Association of bovine β-casein protein variant I with milk production and milk protein composition.
The aim of this study was to detect new polymorphisms in the bovine β-casein (β-CN) gene and to evaluate association of (new) β-CN protein variants with milk production traits and milk protein composition. Screening of the β-CN gene in genomic DNA from 72 Holstein Friesian (HF) bulls resulted in detection of 19 polymorphisms and revealed the presence of β-CN protein variant I in the Dutch HF population. Studies of association of β-CN protein variants with milk composition usually do not discriminate protein variant I from variant A2. Association of β-CN protein variants with milk composition was studied in 1857 first-lactation HF cows and showed that associations of protein variants A2 and I were quite different for several traits. β-CN protein variant I was significantly associated with protein percentage and protein yield, and with αs1 -casein (αs1 -CN), αs2 -casein (αs2 -CN), κ-casein (κ-CN), α-lactalbumin (α-LA), β-lactoglobulin (β-LG), casein index and casein yield. Inferring β-κ-CN haplotypes showed that β-CN protein variant I occurred only with κ-CN variant B. Consequently, associations of β-κ-CN haplotype IB with protein percentage, κ-CN, α-LA, β-LG and casein index are likely resulting from associations of κ-CN protein variant B, while associations of β-κ-CN haplotype IB with αs1 -CN and αs2 -CN seem to be resulting from associations of β-CN variant I.
Animal Breeding and Genomics Centre, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.Dairy Science and Technology Group, Wageningen University, PO Box 8129, 6700 EV Wageningen, the Netherlands.
M H P W
MH
Visker
B W
BW
Dibbits
S M
SM
Kinders
H J F
HJ
van Valenberg
J A M
JA
van Arendonk
H
H
Bovenhuis
D000818:Animals; D002364:Caseins / Q000235:genetics* / Q000378:metabolism; D002417:Cattle / Q000235:genetics* / Q000502:physiology; D005260:Female; D005838:Genotype; D006239:Haplotypes; D007774:Lactation; D008297:Male; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis / Q000235:genetics*; D010641:Phenotype; D011110:Polymorphism, Genetic / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000662:veterinary
D002364:Caseins; D008894:Milk Proteins
Dutch Holstein Friesian cow; milk protein composition; β-casein protein variant I; β-κ-casein haplotype