1762
Use of virginiamycin and monensin sodium in diets of confined beef steers
Feed additives are used as tool of nutrition management to enable the supply of high concentrate diets. The association of antibiotics may improve the response of ruminal fermentation manipulation and increase performance. The objective of this study was to evaluate the isolated and combined effects of the virginiamycin (VM) and monensin sodium (MON) in diets of crossbreed steers in feedlot. The animals were kept in feedlot in group pens for 105-d with a 28-d adaptation period . Three hundred and thirty nine ½Nellore x ½ Guzera beef steers (402.7 ± 1.3 kg of initial BW) were used in a randomized complete block design with 5 treatments and 7 replicates. The blocks were defined by initial BW. Treatments were defined by levels of VM and MON (mg/ kg of dry matter) as follows: 30MON; 15VM+30MON; 25VM+30MON; 34VM+ 30MON e 34VM. Animals were fed <i>ad libitum</i> twice daily with isonitrogenous and isoenergetic diets, with a 88:12 concentrate:forage (sugarcane bagasse) ratio. Steers were weighed at the beginning, after the adaptation period and at the end of the trial. Data are shown in Table 1. Dry matter intake (DMI), final BW and average daily gain (ADG) were not affected (P>0.05) by treatments. However, effects (P<0.05) were observed on DMI for percentage of body weight (BW) between 34VM and 25VM + 30 MON, with lower DMI/BW (%) for the intermediate association. The treatment 30 MON showed higher feed efficiency (FE) than 34VM. In conclusion, the MON showed higher FE in relation to VM, however, no effects were observed on treatments with different association levels of feed additives. Supported by Phibro/Minerva/FAPEG.
Table 1- Performance of beef steers fed with different levels of feed additives.
|
Treatments |
|
||||
Variables |
30MON |
15VM+30MON |
25VM+30MON |
34VM+30MON |
34VM |
SEM |
Initial BW (kg) |
402.7 |
401.2 |
402.7 |
402.4 |
404.6 |
1.3 |
Final BW (kg) |
569.2 |
560.2 |
563.0 |
565.3 |
564.1 |
3.3 |
DMI (kg/day) |
10.6 |
10.4 |
10.4 |
10.6 |
10.7 |
0.1 |
DMI/BW (%) |
2.19ab |
2.17ab |
2.15b |
2.20ab |
2.22a |
0.02 |
ADG (kg/day) |
1.602 |
1.527 |
1.541 |
1.564 |
1.531 |
0.031 |
FE |
0.150a |
0.146ab |
0.148ab |
0.147ab |
0.143b |
0.002 |
Different superscripts indicate differences among treatments by t test at 5% of probability
Keywords: feed additives, feedlot, performance