1. H.D. Norman* and J.L. Hutchison Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD 20705-2350, USA *duane.norman@ars.usda.gov EAAP – 2009 (1) Effect of sexed-semen use on Holstein conception rate, calf gender, dystocia, and stillbirth in the United States Abstr. 4183

2. Norman EAAP – 2009 (2) Traits l Conception rate l Calf gender w Male, female, single, twins l Dystocia w Births reported as requiring considerable force or extremely difficult l Stillbirth w Born dead or died within 48 hours

3. Norman EAAP – 2009 (3) Data l Holstein breedings from January 2006 through December 2008: Calf gender12%9% Dystocia12%9% Breedings TraitAllSexed semen Stillbirth10%9% Heifers1.3 million116,846 Cows10.6 million24,239 Conception rateAll

4. Norman EAAP – 2009 (4) Extent of sexed-semen use Year of breeding Conventional semenSexed semen Number% % Cows 20062,490,85099.92,0030.1 20074,105,39699.87,9510.2 20083,971,83399.614,2850.4 Heifers 2006396,926995,5451 2007394,6609141,1869 2008341,7008370,11517

5. Norman EAAP – 2009 (5) Sexed-semen breedings (%) by service number Service number 1 2 3 ≥4 Cows 67 20 8 5 Heifers 82 14 3 1 Cows 0.4 0.2 0.1 % of each service using sexed-semen Heifers 12 6 3 1

6. Norman EAAP – 2009 (6) Sexed-semen breedings (%) by service number Service number 1 2 3 ≥4 Heifers 82 14 3 1 Cows by parity 12345 4214731 115211 42110 31100

7. Norman EAAP – 2009 (7) Conception rate (%) by service number Service number Conventional semen Sexed semen Heifers 60 56 51 44 45 38 35 30 Cows 32 31 30 27 28 26 24 20 All 57 31 All 43 27 1 2 3 ≥4 1 2 3

8. Norman EAAP – 2009 (8) Conception rate (%) by service number Service numberHeifers Cows by parity 12345 Conventional semen 1603531302826 2563431302928 3513130 28 ≥44427 2625 All573330292827 Sexed semen 1452926222322 2382724232226 3452523291520 ≥4302217201921 All432825232223

9. Norman EAAP – 2009 (9) Calf gender (%) Gender Single females Single males Twins Cows Conventional semen Sexed semen 4685 4911 54 Heifers Conventional semen Sexed semen 5090 499 11

10. Norman EAAP – 2009 (10) Dystocia incidence (%) Gender Single females Single males Twins Cows Conventional semen Sexed semen 2a2a 1a1a 3b3b 1a1a 5c5c 2b2b Heifers Conventional semen Sexed semen 4a4a *4a4a 8b8b 9b9b 8c8c 4c4c *Different superscripts represent statistical differences within column (P < 0.05) Weighted mean 6431

11. Norman EAAP – 2009 (11) Stillbirth incidence (%) Gender Single females Single males Twins Cows Conventional semen Sexed semen 4a4a 3a3a 4b4b 4a4a 8c8c 8b8b Heifers Conventional semen Sexed semen 9a9a *10 a 11 b 15 b 15 c 13 c *Different superscripts represent statistical differences within column (P < 0.05) Weighted mean 101143

12. Norman EAAP – 2009 (12) Conclusions l Increased use of sexed semen since 2006 when it became commercially available l Primarily used for breeding heifers and first services of cows when conception rates are traditionally higher l Mean conception rate with sexed semen lower than that with conventional semen by about 25% for heifers and 13% for cows

13. Norman EAAP – 2009 (13) Conclusions (cont.) l 90% heifer calves when using sexed semen l No increase in incidence of dystocia with sexed semen, a reduction for twins l Slight increase in stillbirths for single male calves born to heifers when sexed semen was used