Exploring Coagulation Properties in Bovine Milk Using Milk Genomics Approaches
Author
Summary, in English
The present thesis showed that the variation in milk composition, and consequently milk gelation properties, could be explained by genetic variation. This genetic variation could be observed between different dairy cattle breeds (SR, DH and DJ), but also within the breeds. Milk from SR cows had poorer milk gelation properties than milk from DJ cows and to some extent also than milk from DH cows. Furthermore, 18% of the SR cows produced non-coagulating milk. However, large variations were found within the SR breed showing that there is room and possibilities for improvement of gelation properties. The variation in gelation properties was best explained by variations in ionic calcium concentration, total calcium content and casein micelle size.
Heritability estimates were found to be moderate to high for the rennet-induced milk gelation properties and compositional traits. The high heritability for gelation properties suggests that this trait can be improved through breeding and that the problem with non-coagulating milk could be eliminated. Composite casein genotypes were found to affect rennet-induced gelation and the most common composite genotype in SR was associated with poorer coagulation properties than five other composite genotypes present within this breed which was suggested to be due to variations in casein micelle size. The study showed that composite αS1-β-κ-casein genotype BB/A1A2/AB and BB/A1A1/AE could be used as markers for good gelation properties in SR milk. Furthermore, new quantitative trait loci (QTL) affecting milk gelation properties have been identified which were not only situated in the casein gene cluster on chromosome 6 but also on other chromosomes. These QTL can be used to pin point new genetic markers for rennet-induced milk gelation properties which can be incorporated into genomic breeding schemes.
With knowledge on how cow genetics affect milk composition and milk gelation properties, both using the well-known genetic protein variants as genetic markers and using the new haplotypes found in this thesis, the best cows and bulls can be chosen for future breeding. This will be economically beneficial for farmers, breeding companies and the dairy industry
Department/s
- Department of Food Technology, Engineering and Nutrition
Publishing year
2014
Language
English
Document type
Dissertation
Publisher
Department of Food Technology, Engineering and Nutrition, Lund University
Topic
- Food Engineering
Keywords
- Bovine milk
- rennet-induced gelation
- milk genomics
- Swedish Red dairy cattle
- milk composition
- technological properties
- cheese
- genetic polymorphism
- quantitative trait locus
- protein profile
- casein micelle
- calcium content
Status
Published
Supervisor
- Marie Paulsson
- Maria Glantz
- Helena Lindmark Månsson
- Anders Andrén
- Hans Stålhammar
ISBN/ISSN/Other
- ISBN: 978-91-87743-00-9
Defence date
23 May 2014
Defence time
10:15
Defence place
Lecture hall D, Chemical Centre, Getingevägen 60, Lund University Faculty of Engineering, Lund
Opponent
- Jacob Holm Nielsen (Prof)