NR 04. Ruminal amino acid degradability of soybean meal in bovines

Four steers fitted with rumen cannulae were used to study the in situ degradability of crude protein and amino acids (AA) of soybean meal at 6; 12; 24 and 48 h incubation times. AA analysis were performed by HPCL after acid hidrolysis. Equation parameters were determined for protein and each individual AA through the equation Dg = A - Bct, being Dg = degradability, A = degradation potential, c = degradation constant and t = time. B has no biological significance. There were differences among AA disapearnces being Met the least degradable and Ileu the most. Lys has degradation values superior to that of protein. Degradation constants were also different with that of Met being the lowest and Ileu the highest. At 12 h of incubation (0.08 rate of passage), protein degradation was 72 % and the AA profile was different than the original soy, showing increase of Met, Leu and Val and decrease of Ileu and glutamic acid. Lysine maintained the same concentration as in the original material. It does not seem reasonable to use the original AA profile for ration formulation. Equations for adjustments are reported.