Using a patented technology, Semex is now able to measure an animal’s immune response and their ability to combat infection and disease. These animals are considered High Immune Responders (HIR) and Semex’s HIR sires are known as Immunity+™ bulls. By using this information in breeding decisions, dairymen can ask how well a bull’s daughters respond to infection instead of how often they get diseases like mastitis.

This is important because traditional health-related genetic traits such as Productive Life, Somatic Cell Score and Daughter Pregnancy Rate are result-oriented measurements, with an indirect association to health. Even more restrictive, these traits are less than 10% heritable.

By contrast, immune response is highly heritable at 25%, making genetic gain much easier. This technology’s immune tests measure two types of immune response, linking a vast assortment of viral and bacterial infections. The net result is a broad-based disease defense.

With over 22 years of research and thousands of animals tested, the science behind Immunity+ is sound. Dr. Bonnie Mallard, University of Guelph Professor of Immunogenetics, has chaired a comprehensive research program for the past 22 years investigating the genetic regulation of the immune system, focusing on dairy cattle. Animals that made robust and beneficial immune responses were termed high immune responders.

Many independent studies also confirm the benefits of HIR. Research across 64 dairy herds shows HIR cows have a lower disease incidence. Seven hundred cows were tested in a 3,000-cow dairy in north Florida. The results showed that HIR cows had 27% less mastitis, 17% less metritis and 32% less retained placenta compared to average.



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