Source: Lactanet Canada
Each year, based on official animal registration and pedigree information within its database, Lactanet Canada computes current statistics related to the level of inbreeding within the Canadian cow population of each dairy breed. In this way, the average level of inbreeding for animals born in the most recent complete calendar year as well as trends in the level of inbreeding over time can easily be monitored. The following table is based on females born in Canada since 1970 up to and including registered heifers born in 2018.
Among the four major dairy breeds in Canada, the average inbreeding level for heifers born in 2018 is highest for Holstein at 7.85%, followed by Brown Swiss (6.98%), Jersey (6.65%) and Ayrshire (6.37%). In terms of controlling the rate of increase in inbreeding for females born since 2010, the Brown Swiss breed is doing best among these breeds, averaging +.06% per year, compared to rates of increase of +.08%, +.10% and +.23% per year for the Jersey, Ayrshire and Holstein breeds, respectively.
Among the breeds with the smallest populations in Canada, Canadienne continues to have the highest average inbreeding, now at 8.45% for females born in 2018, but the average rate of increase since 2010 has been decreasing, especially since 2015. Guernsey heifers born in 2018 average 6.69% inbreeding and the average change since 2010 has been decreasing by -.05% per year. For Milking Shorthorn, heifers born in 2018 average 2.95% inbreeding based on available pedigree data for the breed and the rate of increase has been moderate at +.09% per year for heifers born since 2010.
Below is a graph showing the inbreeding trend for the four largest dairy breeds based on registered females born in Canada since 1970 as well as a specific graph for the Holstein population alone. For further information, please feel free to contact Lactanet Canada staff.