Validation of new models to balance dairy ration for protein under Quebec conditions.

To ensure its sustainability, the Quebec dairy industry must be profitable while reducing its environmental footprint. By optimizing the supply of protein and amino acids (AA) digested by the cow, it is possible to reduce the amount of crude protein in the ration without compromising milk and milk protein yields and therefore reduce production costs while decreasing the faecal and urinary nitrogen loss. The objective of this research project is to validate the impact of the revision of 3 models used to formulate dairy rations on the recommendations of protein and AA in a Quebec context. These 3 models are among the most popular in North America [National Research Council (NRC) 2018, Cornell Net Carbohydrate and Protein System (CNCPS v 6.5) 2016] and Europe (new French system Systali). Specifically, we aim to 1) determine the influence of the characteristics of rations on the ability of the models to predict protein and AA duodenal flows by comparing the predictions of the 3 models and measured protein and AA duodenal flow; 2) compare milk and milk protein yield predicted by the 3 models with values reported in the literature and measurements from 100 Quebec farms; and 3) provide, if necessary, adjustments to ration formulation model used by the Dairy Centre of Expertise Québec-Atlantic (Valacta: currently based on NRC 2001) and other ration systems used in Quebec reflecting the characteristics of Quebec rations. The proposed study will allow us, for example, to check whether the new model predictions apply equally to typical Quebec rations vs. those based on alfalfa / corn (United States) or multiple forages (Europe). Results will also be applicable to similar environments (eg. other provinces in Canada and Northern United States). The fact that comparisons between predicted and observed values are also made from Quebec values measured on dairy farms gives a unique value to this project that will never be made outside Quebec. If it appears that biases are present with certain types of rations particularly used in Quebec, corrections to these biases can be integrated to better adapt the Valacta model and other Quebec institutions models, to the Quebec reality. Thus, our study will validate and allow a rapid transfer, on Quebec dairy farms, of advances resulting from the application of new US and European ration models. These changes will reduce the crude protein in the rations, production costs and nitrogenous excretion in the environment. The benefits of this project will therefore be economical at the farm and consumer level, environmental for the whole society and advanced knowledge at scientific level.