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Health Traits

The growth and evolution

of health traits By Jaclyn Krymowski for American Dairymen Magazine

H

ealth traits and their genetic selections are a hot topic and growing interest across the dairy industry. Due to their low heritability, they can be tricky to work with but have a high payoff in economic value because of their potential cost savings. In days gone by, a 1998 study in the Journal of Dairy Science noted a negative relationship between production and health/ fitness traits, largely due to the impact of genetic selection exclusively focusing on production rather than wellness at the time. However, the economics around the cost of treatments have changed dramatically since then making the correlation between production and wellness more positive and profitable. Why breed for health?

Health traits are a powerful tool against disease. Essentially, they’re a literal application of the old idiom “an ounce of prevention is worth a pound of cure.� Animal welfare is an industry issue also fueling the widespread utilization and research of health as a

genetic component. From a practical view, the shortage of food animal veterinarians coupled with the growing cost of animal treatment makes prevention a very attractive avenue for producers everywhere. That aside, dairymen using health as one of their advantages must be mindful to keep

this breeding as one part of a balanced strategy that still includes things such as fertility, milk production, productive life, and the like. Even with favorable genetics, the environment is still a major factor in disease prevention. The lower the heritability of any given trait, the higher variability the environment has. The average genetic heritability for traits pertaining to health and wellness tend to be only 5% or less. Of the researched traits recently released to the public sire evaluations, the highest (mastitis) heritability is only 3.1% and the lowest (hypocalcemia) is 0.6%.

Increasing industry application

The Holstein sire evaluations * Continued on page 36

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July 2018

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