Association of kappa-casein glycosylation with milk production and composition in Holsteins.
A total of 545 milk samples were collected from 53 Holstein cows for 1 yr. On test day, morning milk yields were recorded; milk samples were analyzed for N-acetylneuraminic acid, protein, fat, casein, kappa-casein, and SCC. the relationship between the degree of glycosylation of kappa-casein and morning milk yield and composition was investigated. Data were analyzed using least squares procedures with a model that included test day, parity, stage of lactation, SCC, and phenotype for kappa-casein as fixed effects and N-acetylneuraminic acid content of kappa-casein as covariate. After adjustments were made for effects of environmental and genetic factors, the degree of glycosylation of kappa-casein was associated with morning milk yield, protein, and casein content. Milk yield increased linearly with an increase of N-acetylneuraminic content up to approximately 70 micrograms/mg of kappa-casein.
Robitaille
G
G
Department of Animal Science, Macdonald College, McGill University, Ste. Anne de Bellevue, PQ, Canada.
Ng-Kwai-Hang
K F
KF
Monardes
H G
HG
D000818:Animals; D002364:Caseins / Q000032:analysis / Q000378:metabolism*; D002417:Cattle / Q000502:physiology*; D005260:Female; D006031:Glycosylation; D007774:Lactation; D016018:Least-Squares Analysis; D008055:Lipids / Q000032:analysis; D008892:Milk / Q000032:analysis / Q000378:metabolism*; D008894:Milk Proteins / Q000032:analysis; D008954:Models, Biological
D002364:Caseins; D008055:Lipids; D008894:Milk Proteins