The crossbred sire: experimental results for cattle.

Area of Science:

• Animal Science
• Reproductive Biology
• Quantitative Genetics

Background:

• Crossbreeding is a common strategy in cattle production to leverage heterosis and combine desirable traits.
• Evaluating the reproductive and progeny performance of crossbred bulls relative to straightbred bulls is crucial for optimizing breeding programs.

Purpose of the Study:

• To compare the reproductive and progeny growth traits of crossbred bulls (Bos taurus X Bos taurus and Bos indicus X Bos taurus) against straightbred bulls.
• To quantify the advantages of crossbred bulls in traits such as puberty, sperm concentration, pregnancy rate, and weaning rate.

Main Methods:

• Summarized and compared performance data for reproduction and progeny growth traits.
• Data were analyzed separately for Bos taurus X Bos taurus (Bt X Bt) and Bos indicus X Bos taurus (Bi X Bt) crosses against straightbred bulls.

Main Results:

• Crossbred bulls reached puberty earlier than straightbred bulls (Bt X Bt: 1.8% younger; Bi X Bt: 5.0% younger).
• Crossbred bulls exhibited significantly higher sperm concentration (Bt X Bt: 36.4% greater; Bi X Bt: 56.0% greater).
• Crossbred bulls improved pregnancy and weaning rates, with notable advantages for Bi X Bt crosses (1.4% and 3.7%, respectively).

Conclusions:

• Both Bt X Bt and Bi X Bt crossbred bulls demonstrate superior reproductive performance compared to straightbred bulls.
• The Bos indicus X Bos taurus crosses offer substantial improvements in fertility traits, contributing to enhanced herd reproductive efficiency.
• Calf birth and weaning weights were not significantly different between calves sired by straightbred and crossbred bulls.