An Overview of Dairy Cattle Models for Predicting Milk Production: Their Evolution, Evaluation, and Application for the Agricultural Model Intercomparison and Improvement Project (AgMIP) for Livestock.

The contemporary concern about anthropogenic release of greenhouse gas (GHG) into the

environment and the contribution of livestock to this phenomenon have sparked animal

scientists’ interest in predicting methane (CH4) emissions by ruminants. Focusing on milk

production, we address six basic nutrition models or feeding standards (mostly empirical

systems) and five complex nutrition models (mostly mechanistic systems), describe their key

characteristics, and highlight their similarities and differences. Four models were selected to

predict milk production in lactating dairy cows, and the adequacy of their predictions was

measured against the observed milk production from a database that was compiled from 37

published studies from six regions of the world, totalling 173 data points. We concluded that

not all models were suitable for predicting predict milk production and that simpler systems

might be more resilient to variations in studies and production conditions around the world.

Improving the predictability of milk production by mathematical nutrition models is a

prerequisite to further development of systems that can effectively and correctly estimate the

contribution of ruminants to GHG emissions and their true share of the global warming event