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Chromium yeast and ractopamine in diets for finishing pigs
To evaluate nutritional plans (NP) with chromium yeast (CrY) and ractopamine (RAC) for finishing pigs, 72 barrows with initial BW 72.10 ± 3.38 kg, genetically selected for lean deposition (DanBred x DanBred lines), were allotted in a randomized block design with four treatments, nine replicates and two pigs per experimental unit. Diets with or without CrY and RAC were used in two experimental periods of 14 and 28 days, respectively, resulting in four NPs: NP1=Control/Control; NP2=Control/RAC; NP3=CrY/CrY and NP4=CrY/CrY+RAC. CrY and RAC were added to the diets at 400 ppb and 10 ppm, respectively. For the first experimental period, diets were formulated to contain 3300 kcal/kg ME, and 15.35, 0.54, 0.26% CP, Ca and available P, respectively. For the second experimental period, diets were formulated to contain 3300 kcal/kg ME, and 14.91, 0.53 and 0.24% CP, Ca and available P, respectively. SID lysine in the diets with or without RAC were 0.93 and 0.78%, respectively. The effects of the NP were analyzed using the MIXED procedures of SAS (SAS Inst, Cary, NC) with blocks used as random effect in the model. Barrows in the Control/RAC NP had greater (P < 0.001) final BW and ADG than those fed Control/Control and CrYr/CrY NPs. Pigs in the CrY/CrY+RAC NP showed higher (P < 0.001) final BW and ADG compared to pigs in the Control/Control NP. The NPs had no effect (P > 0.05) on ADFI. Pigs in the Control/RAC and CrY/CrY+RAC NPs had best F:G compared to pigs in Control/Control NP. Pigs fed CrY/CrY NP had intermediate F:G (P<0.001) that was similar to the results obtained with the others NPs. These results confirm the potential of CrY and RAC as feed additives to improve pig performance during the finishing phase.
Table 1 – Performance of barrows in different nutritional plans during the finishing phase
|
NP1 |
NP2 |
NP3 |
NP4 |
|
Item |
Control/Control |
Control/RAC |
CrY/CrY |
CrY/CrY+RAC |
P-value |
Final BW, kg |
125.35C |
135.00A |
128.25BC |
132.21AB |
<0.001 |
ADG, kg/day |
1.27C |
1.50A |
1.34BC |
1.43AB |
<0.001 |
ADFI, kg/day |
3.69 |
3.75 |
3.63 |
3.61 |
0.638 |
F:G |
2.91A |
2.50B |
2.74AB |
2.57B |
<0.001 |
A, B, C– Different letters in the same row differ (P<0.05) for Tukey-Krammer adjusting t-test.
Keywords: additives, microminerals, swine