The Sire Effect on Gestational Length in Wagyu Cattle

Area of Science:

• Animal Science
• Reproductive Biology
• Genetics

Background:

• Understanding factors affecting gestation length is crucial for optimizing cattle breeding programs.
• Wagyu cattle are known for their high-quality beef, making reproductive efficiency a key economic consideration.
• Previous research has not fully elucidated the genetic influences on gestation length in Wagyu cattle.

Purpose of the Study:

• To investigate the genetic factors influencing gestation length in a Wagyu cattle herd.
• To determine the relationship between calf gender, birth weight, and gestation length.
• To identify the impact of sire genetic lines and maternal grandsires on pregnancy duration.

Main Methods:

• Fifty-five multiparous Wagyu cows were subjected to Fixed-Time Artificial Insemination (FTAI).
• Semen was used from bulls representing three distinct genetic lines.
• Calf gender, weight, and gestation length were recorded and analyzed using ANOVA.

Main Results:

• No significant effect of calf gender on gestation length was observed (p = 0.6).
• Sire's genetic line (p < 0.0001) and maternal grandfather (p < 0.0001) significantly influenced gestation length.
• Longer gestation periods were positively correlated with heavier calf birth weights (p < 0.0001).

Conclusions:

• Genetic background, specifically sire line and maternal grandsire, plays a significant role in Wagyu cattle gestation length.
• This study is the first to demonstrate the effect of Wagyu breed lines on pregnancy duration.
• The findings have implications for improving reproductive management and predicting calving outcomes in Wagyu herds.