Rumen effective degradability of amino acids from soybean meal corrected for microbial contamination.
Rumen degradation kinetics and effective degradability of individual amino acids, total analysed amino acids (TAA) and crude protein (CP) of soybean meal were measured on four rumen-cannulated wethers using the nylon bag technique. Microbial contamination of the incubated residues was corrected using a continuous 15N intraruminal infusion and isolated solid associated bacteria as a reference sample. TAA showed a lower soluble fraction (14.9 vs. 20.8%; P < 0.01), a similar insoluble-degradable fraction (79.0 vs. 79.2%) and a higher degradation rate (11.5 vs. 8.4% x h(-1); P < 0.05) than CP. As a consequence, effective degradability was similar for TAA and CP (74.7 vs. 75.7%). Degradability values of individual amino acids varied moderately (range: +/-6% of TAA degradability). Valine, isoleucine, leucine, alanine, aspartic acid and tyrosine showed significantly lower degradability than TAA, while the opposite effect was observed for histidine, threonine and glutamic acid. Degradability of individual amino acids was related to their soluble fraction (r = 0.877; P<0.001).
González
J
J
Departamento de Producción Animal, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Spain. jgonzalez@pan.etsia.upm.es
Rodríguez
C A
CA
Centeno
C
C
Lamnari
F
F
D000596:Amino Acids / Q000378:metabolism*; D000821:Animal Feed / Q000382:microbiology*; D000818:Animals; D005285:Fermentation; D008297:Male; D009584:Nitrogen; D012417:Rumen / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*; D030262:Soybean Proteins / Q000378:metabolism*; D013025:Glycine max
D000596:Amino Acids; D030262:Soybean Proteins; D009584:Nitrogen