Breeding programs compared across countries, continents, and breeds

Abstract

Breeding programs differ in generation intervals, pedigree completeness, genomic merit, and relationships to recent US animals as measured by expected future inbreeding (EFI) using pedigree or by genomic future inbreeding (GFI). Properties were examined using December 2023 files for proven bulls born 2016-2017 with milk-recorded daughters in ≥10 herds from Interbull, and genotyped females born 2018-2023 from the Council on Dairy Cattle Breeding (CDCB). Those genotypes included 3,709,707 females from USA and Canada, 498,480 from 13 countries in Asia, 378,650 from 17 countries in western Europe, 125,849 from 17 countries in eastern Europe, 153,362 from 12 countries in Latin America, 53,235 from 3 countries in Oceania, and 4,082 from 5 countries in Africa. Percentages of bulls with a foreign sire averaged 43% in Holsteins (HOL) and Brown Swiss, 12% in Red Dairy Cattle, and 9% in Jersey. The sire’s age at son’s birth averaged 2.2 to 2.9 years in 11 of the 20 countries for HOL, indicating rapid use of young sires, whereas other countries and breeds chose older sires of sons. Numbers of first crop daughters per selected young bull averaged 771 in HOL and 201-676 daughters in other breeds. Percentages of proven HOL bulls with genotypes used in the USA reference population differed widely by country from 0-100% and averaged 66%. Average pedigree completeness for HOL females ranged from 64.2% for Latin America to 86.1% for western Europe but was much higher and averaged 98% for proven bulls due to the Interbull exchange. Pedigree inbreeding, EFI, and GFI showed that proven bulls and genotyped females in many countries and continents are almost as related to US animals as US animals are to each other, but relationships are lower in other breeds and with wider ranges due to less genetic exchange. Other populations have higher genetic merit bulls for some breeds, but North American HOL had higher merit than all other regions.