Questions from our readers . . .
What are current dystocia and stillbirth rates among Holsteins? Have there been any comparisons between sexed and conventional semen?
S.H., New York
We looked at 10.8 million conventional and 122,705 inseminations with sexed semen from January 2006 to October 2008. The dystocia rates, shown as percent difficult calving, are shown in the table. As you can see, there is very little difference in dystocia scores between sexed and conventional semen amongst heifers. There are a few percentage point differences in difficult calving among cows. Please keep in mind that sexed semen results in more heifer calves and almost 90 percent heifer calves compared to 50 percent with conventional semen. With that in mind, there are fewer difficult calvings when using sexed semen due to the higher heifer ratio which results in lower dystocia scores.
Stillbirth rates are quite similar when comparing sexed and conventional semen. Overall, stillbirth rates are higher among first calf-heifers as shown in the table, while those rates dropped considerably for cows that have calved at least one time.
- Jana Hutchison, USDA-AIPL