Risk factors associated with detailed reproductive phenotypes in dairy and beef cows

Area of Science:

• Veterinary Medicine
• Animal Science
• Reproductive Biology

Background:

• Detailed fertility assessment in cattle is crucial for herd management and productivity.
• Transrectal ultrasonography provides valuable data on reproductive status.
• Understanding risk factors associated with fertility traits can improve breeding strategies.

Purpose of the Study:

• To identify detailed fertility traits in dairy and beef cattle using transrectal ultrasonography.
• To quantify risk factors associated with these fertility traits.
• To provide data for improving reproductive management in cattle herds.

Main Methods:

• Analysis of 148,947 transrectal ultrasound observations from 75,949 cows across Irish dairy and beef herds (2008-2012).
• Identification of fertility traits: cycling, cystic structures, early ovulation, embryo death, and uterine score.
• Statistical analysis using generalized estimating equations and linear mixed models to identify associated risk factors.

Main Results:

• Prevalence rates: 84.75% cycling, 3.87% cystic structures, 7.47% early ovulation, 3.84% embryo death.
• Dairy cows had lower odds of cycling (0.51) and poorer uterine scores compared to beef cows.
• Parity and lactation stage positively influenced cycling, cystic structures, embryo death, and uterine score; dystocia negatively impacted uterine score.

Conclusions:

• Transrectal ultrasonography effectively identifies key fertility traits in cattle.
• Factors such as herd type, parity, lactation stage, and calving history significantly influence reproductive performance.
• The identified fertility traits and risk factors offer valuable insights for optimizing cattle reproduction management.