Selection for disease resistance.

Area of Science:

• Animal breeding and genetics
• Veterinary medicine
• Livestock health management

Background:

• Disease control is a priority in animal agriculture.
• Genetic improvement offers potential to reduce treatment and culling, but not replace management and sanitation.
• Selection for high milk yield is linked to increased disease incidence and costs in several studies.

Purpose of the Study:

• To evaluate the role of genetic improvement in disease resistance.
• To discuss the inclusion of disease traits in breeding programs.
• To highlight the need for industry-wide data recording and collaboration.

Main Methods:

• Review of existing studies on genetic selection and disease incidence.
• Discussion of genetic variance and loci involved in disease resistance (e.g., major histocompatibility complex).
• Analysis of criteria for trait inclusion in breeding programs.

Main Results:

• Disease incidence and cost increase with selection for milk yield.
• Numerous loci contribute to disease resistance, with some (like MHC) potentially explaining significant genetic variance.
• Genetic variation for disease incidence is economically significant despite low heritability of disease traits.

Conclusions:

• Including disease resistance in breeding programs is justified due to economic importance.
• Genetic improvement alone cannot substitute for essential management and sanitation practices.
• Industry-wide data standards and collaboration are necessary for effective genetic improvement in disease resistance.