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Genetic Factors of Milk Yield in Dairy Cattle – Advances in the Quest for Universal Markers
Żukiewicz, A., Grzesiak, W., Szatkowska, I., Błaszczyk, P. and Dybus, A.
Faculty of Biotechnology and Animal Science, Department of Ruminants Science
Corresponding author: Agata Żukiewicz, Katedra Nauk o Zwierzętach Przeżuwających, Zachodniopomorski Uniwersytet Technologiczny w Szczecinie, Dr Judyma 10, 71-450 Szczecin, Poland. Tel./Fax: 91-449-6800, e-mail: agata.zukiewicz@zut.edu.pl
AB S T RAC T
The current state of knowledge of milk-protein coding genes and prolactin is presented in this review. Genes encoding milk proteins (caseins and whey proteins) are discussed as well as the genes of the factors regulating expression milk protein genes, such as prolactin, prolactin receptor, and the genes of the somatotropic (somatotropin growth hormone) axis (growth hormone, GH-releasing hormone, Pit1 –Pituitary-specific Transcription Factor-1, growth hormone receptor, insulin-like growth factor 1, and STAT5A- Signal Transducers and Activators of Transcription). Also findings on diacylglycerol acyltransferase 1 and leptin genes are reviewed in terms of milk yield traits of dairy cattle. Key words: Milk yield, genetics, dairy cattle, prolactin, somatotropic axis
Milk yield in dairy cattle is governed both by genetic and environmental factors. Animals are subject to constant improvement for this quantitative trait, which is based on phenotype observations of cows and evaluation of the progeny and kins. These processes are both time-consuming and expensive. With the observed advances in molecular genetics, one may presume however that animal evaluation techniques based on differences at the DNA level will be available in the near future. Consequently this may dramatically accelerate genetic improvement of dairy cattle, especially due to genotyping of young animals. The bovine genome was completely sequenced in 2007 (1). About 22,700 genes and about two million SNPs (single nucleotide polymorphisms) were found. The variability of the genotype caused by the simple polymorphisms of the substitution or insertions or deletions is great; however, only a small portion of these are of a functional character. Most associations between the polymorphism at a given locus and the phenotypic variability are virtually meaningless or appears in local populations only. Thus, the research in pursuit
INTRODUCTION
of a functional marker that would be of importance for selection, focuses mainly on protein-coding genes, involved in the processes of lactation, as well as the genes that regulate these complex processes. This review presents a short characterization of milkprotein coding genes and prolactin. GENES ENCODING MILK PROTEINS Casein content in bovine milk ranges from 2.4% to 2.6%, which represents about 78% of all milk proteins (2). There are four primary casein fractions of excellent nutritive value: αS1 (CASA1, CSN1S1), αS2 (CASA2, CSN1S2), β (CSN2, CASB), κ (CSN3, CASK) (2). These forms differ primarily in amino-acid composition, number of polymorphic variants, molecular weight, as well as in their content in milk and the amount of phosphorus. Caseins are encoded for by single autosomal genes that occupy approximately 200 Kbp on the sixth chromosome (2). The linked genes are present in the sequence: αS1, β, αS2, κ, which means that their expression
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Caseins
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Table 1. Milk-yield associated bovine genes and their polymorphism Gene CSN1S1, CASA1 Product αS1 casein Polymorphism 1) Transition A/G, exon XVII, change in polypeptide chain: E 192 G 2) Transition A/G, region 5’ UTR (-175); restriction endonuclease MaeIII CSN2, CASB CSN1S2, CASA2 CSN3, CASK LGB, BLG LTF PRL PRLR GHRH, STH-RH GH, STH β casein αS2 casein κ casein β-lactoglobulin lactoferrin prolactin Prolactin receptor Somatoliberin Somatotropin (growth hormone) Transversion C/A, change in polypeptide chain: H67P (allel A 2), H106E (A3), S122R (B) Transition C/T, promoter (-1084), restriction endonuclease MaeII Double mutation in exon IV, changes in polypeptide chain: T36I, D 148 A, restriction endonuclease HindIII Double mutation C/T, T/C, changes in polypeptide chain D64G, V118A, restriction endonuclease HaeIII 1) Transversion G/C, region 3’UTR (+32) 2) exon VI, restriction endonuclease EcoRI Transition A/G in exon III (or IV, see text). restriction endonuclease: RsaI Transversion A/C, intron 9 (209) Intron 2, restriction endonuclease: HaeIII, 1) Transversion G/C, exon V, change in polypeptide chain: L 127 V, restriction endonuclease AluI 2) Simultaneous insertion and transition TC/G, restriction endonuclease: MspI Transition A/G, exon VI, restriction endonuclease: HinfI 1) Transversion A/T, region 5’UTR (-1182), restriction endonuclease: AluI 2) Transversion T/A, exon VIII, change in polypeptide chain F/Y Transition C/T, restriction endonuclease: SnaBI. 1) Transition T/C, exon XVI (12743), restriction endonuclease: MslI 2) Transition A/G, intron 9 (9501), restriction endonuclease: RsaI, change in polypeptide chain V686A Dinucleotide substitution AA/GC, exon VIII (10433-10434), change in polypeptide chain: K232A 1) Intron 2, restriction endonuclease: SauAI 2) Transition C/T, exon II, change in polypeptide chain: R/C, restriction endonuclease: Kpn2I 3) Transition C/T, exon III, change in polypeptide chain: A/V, restriction endonuclease: HphI Alleles B, C (A, D, E, F–rare) A, G A1, A 2, A3, B, (D, E, C) C, T A, B – most common A, B G, C A, B A, B A, C A, B L, V MspI(+), MspI (-) A, B
Pit1 GHR IGF-I STAT5A DGAT1 LPT
Insulin-like growth factor 1 STAT5A transcription factor Diacylglycerol acyltransferase 1 Leptin
Pit1 transcription factor Growth hormone receptor
+, -
Y, F A, B C, T A, G K, A A, B, C C, T C, T
1), 2), 3) – Polymorphisms within the same gene
during lactation is regulated in a synchronic way. It is possible that a LCR (locus control region) exists for the casein genes. The α-casein coding gene is 17508 bp in length and is built of 19 exons (2). Five genetic variants of CSN1S1 have been identified: A, B, C, D, and E (3). The allele B is of the highest frequency in Bos taurus, whereas C is the most common in B. indicus and B. grunienns (3). The allele B encodes glutamine whereas C encodes glycine, both at position 192. Table 2 presents the effects of particular variants on various milk performance parameters. Some authors studied mutaIsrael Journal of Veterinary Medicine  Vol. 67 (2)  June 2012
tions in the promoter of this gene and their possible effects on the performance of dairy cattle (Table 2). The 8498-bp β-casein gene is composed of 9 exons. Seven variants of CSN2 were identified in cows, i.e. A1, A2, A3, B, D, and E (Table 1), of which A is the most common allele (2). Their associations with milk yield is described in Table 2. The κ-casein coding gene is divided into 5 exons and is 13070 bp long (4). As a result of a double point mutation in exon IV at positions 136 (Thr/Ile) and 148 (Asp/Ala), the gene has two most commonly found alleles, A and B (4). The allele
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Table 2. Effect of particular mutations on milk performance parameters CSN1S1 Milk yield [+] CC (53, 52), [–] BB (54),[0] (55) Fat yield (kg) Fat content (%) Protein yield (kg) [+] CC (52) [+] AG, [–] AA (56), (no ind. GG) [0] (60) Protein content (%) [+] AG, [–] AA (56) (no ind. GG)
[+] AA (55) CSN2 CSN1S2 CSN3 LGB LTF PRL PRL GH GHRH
[+] A1 A1 (20, 57), [–] BB (57), [+] A1 A3 (59) [0] (60)
[0] (61, 62), [–] B (0) (61, 62) (63, 64, 65), [+] B (66, 67) [+] AA (58, 71, 72, 61), [0] (54, 57) [+] CC (73) [+] AA (74) [+] AA (18, 19, 72), [0] (8) [+] CC (25) [0] (76) [0] (8)
[0] (60)
[+] A1 B (58), [+] A 2 A3 (57) [0] (60) [0] (62), [+] B (68, 6, 69, 57) [+] AA (70, 71), [–] BB (58, 61), [0] (54, 57)
[+] A1 B (58), [+] A 2 A3 (57), [–] A1 A3 (59) [0] CC (60) [0] (61, 62), [+] B (68, 6, 69, 60)
[0] (61, 62) [0] (54, 57)
[0] (54, 57)
[+] AA (71), [–] BB (49), [0] (54, 57) [+] CC (73)
[+] AA (18, 19), [0] (16) [+] AA (38,78), [0] (76) [+] VV (82, 80) [+] MspI(+) (84) [–] AA (88), [+] AA (90), [0] (89) [+] ++ (38), [0] ++ (91) [+] Y (41), [-] Y (92) [0] (93), [+] AB (94) [0] (45) (+) AA (96) [0] (102) [0] (102)
[0] (16) [0] (76) [+] LL (79), [0] (83) [+] MspI(–) (85), [–] MspI(–) (84), [0] (38) [+] AA (88), [0] (89) [0] ++ (91) [+] Y (83) [-] Y (92) [0] (45) [0] (100) [+] TT (55), [0] (20) [+] TT (18), [0] (20) [+]TT (102), [0] (101) [0] (93), [+] AA (95)
[+] AA (18), [0] (16) [+] CC (25) [0] (76)
[+] LL (53, 79), [+] VV (82), [0] (83) [+] MspI(+) (84)
[+] AA (38, 77), [0] (76)
[+] LL (80, 81, 79), [0] (83)
Pit1 GHR IGF 1 STAT5A DGAT1 LPT
[+] AA (87, 88), [0] (89) [0] ++ (91) [+] Y (41, 83)
[+] MspI(–) (31, 85, 86), [–] MspI(–) (84), [0] (38) [0] (89) [0] ++ (91) [+] Y (83) [0] (93), [+] AA (95) [0] (45)
[+] MspI(–) (31), [+] MspI(+) (84) [+] AA (88), [0] (89) [0] ++ (91) [0] (93), [+] AB (94) [0] (45) [–] K (47, 97, 98, 99, 100) [0] (102) [0] (102)
[0] (93), [+] AB (94), [+] AA (95) [+] GG (96)
[+] TC (no ind. CC) (45) [–] K (47, 97, 98, 99, 100)
[+] TT (101), [0] (102) [+] TT (102), [0] (101)
[+] K (47, 97, 98, 99, 100) [0] (102) [0] (102)
[+] K (47, 97, 98, 99), [0] (100)
[+] TT (78, 103), [0] (20)
Explanation: effect of genotype/allele on the trait: [+] positive, [–] negative, [0] no effect; (1, 2, 3...)literature citation; “no ind.” means no individuals of particular genotype
A frequency is higher compared to B in most studied cattle breeds. The polymorphism of this gene is reflected by a varied milk yield (Table 2). Some authors demonstrate that the milk BB homozygotes will yield 10% more curd in relation to milk of AA cows (5). A similar association was also found by other
authors, although at a lower level, i.e. about 5% (6).
Whey proteins
Whey proteins represent 0.6-0.7% of the cow milk overall composition, of which albumins (beta lactoglobulin and alIsrael Journal of Veterinary Medicine  Vol. 67 (2)  June 2012
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pha lactoglobulin) constitute about 75% of proteins, and the remaining represent immunoglobulins, lactoperoxidase, and lactoferrin (2). These proteins are very nutritious due to a high content of exogenous amino acids (2). Whey proteins coding genes are shorter and more simple in their structure as compared with caseins genes (2). The beta-lactoglobulin (LGB, BLG) gene, located on the chromosome 11, is 4723 bp in length, whereas alpha-lactoglobulin gene in cattle has been mapped to the chromosome 5 (7). The most frequent LGB gene alleles are A and B. The previous allele encodes for aspartic acid at position 64 and valine at position 118, whereas the latter encodes for glycine and alanine at these positions, respectively. The effects of these alleles on milk performance of cows is presented in Table 2. Lactoferrin (LF, also known as lactotransferrin (LTF)) is a multifunction protein primarily involved in a barrier against bacterial infections (8). The LF gene is located on chromosome 22 in cattle and includes 17 exons. An association of this gene with a risk of mastitis has drawn much attention (9). In 2008, 29 SNP mutations were found in the promoter region of the lactoferrin gene and 47 in exons (10). More than 140 SNPs in this gene have been identified, but none have been verified as a potential genetic markers (11). Such a high variability implies that a mastitis-resistance marker is very likely to exist within this gene, or possibly also a marker of milk yield. GENES ENCODING FACTORS THAT REGULATE MILK PROTEIN EXPRESSION
prolactin gene, a 10 kbp sequence including five exons separated by four introns, is located on chromosome 23 (14). Much research has been carried out on the RFLP-RsaI, a polymorphism in exon 3 which is a silent A/G transition at codon 103 that does not change the amino acid sequence of the resulting protein (15). The allele A is usually more frequent than B (16, 17, 18 19), although the associations between particular genotypes and milk yield of cows remain unclear (Table 2). In 2005, another six SNP-type mutations were found; however, none of them affected the amino acid sequence of the prolactin polypeptide (17). Mutations at positions 8362, 8377, and 8398 were located in exon IV, those at positions 8307 and 8314 in intron 3, whereas that at 8510 in intron 4 (17). The authors (17) claim that the mutation at position 8398 represents a silent A/G transition described above and detected using the RsaI restriction enzyme, which stands in contradiction with previous findings as to its location in exon III (17). In 2008, 4 SNP mutations were detected at positions 6237, 6263, 6268, and 6297, two of which (6237 and 6268) change the amino acid sequence, which theoretically could affect the characteristics associated with the synthesis of milk, although such effects have not been confirmed yet (20). Using the SSCP (Single Strand Conformation Polymorphism) method, several polymorphisms in the 5'UTR region were also described, without showing a significant linkage of these mutations with milk performance of cows (21, 22). Prolactin interacts with target cells by binding to the PRL receptor located in the membrane. Prolactin receptor - PRLR, discovered more than 20 years ago, belongs to the class I cytokine receptor family, which shows a high homology with the growth hormone receptor (23). In cattle, two isoforms of PRLR have been found, resulting from alternative splicing: a long form, with a length of 557 amino acids, and a short one, with a length of 272 amino acids. The PRLR gene is mapped on the bovine chromosome 20q17 (24). The first polymorphism in the bovine prolactin receptor gene, identified in 2005, was an A/C transversion (205th nucleotide, intron 9) in the region involved in the alternative splicing of the transcript (25). In Jersey and Black-and-White cows, the allele C was of the lowest frequency, respectively 0.02 and
Genetic Factors of Milk Yield in Dairy Cattle
Prolactin (PRL)
1.1. Prolactin receptor (PRLR)
Prolactin is a peptide hormone released by the anterior pituitary; however, its secretion is also attributed to central nervous system, immunological system, and mammary gland (12). Prolactin, as a prohormone, consists of 227 amino acids, whereas the bovine proper hormone is composed of 199 amino acids (13). It is a multipurpose hormone, since more than 300 biological functions have been attributed to prolactin (12). The primary function of prolactin is initiation and maintenance of lactation, as it is responsible for synthesis of the main components of milk. Prolactin is involved in each stage of milk protein genes expression, i.e. transcription, mRNA stabilization, translation, and posttranslational modifications of the proteins (2). The bovine
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0.19, yielding much to the allele A (0.80) (25). The impact of this polymorphism on milk yield is presented in Table 2. In Finnish Ayrshire cows, two other polymorphic sites in the bovine PRLR gene were discovered in 2006. The sites imply amino acid substitutions: in exon III, a GT/AC mutation of the frequency 0.86/0.14, and in exon VII, T/C transitions with the frequency 0.45/0.55 (26).
GH-releasing hormone
SOMATOTROPIC AXIS
Encoded by the gene GHRH, the growth-hormone-releasing hormone is a neuropeptide consisting of 44 amino acids, synthesized and released by the hypothalamus (27). GHRH triggers the production and release of growth hormone by the pituitary gland. The gene is mapped on chromosome 13 and contains five exons separated by four introns. Due to the fact that administration of somatoliberin increases the level of GH in blood serum, thereby increasing milk production, the GHRH gene was considered a possible marker of that trait. The GHRH gene reveals a single, welldescribed polymorphism, recognized by HaeIII restriction enzyme in intron 1 (Table 1). The frequencies of two possible alleles A and B vary greatly depending on the breed. The allele A is characterized by the highest frequency in the Angus breed of cattle (0.70), while the lowest in Hereford and Limousine (0.07) (28).
Definitely the most intensively studied polymorphism is that at the beginning of exon V, detected by AluI, and formed by a G/C substitution. Another polymorphism frequently studied consist in a simultaneous insertion and transition TC/G in intron 3, at position +838, first identified in 1993 (31). This region is recognized by MspI and located in the vicinity of the potential binding transcription factor, coupled with the insertion / deletion of 0.9 kbp in the region 3'UTR, which also have potential binding sites for transcription factors (33). As with the mutations described earlier, there are many reports on this polymorphism and its various effects on milk yield in cattle; however, these mutations have no major impact on the production traits. Also, a long list of polymorphisms have been described more or less accurately in introns 1, 2, and 3, as well as in the promoter and the regions 5' and 3' UTR.
Pit1 transcription factor
Growth hormone (GH)
This factor regulates the expression of growth hormone and prolactin in the anterior pituitary gland (34). It belongs to the family of POU domain containing proteins (transcription factors, activating the expression of target genes). The Pit1 gene locus is located in the centromeric part of the first chromosome (34). The most common polymorphism in this gene and its effect on particular milk yield parameters is shown in Table 2.
Growth hormone is a pleiotropically acting polypeptide, whose pulsatile secretion of the anterior pituitary is regulated primarily by the antagonistic hypothalamic hormones: growth-hormone-releasing hormone and somatostatin (29). It consists of a single polypeptide chain, formed of 191 amino acids. At the N-end, the somatotropin molecule may have alanine or phenylalanine. The gene encoding bovine growth hormone is mapped on chromosome 19 of the genome and consists of five exons and four introns of a total length 1792 bp (30). Somatotropin plays a key role in the regulation of lactation, hence its gene (GH) seems to be an excellent marker for the genetic traits associated with milk yield. A number of polymorphisms in the bovine GH have been described (some examples appear in table 1), as well as their effect on the milk performance; the results of the research, however, are inconclusive. (Table 1)
Growth hormone receptor (GHR)
Growth hormone acts on target cells through a cytokine receptor, which is characterized by the presence of a transmembrane domain, co-operating with JAK tyrosine kinase (35). The kinase, activated by intracellular transmitters, phosphorylates the transcription factor STAT5. GH receptor is encoded by a single gene with a length of 110 kbp, consisting of 10 exons, mapped on chromosome 20. The gene of this receptor (GHR) is characterized by the presence of several exons whose transcripts undergo alternative splicing (36). The amino acid sequence of a protein product is the same regardless of the variant of exon I. The place of transcripts splicing of all variants of exon I and exon II is located 9-11 nucleotides upstream of the start codon (37). Growth hormone activity depends on the receptor and therefore its gene may be a possible marker candidate. Particularly interesting
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is the mutation in the region of 5' UTR due to the presence of LINE retrotransposon insertion with a length of 12 kbp in cattle. Three polymorphic sites have been located in the region of Holstein cattle using restriction enzymes (38). Exon X proved to be extremely polymorphic in the structural part of the gene, in which several SNPs have been located (26, 39, 40, 41).
Insulin-like growth factor 1 (IGF-1)
This factor, also known as somatomedin C, is a single polypeptide chain with a length of 70 amino acids (42). It mediates the action of growth hormone on target cells, mainly in the regulation of growth. The bovine IGF-1 gene was mapped on the long arm of chromosome 5 (43). It consists of seven exons, separated by long introns. Due to the alternative splicing of exon I and the presence of two different promoters, the transcript has a length of 1, 155 bp or 750 bp. The promoters did not reveal, however, the TATA or CCAAT motifs, characteristic for most promoters and conserved, or regions rich in GC residues. In all, 4 transcription start sites have been detected (44) and a number of mutations, although these have not been sufficiently studied so far – especially in terms of milk yield – these still wait for verification and extensive studies. The STATs (signal transducers and activators of transcription) are the family of proteins that transfer signals from cytokine receptors to the cell nucleus where they activate transcription (45). STAT5 proteins are important in the growth and differentiation of cells, since they mediate in the activity of GH and prolactin (main lactation regulators), therefore mutations in the genes encoding these hormones might modify their behavior (39). STAT5A and STAT5B have been mapped on chromosome 19, at q17, very closely to each other. The STAT5A gene is composed of 15947 bp, has 19 exons, and encodes for 794-amino-acid protein, being expressed mainly in the mammary gland, in which it differs from the STAT5B gene, whose expression was also found in the liver (46). Polymorphic studies on bovine STAT5A led to discoveries of a range of mutations, primarily SNPs, which demonstrates a rapid evolution of the sequence (47).
lycerols, the major fraction of milk fat compounds. Bovine DGAT1 locus is found on chromosome 14. The often studied AA/GC dinucleotide substitution at positions 10433-10434 (exon VIII), which is potentially important for milk yield, results in a substitution of lysine in place of alanine at position 232 of the resulting protein. It has been proposed that the mutation, referred to as K232A, appeared at a very early stage of cattle domestication and is associated with milk fat content (48). The effects of this mutation on milk performance is presented in Table 2. In Holstein-Fresian cows, the AA to GC ratio ranges between 0.40 and 0.60, with a total lack of AA/AA genotypes (49). In 2007, 5 VNTR (variable number tandem repeats) alleles were found in the DGAT1 promoter (48); it was also concluded that the effect of K232A polymorphism on milk yield should be considered jointly with the VNTR in the gene promoter (CCCGCC repeating motif ). Other authors state that none of the VNTR alleles is useful as a QTL, and their results rather indicate that there is some other unrecognized polymorphism in the DGAT1 gene which may be of importance in terms of milk productivity (50).
Leptin (LEP)
STAT5A transcription factor
Diacylglycerol acyltransferase 1 (DGAT1)
DGAT1 is the key enzyme for the synthesis of triacylgIsrael Journal of Veterinary Medicine  Vol. 67 (2)  June 2012
The leptin encoding gene is located on chromosome 4. Leptin is synthesized predominantly by adipocytes, i.e. fat tissue cells (51). Its blood level is a signal for the central nervous system on the energy resources of the body. Besides the maintenance of energy homeostasis, leptin also regulates endocrine processes and may take part in prolactin secretion regulation. The latter effect was demonstrated on mice with non-functional leptin genes, which had a lower PRL secretion (15). Lactation is accompanied by increased food intake, a shift in metabolism, and the employment of energy resources from the fat tissue, so the interaction between hormones regulating mammogenesis and milk production, as well as those that affect energy homeostasis and fat metabolism, gain in importance. It seems justified therefore to search for the genetic marker of milk yield within the leptin gene, as has been evidenced by previous studies (Table 1). It should however be noted that milk yield also depends on the impact of other factors such as breed, population, herd, subsequent lactation, cow age, calving season, and other more or less specified factors. Applied statistical models, which are used to estimate associations between particular genotypes and milk yield, often miss the effects of these facGenetic Factors of Milk Yield in Dairy Cattle
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tors. Occasionally, a given genotype is represented by a few individuals in the population, which in consequence resulted in biased analysis results. It is hoped that this breakdown of research data will be taken into account in efforts aiming to determine various dependencies between genes and milk yield.
1. Khatkar, M., Zenger, K., Hobbs, M., Hawken, R., Cavanagh, J., Barris, W., McClintock, A., McClintock, S., Thomson, P., Tier, B., Nicholas, F. and Raadsma, H.: A primary assembly of a bovine haplotype block map based on a 15,036-single-nucleotide polymorphism panel genotyped in Holstein–Friesian cattle. Genetics. 176:763-772, 2007. 2. Zwierzchowski, L.: Biotechnological application of mammary gland in the scope of genetic manipulations in milk proteins. [Biotechnologiczne wykorzystanie gruczołu mlecznego perspektywy manipulacji genetycznych białek mleka.] Biotechnol. Prz. Inf. 2:33-56, 1998. [In Polish] 3. Eigel, W. N., Butler, J. E., Ernstrom, C. A., Farrell, H. M., Harwalkar, V. R., Jennes, R. and Whitney, R. McL.: Nomenclature of proteins of cow’s milk. J. Dairy Sci. 67:1599–1631, 1984. 4. Neelin, J. M: Variants of κ-casein reealed by improved starch gel electrophoresis. J. Dairy Sci. 47:506-509, 1964. 5. Marziali, A. S. and Ng-Kwai-Hang, K. F.: Effects of milk composition and genetic polymorphism on cheese composition. J. Dairy Sci. 69:2533-2542, 1986. 6. Denisenko, E. A.: Milk production and technological property milk of Black Pied breeds with difference genotypes of kappa casein in region Siberia. PhD theses, All Russian Research Institute of Animal Breeding, Moscow, Russia, 2004. 7. Hayes, H. C, Petit, E. J., Lemieux, N. and Durtillaux, B.: Chromosomal localization of ovine β-casein gene by non isotopic in situ hybridization and R-banding. Cytogenet. Cell Genet. 61: 286, 1993. 8. Schwerin, M., Solinas-Toldo, S., Eggen, A., Brunner, R., Seyfert, H. M. and Fries, R.: The bovine lactoferrin gene (LTF) maps to Chromosome 22 and syntenic group U12. Mamm. Genome 5:486-489, 1994. 9. Wojdak-Maksymiec, K., Kmieć, M. and Ziemak, J.: Associations between bovine lactoferrin gene polymorphism and somatic cell count in milk. Vet. Med. 51:14–20, 2006. 10. O’Halloran, F., Bahar, B., Buckley, F., O’Sullivan, O., Sweeneey, T., and Giblin, L.: Characterization of single nucleotide polymorphisms identified in the bovine lactoferrin gene sequences across a range of dairy cow breeds. Biochemie. 91:68-75, 2009. 11. Huang, J., Wang, K., Wang, C., Li, J., Li, Q., Hou, M. and Zhong, J.: Single nucleotide polymorphisms, haplotypes and combined genotypes of lactoferrin gene their associations with mastitis in Chinese Holstein cattle. Mol. Biol. Rep. 37:477-483, 2010. 12. Bole-Feysot, Ch., Goffin, V., Edery, M., Binart, N. and Kelly, P. A.: Prolactin (PRL) and its receptor: actions, signal transduction pathways and phenotypes observed in PRL receptor knockout mice. Endocr. Rev. 19:225-268, 1998.
REFERENCES
13. Wallis, M.: The primary structure of bovine prolactin. FEBS Lett 44:205-208, 1974. 14. Hallerman, E. M., Thelimann, J. L., Beckmann, J. S., Soller, M. and Womack, J. E.: Mapping of bovine prolactin and rhodopsin genes in hybrid somatic cells. Anim. Genet. 19:123-131, 1988. 15. Larson, B., Sinha, Y. and Vanderlaan, W.: Serum growth hormone and prolactin during and after the development of the obese-hyperglycemic syndrome in mice. Endocrionology. 98:139-145, 1976. 16. Dybus, A., Grzesiak, W., Kamieniecki, H., Szatkowska, I., Sobek, Z., Błaszczyk, P., Czerniawska-Piątkowska, E., and Zych, S.: Association of genetic variants of bovine prolactin with milk production traits of Black-and-White and Jersey cattle. Arch. Tierz. 48:149-156, 2005. 17. Brym, P., Kamiński, S. and Wójcik E.: Nucleotide sequence polymorphism within exon 4 of bovine prolactin gene its associations with milk performance traits. J. Appl.Genet. 45:179-185, 2005. 18. Alipanah, M., Kalashnikova, L. and Rodionov, G.: Association of prolactin gene variants with milk production traits in Russian Red Pied cattle. Iran. J. Biotechnol. 3:158-161, 2007. 19. Wojdak-Maksymiec, K., Kmieć, M. and Strzalaka, J.: Prolactin Gene Polymorphism and Somatic Cell Count in Dairy Cattle. J. Anim. Vet. Adv. 7:35-40, 2008. 20. Halabian, R., Nasab, M. P. E., Nassiry, M. R., Mossavi, A. R. H., Hosseini, S. A. and Qanbari, S. Characteryzation of SNPs of Bovine Prolactin Gene of Holstein Cattle. Biotechnology. 7:118123, 2008. 21. Hart, G. L., Bastiaansen, J., Dentine, M. R. and Kirkpatick, B. W.: Detection of a four-allele single strand conformation polymorphism (SSCP) in the bovine prolactin gene 5' flank. Anim. Genet. 24:149, 1993. 22. Zhang, H., Denise, S. K. and Ax, R. L.: Rapid communication: Dialleic single-stranded conformational polymorphism detected in the bovine prolactin gene. J. Anim.Sci. 72:256, 1994. 23. Kelly, P. A, Dijane J., Postel-Vinay, M. C. and Edery M.:The prolactin/growth hormone receptor family. Endocr. Rev. 12:235-251, 1991. 24. Hayes, H., Le Chalony, C., Goubin, G., Mercier, D., Payen, E. J., Bignon, C. and Kohno, K.: Localization of ZNF164, ZNF146, GGTA1, SOX2, PRLR and EEF2 on homeologous cattle, sheep, and goat chromosomes by fluorescent in situ hybridization and comparison with human gene map. Cytogenet. Cell Genet. 72:342-346, 1996. 25. Brym, P., Kamiński, S. and Wójcik E.: Polymorphism within the bovine prolactin receptor gene (PRLR). Anim. Sci. Pap. Rep. 23:61-66, 2005. 26. Viitala, S., Szyda, J., Blott, S., Schulman, N., Lidauer, M., Maki-Tanila, A., Georges, M. and Vilkki, J.: The Role of the Bovine Growth Hormone Receptor and Prolactin Receptor Genes in Milk, Fat and Protein Production in Finnish Ayrshire Dairy Cattle. Genetics. 173:2151–2164, 2006. 27. Guillemin, R., Brazeau, P., Bohlen, P., Esch, F., Ling, N. and Wehrenberg, W. B.: Growth hormone relealising factor from a human pancreatic tumor that caused acromegaly. Science. 218:585-587, 1982. 28. Moody, D. E, Pomp, D. and Barendse, W.: Rapid communicaIsrael Journal of Veterinary Medicine  Vol. 67 (2)  June 2012
88
Żukiewicz, A.
Review Articles
29. 30. 31. 32.
33. 34.
35. 36. 37.
38.
39. 40.
41.
42.
43.
tion: Restriction fragment polymorphism in amplification products of the bovine growth hormone-releasing hormone gene. Anim.Sci. 73:3789, 1995. Wallis, M.: The primary structure of bovine growth hormone. Febs Letters. 35:11-14, 1973. Gordon, D. F, Quick, D. P., Erwin, C. R, Donelson, J, E. and Maurer, R. A: Nucleotide sequence of bovine growth hormone chromosomal gene. Mol. Cell. Endocrinol. 33:81-95, 1983. Hoj, S., Fredholm, M., Larsen, N. J. and Nielsen, H. V.: Growth hormone gene polymorphism associated with selection for milk fat production in lines of cattle. Anim. Genet. 24:91-96, 1993. Theilmann, J. L., Skow, L. C., Baker, J. F. and Womack, J. E.: Restriction fragment length polymorphisms for growth hormone, prolactin, osteonectin, α crystallin, γ crystallin, fibronectin and 21-steroid hydroxylase in cattle. Anim. Genet. 20:257-266, 1989. Furu, L., Kazmer, G., Zinn, S. A. and Rycroft, H.: Somatotropin MspI and AluI polymorphisms relative to indicators of the genetic merit of Holstein AI sires. J. Anim. Sci. 76:75, 1998. Bodner, M., Castrillo, J. L., Theill, L. E., Deerinck, T., Ellisman, M. and Karin, M: The pituitary-specufic transcription factor GHF-1 isa a homeobox-contaiting protein. Cell. 55:505-518, 1988. Zhu, T., Goh Eyeen, L. K, Graichen, R., Long, L., Lobie, P. E.: Signal transduction via the growth hormone receptor. Cell. Sign. 13:599-616, 2001. Edens, A. and Talamantes, F.: Aleternative processing of Growth homone receptor Transcripts. Endocr. Rev. 19:559-583, 1998. Menon, R. K., Shaufl, A., Yu, J. H., Stephan, D. A. and Friday, R. P.: Identification and characterization of a novel transcript of the murine growth hormone receptor gene exhibiting development and tissue-specific expression. Mol. Cell. Endocrinol. 172:135146, 2001. Aggrey, S. E., Yao, J. Sabour, M. P., Lin, C. Y., Zadworny, D., Hayes J. F. and Kuhnlein, U.: Markers within the regulatory region of the growth hormone receptor gene and their association with milk-related traits in Holsteins. J. Hered. 90:148-151, 1999. Moisio, S., Elo, K., Kantanen, J. and Vilkki, J.: Polymorphism within the 3’-flanking rejon of the bovine growth hormone receptor gene. Anim. Genet. 29:55-57, 1998. Ge, W., Davis, M. E., Hines, H. C. and Irvin, K. M.: Rapid communication: Single nucleotide polymorphism detected in exon 10 of the bovine growth hormone receptor gene. J Anim. Sci. 78: 2229-2230, 2000. Blott, S., Jong-Joo, K., Moisio, S., Schmidt-Kuntzel, A., Cornet, A., Berzi, P., Cambisano, N., Ford, Ch., Grisart, B., Johnson, D., Karim, L., Simon, P., Snell, R., Spelman, R., Wong, J., Vilkki, J., Georges, M., Farnir, F. and Coppieters W.: Molecular dissection of a quantitative trait locus: A phenylalanine-to-tyrosine substitution in the transmembrane domain of the bovine growth hormone receptor is associated with a major effect on milk yield and composition. Genetics. 163:253–266, 2003. Daughaday, W. H. and Rotwein, P. Insulin-like growth factors I and II. Peptide messenger ribonucleic acid and gene structures, serum, and tissue concentrations. Endocrinology Reviews 10:6891, 1989. Miller, J. R., Thomsen, P. D., Dixon, S. C., Tucker, E. M., Kon-
44. 45. 46. 47.
48.
49.
50.
51.
52. 53. 54.
55.
56.
57.
58.
fortov, B. A. and Harbitz, I.: Synteny mapping of the bovine IGHG2, CRC and IGF-1 genes. Anim. Genet. 23:51-58, 1991. Wang, Y., Price, S. E. and Jiang, H. Cloning and characterization of the bovine class 1 and class 2 insulin-like growth factor- 1 mRNAs. Domest. Anim. Endocrinol. 25:315-328, 2003. Ihle, J. N.: Signal transducers and activators of transcription. Cell 84:331-334, 1996. Paukku, K. and Silvonnoinen, O.: STATs as critical mediators of signal transduktion and transcription: lessons learned from STAT%. Cyt. Growth Fact. Rev. 15:435-455, 2004. Flisikowski, K. and Zwierzchowski, L.: STAT transcription factors. STAT5 gene as a possible livestock animal production trait marker. Works and Materials on Animal Husbandry. Monographs and Theses. [Czynniki transkrypcyjne STAT- gen STAT5A jako potencjalny marker cech produkcyjnych zwierząt gospodarskich. Prace i materiały zootechniczne. Monografie i Rozprawy] 6: 5-19, 2003. [In Polish]. Kuehn, C., Edel C., Weinkard, R. and Thaller, G.: Dominance and parent-of-origin effects of coding and non-coding alleles at the acylCoA-diacylglycerol-acyltransferase (DGAT I) gene on milk production traits in German Holstein cows. BMC Genetics. 8:62, 2007. Strzalkowska, N., Siadkowska, E., Sloniewski, K., Krzyzewski, J. and Zwierzchowski, L.: Effect of the DGAT1 gene polymorphism on milk production traits in Black-and-White (Friesian) cows. Anim. Sci. Pap.Rep. 23:189-197, 2005. Gautier, M., Capitan, A., Fritz, S., Eggen, A., Boichard, D. and Druet, T.: Characterization of the DGAT1 K232A and Variable Number of Tandem Repeat Polymorphisms in French Dairy Cattle. J. Dairy Sci. 90:2980–2988, 2007. Halaas, J. L., Gajiwala, K. S., Maffei, M., Cohen, S. L., Chait, B. T., Rabinowitz, D., Lallone, R. L., Burley, S. K. and Friedman, J. M.: Weight-reducing effects of the plasma protein encoded by the obese gene. Science. 269:543-546, 1995. Eenennaam, A. and Medrano, J. F.: Milk protein polymorphisms in California dairy cattle. J. Dairy Sci. 74:1730–1742, 1991. Lagziel, A., Lipkin, E. and Soller, M.: Association between SSCP haplotypes at the bovine growth hormone gene and milk protein percentage. Genetics. 142:945-951, 1996. Barreras, A., Robinson, O. Monge, F. J. Vizcarra, O. and Navarro, L. H.: Effects of genotypes of casein and serum proteins on milk production in Holsteins. WSASAS Proceedings. 52:127129, 2001. Gonyon, D. S., Mather, R. E., Hines, H. C., Haenlein, G. F. W., Arave, C. W. and Gaunt, S. N.: Associations of bovine blood and milk polymorphisms with lactation traits: Holsteins. J. Dairy Sci. 70:2585-2598, 1987. Kuss, A. W., Gogol, J., Bartenschlager, H. and Geldermann, H.: Polymorphic AP-1 binding site in bovine CSN1S1 shows quantitative differences in protein binding associated with milk protein expression. J. Dairy Sci. 88:2246–2252, 2005. Kučerova, J., Matějiček, A., Jandurova, O. M., Sorensen, P., Němcova, E., Štipkova, M., Kott, T., Bouška, J. and Frelich, J.: Milk protein genes CSN1S1, CSN2, CSN3, LGB and their relation to genetic values of milk production parameters in Czech Fleckvieh. Czech J. Anim. Sci. 51:241–247, 2006. Bovenhuis, H., Van Arendonk, J. A. M and Korver S.: AssociaGenetic Factors of Milk Yield in Dairy Cattle
Israel Journal of Veterinary Medicine  Vol. 67 (2)  June 2012
89
Review Articles
59. 60.
61. 62.
63.
64.
65.
66. 67. 68. 69. 70. 71.
72.
73.
tions between milk protein polymorphisms and milk production traits. J. Dairy Sci. 75:2549-2559, 1992. Ng-Kwai-Hang, K. F.: Genetic polymorphism of milk proteins: Relationships with production traits, milk composition and technological properties. Can. J. Anim. Sci. 78:131–147, 1998. Szymanowska, M., Strzałkowska, N., Siadkowska, E., Krzyżewski, J., Ryniewicz, Z. and Zwierzchowski, L.: Effects of polymorphism at 5’-noncoding regions (promoters) of αS1and αS2-casein genes on selected milk production traits in Polish Black-and-White cows. Anim. Sci. Pap. Rep. 21:97-108, 2003. Ron, M., Yoffe, O., Ezra, E. and Medrano, J. F., Weller J. I.: Determination of Effects of Milk Protein Genotype on Production Traits of Israeli Holsteins. J. Dairy Sci. 77:1106-1113, 1994. Sabour, M. P., Lin, C. Y., Lee, A. J. and McAllister, A. J.: Association Between Milk Protein Genetic Variants and Genetic Values of Canadian Holstein Bulls for Milk Yield Traits. J. Dairy Sci. 79:1050-1056, 1996. Boettcher, P. J., Caroli, A., Stella, A., Chessa, S., Budelli, E., Canavesi, F., Ghiroldi, S. and Pagnacco G.: Effects of casein haplotypes on milk production traits in Italian Holstein and Brown Swiss cattle. J. Dairy Sci. 87:4311–4317, 2004. Curi, R. A., Oliveira, H. N. D., Gimenes, M. A., Silveira, A. C. and Lopes, C. R.: Effects of CSN3 and LGB gene polymorphisms on production traits in beef cattle. Genet. Mol. Biol. 28:262-266, 2005. Matějíček, A., Matějíčková, J., Němcová, E., Jandurová, O. M., Štípková, M., Bouška, J. and Frelich, J.: Joint effects of CSN3 and LGB genotypes and their relation to breeding values of milk production parameters in Czech Fleckvieh. Czech J. Anim. Sci. 52:83–87, 2007. Lin, C. Y., McAllister, A. J., Ng-Kwai-Hang, K. F. and Hayes, J. F.: Effects of milk protein loci on first lactation production in dairy cattle. J. Dairy Sci. 69:704-712, 1986. Rachagani, S. and Gupta, I. D.: Bovine kappa-casein gene polymorphism and its association with milk production traits. Genet. Mol. Biol. 31:893-897, 2008. Alipanah, M., Kalashnikova, L. and Rodionov, G.: Kappa-casein genotypic frequencies in Russian breeds Black and Red Pied cattle. Iran. J. Biotechnol. 3:191-194, 2005. Freyer, G., Liu, Z., Erhardt, G. and Panicke, L.: Casein polymorphism and relation between milk production traits. J. Anim. Breed. Genet. 116:87-97, 1999. Sitkowska, B., Neja, W. and Wisniewska, E.: Relations between kappa-casein polymorphism (CSN3) and milk performance traits in heifer cows. JCEA. 9: 641-644, 2010. Kamiński, S., Rymkiewicz-Schymczyk, J., Wojcik, E. and Rusc, A.: Associations between bovine milk protein genotypes and haplotypes and the breeding value of Polish Black-and-White bulls. J. Anim. Feed Sci. 11:205–221, 2002. Ng-Kwai-Hang, K. F., Monardes, H. G. and Hayes, J. F.: Association between genetic polymorphism of milk proteins and production traits during three lactations. J. Dairy Sci. 73:3414-3420, 1990. Kamiński, S., Oleński, K., Brym, P., Malewski, T. and Sazanov, A. A.: Single nucleotide polymorphism in the promoter region
74.
75. 76. 77.
78.
79.
80. 81.
82.
83.
84.
85.
86.
of the lactoferrin gene and its associations with milk performance traits in Polish Holstein–Friesian cows. Russ. J. Genet. 42:924– 927, 2006. Sender, G., Dymnicka, M., Korwin-Kossakowska, A., Gralak, B., Arkuszewska, E. and Łozicki, A.: Linkage between lactoferrin gene polymorphism and milk yield in Polish HF cattle. [Związek polimorfizmu genu laktoferyny z wydajnością mleka krów rasy polskiej holsztyńsko-fryzyjskiej.] Roczn. Nauk. Pol. Tow. Zoot., 4:89-94, 2007. [In Polish]. Ghasemi, N., Zadehrahmani, M., Rahimi, G. and Hassan, S.,: Associations between prolactin gene polymorphism and milk production in montebeliard cows. Int. J. Genet. Mol. Biol. 1, 2009. Dybus, A. and Grzesiak, W.: GHRH/HaeIII gene polymorphism and its associations with milk production traits In Polish Black-and-White cattle. Arch. Tierz. 5:343-348, 2006. Paramentier, I., Portetelle, D., Fengler, N., Prani, A., Bertozzi, C., Vlecrick, L., Gilson, R. and Renaville, R.: Candidate gene markers associated with somatotropic axis and milk selection. Domest. Anim. Endocrinol. 17:139-148, 1999. Buchanan, F. C., Van Kessel, A. G., Waldner, C., Christensen, D. A., Laarveld, B. and Schmutz S. M.: An association between a leptin single nucleotide polymorphism and milk and protein yield. J. Dairy Sci. 86:3164–3166, 2003. Shariflou, M. R., Moran, C. and Nicholas, F. W.: Association of the Leu (127) variant of the bovine growth hormone (bGH) gene with increased yield of milk, fat and protein in Australian Holstein-Fresian. Aust. J. Agric. Res. 51:515-522, 2006. Dybus, A.: Association between Leu/Val polymorphism of growth hormone gene and milk production traits in polish Blackand-White cattle. Arch. Tierz. 45:421-428, 2002. Lucy, M. C., Hausner, S. D., Eppard, P. J., Krivi, G. G., Clarck, J. H., Bauman, D. E. and Collier, R. J.: Variants of somatotropin in cattle: gene frequencies in major dairy breeds and associated milk production. Domest. Anim. Endocrinol. 10:325-333, 1993. Khatami, S. R., Lazebny, O. E., Maksymienko, V. R. and Sulimova, G. E.: Association of DNA polymorphism of growth hormone and prolactin genes with milk productivity in Yaroslavl and Black-and-White cattle. Russ. J. Genet. 41:167-173, 2005. Komisarek, J., Michalak, A. and Walendowska, A.: The effects of polymorphisms in DGAT1, GH and GHR genes on reproduction and production traits in Jersey cows. Anim. Sci. Pap. Rep. 29:29-26, 2011. Yao, J., Aggrey, S. E., Zadworny, D., Hayes, J. F. and Kuhnlein, U.: Sequence variations on the bovine growth hormone gene characterized by single-strand conformation polymorphism (SSCP) analysis and their association with milk production traits in Holsteins. Genetics. 144:1809-1816, 1996. Falaki, M., Gengler, N., Sneyers, M., Prandi, A., Massart, S., Formigoni, A., Burny, A., Portetelle, D. and Renaville, R.: Relationships of polymorphism for growth hormone and growth hormone receptor genes with milk production traits for Italian Holstein-Fresian bulls. J. Dairy Sci. 79: 1446-1463. 1996. Lee, B. K., Lin, G. F., Croocker, B. A., Murtaugh, M. P., Hansen, L. B. and Chester-Jones, H.: Association of somatotropin (bST) gene polymorphism with selection for milk in Holstein cows. J. Dairy Sci. 76:149-153, 1993.
Israel Journal of Veterinary Medicine  Vol. 67 (2)  June 2012
90
Żukiewicz, A.
Review Articles
87. Hori-Oshima, S. and Barreras-Serrano, A. Relationships between DGAT1 and Pit-1 genes polymorphism and milk yield in Holstein cattle. J. Anim. Sci. (Suppl.1) 81:252, 2003. 88. Renaville, R., Gengler, N., Vrech, A., Prandi, A., Massart, S., Corrdinani, C., Bertozzi, C., Mortiaux, F., Burny, A. and Portetelle, D.: Pit-1 gene polymorphism, milk yield, and conformation traits for Italian Holstein-Friesian bulls J. Dairy Sci. 80:3431-3438, 1997. 89. Dybus, A., Szatkowska, I., Czerniawska-Piątkowska, E., Grzesiak, W., Wójcik, J., Rzewucka, E. and Zych, S.: PIT1-HinfI gene polymorphism and its associations with milk production traits in polish Black-and-White cattle. Arch. Tierz. 476:557563, 2004. 90. Zwierzchowski, L., Krzyżewski, J., Strzałkowska, N., Siadkowska, E. and Ryniewicz, Z.: Effects of polymorphism of growth hormone (GH), PIT-1, and leptin (LEP) genes, cow’s age, lactation stage and somatic cell count on milk yield and composition of polish Black-and-White cows. Anim.Sci.Pap. Rep. 20:213-227, 2002. 91. Komisarek, J. and Dorynek, Z.: Polymorphism of BTN and GHR genes and its impast on bull’s beeding value for milk production traits. J. Anim. Feed Sci. 12:681-688, 2003. 92. Waters, S. M., McCabe, M. S., Howard, D. J., Gibilin, L., Magess, D.A., MacHughs, D.E. and Berry D.P. Associations between newly discovered polymorphism in the Bos Taurus growth hormone and performance traits in Holstein- Friesian dairy cattle. Anim. Genet. 42:39-49, 2011. 93. Hines, H. C., Ge, W., Zhao, Q. and Davis, M. E. Association of genetic markers in growth hormone and insulin-like growth factor I loci with lactation traits in Holsteins. Anim. Genet. 29:69, 1998. 94. Siadkowska, E., Zwierzchowski, L., Oprządek, J., Strzałkowska, N., Bagnicka, E. and Krzyżewski, J.: Effect of polymorphism in IGF-1 gene on production traits in Polish Holstein-Friesian cattle. Anim. Sci. Pap. Rep. 24:225-237, 2006. 95. Zych, S. 2006. Expression and polymorphism of selected somatotropin axis genes in association with milk production traits of Black-and-White cows with varied proportion of HF genes.
96.
97. 98. 99.
100. 101.
102.
103.
[Ekspresja i polimorfizm wybranych genów osi somatotropowej w powiązaniu z cechami produkcyjności mlecznej krów czarnobiałych z różnym udziałem genów HF.] PhD Theses, Faculty of Biotechnology and Animal Science, Agricultural University of Szczecin, Poland, 2006. [In Polish]. Brym, P., Kamiński, S. and Ruść A.: New SSCP polymorphism within bovine STAT5A gene and its associations with milk performance traits in Black-and-White and Jersey cattle. J. Appl. Genet. 45: 445-452, 2004. Spelman, R., Ford, C. A., McElhinney, P., Gregory, G. C. and Snell R. G.: Characterization of the DGAT1 gene in the New Zealand dairy population. J. Dairy Sci. 85:3514–3517, 2002. Thaller, G., Krämer, W., Winter, A., Kaupe, B., Erhardt, G. and Fries, R.: Effects of DGAT1 variants on milk production traits in German cattle breeds. J. Anim. Sci. 81:1911-1918, 2003. Sanders, K., Bennewitz, J., Reinsch, N., Thaller, G, Prinzenberg, E. M., Kuhn, C. and Kalm, E.: Characterization of the DGAT1 Mutations and the CSN1S1 Promoter in the German Angeln Dairy Cattle Population. J. Dairy Sci. 89:3164–3174, 2006. Smaragdov, M. G.: Association of the DGAT1 gene polymorphism in bulls with cow milk performance. Russ. J. Genet. 47:110-115, 2011. Liefers, S. C., Pas, M. F, Veerkamp, R. F. and van der Lende, T.: Associations between leptin gene polymorphisms and production, live weight, energy balance, feed intake, and fertility in Holstein Heifers. J. Dairy Sci. 85:1633–1638, 2002. Madeja, Z., Adamowicz, T., Chmurzynska, A., Jankowski, T., Melonek, J., Świtonski, M. and Strabel, T.: Short communication: Effect of leptin gene polymorphisms on breeding value for milk production traits. J. Dairy Sci. 87:3925-3927, 2004. Kulig, H., Kmieć, M., Kowalewska-Łuczak, I., Wojdak-Maksymiec, K. and Torchała-Bielaszewska, K.: Associations between leptin gene polymorphism and somatic cell count as well as milk performance in dairy cows. [Zależności między polimorfizmem w genie leptyny a liczbą komórek somatycznych i cechami użytkowości mlecznej krów]. Medycyna Wet. 64:915917, 2008. [In Polish].
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