Brief project description
Calves and heifers are the future dairy cows. This makes young stock rearing an essential part of dairy farm (Boersema et. al., 2010). Most farmers are, however, not aware of the total costs of young stock rearing, and probably therefore young stock rearing do not get the attention it requires (Bach and Ahedo, 2008; Gulliksen et al., 2009). If the farmers are aware of the distribution of the total costs of young stock rearing, they can start to prioritize and change the young stock rearing management to improve the farm profitability. Decisions to change the management occur between the time young stock is born until the time these young stock successfully replace a dairy cow (on average 26 months) (CRV, 2009), and should result in heifers that are healthy, have a good conformation and produce enough milk (Le Cozler et al., 2008; Boersema et al., 2010; Heinrichs et al., 2010). Therefore, improvement in first calving age and heifer’s milk production can be expected once farmers have decided to improve herd circumstances. Besides that, farmers have to ensure that enough heifers are reared on the farm and able to replace culled dairy cows when needed. Thus, farmers have to decide whether a newborn heifer calf must be kept or sold. Dairy farms are becoming larger. Consequently, it is becoming more difficult to give young stock the attention it requires. The decision to outsource or to buy new heifers will enable the farmers to focus only on dairy cows. For all the decisions needed to be made during rearing young stock, supporting tools areneeded yet are not available.
Main goal and objectives
The main goal of this research is to develop a herd level simulation model that can give insights in the consequences of decisions made on young stock management on dairy farms (objective 5). The results of the other 4 objectives will give insights in specific decisions made for young stock management. In addition, these results will serve as inputs for the final model (objective 5).
The specific objectives are:
- To estimate the total costs of young stock rearing at calf level using Monte Carlo simulation model that take into accounts variation in growth and uncertainty in disease incidence and reproduction. (Study finished in January, 2011).
- A. To identify the explaining variables for first calving age and heifer milk production at herd and calf level in the Netherlands using regression models. B. To analyze the association and correlation between first calving age and heifer milk production.
- To determine the culling rate of dairy cows, and its variation over several years, at farms that rear own young stock and at farms that culled newborn heifer calves.
- To identify the technical aspects and costs of rearing young stock in farms that only rear young stock
- To develop a herd level stochastic simulation model that is able to support decisions in young stock rearing.
Promoter(s) Prof. J. A. Stegeman