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Ureatic activity and protein solubility in KOH of soybean meal samples obtained in poultry feed mills

Jardim, M., E. Arnhold, F. de Carvalho, R. Filho and J. Stringhini

The use of soybean meal in poultry diets can must be tested for antinutritional factors, which is easily identified with ureatic activity and protein solubility in KOH analysis. This research aimed to evaluate soybean meal quality measured by ureatic activity and KOH solubility in poultry feed mills. For this analysis, 283 samples were obtained from a broiler producing company located in the state of Goiás, Brazil. Soybean meal samples were categorized by the amount of KOH-soluble protein in 5 groups: < 75%; 75% to 80%; 80% to 85%; 85% to 90% and > 90% and 5 other categories regarding ureatic activity: 0; 0.01; 0.011-0.05; 0.051-0.1 and > 0.1. Descriptive statistics was used to evaluate results. Great variation was observed for the ureatic activity index and solubility in KOH. The percentage of samples obtained were classified in 5 categories of protein solubility in KOH (%): < 75%-3.18%; 75% to 80%-7.77%; 80% to 85%-52.64%; 85% to 90%-35.33%; > 90%-1.06%. For the categories of Ureatic activity index (Δ pH), the percentual values found for each of the 5 categories evalu- ated were, as follows: 0 – 15.2%; 0.01 – 14.12%; 0.011-0.05 – 39.92%; 0.051-0.1 – 17.67%; > 0.1 – 13.07%. For protein solubility in KOH, it was observed that 60.41% of the samples analyzed presented levels varying from 75 to 85% of protein solubility in KOH, that could be considered as a secure index to identify any change in soybean meal processing. But, it is necessary to pay attention to the 39.59% of these samples that the results were outside of the safe range. On the other hand, 87.0% of soybean meal samples had an ureatic activity index lower than 0.1 Δ pH, which can be considered adequate for chickens. But it is important to consider that 13.0% of these samples can be classified as low quality samples. Another value that draws attention is 10.25% of samples with ureatic activity value higher than 0.1 Δ pH and protein solubility greater than 85%.

This number of samples exceeding 10% means the possibility of reducing the ingredient quality soybean meal and eventual hazards in broiler performance when this ingredient is added to broiler diets. However, it is important to investigate the possibility of errors in sampling or analysis to ensure effective quality control of the ingredients.