Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2012
Publication Date: 6/28/2012
Citation: Norman, H.D., Hutchison, J.L., Cole, J.B. 2012. Increased use of young bulls in dairy cattle breeding programs. Journal of Dairy Science. 95(Suppl. 2):521–522(abstr. W60). 2012. Interpretive Summary:
Technical Abstract: Availability of genomic evaluations since 2008 has provided many benefits with regard to improving the rate of genetic gain in dairy cattle breeding programs, one of which is a greater accuracy for young animals. As a result, AI organizations have been aggressively promoting young bulls and producers have been using young bulls more extensively. The objective of this research was to compare reliabilities of traditional parent averages to reliabilities of genomic PTA’s of young Holstein (HO) and Jersey (JE) bulls, and to investigate the increased use of young bulls in breeding programs. Young bulls were defined as 0.8 to 3.9 years of age. Mean gain in genomic reliability (%) for 5,490 young HO bulls from December 2011 evaluations above that from traditional parent averages was 42 for yield traits and somatic cell score, 39 for productive life, 37 for daughter pregnancy rate, and 40 for net merit, resulting in reliabilities of 77, 73, 67, 65, and 72, respectively. Gain in reliabilities for 724 young JE bulls was 30, 30, 27, 24, 20, and 29, resulting in reliabilities of 64, 56, 51, 47, and 59, respectively. There were a total of 19,359,730 inseminations for HO, and 1,133,090 for JE that were investigated by year using US breeding records from 2007 through 2011. The percent of inseminations to young HO bulls for 2007, 2008, 2009, 2010, and 2011 were 28, 29, 39, 43, and 48% of the total breedings for that year, and to young genotyped HO bulls were 0, 8, 36, 42, and 48%. Thus, breedings to young genotyped HO bulls accounted for 0, 26, 92, 98, and 99%, respectively. The percent of inseminations using young JE bulls were 25, 27, 31, 33, and 40 and young genotyped JE bulls were 0, 0, 22, 32, and 39%. Therefore, breedings to young genotyped JE bulls accounted for 0, <1, 72, 98, and 98%, respectively. The percent of female offspring sired by young bulls was also investigated by birth year of the offspring, with 5,035,103 HO and 496,062 JE offspring. There were 24, 23, 23, 33, and 40% of the HO female offspring with a birth year of 2007, 2008, 2009, 2010, and 2011 sired by young HO bulls, and 29, 27, 30, 33, and 35% of the JE female offspring sired by young JE bulls, respectively. With the development of genomic evaluations, young bulls have increased accuracy, and thus have become more popular in breeding programs.