Multi-criteria evaluation of dairy cattle feed resources and animal characteristics for nutritive and environmental impacts
2018
van Lingen, H. J. | Fadel, J. G. | Bannink, A. | Dijkstra, J. | Tricarico, J. M. | Pacheco, D. | Casper, D. P. | Kebreab, E.
On-farm nutrition and management interventions to reduce enteric CH₄ (eCH₄) emission, the most abundant greenhouse gas from cattle, may also affect volatile solids and N excretion. The objective was to jointly quantify eCH₄ emissions, digestible volatile solids (dVS) excretion and N excretion from dairy cattle, based on dietary variables and animal characteristics, and to evaluate relationships between these emissions and excreta. Univariate and Bayesian multivariate mixed-effects models fitted to 520 individual North American dairy cow records indicated dry matter (DM) intake and dietary ADF and CP to be the main predictors for production of eCH₄ emissions and dVS and N excreta (g/day). Yields (g/kg DM intake) of eCH₄ emissions and dVS and N excreta were best predicted by dietary ADF, dietary CP, milk yield and milk fat content. Intensities (g/kg fat- and protein-corrected milk) of eCH₄, dVS and N excreta were best predicted by dietary ADF, dietary CP, days in milk and BW. A K-fold cross-validation indicated that eCH₄ and urinary N variables had larger root mean square prediction error (RMSPE; % of observed mean) than dVS, fecal N and total N production (on average 24.3% and 26.5% v. 16.7%, 15.5% and 16.2%, respectively), whereas intensity variables had larger RMSPE than production and yields (29.4%, 14.7% and 14.6%, respectively). Univariate and multivariate equations performed relatively similar (18.8% v. 19.3% RMSPE). Mutual correlations indicated a trade-off for eCH₄ v. dVS yield. The multivariate model indicated a trade-off between eCH₄ and dVS v. total N production, yield and intensity induced by dietary CP content.
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