Nomenclature of the proteins of cows' milk--sixth revision.

This report of the American Dairy Science Association Committee on the Nomenclature, Classification, and Methodology of Milk Proteins reviews changes in the nomenclature of milk proteins necessitated by recent advances of our knowledge of milk proteins. Identification of major caseins and whey proteins continues to be based upon their primary structures. Nomenclature of the immunoglobulins consistent with new international standards has been developed, and all bovine immunoglobulins have been characterized at the molecular level.

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.

Identification of kappa-casein genotype in Holstein sires: a comparison between analysis of milk samples from daughters and direct analysis of semen samples from sires by polymerase chain reaction.

Two different methods were used to determine kappa-casein genotypes of Holstein sires. In the earlier procedure, genotypes of sires were deduced by analyzing frequency distribution data of kappa-casein variants obtained through typing of milk samples from daughters by electrophoresis. The second method involved direct analysis of DNA obtained from semen samples of the sires.

Relationships of milk protein types to lifetime performance.

Data from 889 cows at five research stations of Agriculture Canada were used to study the effects of alpha s1-casein, beta-casein, kappa-casein, and beta-lactoglobulin loci on herdlife and total yield over fixed parities (one, two, and three parity) and to a fixed age (36, 48, and 61 mo). Actual yields of all cows were utilized to compute total milk regardless of lactational length. The model consisted of station, breed, year of birth, season of birth, and milk protein types with age at first calving as a covariate.

Environmental factors affecting plasmin activity in milk.

A total of 367 milk samples were collected from 43 individual Holstein cows during 1 yr. Samples were analyzed for plasmin activity, total casein, alpha s-casein (alpha s1-casein + alpha s2-casein), beta-casein, kappa-casein, and SCC. Least squares analyses showed that SCC in milk were positively related (r = .

A study of the stability of Record of Performance milk samples for infrared milk analysis.

The effect of switching individual cow Record of Performance milk samples from on-farm Babcock analytical system to centralized infrared analysis was investigated. The effects of lipolytic activity on the signals of the fat (5.73/5.

Variation in milk protein concentrations associated with genetic polymorphism and environmental factors.

Concentrations of alpha s-casein, beta-casein, kappa-casein, beta-lactoglobulin, alpha-lactalbumin, serum albumin, and immunoglobulin in milk from 1888 Holstein cows were determined monthly over the lactation period. Cows were phenotyped for genetic variants of alpha s1-casein, beta-casein, kappa-casein, and beta-lactoglobulin. Least squares analyses showed variations in individual proteins due to parity number, month of test, stage of lactation, somatic cell count, fat content, milk yield, and phenotypes of cows for milk proteins.

Association of milk protein types with growth and reproductive performance of dairy heifers.

A total of 890 heifers was used to study the effects of four milk protein loci (alpha S1-casein, beta-casein, kappa-casein, and beta-lactoglobulin) on heifer growth and reproduction. The additive effects of gene substitutions at the four milk protein loci were significant only in 4 of 56 cases for all traits studied. Dominance effects at alpha S1-casein, beta-casein, and kappa-casein loci were not significant for any traits except beta-casein locus on body weight at first calving.

Effects of milk protein loci on first lactation production in dairy cattle.

A total of 920 cows of Holstein-based H line, Ayrshire-based A line, and cross-bred C line between H and A lines was used to determine the genotypic and gene frequencies of milk protein types and to study the relationships of milk protein loci to first lactation yields. Effects of milk protein loci on first lactation performance were examined using classification and gene substitution models. Gene frequencies at the five milk protein loci studied were similar to those reported in the literature.

Percentages of protein and nonprotein nitrogen with varying fat and somatic cells in bovine milk.

Over 15 mo, 28,390 individual milk samples from 3,600 cows in 62 Quebec Holstein herds were analyzed for crude protein, true protein, nonprotein nitrogen, fat, and somatic cell counts. Unadjusted means with standard errors were 3.51% +/- .

Heritability of milk casein and genetic and phenotypic correlations with production traits.

Individual milk samples were obtained monthly from November 1979 to November 1981 from approximately 2,800 Holstein cows in 63 herds enrolled in the Quebec Dairy Herd Analysis Service. These milk samples were analyzed for fat, total protein, casein, and serum protein. After editing, the data comprised 2,813 lactations representing 109 sires.

Association of genetic variants of casein and milk serum proteins with milk, fat, and protein production by dairy cattle.

Polyacrylamide gel electrophoresis methods were used to phenotype caseins for 2045 cows and milk serum proteins for 3870 cows distributed in 63 Quebec dairy herds. Frequencies were: alpha s1-casein A .003, alpha s1-casein B .

Variability of test-day milk production and composition and relations of somatic cell counts with yield and compositional changes of bovine milk.

Between November 1979 and November 1981, 41,783 test-day observations were obtained from 63 Holstein herds in the province of Quebec. Measured were milk yield, percentages of fat, protein, casein, and serum protein, and somatic cell counts that had unadjusted means with standard errors 20.44 +/- .

Plasma protein patterns in captive American kestrels.

Plasma proteins of the American kestrel (Falco sparverius) were analyzed by polyacrylamide disc electrophoresis for 3 different groups of birds: laying and non-laying females, and males. The electrophoretic patterns were homogeneous for each group and showed differences in the mobility of some proteins among the 3 groups. There was no significant difference among the 3 groups in the amount of proteins and in the standard parameter of albumin to globulin ratio.

Effects of potassium dichromate and sample storage time on fat and protein by Milko-Scan and on protein and casein by a modified Pro-Milk Mk II method.

A rapid procedure is described for measuring casein in milk by a combination of isoelectric precipitation and amido black dye-binding. Individual milk samples from 38 cows were subsampled, preserved with potassium dichromate at a concentration of 8 mg/ml of milk, and analyzed for fat and protein by the Milko-Scan 300 and for protein and casein by the dye-binding procedure on day 1, 4, 7, and 10 after milk collection. Fat tests were not affected by sample storage time, but protein tests showed variation depending on the interval between milk sample collection and analysis.

Environmental influences on protein content and composition of bovine Milk.

A total of 24,405 individual milk samples from approximately 2,800 Holstein-Friesian cows in 63 dairy herds enrolled in the Quebec Dairy Herd Analysis Service program were analyzed monthly for protein, serum protein, casein, and somatic cell counts during 17 mo. Unadjusted means for protein, serum protein, and casein were 3.396% +/- .

Studies on the in vivo uptake and incorporation of 1-14C-labeled D-hexosamines in tissues, mucopolysaccharide-peptide complexes, and glycosaminoglycans of the domestic fowl.

The incorporation of radioactivity from D-[1-14C]glucosamine and D-[1-14C]galactosamine into the tissues of skin, comb, wattle, liver, kidney, spleen, lung, heart, ovaries, egg yolk, infundibulum, magnum, isthmus, shell gland, and vagina of the White Leghorn laying hens was studied for different time intervals up to 120 h. A total of 28 laying hens were involved in this experimentation. The radioactivity was measured in the above whole tissue, the acetone extracts, the acetone-extracted tissues, the mucopolysaccharide-peptide complex (MPS-P), and in individual glycosaminoglycan (GAG) isolated from skin, comb, liver, kidney, and egg yolk.

Glycosaminoglycans of tissues of the domestic fowl.

Mucopolysaccharide-peptide complexes (MPS-P) from skin, comb, wattle, liver, kidney, spleen, lung, heart, ovaries, egg yolk, infundibulum, magnum, isthmus, shell gland, and vagina of the White Leghorn laying hens were isolated after extraction with acetone, papain hydrolysis, and cetyl pyridinium chloride precipitation. They were analyzed for characteristic components of the glycosaminoglycan (GAG) and carbohydrate parts of glycoproteins and for amino acids. The infrared spectra of the MPS-P were studied for detection of the GAG present.