Genetic factors affecting susceptibility to udder pathogens

Abstract

11 12Many studies have identified genetic factors underlying resistance or susceptibility to 13 mastitis in dairy cows and heifers. Some authors focused on polygenic variation while others 14 searched for genes and/or quantitative trait loci with major effects on mastitis. Classical traits related 15 to mastitis include somatic cell counts, electrical conductivity and clinical cases of the disease. With 16 the development of automatic milking devices and '-omics' technologies, new traits are considered, 17 such as acute phase proteins, immunological assays, and milk flow patterns, and new biological 18 pathways are discovered, for example the role of mammary epithelium and the nervous system. The 19 usefulness of these traits for identification of resistant cows is discussed in relation to the biological 20 mechanisms underlying the development of the disease. In addition, the utility of these traits for 21 genetic improvement is reviewed. Finally, the problem of durability in resistance is addressed, 22 including co-evolution and the cost of resistance. 23 24

Effect of mastitis during the first lactation on production and reproduction performance of Holstein cows

“…Although we did not see any sire origin effect on the number of mastitis episodes and calving to mastitis interval, sufficient evidence exists that genetic factors may control resistance or susceptibility to mastitis in dairy heifers (Detilleux 2009) and needs to be investigated.…”

Associations between CXCR1 polymorphisms and pathogen-specific incidence rate of clinical mastitis, test-day somatic cell count, and test-day milk yield

“…Resistance to mastitis is genetically determined (Detilleux, 2009), making a decrease in the incidence of mastitis by breeding a possibility (Windig et al, 2010). Identification of genetic polymorphisms linked with mastitis resistance would allow evaluation of the genetic make-up of male and female breeding animals for udder health, even before their offspring is born (Ogorevc et al, 2009).…”

“…Marker-assisted selection against mastitis is a noble goal, but would receive little attention if it would decrease the genetic merit for production (Detilleux, 2009). Unfavorable genetic correlations between CM and MY traits have been described (Koivula et al, 2004).…”

Detection of quantitative trait loci for clinical mastitis in crossbred Holsteins in the tropics

“…An estimation of the genetic correlation between mastitis susceptibility and milk production ranged from 0.24 to 0.55 (Heringstad et al, 2000). Therefore, improvement of milk production tends to be associated with increased risk of mastitis (Detilleux, 2009;Vallimont et al, 2009). Because of the serious effects of this disease, mastitis resistance is generally included in breeding objectives (Carlén et al, 2005;Heringstad et al, 2003a).…”