immune response over successive generations, as has been achieved for production traits, while progressively reducing the incidence of health problems in our dairy cows. The immune response test requires three visits to the farm over a 15-day period. The animals are immunized with safe and inert test antigens to measure their ability to mount immune responses to the challenge. There are two distinct types of immune responses measured that are critical in providing a defense against a diverse group of microorganisms found in the broad-based spectrum of viral and bacterial infections that can be present on farm. Once the immune response measurements have been made, they are entered in a genetic evaluation system that provides estimated breeding values for overall immune response.
high immune response cows, and the severity of disease was also greater in the low immune responders. Preliminary research also indicates a reduced incidence of sero-positive Johne’s cows in the group that are high for cell-mediated immune response, compared to cows classified average or low. A similar benefit is expected for a wide range of other viral and bacterial diseases since the immune system shows little preference for any one infectious disease over another.
Research has also shown that individuals ranked as high immune responders have a better response to commercial vaccines. This really shouldn’t be a surprise since the response to an introduced antigen is precisely what is measured in the immune response test. By genetically selecting for higher immune 16% response, dairy producers will develop animals that take better 14% advantage of vaccination. Therefore they can The list of benefits demonstrated by this research maximize the return on their12% investment in a technology is quite impressive. Research across herd vaccination program. 10% 64 dairy herds has shown that high immune have also been response cows have a lower incidence of disease. High immune response cows 8% shown to produce higher quality colostrum with In a 3,000 cow dairy in North Florida, well over 6% more antibodies. So, high immune response 700 cows were tested. The results showed that immune 4% high immune responders had 27% less incidence cows not only pass on their higher response genes to their offspring, but they also of mastitis, 17% less incidence of metritis 2% pass on early life immune benefits through their and 32% less incidence of retained placentas colostrum. Herd strategies to0%build colostrum compared to herd average cows. Across all inventories from high immune response HIGH cows AVERAGE tested herds, and by averaging the incidence could be a future possibility. of all diseases recorded, low immune response cows had twice as much disease compared to
Given the low heritability of most health traits used until now it has been somewhat frustrating for dairy producers to try to improve animal health. And, this lower heritability has limited the gains that could be achieved. The High Immune Response technology and the use of Semex Immunity+ bulls can help reverse this situation. These bulls present the opportunity to breed healthy cattle that are naturally disease resistant.
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16% 14%
DISEASE OCCURRE BY IMMU RESPONS CATEGOR
12% 10% 8% 6% 4% 2% 0%
HIGH AVERAGE
LOW
DISEASE OCCURRENCE BY IMMUNE RESPONSE CATEGORY LOW