Stoichiometric models for prediction of enteric methane production

Abstract

This study aimed to empirically evaluate the adjustment quality of two stoichiometric models of methane production from diets that used different rumen fermentation modulators. We used the models proposed by Moss et al. (2000) and Blümmel et al. (1997). The data set consisted of 169 observations of in vitro methane production and volatile fatty acids (acetate, propionate, and butyrate) from dissertations, theses, and scientific articles. The model’s adequacy evaluation was only possible through combination of several statistical analyzes. The models were unable to predict the enteric methane precisely and accurately. Despite this, the model proposed by Moss et al. (2000) showed a better fit based on the mean bias (% of observed, MB), MEF, RMSEP, Cb and CCC measures compared to the model proposed by Blümmel et al. (1997). However, both models presented strong evidence against the general hypothesis H0: a = 0 & b = 1. Thus, the model proposed by MOSS et al. (2000) was more efficient, whereas the model by Blümmel et al. (1997) showed a better fit for diets with high availability of H2.

Stability and Effects of Protected Palmitic Acid on In Vitro Rumen Degradability and Fermentation in Lactating Goats

“…The gas production kinetics (GP) content was calculated using the inverted exponential function [29] using Sigma Plot (10.0): P = a + b (1 − e -ct ), where P is the gas production volume at time t, 'a' and 'b' are mathematical parameters, 'c' is a constant fractional of gas production rates, and a + b is theoretical maximum gas production volume: lim t→+∞ a + b (1 − e − ct) = a + b. Methane production was determined as follows: CH 4 = 0.45 × (% acetate) − 0.275 × (% propionate) + 0.40 × (% butyrate) [30]. The biohydrogenation (BH,%) of fatty acids was calculated using the following equation: BH = 100 -100 [(residual unsaturated FA/total FA in residual digest)/(unsaturated FA feed sample/total FA feed sample)] [31].…”