Genetics of resistance to mastitis in dairy cattle

Abstract

-Genetic variability of mastitis resistance is well established in dairy cattle. Many studies focused on polygenic variation of the trait, by estimating heritabilities and genetic correlation among phenotypic traits related to mastitis such as somatic cell counts and clinical cases. The role of Major Histocompatibility Complex in the susceptibility or resistance to intrammamary infection is also well documented. Finally, development from molecular genome mapping led to accumulating information of quantitative trait loci (QTL) related to mastitis resistance and better understanding of the genetic determinism of the trait. From economic and genetic analyses, and according to welfare and food safety considerations and to breeders and consumer's concern, there is more and more evidence that mastitis should be included in breeding objective of dairy cattle breeds. Many countries have implemented selection for mastitis resistance based on linear decrease of somatic cell counts. Given biological questioning, potential unfavourable consequences for very low cell counts cows are regularly investigated. Improvement of selection accuracy for mastitis resistance is ongoing and includes: advances in modelling, optimal combination of mastitis related traits and associated predictors, such as udder morphology, definition of global breeding objective including production and functional traits, and inclusion of molecular information that is now available from QTL experiments. mastitis / somatic cell count / genetic parameter / QTL / breeding program / dairy cattle

Genetic variations of the bovine MX1 and their association with mastitis

“…The bovine MX1 has been mapped to the BTA (Bos taurus autosome) 1 (from approximately 143.16 to 143.20 Mb). Alignment of BTA 1 on the radiation hybrid (RH) map of the USDA-MARC cattle database indicated within a specific region (DIK4116), QTLs associated with mastitis and production, such as SCS (Rodriguez-Zas et al 2002;Rupp and Boichard 2003;Daetwyler et al 2008), milk profitability index (Chamberlain et al 2012), and milk protein yield (Heyen et al 1999). Our association analysis showed that g.143181370 T>C and g.143182088 C>T were significantly associated with the mean SCS.…”

Identification mutation of theCACNA2D1gene and its effect on somatic cell score in cattle

“…The candidate gene approach may provide a more direct understanding of the genetic basis for the expression of quantitative differences between individuals (Noguera et al 2003) and revealing genomic regions and specific markers that are associated with traits. In the present study, CACNA2D1 was considered to be a potential candidate gene influencing mastitis, because the cattle CACNA2D1 gene has been mapped to BTA 4q18 (Buitkamp et al 2003) and located within the genomic region of QTL for SCS (Zhang et al 1998;Rupp and Boichard 2003) and nearby SCC (Longeri et al 2006). A novel SNP of the CACNA2D1 gene, which was located in Intron 5, was preliminarily identified by PCR-SSCP and DNA sequencing.…”

“…The cattle CAC-NA2D1 gene has been mapped to BTA 4q18 (Buitkamp et al 2003). It is located within the genomic region of SCS QTL (Rupp and Boichard 2003) and nearby the QTL of SCC (Longeri et al 2006;Daetwyler et al 2008) (http://www.animalgenome.org/ cgi-bin/QTLdb/BT/draw_chro-map?optqtl0,chromos 04,orderqtl0QTL_symbol,scale04,density010, submit0GO). Therefore, the CACNA2D1 gene is considered to be one of the potential candidate genes influencing SCS and mastitis.…”

Bovine P-selectin mediates leukocyte adhesion and is highly polymorphic in dairy breeds

“…It remains to be seen whether this difference translates into differences in the health status of these breed groups. Different cow breeds have, however, been reported to show higher or lower genetic resistance to mastitis (Rupp and Boichard, 2003).…”