Mathematical models for estimating the parameters of ruminal degradation kinetics of protein concentrates

SUMMARY This studied aimed to evaluate the parameters of ruminal degradation kinetics of protein concentrates, soybean meal (SM) and cotton cake (CC).To estimate the in situ degradation parameters of DM and CP from coproducts were fitted 5different non-linear mathematical models: Exponencial, Van Milgen, Logístico, Gompertz and Richards. For in situ evaluation were used two cattle cannulated in the rumen. The samples were incubate dat 0, 2, 4, 6, 12, 16, 24, 36, 48 and 72 hours and in the incubation residues were determined DM and CP and their degradability. The DM degradability of SM were 86.35, 74.23, 65.50% and to CC were 53.44, 41.70 and 35.21% in passage rates of 0.02; 0.05 and 0.08.h-1, respectively. The SM and CC showed values for the CP soluble fraction of the 18.15, 34.77% and 79.76, 55.10% to insoluble potentially degradable fraction, respectively. According to the Akaike weights (Wi) the model of Richards has 95.45 and 49.64% of chance to be the most suitable model to characterize the in situ DM degradation of SM and CC. However, the Gompertz model has 63.86 and 66.49% chance to be the most suitable model to characterize the CP in situ degradation of SM and CC.