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Evaluation of protein dispersibility index as an indicator for soybean meal protein quality in growing pigs: I. Metabolic study.

Korean research examined various methods to evaluate the quality of soybean meal in growing pig diets. Five different heat-treated soy flake treatments were prepared to provide different levels of heat denaturalization (1) raw; (2) steamed for five minutes at 950C; (3) steamed for 15 minutes at 11 00C; (4) steamed for 15 minutes at 1100C; and (5) steamed for 60 minutes at 110∞C. Twenty barrows weighing 14.1± 0.9 kg were randomly assigned to the dietary treatments. The pigs were fed the diets for three days prior to fecal and urine collection for four days. The results indicated that pigs fed the diet containing the soy flakes heat-treated for 15 minutes at 1100C (treatment 4) had the highest nitrogen retention, average daily gain and average daily feed intake. Both protein solubility in potassium hydroxide and protein dispersibility index values were significantly (P<0.00l) inversely related to nitrogen retention with regression correlations of -0.893 and -0.841, respectively. Urease activity and pepsin digestibility were not correlated to nitrogen retention in this experiment. Feed intake and feed efficiency (G/F) values were significantly lower for the pigs fed the diet containing raw soybean flakes. These results indicate that PDI is as effective as KOH protein solubility as an indicator of soybean meal protein quality for the growing pig.

Treatments 1 2 3 4 5
Urease activity 1.95a 0.10b 0.02c 0.03c 0.01c
Pepsin digestion, % 95.2a 95.1a 94.7a 94.5a 93.3a
KOH protein sol. % 96.1a 84.8b 79.1c 77.0d 41.7e
PDI, % 65.4a 33.8b 22.6c 21.1c 8.6d
N retention, % 7.5c 67.2b 69.9ab 71.6a 67.5b
           
ADG,g 324c 555b 583b 625a 550b
ADFI, g 848c 1,039b 1,041b 1,128a 1,063ab
G/F 0.38b 0.54a 0.56a 0.55a 0.52a

(Treatments with different subscripts are significantly different)

Lee, H. S. and co-workers. 2004. Evaluation of protein dispersibility index as an indicator for soybean meal protein quality in growing pigs: I. Metabolic study. Poster T42, p174 of the 2004 Joint Annual Meeting abstracts.