Researchers at Ohio State University recently conducted a study to determine if using disposable plastic sheath protectors (on top of the regular AI sheath) — which minimize contamination of the AI catheter — has an impact on pregnancies per AI. They followed 996 services from 773 lactating dairy cows on a commercial Ohio dairy to find an answer.

About half of the breedings featured the use of a plastic sheath (treatment group). No plastic sheath was used during the other inseminations.

Samples were taken with a sterile cotton swab from the tip of the AI catheter after AI from both treatment groups. Cultured swab samples revealed that the use of plastic sheath was effective in minimizing contamination of the catheter (positive bacterial growth: 61.53 percent vs. 100 percent for the group bred without the plastic sheath).

Overall, the proportion of cows pregnant was greater for cows in the treatment group (42.7) compared with the other group (36.1).

Interestingly, for first services postpartum, the use of the plastic sheath did not differ between groups. However, pregnancies per AI for second or greater services were greater in the treatment group (43.8 percent) than in the other group (32.3 percent).

Results from this study were published in the February Journal of Dairy Science and provide evidence that the use of plastic sheaths during AI improved pregnancies per AI for second or greater services in lactating dairy cows. Performing a clean AI technique through the use of these tools may be an effective strategy to improve reproductive outcomes in dairy cattle, the researchers conclude.