Two novel bovine beta-lactoglobulins I and J have been isolated from bovine milk and characterized by isoelectric focusing. Their primary structure was determined by a very rapid method consisting of a combination of Edman sequencing, mass analysis, and ladder sequencing by mass spectrometry. We found that both new beta-lactoglobulins are of the bovine beta-lactoglobulin B-variant type. beta-lactoglobulin I shows Gly instead of Glu at position 108, whereas beta-lactoglobulin J shows a Pro-to-Leu exchange at position 126.
Zusammenfassung
An zwei umfangreichen Stichproben der bayerischen Fleckvieh‐ und Braunviehpopulation mit jeweils etwa 2000 Tieren wurden bei den Merkmalen Milchserumeiweißgehalt, Caseingehalt, Gesamteiweißgehalt und Fettgehalt pleiotrope Wirkungen von β‐Lactoglobulin‐ und Casein‐Genotypen geschätzt. Alle Genotypen zeigten bei allen Eigenschaften und bei beiden Rassen Einflüsse, wobei zwischen den Wirkungen der Fleckvieh‐ und Braunviehpopulation eine gute Übereinstimmung deutlich wird. Die deutlichsten Effekte zeigten sich bei den Teilmerkmalen Milchserumeiweißgehalt und Caseingehalt. Ein beträchtlicher Teil der Genotypeneffekte verhält sich antagonistisch, so daß Kompensation bei den Hauptmerkmalen vorliegt.
Summary
Pleiotropy of β‐lactoglobulin und casein genotypes on milk composition in Bavarian Fleckvieh and Braunvieh
The effects of β‐lactoglobulin and casein alleles on milk content of whey protein, casein, total protein and fat were estimated on some 2000 cows each of Bavarian Fleckvieh and Braunvieh. The effects of the alleles appeared to be similar in the two populations. The effects were most prominent on whey protein and casein content. Quite a number of alleles affect the contents of the different proteins antagonistically. Therefore the effects on the components of the total milk protein compensate each other.
Résumé
Effets pléiotropiques des génotypes β‐lactoglobuline et caséine dans la composition du lait du Fleckvieh bavarois et Braunvieh
Les effets des alléles lactoglobuline et caséine de la teneur en lait de protéine du petit‐lait, caséine, protéine totale et teneur en graisse ont été estimés à environ 2000 vaches respectives des races Fleckvieh bavorois et Braunvieh. Les effets des alléles semblaient étre similaires dans les deux populations. Les effets les plus proéminents se montraient pour protéine du petit‐lait et teneur en caséine. Un antagonisme fut observé pour un nombre considérable d'effets génotypiques, de sorte qu'il existe compensation pour les caractéristiques principales.
Resumén
Efectos pleiotropicos de β‐Lactoglobulina y Caseína genotipos sobre los componentes de la leche en ganado manchado y pardo bavarico
Los efectos de los alelos de β‐Lactoglobulina y Caseína sobre los componentes de la leche, como proteín séríca de la leche, caseína, proteîna y grasa total fueron estimados en las mismas 2000 vacas, en cada población de ganado manchado y pardo bavarico. Todos genotipos mostraron para todas las propiedades y en ambas razas influencias, donde una buena concordancia pudo ser obtenida entre los efectos de ambas poblaciones. Los efectos más claros se mostraron en el contenido de proteína séríca de la leche y contenido de caseína. Una considerable parte de los efectos genotípicos se portaron antágonicamente, pero mostraron compensación en las características principales.
The genetic variants of bovine beta-lactoglobulin (beta-lg) from the "Murnau-Werdenfelser" breed were analyzed in three different isoelectric focusing (IEF) systems. While carrier ampholyte IEF with a pH gradient of 0.2 pH/cm did not resolve the new variant W from the B variant and IEF in immobobilized pH gradients (IPG) with 0.1 pH/cm only partially resolved it, adequate separation was achieved with IPG-IEF in a pH 5.25-pH 5.7 gradient, in presence of 0.8 % w/v carrier ampholytes, both over a 10 and 17 cm separation distance. Apparent isoelectric points (pI's) and genetic frequencies (f) were as follows: beta-lg A, pI = 5.370, f = 0.364; beta-lg B, pI = 5.485, f = 0.480; beta-lg W, pI = 5.492, f = 0.076; and beta-lg D, pI = 5.610, f = 0.080. The small difference of delta pI = 0.007 between beta-lg B and beta-lg W respectively, seems to originate from a "silent" substitution of neutral amino acid residues as compared to the larger delta pI's of the other genetic variants of beta-lg, which result from substitution of charged amino acids.
Gene frequencies were estimated in a sample of Baladi cattle for milk proteins, blood proteins and blood groups. Gene frequency estimates of Bos taurus, Bos indicus and Sanga breeds were assembled from the literature. The gene frequencies were utilized for estimating the genetic distance between the breeds and breed groups. The Egyptian Baladi cattle appeared to be closer to Bos taurus breeds than to the Sanga. They are far removed from Zebus.
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