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Determining the impact of By-O-Reg+ in diets with or without feed grade antibiotic on growth performance of nursery pigs
A total of 717 nursery pigs (PIC C-29×28 and PIC L3×1040, initially 5.67±.05 kg BW) from two consecutive nursery groups were used in a 35-d growth study. The objective was to determine the impact of feeding increasing levels of By-O-Reg+ in diets with or without antibiotic on nursery pig growth performance. By-O-Reg+ is registered trademark of Advanced Ag Products, Hudson, South Dakota and is a unique mixture of essential oils primarily based on oregano. Dietary treatments were offered immediately after weaning at approximately 21 d of age and were organized in a 2×3 factorial with main effects of antibiotic (none vs. 55 mg/kg of Carbadox) and By-O-Reg+ (0, 0.05, or 0.10%). Experimental diets were fed for 21 d and then fed a common diet for the final 14 d. Pens of pigs (5 barrows and 5 gilts) were balanced by initial BW and randomly allotted to treatments with 12 pens/treatment. During the period when treatments were fed (d 0 to 21), there were no interactions observed between By-O-Reg+ and Carbadox but increasing By-O-Reg+ improved (quadratic, P=0.016) G:F. Pigs fed diets with Carbadox had improved (P<0.007) ADG, ADFI, and G:F. From d 0 to 35, there was an interaction (linear, P=0.031) observed for ADFI with pigs fed diets without Carbadox having decreased ADFI as By-O-Reg+ level increased, whereas when pigs were fed diets containing Carbadox, ADFI increased with increasing By-O-Reg+. There were no main effects of By-O-Reg+ observed for the overall data; however, adding Carbadox for 21 d after weaning improved (P<0.015) ADG, ADFI, and final BW and tended to improve (P<0.087) G:F d 0 to 35. Overall, this study confirms the benefit of including a feed grade medication in nursery pig diets to improve growth performance. Increasing By-O-Reg+ in diets elicited few changes in performance, but during the test period the pigs fed 0.05% By-O-Reg+ had better G:F than those fed none or 0.10% By-O-Reg+.
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Probability, P< |
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Antibiotic |
- |
- |
- |
+ |
+ |
+ |
By-O-Reg+ |
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Interaction |
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Added By-O-Reg+, % |
0 |
0.05 |
0.10 |
0 |
0.05 |
0.10 |
Linear |
Quadratic |
Carbadox |
Linear |
Quadratic |
d 0 to 21 |
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ADG, kg |
0.19 |
0.20 |
0.19 |
0.21 |
0.22 |
0.22 |
0.215 |
0.463 |
<0.0001 |
0.455 |
0.105 |
ADFI, kg |
0.26 |
0.25 |
0.25 |
0.27 |
0.26 |
0.28 |
0.984 |
0.353 |
0.007 |
0.186 |
0.564 |
G:F |
0.74 |
0.80 |
0.77 |
0.81 |
0.82 |
0.82 |
0.128 |
0.016 |
<0.0001 |
0.394 |
0.108 |
SEM = 0.006 for ADG, 0.021 for ADFI, and 0.051 for G:F |
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Keywords: antibiotics, nursery pigs, oregano