Feed cost is the single-largest expense of dairy production and has increased substantially over the last few years. Although it is a crucial factor in the profitability of the dairy industry, little attention has been paid to improve feed efficiency through direct selection on it. This is mainly due to the difficulties and costs associated with individual feed intake measurements.
In order to increase the availability of individual feed intake measurement, there has been recent interest in (a) combining data from international research populations for genetic analysis, or in (b) using predictor traits as indicators for dry matter intake. Reasons why genotypes and phenotypes from different research organisations are combined include adding statistical power to genome wide association studies and/or trying to improve the accuracy of genomic prediction. Useful predictors for dry matter intake are milk yield traits and live weight, because they allow proper accounting for the amount of feed required for production and maintenance.
The proposed breeding value for feed intake is based on a combination of predictor traits and genomic predictions for dry matter intake. The predictor traits are milk, fat and protein yield as a prediction for the feed required for production, and stature, body depth and chest width as a prediction for live weight and therefore for feed required for maintenance. Reliabilities higher than 30% (i.e., the national threshold for publication) are achieved for the breeding values for dry matter intake. The breeding values range from -2 to +2 kg dry matter per day; so -600 to +600 kg dry matter per lactation.
The aim is to implement these breeding values late 2014; first by CRV and after that they will become nationally available through GES (Genetic Evaluation Sires). The Netherlands are then the first country that will have these breeding values available. This increases the opportunities to work together with other countries, like for example in the global Dry Matter Initiative (gDMI). This is an initiative of 10 institutions and universities that have combined their data on individual dry matter intake of dairy cattle to estimate more accurate genomic predictions that could then be used in national breeding value estimations.
For more information, please contact Roel.Veerkamp@wur.nl