RESUMO
First lactation milk yield and percentages of fat, solids-not-fat, and protein were analyzed to determine the possible relationships between 14 polymorphic loci and production in Holstein cows. The polymorphic systems examined were blood groups (A, B, C, F, J, L, M, S, and Z), serum transferrin, and milk proteins (beta-lactoglobulin, alpha s1-casein, beta-casein, and kappa-casein). Several statistical models were utilized. Although results differed according to the analysis conducted, in general, no system had a significant association with first lactation milk yield expressed as a herdmate deviation. Most striking were the relationships between milk protein polymorphisms and percent solids-not-fat and protein deviations; beta-casein and kappa-casein alleles had statistically significant associations with these traits. The F system was significant for percent fat deviations, whereas J x L system interactions were significant for all traits. Degree of heterozygosity over the 14 systems was positively associated with percent protein deviations.
Assuntos
Antígenos de Grupos Sanguíneos/genética , Bovinos/genética , Lactação/fisiologia , Proteínas do Leite/genética , Polimorfismo Genético , Animais , Bovinos/sangue , Feminino , Genótipo , Fenótipo , Gravidez , Especificidade da EspécieRESUMO
Analyses were of lactoferrin and mastitis of milk samples taken every other month from 830 Holstein cows in eight herds for 1 yr. Patterns of variation and amounts in lactation, colostrum, and dry period were similar to reports. In negative mastitis tests of milk samples, lactoferrin content was lower during lactation and lower as age of the cow advanced than for positive tests. However, heritability of mastitis was .14, whereas for lactoferrin was .44 in records of 289 cows. This latter is high enough to be useful but unreliable with large standard error .30. Several sire groups differed significantly.
Assuntos
Lactoferrina/metabolismo , Lactoglobulinas/metabolismo , Mastite Bovina/metabolismo , Animais , Bovinos , Feminino , Lactação , Lactoferrina/genética , Mastite Bovina/genética , GravidezRESUMO
The possible existence of multiple forms in the whey proteins of mare's milk was investigated. When individual milk samples from over 300 animals of various breeds were examined, four forms of an undescribed whey protein could be observed. Based on chemical properties and electrophoretic behavior, this protein has been identified tentatively as Whey1 (Wh1). A single case of heterogeneity in mare's alpha-lactalbumin also was observed. Previously described variation in beta-lactoglobulin could not be confirmed. The results of this study provide further evidence of the widespread, perhaps universal, occurrence of polymorphism in milk proteins.
