Individual Effect of Bull Prevails over Sperm Characteristics in Predictive Models.

Area of Science:

• Reproductive Biology
• Animal Science
• Biotechnology

Background:

• Sperm quality is a critical factor in bovine in vitro embryo production (IVEP).
• Linear regression models can predict IVEP outcomes by analyzing sperm variables.
• Early indicators like cleavage rate can optimize recipient preparation schedules.

Purpose of the Study:

• To develop linear regression models assessing the influence of sperm variables and cleavage rate on IVEP yields.
• To identify key sperm parameters affecting IVEP success in Nellore bulls.
• To evaluate the predictive capability of sperm analysis for IVEP outcomes.

Main Methods:

• Compiled data from 51 semen batches (23 Nellore bulls) and 184 IVEP procedures.
• Included 26 sperm variables analyzed via computer-assisted sperm analysis (CASA) and flow cytometry.
• Constructed linear regression models to correlate sperm traits and cleavage rates with IVEP success.

Main Results:

• The most robust predictive model achieved a coefficient of determination (R²) of 0.6358.
• The 'BULL' variable was the most influential predictor (R² = 0.5218); sperm analysis alone had minimal predictive power (R² < 0.04).
• Individualized models for specific bulls showed high predictive accuracy (R² from 0.58 to 0.99), indicating bull-dependent variable influence.

Conclusions:

• The bull's identity is the dominant predictor of in vitro embryo production success.
• Cleavage rate serves as a reliable early indicator for predicting blastocyst rates.
• Individualized predictive models are valuable for selecting optimal semen batches within IVEP programs, enhancing blastocyst rates.