Evaluation of mathematical models to describe gas production kinetics of some tropical and temperate forages

Abstract

Our objective was to identify the best fit mathematical models for in vitro gas production kinetics using rumen fluid and forage plants commonly used in ruminant feed to obtain better estimates of parameters that describe the rumen fermentation. Four mathematical models were tested, two unicompartmental (M1 = first order, M2 = Gompertz) and two bicompartmental (M3 = M1 + M2; M4 = M2 + M2). Two temperate grasses were evaluated, as well as four tropical grasses and three temperate forage legumes. The fit of the models was verified by the corrected Akaike information criterion (AICc r ) and the difference among AICc r values (Δ r ), likelihood probability (W r ), and relative likelihood (ER r ). Temperate forages reached maximum gas production between 48 and 72 h. In the tropical forages, it occurred only after 72 h. In profiles in which M3 was the best choice, the values of parameters V f 1 were higher than those of V f 2 , and k 1 values were higher than k 2 values. The only exception was for Tifton 85 profile, whose V f 2 value was higher than V f 1 . The model M3 has a better fit for tropical forages with higher fiber content and lower levels of nonfibrous carbohydrates and crude protein. The model M1 has a better fit for forage with higher nonfibrous carbohydrate contents and low lignin content.

Silage Fermentation Quality, Anthocyanin Stability, and in vitro Rumen Fermentation Characteristic of Ferrous Sulfate Heptahydrate-Treated Black Cane (Saccharum sinensis R.)

“…This was not unexpected, considering that the carbohydrate and glucose levels of SHF and FBC were essentially identical throughout substrate fermentation ( Table 1 ). Our results were comparable with those of a previous study ( 49 ) that investigated the addition to carbon dioxide yields of many tropical and temperate forages with high nonfibrous carbohydrate content and low lignin concentration.…”