Milk Protein Polymorphism Research Articles

Milk protein polymorphisms and casein haplotypes in Blanco Orejinegro cattle of Colombia

The aim was to determine the genetic variation in the CSN1S1, CSN2, CSN1S2, CSN3 and LGB genes in Blanco Orejinegro cattle. 419 animals from 15 herds were genotyped with GGP Bovine 150 K (n= 70) and 50 K (n= 349) chips. Information was obtained from 43 SNPs in the mentioned genes and protein variants *B, *C and *D of αS1-CN; *A1, *A2, *B, *H2 and *F of β-CN; *A and *D of αS2-CN, *A, *A1, *B, *I and *H of κ-CN and *A, *B, *C, *D, *E, *F and *H of β-LG were reconstructed. Allele and genotypic frequencies were estimated for SNPs and for protein variants; Hardy-Weinberg equilibrium and FST values were evaluated for each of the SNPs under different structuring criteria. LD values and haplotypic frequencies were estimated for caseins. The most frequent variants were CSN1S1*B (0.804), CSN2*A2 (0.509), CSN1S2*A (0.997), CSN3*A (0.679) and β-LG*B (0.657). None of the variants showed deviations from HWE, but the CSN2*A2 allele showed a slight increasing trend over time. The FST values were low (0.035) regardless of the structuring criteria. Twenty-eight CSN1S1-CSN2-CSN1S2-CSN3 haplotypes were found, 22 of them with frequencies <5%; the three most frequent were BB-A1A2-AA-AA-AA-AA (16.6%), BB-A1A2-AA-AA-AA-AB (14.1%) and BB-A2A2-AA-AA-AA (10.1%). A good potential of BON cattle to produce high quality milk with functional value was reported.

Milk protein polymorphisms of Aosta Valley cattle breeds

Abstract Cow’s milk proteins are encoded by highly polymorphic genes characterized by several mutations which result in different allelic variants. Each allelic variant has different possible effects on cheese-making properties and on human health. β-casein A1-A3-I-B, k-casein B and β-lactoglobulin B are supposed to influence milk cheese-making properties by increasing cheese or milk yield, by varying chemical parameters, by having small casein micelle size, and by influencing rennet coagulation time (RCT) and curd-firming rate (CFR). In addition, β-casein A1-B are also considered to be a risk factor for different health diseases such as ischemic heart disease (IHD), type 1 diabetes (T1D), decreased glutathione (GSH) concentration, and milk intolerance. An LC-MS method was applied to profile, for the first time, the main milk proteins genetic variants from Aosta Valley autochtonous cattle breeds. Analyses performed on milk collected from bovines of three cattle breeds (Red Pied – VRP, Black Pied – VNP and Chestnut – CAS), either from IAR experimental farm or from herds of dairy-producers in Aosta Valley region, showed quite high frequencies of β-casein A2 and A3/I, and low frequencies of β-casein A1. Moreover, low frequencies of β-casein B in VRP breed and high frequencies of the same variant in CAS, and VNP breeds have been found. As far as k-casein is concerned allelic variant B is the most diffused in VRP while allelic variant A in VNP and CAS breeds. Finally, β-lactoglobulin most diffused allelic variant for all breeds is B. Results suggest that Aosta Valley milk has good cheese-making properties and good frequencies of β-casein A2 which may be related to beneficial effects on human health. In light of these results, it is important to develop breeding programs which take into consideration milk proteins polymorphisms to further increase the milk suitability for cheese-making process and to decrease the presence of β-casein A1 and B in drinking milk which can be a risk factor for human health.

Identification of the coagulation properties of Chinese Holstein bovine milk: Effects of milk compositions, milk protein polymorphism, and phosphorylation levels on milk coagulation ability

Milk coagulation ability plays critical roles in cheese production. To assess the effects of milk composition, protein polymorphisms, and phosphorylation levels on milk coagulation properties, milk samples were collected from 3625 Chinese Holstein cows and milk was pooled based on their coagulation properties. The results showed that good coagulating milk had shorter rennet coagulation time and higher gel firmness with tighter connections within the formed gel. Multiple factors were observed to differ among milk with different coagulation ability. For example, lower milk pH, higher amounts of proteins and casein, were related to good coagulation properties. The salt distributions also influenced milk coagulation ability. Especially the calcium content has a large influence on milk coagulation. This may be due to its influence on the aggregation of paracasein micelles in the secondary phase of rennet coagulation. Protein polymorphisms and phosphorylation degrees were found being higher in non-coagulating milk. The proteomics results showed that lower amounts of αS1-casein may result in non-coagulation. Differences of milk fat globule membrane proteins were also observed among milk samples with different coagulation ability, possibly being related to milk protein and fat synthesis, in turn influencing the coagulation process. In addition, Ser76 of αS2-CN was found being highly phosphorylated in non-coagulating milk which may be related to its binding with other caseins during the second phase of rennet coagulation. Of these factors, salt distribution, mainly calcium and magnesium, may be the most important factor affecting casein structures and thereby milk coagulation. Importantly, these factors can affect each other while forming the cheese matrix, resulting in a complex relation with milk coagulation.

MOLECULAR GENETIC MARKERS IN GOAT BREEDING

Introduction. The study of the genetic structure of the goat population by candidate genes associated with indicators of animal development and milk productivity is a promising direction, because the developing industry requires the introduction of advanced research methods. The use of methods of molecular genetic analysis can supplement breeding work to create optimally productive herds. In this connection, research is actively being conducted to study the influence of milk protein and hormone gene polymorphisms on milk productivity.
 Materials and methods of research. This work was carried out as a search for molecular genetic markers of productive traits in goat breeding, based on research in the world scientific literature on this topic.
 Research results. Goat breeding is an important branch of world animal husbandry. Goats are bred in all parts of the world, but the distribution of breeds in terms of productivity varies depending on the consumption tradition. For example, Europe is characterized by a predominance of dairy breeds, in Asia combined breeds, and in Africa meat breeds of goats are most often bred. The largest population of goats is kept in Asia and Africa. Significant producers of goat milk in the world are India, Bangladesh, Pakistan and Sudan. Global production of goat meat has increased by 41.66% over the past few years. Asia has the largest contribution to total meat production (70.7%). The leader in meat production is China, which produces 35.89% of goat meat from the entire world production. Goat breeding is widespread due to the ability of small cattle to easily adapt to different management systems and the ability to adapt to various climatic conditions and features of the terrain. A review of the world scientific literature confirms the fact that countries with significant demographic growth are most interested in selection work in goat breeding, taking into account genotyping by allelic variants of candidate genes for productive traits.
 Conclusions. As a result of the work, two proteins associated with quality indicators of milk were selected as candidate genes for productive traits: kappa-casein and beta-lactoglobulin, and two hormones that indirectly affect the growth and development of animals: leptin and somatotropin. The article briefly describes their functions in the body and the localization of the corresponding loci in the genome of animals. These markers are widely used for researching populations of cattle, goats and sheep in the world. This search for molecular genetic markers is aimed at carrying out similar studies in Ukraine to promote selection work in goat breeding.

Relationship between Milk Protein Polymorphism and Selected Cows' Reproductive Indices.

This research sought to determine the effect of selected milk protein polymorphisms on the reproduction parameters of 598 black and white Polish Holstein-Friesian cattle. The analyzed genes were kappa-casein (CSN3) and beta-lactoglobulin (BLG). The following reproductive indexes were selected: the age at first calving, the interpregnancy period, the calving interval, and the insemination index. The influence of the identified genotypes on the course of parturition in cows was also analyzed. Source data were collected for each cow from the beginning of the herd life and reproduction to its culling from the herd or the end of its third lactation. Data on the age at first calving, the amount of semen portions for artificial insemination (insemination index), the interpregnancy period, and the calving interval for each cow were also collected. A contingency analysis was performed through contingency tables using a Pearson's chi-squared test for each CSN3 and BLG genotype. The results show that the BB genotype of the kappa-casein gene was associated with the most favorable values of reproductive indicators. In the case of the calving interval, the values were significantly more favorable than those of other genotypes (p ≤ 0.05). No effect of beta-lactoglobulin polymorphism on the analyzed reproductive indices was observed. On the other hand, in the case of the interpregnancy period, significant statistical differences were obtained between the AA and BB genotypes. The analyzed kappa-casein and beta-lactoglobulin genotypes did not significantly influence the course of parturition in cows. To conclude, the genotype polymorphism BB CSN3 is the most favorable for the performance of the cows in the examined herd.

Comparative Analysis of the Protein Composition of Goat Milk from French Alpine, Nubian, and Creole Breeds and Holstein Friesian Cow Milk: Implications for Early Infant Nutrition.

Simple SummaryGoat’s milk is a food that contains proteins of value for nutrition. The protein profile in the milk of goat breeds is different from that of cow milk, with a lower relative abundance of allergenic proteins. In addition, regardless of the breed, goat milk has beta-casein of type A2 in a more significant proportion than cow milk, which impacts different bioactive peptides hydrolyzed in the milk of the species.Of the diversity of proteins and high digestibility, goat milk will be a food of significant value for infant nutrition. The genetic polymorphisms of milk proteins play an essential role in the different degrees of allergic reactions. This work aimed to identify the proteins and peptides in the composition of goat milk and compare them to those in cow’s milk. The work was performed with goats French Alpine, Nubian, and Creole breeds and Holstein Friesian milking cows at the Universidad Autónoma de Querétaro, Amazcala. We investigated the relative abundance of goat and cow milk protein fractions by SDS-PAGE resolution and the densitometric analysis of gels. The protein alfa-casein was (17.67 ± 0.46) for Creole, (19.18 ± 0.88) French Alpine, (17.35 ± 0.49) Nubian, and (35.92 ± 1.96) Holstein cows. The relative abundance obtained from alfa-casein was statistically different between goats and cows, and this protein was vital because it is a protein related to allergies. On the other hand, the amino acid in position 67 of the beta-casein from three goat breeds is a Proline, so it is assumed that the beta-casein variant of goat milk is an A2-type. The latter has excellent relevance for infant nutrition and differs from cow milk.

Поліморфізм гена капа-казеїну у корів різних порід молочного напряму продуктивності

Genetic polymorphism of milk proteins, in particular kappa-casein, is of considerable research interest due to its possible associations with economically important traits of dairy cattle. The aim of the study was to determine the polymorphism of the kappa-casein gene and its association with signs of milk productivity in cows of different breeds. Polymorphism of the kappa-casein gene was studied in cows of Ukrainian red-spotted dairy (UCHERM), Ukrainian black-spotted dairy (UCHRM), Montbeliard (M) breeds and crossbred cows obtained by crossing cows of Ukrainian red-spotted dairy breed with Mongolians. DNA studies were performed in the Department of Animal Genetics and Biotechnology of the Institute of Animal Breeding and Genetics nd. a. M.V.Zubets NAAS using the PCR-RFLP method. As a result of research, three genotypes of the kappa-casein gene were identified: AA, AB, BB. Genotypes AA and AB were found in all studied groups of cows, genotype BB was found only in cows of Montbeliard breed with a frequency of 0.366. The highest hopes for 305 days of the first lactation among all studied cows were in crossbred cows with genotype AB (7029 kg), the lowest - in crossbred animals with genotype AA (6359 kg). According to the distribution of genotypes and alleles of the kappa-casein gene, domestic breeds of UCHRM and UCHERM are similar in genetic structure and have a low concentration of B-allelic variant, apparently due to the fact that these breeds were created by reproductive crossing with Holstein breed, in populations of which this allele quite low. The presence of such genotypes in the studied groups of first-borns is determined by the peculiarities of selection work in the herd of SE "DG" Niva "of the Institute of Animal Breeding and Genetics named after MV Tooth of NAAS ». Research results genotypes and alleles of the kappa-casein gene is an additional genetic characteristic of animals, which makes it possible to create herds with the desired characteristics of milk productivity

​Importance of Genetic Polymorphism of Goat Milk Proteins on Human Nutrition and Health: A Review

The objective of the study is impotance of casein protein genetic polymorphism of goat milk. Goat milk is highly digestible and has medicinal properties in human being. Goat milk and its value added dairy products have higher demand in many contries of world. Due to evolution process, much genetic variability has been developed in casein protein genes. This is originatd due to point mutation; addition/deletion and many other factors lead to huge genetic variation in goat casein genes. Because of this goat milk, chemical and biological properties have been affected. Goat milk casein contents decide the cheese making properties as well as nutritional and medicinal values. Goat milk is good alternative source of nutrition in human when people have cow milk problems. Goat milk has humerous inactive bioactive peptides in their casein protein. These have important place for human health and nutrition. In the future, this is great possibility for development of medicinal value functional dairy products from functional bioactive peptides.

Influence of milk protein polymorphism of Italian Brown and French Holstein cows on curd yield

The influence of protein polymorphism on curd yield from the milk of 16 Italian Brown (IB) and 18 French Holstein (FH) primiparous cows was evaluated. The cows were bred on the same farm and fed with the same ration ad libitum. The chemical composition and protein polymorphism were determined in individual milk samples. The amount of real curd yield was monitored at 72 h and evaluated by micro cheese-making. For the same κ-CN genotype, FH primiparous cow produced more milk (+36.13%) with lower protein content than IB primiparous cow, resulting in a lower curd yield. IB primiparous cows presented a higher frequency of κ-CN BB genotype and preserved a better body condition score (BCS) (+0.57 BCS points P < 0.0008) at the end of lactation.

Genetic diversity and population structure in divergent German cattle selection lines on the basis of milk protein polymorphisms.

The aim of this study was to analyze the genetic structure of the casein cluster in eight selection lines of the Holstein Friesian (HF), German Simmental (GS) and German Black Pied cattle (“Deutsches Schwarzbuntes Niederungsrind”, DSN) breeds. A total of 2962 milk samples were typed at -casein (-CN), -casein (-CN), -casein (-CN) and -casein (-CN) loci using isoelectric focusing. The number of alleles per locus ranged from one (-CN) to five (-CN), and the average expected heterozygosity and polymorphic information content of all loci were 0.33 and 0.27, respectively. The unrooted dendrogram revealed that the selection lines of the endangered DSN breed were clearly separated from the HF and GS breeds due to their predominance of the -CN A1 allele and the comprehensive haplotype BA1A (in the abbreviation of ---CN). Temporal changes in allele distributions indicated decreasing genetic diversity at the casein loci, explaining the moderate level of genetic differentiation among selection lines (7.1 %). The variability of the casein should be exploited in future using breeding programs to select genetic lines for specific protein production in bovine milk but also to preserve biodiversity.

Элементарный анализ ассоциаций генетических маркеров с полигенными признаками в популяции крупного рогатого скота

The results of the use of genetic markers of the first and second types in the breeding of farm animals and veterinary medicine are reviewed. The results of the study of relationships between mendelating candidate genes and markers with alleles of complex traits are contradictory. To increase the effectiveness of research, a comprehensive population-hybridological approach to the analysis of relationships of the first type markers with breeding traits is proposed. The effectiveness of this approach is demonstrated by studying the relationship between milk protein polymorphism and the signs of milk productivity in the population of Kholmogorsky cattle. According to β-Cn (CSN2), the association of the β-CnA2 allele with increased milk productivity of cows was established at the population level. The genetic determination of the identified association was confirmed by family (segregation) and twin analysis. No associations were found for β-Lg (LGB) at the level of the population as a whole and for subpopulations stratified by breeding status. The relationships of β-lactoglobulin polymorphism with milk yield in the samples representing individual breeding plants turned out to be multidirectional, but statistically significant in five cases out of five at a significance level of P&lt;0.05. In the herds of the two leading breeding plants, the "marker effects" remained unchanged by sign for several generations. With perfect similarity in the frequencies of the β-Lg genes, opposite associations were observed in these breeding plant herds. In the offspring of heterozygous producers from the analyzing crosses between the mendelating genes and the quantitative trait polygenes, the associations characteristic of the populations from which the heterozygotes originated were preserved in the direction. The level of selection differentiation of marker alleles depended on the level of average milk productivity of the herd. The paper discusses the influence of environmental and genetic factors on the formation of associations. It is concluded that it is impossible to focus research on obtaining "average" effects of genes in "average" conditions, abstracted from specific genotypic and environmental situations of their manifestation. The solution to this problem is to improve the research ideology, which is currently limited to the registration of reliable associations of markers with polygenic quantitative traits in retrospective reference samples, followed by extrapolation of the results obtained to genetically different populations located in other environmental conditions. In animal breeding (for example, with plant selection), it is necessary to develop a theory of the ecological and genetic organization of a quantitative trait, since the structure and relative contribution of genes to the manifestation of a trait can change depending on variations in environmental conditions.

Quantitative and qualitative detailed milk protein profiles of 6 cattle breeds: Sources of variation and contribution of protein genetic variants

Different fractions of milk nitrogenous compounds (not only caseins) have different effects on the nutritional value of milk, its coagulation and curd firming properties, and its cheese-making efficiency. To assess different sources of variation, especially the cows' breed and genetic variants of the main protein fractions, milk samples were collected from 1,504 cows belonging to 3 dairy breeds (Holstein-Friesian, Brown Swiss, and Jersey) and 3 dual-purpose breeds (Simmental, Rendena, and Alpine Grey) reared in 41 multibreed herds. Beyond crude protein, casein (CN), and urea, 7 protein fractions were analyzed using HPLC, and 5 other N fraction traits were calculated. All 15 traits were measured qualitatively (% of milk N) and quantitatively (g/L of milk). The HPLC technique allowed us to discriminate between the main genetic variants of β-CN, κ-CN, and β-lactoglobulin and thus to genotype the cows for the CSN2, CSN3, and BLG genes, respectively. Data were analyzed using 2 mixed models, both including the effects of herd-date, breed, parity, and lactation stage, and only one also including the effects of the genotypes of the milk proteins. Breed of cow explained 2 to 36% of phenotypic variability for all the N fractions, with the exception of the urea and total casein contents of milk and the urea and β-CN proportions of total milk N. Lactation stage had a considerable influence on the amount (g/L) of almost all the protein fractions in milk, but neither the nonprotein N fractions nor the percentage of milk N protein profile were affected. The inclusion of the CSN2, CSN3, and BLG genotypes in the model explained a large part of the total variability in all the milk protein and nonprotein fractions except urea. It also reduced the variance explained by breed and residual factors. An exception was shown by the proportion of αS1-CN variance explained by breed that moved from 13 to 28%. Similarly, for amount (g/L) of β-CN, the effect of breed became significant (12%), whereas it was almost null before inclusion of genotypes. In terms of percentage of milk N, the genotypes of CSN3 notably affected all the casein fractions, whereas the BLG genotypes had a much greater influence on most noncasein traits. The genotypes of the CSN2 gene exerted an appreciable effect on αS2-CN and not β-CN, as expected. Comparing the 2 models, we were also able to discriminate the effect of the breed on a milk N fraction, both quantitatively and qualitatively, in 2 quotas: the first due to the milk protein polymorphisms (major genes) and the second due to other genetic factors (polygene), after correcting for the effect of herd-date of sampling, parity, and lactation stage. The knowledge about the detailed milk protein profile of different cattle breeds provided by this study could be of great benefit for the dairy industry, providing new tools for the enhancement of milk payment systems and breeding program designs.

Aplicação de marcadores SNP em estudos de diversidade genética em Capra hircus: tendencias, vieses e progressos

Os caprinos (Capra hircus) estão distribuídos mundialmente favorecidos por sua capacidade de se adaptar a condições ambientais adversas. A sua importância socioeconômica, têm recebido atenção em pesquisas com o uso de marcadores genéticos (SNP), que possibilitam esclarecer questões envolvendo mudanças evolutivas e auxiliam na conservação da biodiversidade populacional. Com esta revisão, objetivou-se analisar a contribuição de marcadores SNP em estudos com caprinos, com foco na produção e na conservação genética. Utilizou-se o software de pesquisa bibliométrica Bibexcel para análise das publicações da Web of Science TM, até agosto de 2018, rastreando artigos com marcador genético SNP. Das 53.000 produções científicas registradas para a espécie C. hircus, 390 publicações empregaram os marcadores SNPs. Um total de 59 países apresentou publicações envolvendo o uso de SNPs nessa espécie, sendo a maioria das publicações de países asiáticos e europeus. Os cinco países de maior produtividade em publicações no tópico foram a China, a Índia, a Itália, a Espanha e os EUA. O Brasil apresentou-se na décima primeira posição, com registro de 05 publicações. Várias das palavras-chave foram agrupadas por serem de forma semântica equivalentes e associadas a um tema específico; assim, foi possível identificar 23% das produções científicas associadas ao tema polimorfismo de proteínas lácteas, 23% com aspectos da reprodução, 13% ligadas ao crescimento e ganho de peso; e diversidade genética com percentual de 34%. Estudos de GWAS foram citados em 7% das produções e menos de 1% dos estudos foi associado a características de adaptação.

Milk protein polymorphism in Amiata donkey

Interest in donkey milk for human nutrition has been growing steadily, especially in the therapeutic-diet field, due to its similarity to human milk. Caseins are one of the main allergenic components of milk. Whereas cow milk has a high casein content, in donkey milk the casein concentration is lower and is characterized by a greater digestibility. In fact, recent studies have shown that donkey milk can be consumed by children with cow milk protein allergy. The aim of this study was to evaluate the protein profile of individual samples of Amiata donkey milk and to quantify the different protein fractions in order to better understand the characteristics of donkey milk. Protein fractions of 57 individual whole milk samples were analysed by isoelectric focusing (IEF). The main milk protein fractions were quantified both by IEF gel image analysis and directly on milk using the Agilent 2100 Bioanalyzer. The IEF analysis identified 10 different electrophoretic patterns, which differ from each other in terms of the presence of bands that correspond to homozygous or heterozygous genotypes, as well as the presence/absence of specific protein bands. In addition the quantification of different caseins (αS1, β and κ-CN) and whey proteins (β-LG, α-LA and LZ), highlighted a significant phenotypic variability among individuals which seems to be related to the patterns identified. In particular, different casein:whey protein ratios were identified among jennies and this is known to affect the nutritional, allergenic and technological properties of milk. These findings could be useful in the selection of donkeys with specific milk protein polymorphisms.

Milk composition traits in Jamunapari goats: Genetic parameters and effect of CSN1S1 gene variants

Milk protein polymorphism was analysed to improve the protein content in milk. The present study characterises the CSN1S1 gene and the effect of allelic combinations on milk composition traits in Jamunapari goats. The allelic variants obtained from sodium dodecyl sulfate polyacrylamide gel electrophoresis and polymerase chain reaction–restriction fragment length polymorphism were confirmed by cloning and sequencing. Genetic parameters were obtained from 518 records from 48 sires and 131 dams. The A, B and F alleles were observed in the population and the protein percentage in milk was significantly (P &lt; 0.01) affected by allelic variants. The frequencies of A, B and F alleles were 0.456, 0.503 and 0.041, respectively. The protein content in milk was highest in the goats with AB genotype followed by AA &gt; BB &gt; BF &gt; AF &gt; FF. The goats with AB genotype had a significantly (P &lt; 0.01) higher protein percentage in milk than goats with BF (t = 5.311, df = 113), AF (t = 8.13, df = 123) and FF (t = 9.55, df = 115) genotypes. The direct heritability for protein percentage was 0.441. Parity and season of birth had significant effects (P &lt; 0.05) on the solids‐not‐fat percentage and lactose concentrations. The CSN1S1 AA, AB and BB genotypes should be selected for higher protein content and to improve milk quality and processing traits in Indian goats.

ИСПОЛЬЗОВАНИЕ МАРКЕРНОЙ СЕЛЕКЦИИ В ПЛЕМЕННОЙ РАБОТЕ СО СТАДОМ МОЛОЧНОГО СКОТА РАЗНЫХ ПОРОД

Dependence on imports of main food products remains unchanged in the Russian Federation. Government programms set goals to increase quantity as well as quality of manufactured products. It is possible due to the introduction of a DNA technology into dairy cattle breeding. Reliable genetic markers of a cow protein milk ability are kappa casein and beta-lactoglobulin. We have studied milk proteinpolymorphism, genotype combinations in interconnection with milk ability and breed for the Ayrshire, Holstein and Holstein-Yaroslavl cross breed cows. It was found that in the same conditions and with the balanced feeding differences in milk yield and quantity of fat in milk among breeds are statistically unreliable while in milk protein quantity the difference is highly reliable D ≥ 0,999. There is high occurrence frequency of A kappa casein allele (0,74– 0,93) and low of kappa casein allele B (0,07–0,12), especially in case of the Ayrshire breed. B-allele of beta-lactoglobulin in the genotype of all cows is seen with the frequency of 0,58–0,70, A-allele is average (0,30–0,42). In order to increase the protein milk ability of the cows farms are to use more Ballele kappa-casein servicing bulls. Target breeding according to this characteristic as well as milk yield is also recommended.

Influence of genetic polymorphism of milk proteins to the qualitative composition of milk in animals of black-motley breed

Influence of genetic polymorphism of milk proteins to the qualitative composition of milk in animals of black-motley breed

Genetic diversity of milk protein beta-lactoglobulin and association with production traits genomic values among Holstein cattle

The aim of the study was to evaluate the prevalence of beta-lactoglobulin genotypes in Lithuanian Holstein dairy cattle population and to identify possible synergies between the different genotypes of beta-lactoglobulin and genomically predicted values for milk production traits. DNA samples were collected from Holstein cattle (147) and bovine beta-lactoglobulin gene polymorphism study was performed by PCR-RFLP method. A allele was identified with frequency 0.456, B allele, which can be used to carry out selection to improve milk processing properties, was found with 0.544 frequency. Three genotypes, viz. AA, AB, BB at different frequencies were identified. The biggest influence on the milk processing properties having BB genotype was found in 27.3% of the cows. Beta-lactoglobulin AA genotype cows had higher average genomic values for milk yield, while BB genotype cows had higher average genomic values for milk protein percentage, the differences have found statistically significant. Dispersion analysis showed that beta-lactoglobulin genotype influences 8.4% of milk amount genetic variation, 1.2% of milk protein amount genetic variation and 20.6% of milk protein percent genetic variation. Lithuanian Holstein cows population had higher average genomic prediction values for milk yield, milk protein amount and milk percentage than average genomic values of Igenity reference animal group. The existence of the most important genotype BB of beta-lactoglobulin for milk manufacturing properties, in studied population increases the possibility of selecting cows according to milk protein polymorphism, and could be economically important selection criteria for dairy herds designated for industrial milk production.

Relationships between milk protein polymorphisms and production traits in cattle: a systematic review and meta-analysis

Abstract. Many researchers who have studied the relationships between milk protein polymorphisms and some yield traits in dairy cattle have reported incompatible results. In this study, in order to examine the overall relationships between milk protein genes known as major genes (CSN1S1, CSN2, CSN3, and BLG) and some yield traits (daily milk yield, lactation milk yield, fat yield, fat content, protein yield, and protein content), a meta-analysis was performed using some genetic models reported in the results of previous studies on cattle. The results suggest that the relationships of major milk protein genes with other factors should be studied using the codominant genetic model in general. Relationships among some CSN3 genotypes and fat yield, fat content, and protein content, and relationships between some BLG genotypes and daily milk yield, fat content, protein yield, and protein content were significant (P&lt;0.05). No significant (P&gt;0.05) relationships were found between these genotypes and other milk production traits. In addition, no significant (P&gt;0.05) relationships between the CSN1S1 and CSN2 genotypes with the milk production traits examined were observed.

Milk Protein Polymorphism Characterization: a Modern Tool for Sustainable Conservation of Endangered Romanian Cattle Breeds in the Context of Traditional Breeding

The paper aims to review literature data with respect to Romanian native cattle breeds which are considered at risk of extinction. In the last decades, the number of individuals of Romanian indigenous cows decreased significantly, as a consequence of the intensification and specialization of animal productions and agriculture modernization. Some of the native cattle breeds are already lost, due to their crossing with improved breeds. However, after the accession of Romania to the European Union, various preservation programs were initiated, and most of them included biochemical research and studies of molecular or quantitative genetics. All these, associated with the application of reproduction biotechnologies, give a chance to these animals, which are extremely valuable in terms of their genetic resistance to diseases and environmental factors. The reviewed literature on Romanian indigenous endangered cattle breeds confirms that these animals are carriers of a valuable gene pool, which can be kept and bred while applying different reproductive biotechnologies. Consequently, this paper raises awareness on two issues: the decrease of genetic diversity in two Romanian native cow breeds threatened with extinction (Grey Steppe and Romanian Pinzgauer); and the benefits of genetic diversity of the two breeds.