Milk Protein Polymorphism Research Articles

Blood and Milk Protein Polymorphisms in Relation to Feed Efficiency and Production Traits of Dairy Cattle

The relationship was studied between 14 biochemical polymorphisms, including 9 blood antigens, serum transferrin, and 4 milk protein systems, and 8 quantitative traits consisting of measures of milk composition, feed efficiency, and consumption of dry matter. Data from 184 Holstein cows fed experimentally during their first lactation were over 10 year-seasons from 14 sire groups on 4 different rations. In all cases, ration differences were large (P<.01). Sire differences were next most important and nearly all significant (P<.05). Season was relatively unimportant as a cause of variation in feed efficiency but showed significant differences (P<.05) in most other traits. A difference in dry matter consumption of 163kg between F antigen genotypes and 193kg between M genotypes was significant (P<.05). Differences in feed efficiency up to 3.4% for S antigen genotypes and up to 2.4% for Lg genotypes were significant (P<.05). Analysis with dry matter consumption as a covariate revealed significant genotype differences (P<.05) of up to 542kg milk, 43kg solids-not-fat, 58kg total solids, 45kg fat-corrected milk yield and 2.4% efficiency for the Lg system. Squared coefficients of correlation revealed a contribution of genotype from 0 to 4.9% of the variation in traits.

Milk Protein Polymorphisms in the Kerry Breed of Cattle

Polymorphisms of β-lactoglobulin, β-casein, αs1-casein, and κ-casein were investigated in milk from the Kerry breed using starch-gel electrophoresis. Incidences of protein phenotypes and their controlling genes were compared with those from other European breeds. Milk from the Kerry breed contained only Variant A of β-casein and only Variant A of hemoglobin, thus resembling Northern European breeds, especially the Ayrshire and Shorthorn breeds.

Anomalous Electrophoretic Pattern of Milk Proteins

During investigations on the polymorphism of milk proteins, those proteins designated by Wake and Baldwin (7) as bands 1.00 and 1.04 were not found. This anomaly was found in milks of a few cows. The cause of this phenomenon is not known. Further investigations are in progress.

Milk Protein Polymorphism in Swedish Cattle with Special Reference to Strain Differences within the Swedish Friesian Breed

Milk Protein Polymorphism in Swedish Cattle with Special Reference to Strain Differences within the Swedish Friesian Breed

Studies on Milk Protein Polymorphism in Danish Cattle and the Interaction of the Controlling Genes

In milk samples from 1520 heifers and 542 dams the αsl-, β- and x-casein types and the β-lactoglobulin components, A and B, were determined simultaneously by means of electrophoresis in thin starchurea-gels. The theory of inheritance advanced within each system from previous investigations was confirmed. Family data on the transmission of the two x-casein components A and B are given (Table 3). The frequencies of the controlling genes in Danish cattle were computed for each of the systems (Table 2). With traditional starch-gel-electrophoresis, four components, termed A, B, G and D, could be demonstrated in the β-lactoglobulin (Figs. 3 and 4). The four components are presumed to be controlled by four allele genes. The αsl-, β- and ϰ-casein phenotypes were not independently distributed and the segregation of casein types among offspring from bulls heterozygotic in two or three casein type-systems strongly suggests that the genetic variations of the αsl-, β- and ϰ-casein are controlled by genes at a single locus. Then, a minimum of 8 alleles may account for the phenotypes observed among 521 Danish cows (Table 6). Linkage of less than five per cent recombination could be excluded between the casein types and the β-lactoglobulin types. Mit Hilfe einer Elektrophorese in dunnen Harnstoff-Starkegelen wurde in Milch von 1520 Starken auf den Nachkommenschaftprufungsstationen und 542 Mutterkuhen eine Bestimmung von αsl-, β- und ϰ-Casein sowie β-Lactoglobulintypen vorgenommen. Die Erbhypothesen innerhalb jedem dieser vier Systeme, die auf Grundlage von fruheren Untersuchungen vorausgesetzt worden waren, konnten bestatigt werden. Die Haufigkeit der kontrollierten Gene bei danischem Vieh ist in Tabelle 2 angegeben. Anhand der traditionellen Starkegelelektrophorese sind vier β-Lactoglobulinkomponente festgestellt worden. Diese bekamen die Bezeichnungen A, B, G und D, und es wird angenommen, dass sie von vier allelen Genen kontrolliert werden. Die αsl-, β- und ϰ-Caseintypen zeigen nicht unabhangige Vererbung, und die Ausspaltungsverhaltnisse unter den Nachkommen von heterozygoten Stieren lassen vermuten, dass die Variationen in den drei Gaseintypsystemen von Genen kontrolliert werden, die demselben Locus angehoren. Unter dieser Voraussetzung lassen die beobachteten Phanotypen bei 521 Kuhen sich durch ein Minimum von 8 Allelen erklaren. Eine Kopplung mit weniger als 5 % Uberkreuzung zwischen den Gaseintypen und den β-Lactoglobulintypen kann ausgeschlossen werden. Ved elektroforese i tynde urinstof-stivelsegeler er der foretaget en bestemmelse af αsl-, β- og ϰ-kasein samt β-laktoglobulintyper i maelk fra 1520 afkomsprovekvier og 542 modrekoer. De ud fra tidligere undersogelser fremsatte arvehypoteser inden for hver af de fire systemer har kunnet bekraeftes, og hyppigheder for de kontrollerende gener hos dansk kvaeg er anfort (Tabel 2). Ved hjaelp af traditionel stivelsesgelelektroforese er der pavist fire β-laktoglobulinkomponenter. Disse er benaevnt A, B, G og D og antages at vaere kontrolleret af fire allele gener. αsl-, β- og ϰ-kaseintyperne viser ikke uafhaengig nedarvning, og udspaltningsforholdene blandt afkom efter heterozygote tyre tyder staerkt pa, at variationerne i alle tre kaseintypesystemer er kontrolleret af gener tilhorende samme locus. Under denne forudsaetning kan de observerede faenotyper hos 521 koer forklares ved et minimum af 8 alleler. Kobling med under 5 % overkrydsning kan udelukkes mellem kaseintyper og β-laktoglobintyper.