Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: March 8, 2010
Publication Date: June 24, 2010
Citation: Norman, H.D., Hutchison, J.L., Van Raden, P.M. 2010. Comparison of Holstein service-sire fertility for heifer and cow breedings with conventional and sexed semen.. Journal of Dairy Science. 93(E-Suppl. 1):595(abstr. W30). Technical Abstract: Sire conception rate (SCR), a service-sire fertility evaluation implemented in August 2008, is based on up to 7 conventional-semen breedings for parities 1 through 5 (Ccow). The same procedure was used to derive SCR for other types of breedings: sexed semen for cows (Scow) and conventional semen and sexed semen for primiparous heifers (Chfr and Shfr, respectively). For all 4 breeding types, SCR were based on breedings from 2006 through 2009. Service-sire age groups were consolidated for sexed-semen breedings because of a limited number of bulls. Only artificial-insemination Holstein bulls with =300 breedings overall and =100 matings during the last 12 mo in =10 herds were included. Number of bulls evaluated was 2,309 for Ccow breedings, 270 for Chfr breedings, 25 for Scow breedings, and 114 for Shfr breedings; respective mean SCR reliabilities were 79, 82, 73, and 75%. Mean SCR for all breeding types was near 0, and standard deviations were 2.21% for Ccow, 2.57% for Chfr, 2.39% for Scow, and 4.34% for Shfr breedings. Correlation between Ccow and Scow SCR was 0.18, which resulted in a genetic correlation (rg) for true SCR of 0.24; corresponding correlations for heifer breedings also were low: 0.08 and 0.11, respectively. Correlation between Ccow and Chfr SCR was 0.67 (rg of 0.82); correlation between Scow and Shfr SCR was 0.75 (rg of 1.02). Among artificial-insemination organizations, absolute differences between mean SCR for conventional and sexed-semen breedings ranged from 1.44 to 4.52% for cows and 0.87 to 6.78% for heifers. Bull age effects were quite large for conventional semen but small for sexed semen. Results suggest that fertility rankings for sexed semen differ markedly from those for conventional semen and separate SCR are needed. Combining cow and heifer inseminations together in some manner would seem to be advantageous.