Analysis of relationships between BoLA-DRB3.2 alleles, mastitis, and milk traits by noninvasive sampling methods
Date Issued
2011
Date
2011
Author(s)
Lin, Jyun-Hong
Abstract
Increasing productivity such as milk yields and milk components is always the main breeding goal for dairy cattle. However, some health traits such as disease resistance have been ignored for a long time. For example, mastitis is an important and world-wide disease in dairy herds and leads to not only add costs, including the expenditures of labors, vet service, drugs, but also the losses from lower production , discarding milk, and culling of cows. Nowadays, it is evident that disease resistance may be genetically determined. Selecting resistance to health problems can reduce the economical losses and increase milk quality, which is important to ranchman and consumers. Consequently, genetic and immunological markers have been widely studied expecting to be used in disease resistance selections.
The major histocompatibility complex (MHC) groups are closely linked to mammalian immune system. For dairy cattle, MHC referred to as the bovine lymphocyte antigen (BoLA) complex, consisting of three classes and being responsible for antigens presentation. Hence, BoLA genes have been examined for various immune issues as well as production traits. The DRB3 locus of BoLA class II is very polymorphic, and exon 2 (DRB3.2) may potentially affect immunity in cattle. In this study, we collected milk samples instead of blood or tissue as the resource of DNA extractions from 23 dairy Holstein cows in NTU Experimental Farm, trying to evaluate the preliminary feasibility of constructing noninvasive sampling methods in dairy herds. Data from Dairy Herd Improvement (DHI) in recently five months were also used to investigate the relationship between somatic cell counts (SCC), milk components, and DRB3.2 alleles. According to the frequency of that SCC reached clinical mastitis we labeled the cows into three classifications, known as resistant group (under 40%), normal (40 to 80%), and sensitive one (100%).
The results showed 17 individuals from 23 dairy cows could be sequenced successfully in PCR-SBT analysis, including six individuals in resistance group, seven in normal, and four in sensitive, respectively. Among these 17 individuals, 11 alleles were found. Alleles *1201 and *2703 were only found in resistance and normal group but not in sensitive one, and this result is in accordance with former study. Individual with allele *1501 homozygous expressed more serious mastitis level and only in sensitive group, which may tend toward inflammation easier. It may be the candidate allele of mastitis in breeding.
Subjects
BoLA
mastitis
cows
Type
thesis
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