Evaluation of the Nordic dairy cow model Karoline in predicting methane production

The objective of this study was to evaluate the Nordic dairy cow model Karoline using a synthetic data-set. The data-set included 120 diets comprised of one of the five grass silages differing in digestibility, red clover silage and concentrate ingredients. The relationship between total methane (CH4) production predicted by Karoline model and that estimated from empirical equation (=observed'), showed that Karoline model over-predicted CH4 production by 30 L/d (P<0.01) with the mean bias having the greatest contribution (59%) of mean squared prediction error (MSPE). The proportion of random error of MSPE was 40%, whereas the contribution of linear bias was small and non-significant (P = 0.11). The residuals were significantly related to dietary crude protein (CP) concentration. It is concluded that Karoline model predicts CH4 production with a reasonable accuracy and that it is a useful tool to understand quantitatively mechanisms influencing CH4 production.