Casein Polymorphism Research Articles

Polymorphism of the <i>Kappa Casein</i> gene and milk production in cows resulting from crossbreeding with holstein or montbeliarde in the peri-urban area of Bamako

The objective of this contribution is to study the polymorphism of the kappa casein gene in crossbred cows in the peri-urban area of Bamako. Fifty (50) cows, including 22 Montbeliarde crosses and 28 Holstein crosses, were subjected to descriptive analysis comparing average milk production and milk fat and protein percentages and genetic analysis of the kappa-casein gene and its interaction with the crossbred types or breed. The results showed 2 types of crosses for each breed, ½ and ¾ exotic blood. The average daily milk production was 8.2±0.46 kg/d for the Holstein crosses and 7.2±0.73 kg/d for the Montbeliarde crosses with a significant difference. No significant differences were observed for the fat and protein content between Holstein crosses (3.56 ± 0.14% and 3.68±0.02%) and Montbeliarde crosses (3.79 ± 0.10% and 3.74±0.02%). Genetic analysis revealed three genotypes of kappa casein (AA, AB and BB). The AA genotype (0.5) was the most frequent followed by AB (0.41) and BB (0.09). A close link was observed between milk production and the polymorphisms of the kappa casein gene. Individuals with the AB genotype had the highest daily milk production followed by individuals with the AA genotype and those with the BB genotype with respective mean values of 8.6±0.64 kg/d; 7.3±0.56 kg/d and 6.6±1.58 kg/d. Individuals of the BB genotype presented a higher fat content (4.0±0.08%) than that of the other genotypes. The mean milk protein content varied little among the genotypes. These results will contribute to the strengthening of knowledge on the genetic effects of kappa casein polymorphisms on milk production performance and milk composition of crossbred cows in Mali.

Bovine beta casein polymorphism and environmental sustainability of cheese production: The case of Grana Padano PDO and mozzarella cheese

Several genetic variants of β-casein have been identified but A1 and A2 are the most common. Bovine β-casein variants may play an important role on cheese yield and quality, besides milk production and composition, and, thereby, affect environmental sustainability of cheese production processes. The aim of the study was to investigate the possible effect on environmental sustainability of cheese production, related to bovine β-casein polymorphism. A Life Cycle Assessment (LCA) was performed, considering Grana Padano PDO and mozzarella cheese, made with either A1A1, A1A2 or A2A2 β-casein milk and using economic and dry matter allocation methods for cheese and co-products. Additionally to characterization, normalization and weighting (endpoints method), were also performed. Results on the environmental impact of 1 kg of packaged cheese showed that, among the β-casein genetic variants, A1A1 seemed to be the most impactful, only due to the lower individual daily milk production of cows belonging to A1A1 group, compared to the cows belonging to A1A2 and A2A2 groups, i.e. 29.6, 37.1 and 34.6 kg of fat and protein corrected milk (FPCM) day cow −1 , respectively. Allocation method strongly affected the impacts per kg of cheese product and, consequently, of co-products. The normalization allowed to understand the relative importance of different impact categories and the result obtained indicated that the notable impact categories of the cheese industry were natural land transformation, aquatic eutrophication and terrestrial acidification. Results of the weighting highlighted that greater damage was given to the ecosystem quality, followed by human health and, finally, resource scarcity. Overall, biggest differences were detected for the two cheeses, rather than for the β-casein genetic variants and the differences in environmental sustainability of cheese made with A1A1, A1A2 and A2A2 milk were mainly due to the different cow milk production, rather than cheese yield. Therefore considering only the technological properties useful for cheese making the selection of milk with A2A2 β-casein may be not so convenient. Normalization and weighting results allow to identify the most impactful categories and so can help decision-makers to determine where to prioritize efforts aimed at reducing cheese environmental impact. • Effect of β-casein polymorphism on environmental impact of cheese was investigated. • LCA of Grana Padano PDO and mozzarella made with different β-casein milk was performed. • A1A1 cows produced slightly lower amounts of milk then A1A2 and A2A2 cows. • Natural land transformation was the most notably affected of the studied categories. • The greatest damage related to cheese production was given to the ecosystem quality.

β casein Polymorphism in Indigenous and Exotic Cattle Breeds of Pakistan

β casein Polymorphism in Indigenous and Exotic Cattle Breeds of Pakistan

First DNA Sequencing in Beninese Indigenous Cattle Breeds Captures New Milk Protein Variants.

This study investigated polymorphisms in the milk protein genes CSN1S1, CSN2, CSN1S2, CSN3, LALBA, and LGB, and casein haplotypes in Beninese indigenous cattle. Considering 67 animals, DNA sequencing of the genes’ exons, flanking regions and parts of the 5′-upstream regions identified 1058 genetic variants including 731 previously unknown. In addition, four novel milk protein variants were detected, including CSN3K (p.Ala66Val), LALBAF (p.Arg58Trp), LGBB1 (p.Ala134Val) and LGBK (p.Thr92Asnfs*13). CSN3K is caused by a novel SNP (BTA6:85656526C>T, exon 4) whereas LALBAF and LGBB1 are due to rs714688595C>T (exon 1) and rs109625649C>T (exon 4), respectively. Regarding LGBK, a frameshift insertion of one adenine residue at BTA11:103257980 (exon 3) induces a premature translation termination resulting in a 46% reduction of the reference protein sequence. The casein polymorphisms formed five main CSN1S1-CSN2-CSN1S2-CSN3 haplotypes including B-A1-A-B, B-A1-A-A and C-A2-A-B which are predominant in the investigated cattle breeds. Moreover, in silico analyses of polymorphisms within the 5′- and 3′- untranslated regions of all six milk proteins revealed effects on microRNA and transcription factor binding sites. This study suggests a large genetic variation of milk protein genes in Beninese cattle, which should be investigated in further studies for their effects on milk production, including quality and yield traits.

Associations between maternal milk protein genotypes with preweaning calf growth traits in beef cattle.

The objectives of this study were to investigate milk casein polymorphisms in dams and to determine the impacts of maternal casein genotypes on growth traits of their sucking calves. Milk samples from 433 dams of the breeds German Angus (GA) and German Simmental (GS) were typed at the milk protein loci α s1-casein (αs1-CN), β-casein (β-CN), α s2-casein (αs2-CN), and κ-casein (κ-CN) via isoelectric focusing. Associations between casein genotypes in maternal milk with growth traits of their 1,872 calves were analyzed until the age of weaning using linear mixed models, considering either genotypes of individual casein loci (model 1) or composite α s1-β-α s2-κ-CN genotypes within the casein cluster (model 2). Besides environmental effects such as sex, age of the dam, and calving year-season, genetic effects (breed group and maternal and paternal effects) were considered in statistical models. The composite casein genotype BBǀA2A2ǀAAǀAB (order of genes on bovine chromosome 6: α s1-ǀβ-ǀα s2-ǀκ-CN) was associated with greater average daily weight gains (ADG) and heavier age-adjusted weaning weights (WW) of calves (P < 0.05). The effects of composite genotypes on birth weight of calves were similar (P > 0.05; model 2). With regard to individual casein loci, greater ADG and WW were observed for calves from dams with the genotypes κ-CN BB and α s1-CN BB, respectively (P < 0.05; model 1). Age-adjusted WW was largest for calves from dams carrying the κ-CN genotype BB (215 kg) compared with calves representing the maternal AB and AA genotypes (both 204 kg). Results from the present study suggested selectable casein genotypes due to their nutritional value of milk (value in terms of offspring performances), offering new perspectives for breeding strategies in beef cattle to improve preweaning calf performance.

Genomic analysis of the origins of extant casein variation in goats

The variation in the casein genes has a major impact on the milk composition of goats. Even though many casein polymorphisms have been identified so far, we do not know yet whether they are evolutionarily ancient (i.e., they existed before domestication) or young (i.e., they emerged after domestication). Herewith, we identified casein polymorphisms in a data set of 106 caprine whole-genome sequences corresponding to bezoars (Capra aegagrus, the ancestor of domestic goats) and 4 domestic goat (Capra hircus) populations from Europe, Africa, the Far East, and the Near East. Domestic and wild goat populations shared a substantial number of casein SNP, from 36.1% (CSN2) to 55.1% (CSN1S2). The comparison of casein variation among bezoars and the 4 domestic goat populations demonstrated that more than 50% of the casein SNP are shared by 2 or more populations, and 18 to 44% are shared by all populations. Moreover, the majority of casein alleles reported in domestic goats also segregate in the bezoar, including several alleles displaying significant associations with milk composition (e.g., the A/B alleles of the CSN1S1 and CSN3 genes, the A allele of the CSN2 gene). We conclude that much of the current diversity of the caprine casein genes comes from ancient standing variation segregating in the ancestor of modern domestic goats.

Evaluation of bovine beta casein polymorphism in two dairy farms located in northern Italy.

Bovine beta casein A1 is one of the most common variants in dairy cattle breeds; it is considered a risk factor in milk intolerance and in other important human diseases, because of the bioactive peptide beta casomorphin-7 (BCM7) produced by raw or processed A1-milk, but not by A2-milk, during digestion. The aim of this study was to perform a cheap and rapid method to investigate beta casein polymorphism in copious animals. The study included 2 dairy farms with a totally of 1230 cows. Beta casein genotypes were estimated evaluating Exon 7 region of bovine beta casein gene (CSN2) by sequences analysis. In the population included in the study 5 variants (A1, A2, B, F, I) and 13 genotypes (A1A1, A1A2, A1B, A1F, A1I, A2A2, A2B, A2F, A2I, BB, BF, BI, FI) were detected. The method showed high sensibility and specificity, resulted low-cost and few time consuming.

Including α s1 casein gene information in genomic evaluations of French dairy goats.

BackgroundGenomic best linear unbiased prediction methods assume that all markers explain the same fraction of the genetic variance and do not account effectively for genes with major effects such as the αs1casein polymorphism in dairy goats. In this study, we investigated methods to include the available αs1casein genotype effect in genomic evaluations of French dairy goats.MethodsFirst, the αs1casein genotype was included as a fixed effect in genomic evaluation models based only on bucks that were genotyped at the αs1casein locus. Less than 1 % of the females with phenotypes were genotyped at the αs1casein gene. Thus, to incorporate these female phenotypes in the genomic evaluation, two methods that allowed for this large number of missing αs1casein genotypes were investigated. Probabilities for each possible αs1casein genotype were first estimated for each female of unknown genotype based on iterative peeling equations. The second method is based on a multiallelic gene content approach. For each model tested, we used three datasets each divided into a training and a validation set: (1) two-breed population (Alpine + Saanen), (2) Alpine population, and (3) Saanen population.ResultsThe αs1casein genotype had a significant effect on milk yield, fat content and protein content. Including an αs1casein effect in genetic and genomic evaluations based only on male known αs1casein genotypes improved accuracies (from 6 to 27 %). In genomic evaluations based on all female phenotypes, the gene content approach performed better than the other tested methods but the improvement in accuracy was only slightly better (from 1 to 14 %) than that of a genomic model without the αs1casein effect.ConclusionsIncluding the αs1casein effect in a genomic evaluation model for French dairy goats is possible and useful to improve accuracy. Difficulties in predicting the genotypes for ungenotyped animals limited the improvement in accuracy of the obtained estimated breeding values.

Identification of an intronic regulatory mutation at the buffalo αS1-casein gene that triggers the skipping of exon 6

The characterization of casein polymorphism is an essential step in order to understand the genetic basis of milk quality in dairy ruminants. In this work, we report the identification of a regulatory mutation at the buffalo αs1-casein (CSN1S1) gene that alters the normal processing of the primary transcript. Sequencing of CSN1S1 cDNA from individuals harbouring this new variant revealed that its most distinctive feature is the loss of exon 6 that encodes eight amino acids between positions 35-42 of mature protein. In an effort to map the causal mutation, we sequenced a genomic region spanning exons 5-7 of the buffalo CSN1S1 gene. This experiment allowed us to establish that exon 6-skipping is produced by a G to C substitution at the first position of intron 6 that inactivates the donor splice site. This mutation can be typed by PCR-RFLP by using either TaaI or Bpu10I diagnostic restriction enzymes, and it has a frequency of 0.18 in Romanian buffaloes. This exon skipping phenomenon is the first one described in buffalo CSN1S1 locus.

Polymorphism of αS1-casein in goat milk: identification of A, B, E and F variants by biochemical and genetic analysis

Many researches, related to genetic polymorphism of αS1-casein in goat milk, showed a marked variability and implications in milk and dairy product traits. The genetic variants (from A to G) were associated with four levels of expression: 3,6 g/L per A, B and C (“strong” alleles); 1,6 g/L per E (“medium” allele); 0,6 g/L per F (“weak” allele) and 0 g/L per O (“null” allele). Differences existing among the A, B, C, D, E, F, G and O have been described (Grosclaude et al., 1994). To analyze genetic polymorphism of caseins from goat milk, distinct electrophoretic (Russo et al., 1986; Addeo et al., 1988) and chromatographic techniques........

Divergence at the casein haplotypes in dairy and meat goat breeds

Casein genes have been proved to have an influence on milk properties, and are in addition appropriate for phylogeny studies. A large number of casein polymorphisms exist in goats, making their analysis quite complex. The four casein loci were analyzed by molecular techniques for genetic polymorphism detection in the two dairy goat breeds Bunte Deutsche Edelziege (BDE; n=96), Weisse Deutsche Edelziege (WDE; n=91), and the meat goat breed Buren (n=75). Of the 35 analyzed alleles, 18 were found in BDE, and 17 in Buren goats and WDE. In addition, a new allele was identified at the CSN1S1 locus in the BDE, showing a frequency of 0.05. This variant, named CSN1S1*A', is characterized by a t-->c transversion in intron 9. Linkage disequilibrium was found at the casein haplotype in all three breeds. A total of 30 haplotypes showed frequencies higher than 0.01. In the Buren breed only one haplotype showed a frequency higher than 0.1. The ancestral haplotype B-A-A-B (in the order: CSN1S1-CSN2-CSN1S2-CSN3) occurred in all three breeds, showing a very high frequency (>0.8) in the Buren.

Casein polymorphism in goat's milk

In this review we summarize the current knowledge on the extensive goat casein poly- morphism. Gene structure, and allelic and non-allelic protein variants, characterized by genomic and proteomic analysis, have been described. The effect of genetic casein polymorphism on techno- logical and nutritional properties of goat's milk has been briefly reported. Goat casein genes show a range of different post-translational modifications and complex patterns of splicing, leading to a great heterogeneity of this fraction. In the light of some recent findings, a genomic and proteomic combined approach appears to be the tool of choice in order to gain an exhaustive characterization of these milk proteins. goat's milk / casein fraction / heterogeneity / genetics / proteomics

Characterization of the Casein Gene Complex in West African Goats and Description of a New αs1-Casein Polymorphism

The analysis of casein polymorphisms was carried out in West Africa goat populations: Red Sokoto (n = 57), West African Dwarf Nigeria (n = 27), West African Dwarf Cameroon (n = 39), and Borno (n = 37). The 4 casein genes αs1 (CSN1S1), β (CSN2), αs2 (CSN1S2), and κ (CSN3) were typed at the DNA level. No null alleles were found in any of the genes analyzed. A PCR single-strand conformation polymorphism method was implemented for the identification of CSN1S1*F allele simultaneously with A/01, B/E, N and the new allele. The allele differed from CSN1S1*B by a synonymous transversion TCG→TCT in the codon corresponding to Ser66 of the mature protein. The new allele, named CSN1S1*B′, occurred at a high frequency in all the populations, ranging from 0.295 (West African Dwarf Cameroon) to 0.405 (Borno). A greater frequency was found for alleles associated with high αs1-casein quantity, as has already been observed in the goat populations from the Mediterranean area. The intermediate E allele occurred only in the Red Sokoto and at a low frequency. The faint F allele occurred in 3 populations at frequencies lower than 0.03. Linkage disequilibrium occurred in all the populations, with highly significant differences in Borno, Red Sokoto, and West Africa Dwarf Nigeria, and significant differences in West Africa Dwarf Cameroon. Only 10 haplotypes showed frequencies ≥0.05 in at least 1 of the 4 populations considered, and the overall frequency was >0.1 only for 4 haplotypes: BAAB, B′ACA, ACAB, and BACA (in the order CSN1S1-CSN2-CSN1S2-CSN3). Haplotype BAAB, postulated as an ancestral haplotype in previous studies, was the most common haplotype in all breeds except Borno, where B′ACA was predominant. The results obtained are of considerable significance given that very little information exists on the subject for African goats. The high frequency of strong alleles in the calcium-sensitive caseins as well as the high linkage disequilibrium found among the casein genes in the African breeds analyzed may suggest that specific casein haplotypes have already been selected due to their advantages for nutrition. Haplotypes providing greater protein and casein content would increase the energy content of milk, thus resulting in more favorable growth and survival of young goats and humans consuming the milk.

Focusing on the Goat Casein Complex

The analysis of casein polymorphisms in goat species is rather difficult, because of a large number of mutations at each locus, and the tight linkage involving the 4 casein genes. Three goat breeds from Northern Italy, Orobica, Verzasca, and Frisa, were analyzed at the casein complex by milk isoelectrofocusing and analyses at the DNA level to identify the majority of all known polymorphisms. The casein gene structure of the 3 local breeds at αS1-casein (CSN1S1), β-casein (CSN2), αS2-casein (CSN1S2), and κ-casein (CSN3) was compared with that of Camosciata, a more widely distributed breed. A new allele was identified and characterized at CSN2 gene, which seemed to be specific to the Frisa breed. It was named CSN2*E, and was characterized by a transversion TCT → TAT responsible for the amino acid exchange Ser166 → Tyr166 in the mature protein. The casein haplotype structure is highly different among breeds. A total of 26 haplotypes showed a frequency higher than 0.01 in at least 1 of the 4 breeds considered, with 12, 3, 5, and 19 haplotypes in Frisa, Orobica, Verzasca, and Camosciata breeds, respectively. Only 13 haplotypes occurred at a frequency higher than 0.05 in at least 1 breed. With the molecular knowledge of each locus, the ancestral haplotype coding for CSN1S1*B, CSN2*A, CSN1S2*A, and CSN3*B protein variants can be postulated. A protein evolutionary model considering the whole casein haplotype is proposed.

Casein genetic polymorphisms in goat breeds of Lombardy

RiassuntoPolimorfismo genetico delle caseine in razze caprine allevate in Lombardia. E’ stato condotto uno studio della variabilità genetica delle caseine in sei razze caprine allevate in Lombardia. La tipizzazione, condotta a livello proteico mediante isoelettrofocalizzazione, è preliminare ad un approccio molecolare dettagliato su un numero più limitato di soggetti, scelti in base a particolari fenotipi caseinici.

A molecular genetic approach for traceability of the source milk in cheese

The valorisation of typical cheeses meets the needs of preserving the local country culture and tradition as well of guaranteeing consumer health by the control of all the steps of production (herd, milk quality, cheese making technology). Among the variability factors significantly affecting cheese peculiarity, biodiversity plays an important role (Gandini et al., 1996; Pieragostini et al., 2002). The possibility of identifying or tracing the primary product, mainly the origin breed, by the use of biologic markers, is an important goal for the safeguard and valorisation of national goat cheese. In this field great interest is paid to milk protein genetic polymorphism. A first study was carried out in order to investigate the possibility of tracing the source milk in dairy products. In particular, the use of molecular techniques for the detection of casein polymorphisms.........

EVALUATION OF MILK PRODUCTION OF DAIRY COWS OF THE SLOVAK SPOTTED BREED ACCORDING TO SELECTION FOR LONGEVITY AND GENETIC VARIANTS OF POLYMORPHIC PROTEINS IN MILK

Milk performance of 681 cows of Slovak spotted breed was evaluated according to the genetic variants of the polymorphic proteins determined by starch gel electrophoresis. In the work the effect of genetic variants of the proteins was analysed on selected performance (production milk in kg, proteins in % and kg). Differences between the productive characters in testing groups were evaluated according to statistic method of Student ttest. Evaluation of performance was done during productive period between 25 - 162 months. The calculation between groups of homozygotes (=AA+ BB + CC genotypes) and heterozygotes (=AB+AC+BC genotypes) in the system of β – casein showed a statistically significant difference (+++P≤0,001), (table 1, 2) in milk production (183,7 kg) and proteins production (7,6 kg). In the systems of alpha s1 – casein, β – lactoglobulin and κ – casein polymorphisms, the differencies between the testing groups of homozygotes and heterozygotes were not statistically significant (-P≥0,05).

Casein polymorphism and relation between milk production traits

Casein polymorphism and relation between milk production traits

Genetic polymorphism of milk proteins in African Bos taurus and Bos indicus populations. Characterization of variants αs1-Cn H and κ-Cn J

The polymorphism of caseins, a-lactalbumin and β-lactoglobulin was investigated in African Bos taurus (N'Dama, Baoule, Kuri) and Bos indicus (Shuwa Arab, Sudanese Flzlani) populations. The respective frequencies of alleles a and a in the N'Dama (0.89 and 0.11) and Baoule (0.92 and 0.08) breeds were almost opposite to those found in the Shuwa Arab zebu (0.22 and 0.78), a true zebu, which confirms a phenomenon already documented in the literature. Because the a/<t-Cn haplotype was strongly predominant in N'Dama and Baoul( and 0as compared to the asl/K-Cn! haplotype in the Shuwa Arab zebu (0.63), an opposite trend in frequencies was also observed between taurines and zebus at the β-Cn and rc-Cn loci. These results confirm that the polymorphism of caseins provides an efficient marker system to discriminate Bos taurus from Bos indicus origins. The Kuri was at an intermediate position, since, in this population, the a allele predominated as in taurines, while the * Correspondence and reprints

Proteolysis of goat casein by calf rennet

Abstract The proteolytic activity of calf rennet on goat casein (CN) was studied under various conditions which affect cheesemaking and ripening processes (pH, salt, calf rennet concentration and α s 1 -CN polymorphism). Electrophoretic studies showed that goat casein was hydrolysed to give characteristic breakdown products derived from individual caseins (β-I to β-V from β-CN, primary hydrolysis product from α s 1 -CN, para-κ-CN from κ-CN and other degradation products from α s 2 -CN). Both goat β-CN and α s 1 -CN were more sensitive to hydrolysis than their bovine counterparts under the same conditions. The pH did not influence the proteolytic specificity of rennet on β-CN, but rennet activity was highly dependent on the pH. However, in the case of α s 1 -CN, the rate of proteolysis and the nature of breakdown products were pH-dependent. NaCl affected only the rate of proteolysis. After prolonged incubation times, the electrophoretic patterns of hydrolysates produced from whole goat casein by rennet were similar to those produced from isolated β-CN, showing that β-CN and its degradation products are quite resistant to proteolysis compared with α s 1 -CN and its primary hydrolysis product. Rennet hydrolysates of goat casein, containing different α s 1 -CN genetic variants, showed slight differences in the electrophoretic profiles which tended to disappear as hydrolysis advanced.