Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2009
Publication Date: 7/12/2009
Citation: Powell, R.L., Wright, J.R., Norman, H.D. 2009. Trends in International Flow of Holstein Genes. Journal of Dairy Science. 92(E-Suppl. 1):209-210(abstr. T39). Interpretive Summary:
Technical Abstract: Holstein genes spread from Europe to much of the world through live cattle more than 100 yr ago. By the advent of artificial insemination, selection emphasis in North America had led to a specialized dairy strain that was in demand internationally. From 1995, genetic evaluations through Interbull more accurately identified the best bulls across countries. Many of the same bulls were used in many countries, particularly to sire sons for progeny testing, so a number of countries had bulls worthy of international consideration. Data from over 100,000 Holstein bulls and 27 countries in the January 2009 Interbull evaluation were used to examine changes over birth years in the direction of gene flow by examining the country of AI bulls’ sires. Birth years ranged from 1986 to 2003. Percentage of bulls having a foreign sire was surprisingly steady, being 56% in 1986 and 55% in 2003, after a high of 65% for 1995 to 1997. Through 1991, nearly all AI bulls progeny tested in France, Germany, Italy, and The Netherlands were sired by bulls from other countries. For bulls from those countries born in 2003, 49 to 87% were by foreign sires. Although the United States used fewer foreign sires of sons, that portion has been about 25% for bulls born this decade. The United States provided the most foreign sires of sons every year, as high as 86%, with Canada second in most years; the two together contributed 56 to 97%. The “hot bulls” syndrome is evident from the dramatic changes in country of foreign sires from one year to year. The Netherlands had not accounted for more than 4% of foreign sires until 12% in 1999 followed by 24, 18, and dropping to 5%. Frequency of German sires went from 1% in 2000 to 12% in 2001 while Italian sires went from 1% in 2001 to 14% in 2002. Sourcing of sires is a dynamic situation with the proportion of sires from a given country rapidly changing. The constant is that foreign sires produce the majority of Holstein bulls progeny tested. The portion of foreign sires has not shown much trend, but certainly the accuracy with which sires are chosen has improved.