10%SB |
0% SB |
10%SB |
0% SB |
Additive |
Roughage |
AxR |
||
DMI (kg/d) |
6.445 |
6.608 |
7.435 |
6.827 |
0.240 |
0.027 |
0.373 |
0.134 |
IBW (kg) |
368 |
369 |
368 |
368 |
2.959 |
0.827 |
0.963 |
0.963 |
FBW (kg) |
521 |
514 |
534 |
510 |
8.097 |
0.615 |
0.083 |
0.334 |
ADG (kg/d) |
1.455 |
1.384 |
1.577 |
1.354 |
0.075 |
0.551 |
0.074 |
0.331 |
DMI/BW (%) |
1.447 |
1.497 |
1.646 |
1.553 |
0.046 |
0.017 |
0.655 |
0.150 |
FE |
0.228 |
0.209 |
0.213 |
0.209 |
0.009 |
0.186 |
0.100 |
0.830 |
Keywords: acidosis, adaptation period, feedlot