The Cornell Net Carbohydrate and Protein System (CNCPS) was developed to evaluate nutritional adequacy and predict nutrient supply and requirements in cattle under most management and environmental conditions. Evaluations of this capability have been published and the model is in continuous development (Tylutki et al., 2008; Van Amburgh et al., 2015). As model precision increases, the ability to develop or integrate extant equations to predict excretion of feces and urine and gasses from digestion also increases as those predictions are outcomes of predicting metabolizable energy and protein supply. For example, the ability to predict urinary and fecal nitrogen (N) was through evaluation of extant equations (feces) and development of a new equation that predicted urinary excretion (Higgs, et al., 2012). Implementation of this capability in 8 herds in NY was shown to reduce manure N excretion by 14% (22 kg/cow/yr) resulting in $163 increased income over feed costs (Chase, 2018). Greenhouse gas (GHG) production from cattle has been extensively studied and modeled as part of the development of DE, ME and NE equations, thus if the model is adequate at predicting those variables, predictions of GHG should be less complicated. Extant equations from Casper and Mertens, (2010) for CO2 and Mills et al. (2003) for methane were tested and adapted and were very robust at predicting GHG emissions. Total emission of CO₂ per cow was positively related to total milk yield (R² = 0.69). However, CO₂ emissions per kilogram of milk as a function of milk yield (kg CO₂/kg milk) resulted in a negative relationship, (R² = 0.81). The average value of CO₂ emission per unit of milk yield was 0.353 kg CO₂/kg, with minimum and maximum values of 0.283 and 0.423 kg CO₂/kg milk, respectively. Methane emissions per kg DMI ranged from 0.021 to 0.027 with a mean of 0.024 kg. Methane emissions were positively correlated with milk yield (slope = 0.004; R² = 0.68) but negative correlated when expressed as a function of milk yield (slope = −0.26; R² = 0.88) (Van Amburgh et al., 2015).