Re-sequencing of the casein genes in Swedish Red cattle giving milk with diverse protein profiles and extreme rennet coagulation properties.

Impaired rennet coagulation properties in milk could lead to prolonged processing times and production losses. Heritability for milk coagulation has previously been estimated to be 0.28 to 0.

Effects of genetic variants and sialylation on in vitro digestibility of purified κ-casein.

Milk with different κ-casein (CN) phenotypes has previously been found to influence its gastric digestion rate. Therefore, the aim of the present study is to disentangle contributions of genetic variation and its related sialylation on the in vitro digestion process of κ-CN. Accordingly, κ-CN was purified from milk representing homozygous cows with κ-CN phenotypes AA, BB, or EE and used as substrate molecules in model studies using the INFOGEST 2.

Phosphorylation and glycosylation isoforms of bovine κ-casein variant E in homozygous Swedish Red cow milk detected by liquid chromatography-electrospray ionization mass spectrometry.

Variations in the phosphorylation and glycosylation patterns of the common κ-casein (CN) variants A and B have been explored, whereas studies on variant E heterogeneity are scarce. This study reports for the first time the detailed phosphorylation and glycosylation pattern of the κ-CN variant E in comparison with variants A and B. Individual cow milk samples representing κ-CN genotype EE (n = 12) were obtained from Swedish Red cows, and the natural posttranslational modifications of its κ-CN were identified and quantified by liquid chromatography-electrospray mass spectrometry.

Naturally Occurring Glycosidases in Milk from Native Cattle Breeds: Activity and Consequences on Free and Protein Bound-Glycans.

Little is known about the extent of variation and activity of naturally occurring milk glycosidases and their potential to degrade milk glycans. A multi-omics approach was used to investigate the relationship between glycosidases and important bioactive compounds such as free oligosaccharides and -linked glycans in bovine milk. Using 4-methylumbelliferone (4-MU) assays activities of eight indigenous glycosidases were determined, and by mass spectrometry and H NMR spectroscopy various substrates and metabolite products were quantified in a subset of milk samples from eight native North European cattle breeds.

Comparison of bovine milk oligosaccharides in native North European cattle breeds.

Milk oligosaccharides are of high interest due to their bioactive properties. This study is the first to characterise milk oligosaccharides from native North European cattle breeds, as represented by 80 milk samples collected from eight native breeds originated from Norway (Norwegian Doela cattle and Norwegian Telemark cattle), Sweden (Swedish Mountain cattle), Denmark (Danish Red anno 1970), Iceland (Icelandic cattle), Lithuania (native Lithuanian Black and White) and Finland (Western Finncattle and Eastern Finncattle). Using high-performance liquid-chromatography chip/quadrupole time-of-flight mass-spectrometry, 18 unique monosaccharide compositions and a multitude of isomers were identified.

Comparison of milk protein composition and rennet coagulation properties in native Swedish dairy cow breeds and high-yielding Swedish Red cows.

Recent studies have reported a very high frequency of noncoagulating milk in Swedish Red cows. The underlying factors are not fully understood. In this study, we explored rennet-induced coagulation properties and relative protein profiles in milk from native Swedish Mountain and Swedish Red Polled cows and compared them with a subset of noncoagulating (NC) and well-coagulating (WC) milk samples from modern Swedish Red cows.

Identification of QTL on Chromosome 18 Associated with Non-Coagulating Milk in Swedish Red Cows.

Non-coagulating (NC) milk, defined as milk not coagulating within 40 min after rennet-addition, can have a negative influence on cheese production. Its prevalence is estimated at 18% in the Swedish Red (SR) cow population. Our study aimed at identifying genomic regions and causal variants associated with NC milk in SR cows, by doing a GWAS using 777k SNP genotypes and using imputed sequences to fine map the most promising genomic region.

Association between the bovine milk metabolome and rennet-induced coagulation properties of milk.

The milk metabolomes of 407 individual Swedish Red dairy cows were analyzed by nuclear magnetic resonance spectroscopy as part of the Danish-Swedish Milk Genomics Initiative. By relating these metabolite profiles to total milk protein concentration and rheological measurements of rennet-induced milk coagulation together using multivariate data analysis techniques, we were able to identify several different associations of the milk metabolome to technological properties of milk. Several novel correlations of milk metabolites to protein content and rennet-induced coagulation properties were demonstrated.

Effect of polymorphisms in the leptin, leptin receptor and acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) genes and genetic polymorphism of milk proteins on bovine milk composition.

The relations between cow genetics and milk composition have gained a lot of attention during the past years, however, generally only a few compositional traits have been examined. The aim of this study was to determine if polymorphisms in the leptin (LEP), leptin receptor (LEPR) and acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) genes as well as genetic polymorphism of β-casein (β-CN), κ-CN and β-lactoglobulin (β-LG) impact several bovine milk composition traits. Individual milk samples from the Swedish Red and Swedish Holstein breeds were analyzed for components in the protein, lipid, carbohydrate and mineral profiles.

Genomic selection in relation to bovine milk composition and processability.

Genomic selection is a new technology in which selection decisions are based on direct genomic values (DGVs) or genomic enhanced breeding values (GEBVs). The objective of this study was to evaluate the relations between DGVs and several milk traits important for both the nutritional value and processability of milk. This is a new approach and can be used to increase the knowledge on how genomic selection can be used in practice.

Revealing the size, conformation, and shape of casein micelles and aggregates with asymmetrical flow field-flow fractionation and multiangle light scattering.

Casein (CN) micelles are naturally occurring colloidal protein aggregates present in a dispersed state in milk. In this paper we aim to obtain a detailed description of physicochemical properties of CN micelles over the entire size distribution using asymmetrical flow field-flow fractionation (AsFlFFF) connected to multiangle light scattering (MALS) and refractive index (RI) detection. Conclusions are drawn on the colloidal level regarding shape and conformation by comparison with models of colloidal particles.