Protein digestibility-corrected amino acid score and digestible indispensable amino acid score in rice, rye and barley
2016
Nitrayová, Soňa (National Agricultural and Food Center, Lužianky (Slovak Republic). Research Institute of Animal Production Nitra, Department of Nutrition) | Brestenský, Matej (National Agricultural and Food Center, Lužianky (Slovak Republic). Research Institute of Animal Production Nitra, Department of Nutrition) | Heger, Jaroslav (National Agricultural and Food Center, Lužianky (Slovak Republic). Research Institute of Animal Production Nitra, Department of Nutrition) | Patráš, Peter (National Agricultural and Food Center, Lužianky (Slovak Republic). Research Institute of Animal Production Nitra, Department of Nutrition)
Better assessment of the quality of dietary protein sources allows their better use. The FAO has recommended replacing the protein digestibility–corrected amino acid score (PDCAAS) with the digestible indispensable amino acid score (DIAAS) in which ileal amino acid digestibility values obtained in pigs are used. A study on growing pigs was conducted to determine true fecal protein digestibility and standardized ileal amino acid digestibility of rice, rye and barley. Using these values the PDCAAS and DIAAS were calculated and compared. A total of 18 gilts with a T-cannula inserted in the terminal ileum were allotted to 3 diets - six replicate pigs per diet. Three semi-purified diets were formulated to contain the tested cereal grains (rice, rye, barley) as the sole nitrogen source and with an indigestible marker (chromic oxide). Each experimental period comprised of a 7-d adaptation followed by 1-d (24 h) collection of feces and ileal digesta. All tested parameters were greatest in rice. Significant differences (P < 0.05) in both protein and amino acids digestibility among the rice and other cereals (rye and barley) were found. True fecal protein digestibility was significantly greater than the mean ileal amino acids digestibility for all tested samples, thus suggesting an overestimation of protein quality determined by means of PDCAAS. Calculated PDCAAS values for rice, rye and barley (81, 65 and 61%) were generally higher than a DIAAS values (79, 56 and 55%), especially for the poorer quality proteins - rye and barley in comparison with rice.
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