Association between LEPR and MC4R genes polymorphisms and composition of milk from sows of dam line

The polymorphisms of LEPR and MC4R genes are involved in appetite control mechanisms and indirectly associated with level of fat content in pig carcasses. Therefore, the aim of our study was to determine if both polymorphisms have an effect on components of colostrum and milk of sows. In our study we used gilts of two Polish breeds: Polish Landrace and Polish Large White, which belong to dam-line in Polish breeding. Colostrum and milk of sows were collected in 7, 14 and 21 day of lactation to assay solids, total protein, fat and lactose. The obtained results showed, that the observed mutation (G/A 1426 MC4R) had a significant effect mainly on the fat and solids content of colostrum. Animals with the MC4R ^AA genotype had 2.13 and 1.91 % (P ≤ 0.01) lower fat content of colostrum compared to sows with the MC4R ^GG genotype and heterozygous MC4R ^AG. The presence of the MC4R ^A allele in the animals’ genotype contributed to a decrease in fat and solids content of colostrum. The LEPR/HpaII mutation was found to have a considerable effect on the level of most colostrum components (fat, protein and solids) in both pig breeds. Significant decrease in the value of the colostrum components (except lactose) was observed only for animals with the allele LEPR ^B. The results obtained suggest that these genes might be used in selection of dam-line pigs as genetic markers of milk quality.     

Single nucleotide polymorphism in the promoter region of the lactoferrin gene and its associations with milk performance traits in Polish Holstein-Friesian cows

Bovine lactoferrin (LTF) is a multifunctional small glycoprotein found in milk acting mainly as a defense factor in the mammary gland. Many polymorphisms have been found in the bovine LTF gene but almost none were considered as genetic markers of production traits in dairy cattle. In this study, the promoter fragment of LTF gene containing mutation (G/C) in position +32 has been amplified by PCR followed by genotyping by the SSCP and RFLP method. Three hundred fifty-eight Polish Holstein-Friesian cows were screened, giving the following frequency of genotypes: 0.628, 0.313 and 0.059 for GG, GC and CC, respectively. GLM (General Linear Model) analysis was applied to evaluate the associations of lactoferrin with milk performance traits, including SCC (somatic cell count). It was found that CC cows show significantly higher (P ≤ 0.01) protein content in milk in comparison with GG cows. The values of other milk performance traits were also higher but at nonsignificant levels. SCC in milk was the lowest in CC cows, but also at a nonsignificant level. The text was submitted by the authors in English.     

The study of the SNP in the corticotropin-releasing hormone gene (exon 2) and milk production traits in cattle

The aim of this study was estimate the relations between CRH C22G and milk production traits (milk yield, yield of protein and fat, content of protein and fat in milk). The study was carried on 169 Polish Holstein-Friesian strain Red-and-White cows kept in the south-western region of Poland. The CRH C22G (exon 2) polymorphisms were detected using PCR-RFLP method. The genotype and allele frequencies were estimated and they were as follows: CC - 0.89, CG - 0.09, GG - 0.02; C - 0.93, G - 0.07. Statistically significant (P < or = 0.05) associations between CRH C22G genotypes and milk production traits like milk yield and protein yield in the second lactation were found. Moreover, the obtained results should be verified by conducting research on a larger group of animals and various cattle breeds.     

Association between polymorphism in bovine <Emphasis Type="Italic">PRKAG3</Emphasis> gene and milk production traits

The aim of the conducted study was to evaluate correlation between genotypes and PRKAG3 compound genotypes and milk production traits (yield of milk, milk fat and milk protein, and protein and fat content in milk). The study covered a herd of 180 Jersey cows. PCR-RFLP method was used for genotyping. The frequencies of alleles that occur mostly and combined genotypes were as follows: T1526G G − 0.57, G1609A G − 0.92 and for T1526G/G1609A TG/GG − 0.54. The results obtained in the study demonstrated the correlation between analyzed genotypes and selected milk production straits; however they are not statistically significant.     

Effect of <Emphasis Type="Italic">UCP2</Emphasis> and <Emphasis Type="Italic">UCP3</Emphasis> Genes Polymorphisms on Functional Traits in Dairy Cattle

The aim of this study was to investigate associations between genotypes of UCP2 and UCP3 genes, milk, and reproduction traits in dairy cattle. The study included two herds: Jersey cows and Polish Holstein-Friesian (Red and White strain) cows. All cows were genotyped using the PCR-RFLP method and allele frequencies were determined. Statistical analysis showed a significant association between polymorphism in the UCP3 gene and the milk yield and fat content of milk (P ≤ 0.05, P ≤ 0.01) and between the UCP2 gene and the calving interval (P ≤ 0.05). Information contained in this study may be useful in further analysis to define the role of analysed genes in relation to functional traits in dairy cattle, nevertheless, the obtained results should be verified by conducting research on a larger group of animals and various cattle breeds.     

DGAT1 K232A quantitative trait nucleotide polymorphism in Polish Black-and-White cattle

The diacylglycerol o-acyltransferase 1 gene (DGAT1) was investigated in Polish Black-and-White cattle. The frequency of the K allele was 0.60, 0.68 and 0.48 for AI sires (n=150), young bulls (n=139) and cows (n=213), respectively. The method of selective genotyping for identification of the quantitative trait nucleotide was verified through identification of DGAT1 effect on milk production traits. Daughters of six heterozygous bulls were selectively genotyped based on their milk traits. The genotypic frequencies differed between high and low yield groups representing milk and fat contents. The Kruskal-Wallis test revealed a highly significant effect of DGAT1 K232A in cows with extremely low fat content and a significant effect in cows with extremely high protein content of milk. No significant effect of AI sires' genotypes on their breeding value was found.     

Correlation analysis between three novel SNPs of the Src gene in bovine and milk production traits

As an essential signaling modulator, Src gene appears to be necessary for increased expression of the prolactin receptor, normal downstream signaling, and alveolar cell organization. In this study, we detected the polymorphism of Src gene by polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP) and DNA sequencing methods in 985 individuals from three Chinese cattle breeds. Three novel single nucleotide polymorphisms (SNPs) (g.14062C>T ss161151834, g.17302G>A ss161151835, g.18107T>C ss161151836) were detected. Least squares analysis showed that cows with g.14062C>T-CC genotypes and g.18107T>C-TT genotypes had the highest protein rate, while the cows with g.17302G>A-GG genotype had higher 305 d milk yield (p < 0.05), fat yield (p < 0.01) and protein yield (p < 0.01) than the ones with genotypes g.17302G>A-GA. These results revealed the statistical significant effects of three SNPs of the Src gene on the milk production traits in Chinese Holstein. In addition, based on the nine genotypes constructed from 27 combined haplotypes, the association analysis between combined haplotypes and milk production traits was carried out. Statistic results showed that the cows with combined haplotypes H2H4(CCGATT) had the highest fat rate and the highest protein rate and the cows with combined haplotypes H1H8(TCGATC) and H3H7(TCGGCC) had greater 305 d mild yield than H1H2(CCAATC)(P < 0.05). Our finding demonstrated that the Src gene possibly contributed to conducting association analysis and can be recognized as genetic marker in milk production traits and other performance for animal breeding and genetics.     

Association of the heart fatty acid-binding protein (FABP3) gene with milk traits in Manchega breed sheep

The ovine fatty acid-binding protein type 3 gene has been chosen as a functional candidate gene for milk traits. Two different single nucleotide polymorphisms (SNPs) of ovine FABP3 gene have been tested in a daughter design comprising 13 families. No association was found between estimated breeding values for milk yield, protein and fat contents (FC) and genotypes across families using anova and transmission disequilibrium test (TDT). In within-family analysis, one family showed a significant effect for FC. These results could indicate linkage disequilibrium between the FABP3 gene and a quantitative trait loci (QTL) for FC, with the heterozygous genotype associated with a positive effect in this trait.     

Deletion/insertion polymorphism of the prion protein gene (<Emphasis Type="Italic">PRNP</Emphasis>) in Polish Holstein-Friesian cattle

The aim of the present study was to identify the deletion/insertion polymorphism of the bovine prion protein gene (PRNP) within the promoter sequence (23 bp), intron 1 (12 bp) and 3’ untranslated region (14 bp). DNA was isolated from blood of 234 randomly tested Polish Holstein-Friesian cows and from semen of 47 sires used for artificial insemination (AI) in 2004. No statistically significant differences were found in the frequency of genotypes and alleles between cows and breeding bulls in the 3 analysed polymorphic sites within thePRNP gene. Only 3 haplotypes were identified in sires and 4 haplotypes in cows.     

Identification of genetic polymorphisms in FABP3 and FABP4 and putative association with back fat thickness in Korean native cattle

The aim of this study was to determine whether single nucleotide polymorphisms (SNP) in the beef cattle adipocyte fatty-acid binding protein 3 and 4 (FABP3 and FABP4) genes are associated with carcass weight (CW) and back fat thickness (BF) of beef cattle. By direct DNA sequencing in 24 unrelated Korean native cattle, we identified 20 SNPs in FABP3 and FABP4. Among them, 10 polymorphic sites were selected for genotyping in our beef cattle. We performed SNP, haplotype and linkage disequilibrium studies on 419 Korean native cattle with the 10 SNPs in the FABP genes. Statistical analysis revealed that 220AG (I74V) and 348+303TC polymorphisms in FABP4 showed putative associations with BF traits (P=0.02 and 0.01, respectively). Our findings suggest that the polymorphisms in FABP4 may play a role in determining one of the important genetic factors that influence BF in beef cattle.     

Fitting and validating the genomic evaluation model to Polish Holstein-Friesian cattle

The aim of the study was to fit the genomic evaluation model to Polish Holstein-Friesian dairy cattle. A training data set for the estimation of additive effects of single nucleotide polymorphisms (SNPs) consisted of 1227 Polish Holstein-Friesian bulls. Genotypes were obtained by the use of Illumina BovineSNP50 Genotyping BeadChip. Altogether 29 traits were considered: milk-, fat- and protein- yields, somatic cell score, four female fertility traits, and 21 traits describing conformation. The prediction of direct genomic values was based on a mixed model containing deregressed national proofs as a dependent variable and random SNP effects as independent variables. The correlations between direct genomic values and conventional estimated breeding values estimated for the whole data set were overall very high and varied between 0.98 for production traits and 0.78 for non return rates for cows. For the validation data set of 232 bulls the corresponding correlations were 0.38 for milk-, 0.37 for protein-, and 0.32 for fat yields, while the correlations between genomic enhanced breeding values and conventional estimated breeding values for the four traits were: 0.43, 0.44, 0.31, and 0.35. This model was able to pass the interbull validation criteria for genomic selection, which indicates that it is realistic to implement genomic selection in Polish Holstein-Friesian cattle.     

FABP5 is a critical regulator of methionine- and estrogen-induced SREBP-1c gene expression in bovine mammary epithelial cells

The intracellular fatty acid-binding proteins (FABPs) are a well-conserved family that function as lipid chaperones. Ongoing studies are focused on identification of the mechanistic complexity and vast biological diversity of different isoforms of FABPs. However, the molecular mechanism of FABP5 in the regulation of milk fat synthesis in the mammary gland of dairy cows is still largely unknown. Here, we report that FABP5 acts as a critical regulator of terol response element-binding protein-1c (SREBP-1c) gene expression induced by methionine (Met) and estrogen (E2) in bovine mammary epithelial cells (BMECs). We observed that the expression of FABP5 was markedly higher in dairy cow mammary tissue during the lactating period than the puberty period and the dry period. FABP5 is located in the cytoplasm, and Met and E2 significantly increase the protein levels of FABP5 in BMECs. Using gene function study approaches, we revealed that FABP5 positively regulates SREBP-1c gene expression and promotes milk fat synthesis. We confirmed that FABP5 is required for Met- and E2-induced SREBP-1c gene expression and milk fat synthesis. We further uncovered that fatty acids are needed for FABP5-mediated SREBP-1c gene expression. Thus, our study demonstrates that FABP5 is a critical regulator of Met- and E2-induced SREBP-1c gene expression leading to milk fat synthesis.     

Single nucleotide polymorphism in the promoter region of the lactoferrin gene and its associations with milk performance traits in Polish Holstein-Friesian cows

Bovine lactoferrin (LTF) is a multifunctional small glycoprotein found in milk acting mainly as a defense factor in the mammary gland. Many polymorphisms have been found in the bovine LTF gene but almost none were considered as genetic markers of production traits in dairy cattle. In this study, the promoter fragment of LTF gene containing mutation (G/C) in position +32 has been amplified by PCR followed by genotyping by the SSCP and RFLP method. 358 Polish Holstein-Friesian cows were screened, giving the following frequency of genotypes: 0.628, 0.313 and 0.059 for GG, GC and CC, respectively. GLM (General Linear Model) analysis was applied to evaluate the associations of lactoferrin with milk performance traits, including SCC - somatic cell count. It was found that CC cows show significantly higher (P < or = 0.01) protein content in milk in comparison with GG cows. The values of other milk performance traits were also higher but at non-significant levels. SCC in milk was the lowest in CC cows, but also at a non-significant level.     

Association of genetic variants for <Emphasis Type="Italic">FABP3</Emphasis> gene with back fat thickness and intramuscular fat content in pig

The swine fatty acid binding protein gene (FABP3) has been screened with 4 primer sets for 270 purebred Yorkshire pigs from National Institute of Animal Science. The selection of primers was based on the swine cDNA sequence (AJ416019), and primer sets (FABP3-2 and FABP3-3) amplified target segments in real time PCR to analyze expression levels at growth stages, producing 235 and 224 bp of fragments, respectively. Relative expression of the swine FABP3 gene for back and intramuscular fat was continuously increased from day 0 to 150, and decreased at day 210, showing the highest expression levels at day 150 compared with day 0. The results may be caused by requirements of high physiological activities with more gene expressions for growth around day 150. Nucleotide variations were observed at nucleotide positions 80 (A/G), 167 (A/G), 260 (A/G), 295 (A/G), 394 (T/C), and 440 (A/G), showing substitutions of amino acids at positions 80 (S to G), 167 (T to A), and 260 (S to G). FABP3 genotypes at positioned nt167 have been associated with carcass back fat thickness (BFT), and dominance genetic effects were observed for BFT with nt167 and intramuscular fat (IMF) contents with nt80. Our results concluded that the FABP3 polymorphisms can be used as genetic markers in breeding programs for IMF content as well as carcass BFT.     

Effect ofABCG2,PPARGC1A,OLR1 andSCD1 gene polymorphism on estimated breeding values for functional and production traits in Polish Holstein-Friesian bulls

This study investigated the impact of 6 polymorphisms located in theABCG2, PPARGC1A, OLR1 andSCD1 genes on estimated breeding values for milk production, longevity, somatic cell count and reproductive traits. The analysis was conducted on 453 Polish Holstein-Friesian bulls. Genotypes were identified using PCR-RFLP, and haplotype inferences were performed for 3 linked mutations ofPPARGC1A. The most significant associations were found between the A/C polymorphism located in exon 14 ofABCG2 and milk fat production traits as well as calving-to-first insemination interval, and between the T/C substitution in intron 9 of thePPARGC1A and non-return rate in heifers.     

Replacement of grass and maize silages with lucerne silage: effects on performance,milk fatty acid profile and digestibility in Holstein-Friesian dairy cows

In total, 20 multiparous Holstein-Friesian dairy cows received one of four diets in each of four periods of 28-day duration in a Latin square design to test the hypothesis that the inclusion of lucerne in the ration of high-yielding dairy cows would improve animal performance and milk fatty acid (FA) composition. All dietary treatments contained 0.55 : 0.45 forage to concentrates (dry matter (DM) basis), and within the forage component the proportion of lucerne (Medicago sativa), grass (Lolium perenne) and maize silage (Zea mays) was varied (DM basis): control (C)=0.4 : 0.6 grass : maize silage; L20=0.2 : 0.2 : 0.6 lucerne : grass : maize silage; L40=0.4 : 0.6 lucerne : maize silage; and L60=0.6 : 0.4 lucerne : maize silage. Diets were formulated to contain a similar CP and metabolisable protein content, with the reduction of soya bean meal and feed grade urea with increasing content of lucerne. Intake averaged 24.3 kg DM/day and was lowest in cows when fed L60 (P<0.01), but there was no effect of treatment on milk yield, milk fat or protein content, or live weight change, which averaged 40.9 kg/day, 41.0, 30.9 g/kg and 0.16 kg/day, respectively. Milk fat content of 18:2 c9 c12 and 18:3 c9 c12 c15 was increased (P<0.05) with increasing proportion of lucerne in the ration. Milk fat content of total polyunsaturated fatty acids was increased by 0.26 g/100 g in L60 compared with C. Plasma urea and β-hydroxybutyrate concentrations averaged 3.54 and 0.52 mmol/l, respectively, and were highest (P<0.001) in cows when fed L60 and lowest in C, but plasma glucose and total protein was not affected (P>0.05) by dietary treatment. Digestibility of DM, organic matter, CP and fibre decreased (P<0.01) with increasing content of lucerne in the diet, although fibre digestibility was similar in L40 and L60. It is concluded that first cut grass silage can be replaced with first cut lucerne silage without any detrimental effect on performance and an improvement in the milk FA profile, although intake and digestibility was lowest and plasma urea concentrations highest in cows when fed the highest level of inclusion of lucerne.