Biodisponibilidad de lisina en dos pastas de soya con diferente nivel de actividad ureásica en pollos de engorda

In order to study bioavailability of lysine of two soybeans meals (PSA and PSB) for broilers with different ureaseactivity (UA of 0.11 and 0.17 units of pH change), an experiment was performed. Two hundred and ten (210) chicksRoss were used from 1 to 21 d of age, in a completely randomized design with 7 treatments with three replicateseach one. Treatments were: 1) Basal diet sorghum-soybean meal (deficient in lysine), 2) Basal diet+0.05% L-lysine,3) Basal diet+0.10% L-lysine, 4) Basal diet+0.05% lysine from PSA, 5) Basal diet+0.10% lysine from PSA, 6) Basaldiet+0.05% lysine from PSB and 7) Basal diet+0.10% lysine from PSB. The growth results obtained were explainedby multiple linear regression equation, based on the data of weight gain, consumption of synthetic lysine and intakesof lysine from soybean meals: Y=X1+ Y= 375.419 + 0.0378 X1 + 0.0366 X2 + 0.0376 X3; where X1 accountedsupplementation with L-lysine, X2 with PSA (with addition of raw hull) and X3 with PSB (with addition of cockedhull). Comparison of the PSA or PSB slopes with the L-lysine slope (i.e. 100 % bioavailability) showed them all tohave >95 % lysine availability: PS A= 97 %, PSB= 99 %. These results indicate that UA of soybean meal affectedthe bioavailability of lysine; therefore more than 0.12 urcase activity units of pH change, lower is the availability.