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CONCLUSIONS

INTRODUCTION

hermione-hodge
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CONCLUSIONS

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  1. INTRODUCTION There has been increasing use of sex-sorted semen since 2006 because producers can obtain more animals of the gender they prefer (usually heifers). The sexing process compromises conception rate (CR), and is the basis for recommending its use primarily on heifers because they have better fertility than older animals. OBJECTIVE To document CR obtained in different situations so producers know more precisely what kind of fertility to expect with various types of breedings. • DATA & METHODS • Breeding reports were provided to AIPL by the dairy records processing centers using AIPL Format 5 • Data included Holstein breedings from January 2006 through December 2008 • 1,250,132 heifer breedings (116,846 with sexed-semen) • 10,592,318 cow breedings (24,239 with sexed-semen) • The outcome for each breeding was coded as a failure (0) or a success (1), and was the basis for deriving CR • CR was derived separately for: • Virgin heifers (first through seventh services) • Cows (first through seventh services for each parity 1 through 5 • Correlation between sire conception rate (SCR) for traditional vs. sexed-semen was calculated RESULTS Extent of sexed-semen usage Cow breedings • 53% of sexed-semen breedings occurred in first 2 services in first lactation; 72% occurred within first 2 lactations and first 2 services • Mean CR achieved with sexed-semen was 27% for cows (31% for conventional semen) • Trend toward increasing usage of sex-sorted semen from 2006 through 2008, nearly doubling in heifer usage in 2008 compared to 2007 • 82% of sexed-semen inseminations were on heifers • 9.3% heifers bred using sexed-semen; 0.23% cows bred using sexed-semen across all years • In most cases, CR decreased 5 to 8 percentage points (16 to 28% reduction) when using sexed-semen compared to conventional semen • Correlation of SCR from conventional vs. sexed-semen was 0.49 for bulls with >300 breedings (51 bulls); 0.78 for bulls with >800 breedings (15 bulls) Heifer breedings • CONCLUSIONS • Trends show increasing usage of sexed-semen, especially in heifers from 2006 through 2008 • 93% of all sexed-semen inseminations were to either heifers or first lactation cows, where CR are typically higher • Mean CR with sexed-semen averaged 43% for heifers (~75% of that achieved with conventional semen) and 27% for cows (~87% of that achieved with conventional semen) • Based on mean CR, it takes 2.3 sexed services/pregnancy for heifers (1.8 using conventional) and 3.7 sexed services/pregnancy for cows (3.2 using conventional); a 0.5 increase in both heifers and cows • Correlations with SCR indicate that success with conventional semen may not always be predictive of success with sexed-semen • 9% of heifer breedings were to sexed-semen (82% in first service); 96% of sexed-semen breedings occurred within first 2 services • Mean CR achieved with sexed-semen was 43% for heifers (57% for conventional semen) • CR decreased 14 to 18 percentage points (25 to 32% reduction) during first 7 services when using sexed-semen compared to conventional semen • Correlation of SCR from conventional vs. sexed-semen was 0.19 for bulls with >300 breedings (67 bulls); 0.32 for bulls with >800 breedings (31 bulls)

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