How does a beef × dairy calving affect the dairy cow's following lactation?

Area of Science:

• Animal Science
• Dairy Cattle Breeding
• Reproductive Performance

Background:

• Research on beef semen use in dairy cows often overlooks cow performance, focusing instead on crossbred calf outcomes.
• Understanding the impact on the dam is crucial for evaluating the overall efficiency and sustainability of beef-dairy crossbreeding programs.

Purpose of the Study:

• To evaluate dairy cow performance (milk yield, fertility, survival) after calving beef × dairy crossbred calves versus purebred dairy calves.
• To investigate if difficult calving effects differ between purebred dairy and beef × dairy crossbred offspring.

Main Methods:

• Analysis of 587,288 calving records (1997-2020) from Swedish Red and Swedish Holstein cows.
• Mixed linear models used to assess 16 traits across yield, fertility, and survival categories for first and second parities.
• Inclusion of specific beef sire breeds (Aberdeen Angus, Hereford, Charolais, Limousin, Simmental) and their interactions with dairy dams.

Main Results:

• Beef × dairy crossbreeding resulted in significantly lower milk yields, particularly cumulative fat and protein yields in second parity.
• Fertility traits showed minimal significant effects across most breed combinations.
• Survival to next lactation and lactation length were significantly reduced in all beef × dairy crossbred combinations.

Conclusions:

• Beef × dairy crossbreeding negatively impacts dairy cow milk production and survival, with more pronounced effects in later parities.
• While difficult calving generally has unfavorable effects, its interaction with breed combination was not significant.
• Further research is needed to fully understand the long-term implications for dairy herd management and cow longevity.