•  
  •  
 

Keywords

sex-sorted semen, beef heifers, artificial insemination

Abstract

Objective: The objective was to evaluate the effect of timing of artificial insemination (AI) relative to the onset of estrus on pregnancy outcome when using sex-sorted semen in beef heifers.

Study Description: Beef heifers were subjected to the melengestrol acetate with prostaglandin (MGA-PG) estrous synchronization protocol and visually observed for estrus every four hours for five days following injection of PG. Following detection of estrus, heifers were inseminated with semen sorted to contain X-chromosome bearing sperm cells (4.0 × 106 live cells per 0.25 mL straw of SexedULTRA 4M). Heifers were retrospectively categorized into one of three intervals from estrus onset to insemination: 1) 12.5–15.9 hours; 2) 16.5–21.0 hours; and 3) 21.4–27.5 hours.

Results: Heifers with the shortest interval (12.5–15.9 hours) from estrus onset to insemination had a similar (P > 0.10) AI pregnancy rate as compared with heifers with the interval from estrus onset to insemination of 16.5 to 21 hours. Heifers inseminated 21.4 to 27.5 hours following estrus onset achieved a greater (P ≤ 0.05) AI pregnancy rate than heifers inseminated 12.5 to 15.9 hours following estrus onset.

The Bottom Line: Insemination of beef heifers with sex-sorted semen later than 21 hours after estrus onset appears to improve pregnancy rate to AI when compared to earlier insemination times.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Download

Included in

Beef Science Commons

Share

COinS