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Effects of increasing crystalline amino acids in sorghum- or corn-based diets on finishing pig growth performance
A total of 288 pigs (PIC 327×1050; initially 45.9 kg) were used in a 90-d study to compare the effects of increasing crystalline AA in sorghum- and corn-based diets on grow-finish pig growth performance. Treatments with 8 pigs per pen and 6 pens per treatment were arranged in a 2 × 3 factorial with main effects of grain source (sorghum vs. corn) and crystalline AA supplementation (low, medium, or high). Because replacing increasing amounts of soybean meal with crystalline AA changes the NE of the diet, all diets were formulated to the same SID Lys:NE ratio. The Lys concentration in the diets was formulated at 95% of the pig’s estimated requirement based on the NRC (2012) to ensure that the other amino acids, as a ratio to Lys, would not be underestimated. The grain sources and soybean meal were analyzed for AA profile and diets formulated from these concentrations. Suggested amino acid ratios to Lys as well as standardized ileal digestibility coefficients (SID) used were obtained from the NRC (2012). The low AA fortification contained L-lysine HCl and DL-methionine. The medium AA fortification contained L-lysine HCl, DL-methionine, and L-threonine, and the high AA fortification contained L-lysine HCl, DL-methionine, L-threonine, and L-valine to sorghum- or L-tryptophan to corn-based diets as Val was 5th limiting in sorghum-based diets and Trp 5th limiting in corn-based diets. Overall, no grain source × crystalline AA interactions were observed. Pigs fed corn-based diets tended to have greater ADG (P<0.072) and had greater G:F (P<0.01) than those fed sorghum-based diets. As crystalline AA concentrations increased, ADG tended to increase then decrease (quadratic; P=0.057), and ADFI decreased (linear; P= 0.019). Pigs fed sorghum had decreased (P<0.01) jowl iodine value (IV) in comparison to pigs fed corn. In conclusion, balancing to the 5thlimiting AA using NRC (2012) suggested amino acid ratios in corn- or sorghum-based diets resulted in decreased ADG and G:F and pigs fed corn-based diets had greater G:F and IV than those fed sorghum.
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Grain source |
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Sorghum |
|
Corn |
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Crystalline AA: |
Low |
Medium |
High |
|
Low |
Medium |
High |
d 0 to 90 |
|
|
|
|
|
|
|
ADG, kg |
0.90 |
0.91 |
0.87 |
|
0.92 |
0.93 |
0.90 |
ADFI, kg |
2.66 |
2.63 |
2.55 |
|
2.62 |
2.63 |
2.54 |
G:F |
0.340 |
0.347 |
0.342 |
|
0.350 |
0.353 |
0.353 |
Jowl IV |
67.9 |
67.9 |
67.3 |
|
68.8 |
68.9 |
69.6 |
SEM was 0.013, 0.037, 0.003, and 0.59 for ADG, ADFI, G:F, and Jowl IV, respectively. |
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Keywords: corn, grow-finish pig, sorghum