View article

As milk production of dairy cows continues to increase, health and fertility of these animals have become a major concern of the dairy industry. Many countries have already shifted their selection goals to put more emphasis on" health and reproduction"(Miglior et al., 2005). However, this group of traits rarely includes direct disease information. Traits selecected generally include calving ease, fertility and udder health traits, where udder health is generally somatic cell score (SCS). Notable exceptions are the Nordic countries, where treatment data have been recorded for up to 30 years and are included in the breeding goal (Osteras et al., 2007; Steine et al., 2008). A precise definition of disease and accurate recording are 2 important prerequisites for the inclusion of disease resistance in breeding programmes. In Canada, 8 diseases were defined by Kelton et al.(1998) according to the following criteria: the traits had to be recorded in farm management systems, they had an economic significance, their median frequency of occurence was above 5 percent and the disease was clinically manifested, so that the trait can be identified clearly by simple observation. Since April 2007, these traits are being recorded on a voluntary basis in a central national database for use in management decisions and in the near future, for genetic evaluations. The data recording is done by the producers. The data are transmitted to the central database, by the Dairy Herd Improvement representative or by a veterinarian (in Quebec). The objective of the present review is to describe all 8 diseases recorded in the Canadian National Health Project (CNHP) and to present the …