The relevance of this study is determined by the need to improve the efficiency of dairy cattle reproduction using molecular genetic markers that can predict animal fertility. The aim of the study was to genotype Holstein cows for the TLR4/AluI gene locus and establish the relationship between its alleles and reproductive function indicators. The objectives included isolating genomic DNA, amplifying a 382-bp TLR4 gene region, and performing restriction analysis with the AluI enzyme. The study included 190 clinically healthy Holstein cows maintained under identical feeding and microclimate conditions at Baiserke-Agro LLP. TLR4/AluI genotyping was performed using PCR-RFLP; the genotype distribution was tested for compliance with Hardy-Weinberg equilibrium. Association analysis was performed taking into account the period of fruitful insemination of cows after calving (45–60; 61–90; 91–120; ≥121 days) and the non-return rate on day 58 (NRI-58). Three genotypes were identified: TT - 39.5%, TC - 43.7%, CC - 16.8%; allele frequencies: T = 0.61, C = 0.39; the distribution corresponds to HWE (χ² = 1.97; p > 0.05). In the 45–60-day group, the TT/TC/CC shares were 42/48/10%, with an increase in the open period (61–90; 91–120 days) an increase in the CC share to 16–22% was noted. According to NRI, 58 animals were registered: TT - 19 heads, TC - 24 heads, CC - 0 (a total of 43 out of 190). The data indicate a favorable role for the T allele and an unfavorable role for the C allele in determining fertility. The TLR4/AluI locus is informative for assessing reproductive function in Holsteins; the T allele is associated with earlier fruitful insemination and better fertility indicators, supporting its use as a selection DNA marker.
The study was conducted to identify the genotypes of single-nucleotide polymorphisms (SNPs) in the GHRL, GAST, and SCTR genes for early performance assessment in Smena 9 poultry. The study was performed on 170 CM5/CM7 roosters and 750 final-hybrid CM5679 broiler chickens with individual feed intake monitoring at ages 36-42 days and 21-42 days, respectively. Groups were formed randomly. Polymorphisms were identified using genotyping using real-time PCR with fluorescently labelled probes. CM5 roosters homozygous for the T allele and heterozygous (TC) for the rs312295326 polymorphism demonstrated improved feed conversion in the 36-42-day period. The feed conversion ratio (FCR) for this period was 1.89 for birds with the TT genotype and 1.91 for TC. The CC genotype was associated with a 7.3-8.5% decrease in FCR (p<0.05). Statistically significant differences in feed conversion efficiency (FCR) were observed in broilers with polymorphic variants of the SCTR gene (rs314830059 and rs736374789). In birds of both sexes with the GG genotype of the rs314830059 polymorphic variant, a decrease in FCR by 8.6-16.9% was observed compared to the GT and TT genotypes from the 24th to the 33rd day (p<0.05). Females with the GG genotype of the rs736374789 polymorphism showed a lower FCR (2.18 to 2.48) compared to individuals with the GT genotype (2.41 to 2.89) on days 39, 40, and 42 (p < 0.05). The identified SNPs in the GHRL (rs312295326), SCTR (rs314830059), and SCTR (rs736374789) genes can be integrated into genomic selection programmes aimed at reducing FCR in meat-producing chickens.
L. G. Korshunova, E. I. Kulikov, D. M. Dmitrenko et al.· Achievements of Science and...· 0 citations
The article presents the results of a study on the combined genotypes of
OPN
(c.8514C/T) and
IGF-1
(512T/C) genes in a population of Holstein heifers (n=202). The experiment was conducted at the Lenin Breeding Farm (Atninsky District, Republic of Tatarstan), and laboratory analyses were carried out at the Tatar Research Institute of Agriculture, Kazan Scientific Center of the Russian Academy of Sciences. The relevance of the study is driven by the need to identify genetic markers associated with reproductive traits in cattle, as fertility indicators alongside milk productivity determine the economic efficiency of dairy farming. The
OPN
and
IGF-1
genes are involved in the regulation of embryogenesis, implantation, folliculogenesis, and early embryonic development; however, their combined interaction remains insufficiently studied. Genotyping was performed using PCR-RFLP with restriction endonucleases
BseI
(for
OPN
) and
BstSNI
(for
IGF-1
). The analysis revealed the presence of all nine possible combined genotype combinations, confirming the genetic heterogeneity of the studied population. The highest frequency was observed for the combined genotype CT/AB (29.7%), while the lowest frequencies were found for CC/BB (2.0%) and CC/AA (3.0%) by
OPN
/
IGF-1
. A pattern of decreasing frequency of combined genotypes was established with an increasing number of homozygous loci. Comparison of the observed and theoretically expected distributions showed no statistically significant deviations (χ² = 4.67; p > 0.05), indicating independent allele combination of the studied genes and the absence of factors disrupting genetic equilibrium in the sample. The obtained data can be applied in breeding programs for marker-assisted selection of parental pairs, genetic passportization, and monitoring of the genetic structure of cattle populations.
N. Safina, E. Mukhanina, E. R. Gainutdinova· Legal regulation in veterina...· 0 citations
Molecular genetic markers, such as the polymorphism of the kappa-casein gene (CSN3), are a important tool for increasing the efficiency of dairy cattle breeding. The aim of this study was to investigate CSN3 polymorphism in a Holstein cattle population and to assess its associations with blood biochemical parameters reflecting the animals’ metabolic status. In the studied herd (146 animals), allele (A — 0,651, B — 0,349) and genotype frequencies were determined using the PCR-RFLP method: AB (47,9 %; 70 animals), AA (41,1 %; 60 animals), and BB (11,0 %; 16 animals). The results of the biochemical analysis for 12 blood serum parameters were statistically processed using t-test Student in the context of the identified genotypes. Significant associations of CSN3 polymorphism with the biochemical profile were revealed. Carriers of the B allele, especially those with the BB genotype, were characterized by a significantly higher level of protein metabolism indicators (total protein, albumin, urea, creatinine) and activity of enzymes from the classes of aminotransferases (AST, ALT) and hydrolases (alkaline phosphatase), as well as lower concentrations of bilirubin and glucose compared to animals with the AA genotype. The obtained data indicate more intensive metabolism and efficient liver function in cows with the B allele. The results confirm the pleiotropic effect of the CSN3 gene, linking the genetic variant not only to milk quality but also to the body’s metabolic profile. This substantiates the feasibility of using this gene as a marker for the comprehensive assessment and prediction of metabolic adaptation in Holstein cattle breeding programs. The work was carried out according to a state assignment, registration number 125031003428-9
N. Safina, E. Krupin, S. Shakirov et al.· International Journal of Vet...· 0 citations
In dairy farming, reproductive efficiency is vital to both profitability and sustainability. However, years of selective breeding for increased milk yield have adversely affected reproductive potential. This study aimed to pinpoint genomic regions and identify potential candidate genes associated with reproductive traits in Chinese Holstein cattle. In this study, a single-step genome-wide association study (ssGWAS) was conducted using 33,202 phenotypic records from 16,379 animals, 55,244 pedigree records, and genomic data from 1,698 cows. These data were integrated into the ssGWAS analysis, resulting in a total pedigree structure of 21,635 animals. A total of 12 significant markers were identified for calving interval (IC), days open (DO), number of services per conception (NS), and conception rate (CR). Among these significant SNPs, 3 SNPs were for IC, 2 SNPs were for DO, 3 SNPs were for NS, and 4 SNPs were for CR. Several promising candidate genes located near these SNPs have been identified, including SFXN4, B3GAT2, GRK5, PRDX3, and MTHFD1L, highlighting their potential involvement in fertility-related biological processes. Furthermore, functional enrichment analysis identified significant enrichment of pathways associated with cell adhesion and embryonic development, suggesting a potential mechanistic role for DSG family members (DSG1, DSG2, DSG3, and DSG4) in fertility regulation. Collectively, our findings enhance understanding of the complex genetic basis of reproductive traits in dairy cattle and may offer a valuable set of genomic targets for precision breeding of Chinese Holsteins. Integrating these markers into genomic selection programs may contribute to genetic improvements in reproductive efficiency and support the long-term sustainability of dairy production.
W. A. Lombebo, Mingxin Du, G. M. Tarekegn et al.· Journal of Animal Science· 0 citations
The aim of the study was to evaluate the effect of 12 complex GN and LEP genotypes on cow productivity in order to identify consistently effective allele combinations that account for genotype-environment interactions, and to develop personalized strategies for herd breeding and management. The conducted study revealed a significant association between complex genotypes of the somatotropin (GH, LV polymorphism) and leptin (LEP, R25C and A80V polymorphisms) genes and milk productivity in Holstein cows. A study of 120 animals (60 animals each from two agricultural organizations) showed a marked uneven distribution of the 12 analyzed genotypes in both herds, due to the farm breeding priorities. A key result was the identification of the GHLVR25CRRA80VAA genotype as the most promising for breeding for high lifetime milk productivity. Animals with this genotype consistently demonstrated maximum milk yields in the first and third lactations and lifetime productivity, demonstrating stability and high genetic potential. In parallel, genotypes associated with milk quality traits were identified. For example, in animals carrying the GHLVR25CCCA80VVV genotype at Organization "K," the lifetime fat and protein content was 3.92 and 3.27 %, respectively. Animals with the GHLVR25CCRA80VAA genotype in Organization "P" had a maximum fat content of 4.13 % while maintaining high milk yield. The study confirmed the critical influence of environmental factors (feeding, management) on the realization of genetic potential. The significantly higher milk yields in Organization "P" compared to Organization "K" highlight the need for a systematic approach combining genetic selection with improved livestock production technologies. The obtained data demonstrate that the complex GH and LEP genotypes serve as informative markers for predicting milk productivity and the adaptive potential of cows.
A. Yaryshkin, O. Shatalina, A. A. Zyryanova· Agricultural science Euro-No...· 0 citations
The genetic and physiological variations among individuals of Holstein dairy cattle contribute to variations in milk yield. Selecting high-yield cows is critical for improving lactation performance. The present study aimed to identify functional genetic variants of the 3′ untranslated region (3′ UTR) in the ELF5 gene associated with milk production traits and to elucidate their underlying molecular mechanisms. A total of 1314 Chinese Holstein cows were genotyped, and a novel single nucleotide polymorphism (SNP), ELF5 g.32793 G>T, was identified in the 3′ UTR of ELF5. This SNP was significantly associated with milk production, such as milk yield, milk fat percentage, milk protein percentage, and somatic cell score. Bioinformatic prediction and dual-luciferase reporter assays demonstrated that the ELF5 g.32793 G>T affects the interaction between bta-miR-487a and the ELF5 3′ UTR. Functional analyses in bovine mammary epithelial (MAC-T) cells showed that bta-miR-487a suppressed cell proliferation by inducing G0/G1 phase arrest and reduced the expression of proliferation-related proteins. Collectively, these findings suggested that bta-miR-487a participates in the regulation of MAC-T cell growth and that the ELF5 g.32793 G>T polymorphism may influence lactation performance through an miRNA-associated mechanism. Therefore, the variant can be used as a functional marker for marker-assisted selection in dairy cattle breeding.
Lin Ma, Li Sun, Haotian Zhang et al.· Biomolecules· 0 citations