Relationships between the first ovulation postpartum and polymorphism in genes relating to function of immunity, metabolism and reproduction in high-producing dairy cows

Association between somatotropic axis gene polymorphisms and reproductive efficiency of bovine females: a review

Abstract Reproductive characteristics directly reflect on productive performance, as they determine the number of calves born annually and the interval between generations, thereby affecting the selection intensity. This allows for the determination of the most important economic variables that directly affect the production system. The present study is a literature review of somatotropic axis gene polymorphisms that are associated with reproductive functions in heifers and cows (Bos taurus taurus and Bos taurus indicus). The following characteristics were analyzed from the various studies reviewed: number of services per pregnancy (Nº services/ pregnancy), age at first calving (AFC), calving interval (CI), and period of service calving conception interval (CCI). The research was conducted during the period from 2011 to 2021, and associations were found among all indicators of reproductive efficiency evaluated in heifers and cows, with 27 single nucleotide polymorphisms (SNPs): 18 in GHR, 5 in IGF-I, and 4 in STAT5A. This study revealed the relationships between SNPs and the reproductive efficiency indicators and demonstrated that molecular genetic techniques enhance the animal selection process, resulting in more profitable systems that are sustainable in the long term.

Associação entre polimorfismos de genes do eixo somatotrópico e eficiência reprodutiva de fêmeas bovinas: revisão de literatura

Resumo Características reprodutivas refletem diretamente no desempenho produtivo visto que são capazes de determinar o número de bezerros nascidos anualmente, além de afetar o intervalo entre gerações e, consequentemente, a intensidade de seleção, fazendo com o que tais atributos sejam apontados como variáveis econômicas das mais importantes que afetam diretamente o sistema de produção. O presente estudo propõe realizar uma revisão de literatura de polimorfismos de genes do eixo somatotrópico associados a funções reprodutivas em novilhas e vacas (Bos taurus taurus e Bos taurus indicus), indicadas pelos índices: número de serviços por gestação (Nº serviços/gestação), idade ao primeiro parto (IPP), intervalo de partos (IP) e período de serviço, como também denominado de intervalo parto-concepção (IPC). As pesquisas encontradas durante o período de 2011 a 2021 demonstraram associações entre todos os indicadores de eficiência reprodutiva analisados de novilhas e vacas com 27 polimorfismos de nucleotídeo único (SNPs), sendo 18 em GHR, 5 em IGF-I e 4 em STAT5A. Dessa forma, este estudo mostrou relação entre os SNPs e os indicadores de eficiência reprodutiva, demonstrando que técnicas de genética molecular potencializam o processo de seleção dos animais, resultando em sistemas mais lucrativos e que se sustentam a longo prazo.

Effect of COQ9 and STAT5A polymorphisms on reproductive performance in a Holstein cow herd in Mexico

Coenzyme Q9 (COQ9), a coenzyme Q (CoQ) precursor, is an essential component of the mitochondrial electron transport chain that drives adenosine triphosphate production. COQ9 polymorphism 18:25527339 is characterized by substitution of guanine (allele G) for adenine (allele A), which modifies the function of the protein encoded by the gene. In Holsteins, allele A has been associated with better reproductive performance in terms of the conception rate, number of services per conception (SPC) and days open (DO). The signal transducer and activator of transcription (STAT) protein is a transcription factor activated in the presence of cytokines and growth factors. STAT5A polymorphism 19:42407732 in exon 8 has been associated with higher fertility and embryonic survival rates. The objective of this study was to determine the relationship of COQ9 and STAT5A polymorphisms with reproductive parameters [calving to first heat interval (CFHI), DO and SPC]. Blood samples were taken from 112 lactating Holstein from a herd in México for allele genotyping by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). To estimate the association between reproductive parameters and genotypes, a linear mixed-effect model was performed. The COQ9 AG genotype was associated significantly with lower SPC (P<0.05) but not with DO or CFHI. No significant association with any reproductive parameter was found for STAT5A. Our findings suggest that the COQ9 18:25527339 polymorphism is a useful molecular marker for improvement of reproductive performance in dairy herds.

Tissue expression and variation analysis of three bovine adipokine genes revealed their effect on growth traits in native Chinese cattle

Adipokines play a crucial role in the regulation of energy homeostasis; however, little is known about genetic alterations in this family that may contribute to economic traits in cattle. Therefore, this study conducts transcript profiles, variations and association studies of three major adipokines, leptin (LEP), tumour necrosis factor (TNF) and angiopoietin-like protein 8 (ANGPTL8), to evaluate their effects on native Chinese cattle. Using quantitative real-time PCR, the study revealed that the bovine LEP was expressed primarily in the back and visceral fat, while TNF was predominantly expressed in spleen and ANGPTL8 was mainly expressed in back fat and liver. Five single nucleotide polymorphisms (SNPs) including two missense SNPs (SNP1: g.12254T>C and SNP2: g.14177C>T) in LEP, a synonymous SNP (SNP3: g.2130A>G) in TNF and two SNPs (SNP4: g.629G>A and SNP5: g.884T>C) in the 5'UTR of ANGPTL8 were identified and genotyped in 537 individuals from six Chinese cattle breeds. Bioinformatics analysis revealed that SNP1 might disrupt the efficient binding of LEP to its receptor, SNP3 might affect translation efficiency of TNF, and SNP4 and SNP5 were likely to affect stability, splicing and nuclear export of ANGPTL8 mRNA. Consistently, association studies indicated that three SNPs (SNP1, SNP3 and SNP5) were significantly associated with body weight, heart girth, average daily gain, hip width and body length in 100 Nanyang cattle (p < 0.05). Overall, our results support the view that LEP, TNF and ANGPTL8 could be used as biomarkers to improve the growth performance in Chinese cattle selection programmes.

Polymorphism in promoter region of growth hormone receptor is associated with potential production capacity of insulin-like growth factor-1 in pre-pubertal Holstein heifers

Insulin-like growth factor-1 (IGF-1) is one of the important factors for growth, milk production and reproductive functions and mainly released from the liver in response to growth hormone (GH) via GH receptor (GHR) in cattle. Recently, some single nucleotide polymorphisms (SNPs) were identified in the bovine GHR gene. Some GHR-SNPs were shown to be related to plasma IGF-1 concentration in cattle. Hence, the capacity to IGF-1 production in the liver might be affected by GHR-SNP and associated with performance in the future. This study examined whether GHR-SNP is associated with IGF-1 production in the liver of pre-pubertal heifers. In 71 Holstein calves, blood samples for genomic DNA extraction were obtained immediately after birth. To genotype the GHR-SNPs in the promoter region, polymerase chain reaction (PCR) products were digested with restriction enzyme NsiI (cutting sites: AA, AG and GG). All heifers at 4 months of age were intramuscularly injected with 0.4 mg oestradiol benzoate. Blood samples were obtained from the jugular vein just before (0 h) and 24 h after injection. The number of AA, AG and GG at the NsiI site was 0, 17 and 54 respectively. In AG and GG, plasma GH concentrations were higher pre-injection than 24 h post-injection (p < 0.01). Moreover, plasma GH concentrations in AG post-injection were higher than in GG (p < 0.05). In contrast, the GG genotype exhibited higher plasma IGF-1 concentrations in pre-injection than post-injection (p < 0.01), although oestradiol did not change IGF-1 concentration in the AG genotype. We conclude that the GG polymorphism in the promoter region of GHR is associated with a higher potential capacity of IGF-1 production in the liver of cattle.

Association between polymorphisms in somatotropic axis genes and fertility of Holstein dairy cows

The aim of this study was to determine the effect of growth hormone receptor (GHR) AluI, insulin-like growth factor type 1 (IGF-I) SnaBI, and signal transducer and activator 5A (STAT5A) BstEII polymorphisms in the reproductive performance of Holstein dairy cows and the frequency of this genotypes in cows managed in different systems. This work studied 381 and 506 Holstein cows from semiextensive and intensive systems, respectively. The frequency of genotypes GHRAluI (+/-), IGF-ISnaBI (-/-) and (+/-), and STAT5ABstEII (-/-) was higher in animals from semiextensive system, whereas the frequency of the genotypes GHRAluI (+/+) and IGF-ISnaBI (+/+) was higher in animals from intensive system (P < 0.05). In the intensive system, cows from the STAT5ABstEII (-/-) genotype had a longer calving-first heat interval (P = 0.03). In conclusion, there was no association between the genotypes of GHRAluI and IGF-ISnaBI and fertility of Holstein cows raised in semiextensive or intensive regimes, although the genotype frequencies of the evaluated polymorphisms were different between the studied systems. The STAT5ABstEII polymorphism was associated with calving-first heat interval in Holstein cows raised in the intensive system, indicating that this gene could be a molecular marker for genetic selection to improve reproductive performance.

Association of polymorphism harbored by tumor necrosis factor alpha gene and sex of calf with lactation performance in cattle

In a majority of mammals, male infants have heavier body mass and grow faster than female infants. Accordingly, male offspring nursing requires a much greater maternal energy contribution to lactation. It is possible that the maternal-fetal immunoendocrine dialog plays an important role in female preparation for lactation during pregnancy. Immune system genes are an integral part of gene regulatory networks in lactation and tumor necrosis factor alpha (TNFα) is a proinflammatory cytokine that also plays an important role in normal mammary gland development. The aim of this study was to evaluate the influence of the sex of calf and/or the -824A/G polymorphism in the promoter region of TNFα gene on milk performance traits in Black Pied cattle over the course of lactation. We also studied the allele frequency differences of -824A/G variants across several cattle breeds, which were bred in different climatic conditions. The G allele frequency decreased gradually over the course of lactation events in the Black Pied dairy cattle because of a higher culling rate of cows with the G/G genotype (p<0.001). In contrast to the genotypes A/A and A/G, cows with G/G genotype showed significant variability of milk and milk fat yield subject to sex of delivered calf. Milk yield and milk fat yield were significantly higher in the case of birth of a bull calf than with a heifer calf (p<0.03). The G allele frequency varies from 48% to 58% in Grey Ukrainian and Black Pied cattle to 77% in aboriginal Yakut cattle. Our results suggest that the TNFα -824A/G gene polymorphism may have an influence on the reproductive efforts of cows over the course of lactation events depending on the sex of progeny. Allocation of resources according to sex of the calf allows optimizing the energy cost of lactation. This may be a probable reason for high G allele frequency in Yakut cattle breeding in extreme environmental conditions. Similarly, the dramatic fall in milk production after birth of a heifer calf increases the probability of culling for the cows with the G/G genotype in animal husbandry.

Discovery of single nucleotide polymorphisms in candidate genes associated with fertility and production traits in Holstein cattle

Background

Identification of single nucleotide polymorphisms (SNPs) for specific genes involved in reproduction might improve reliability of genomic estimates for these low-heritability traits. Semen from 550 Holstein bulls of high (≥ 1.7; n = 288) or low (≤ −2; n = 262) daughter pregnancy rate (DPR) was genotyped for 434 candidate SNPs using the Sequenom MassARRAY® system. Three types of SNPs were evaluated: SNPs previously reported to be associated with reproductive traits or physically close to genetic markers for reproduction, SNPs in genes that are well known to be involved in reproductive processes, and SNPs in genes that are differentially expressed between physiological conditions in a variety of tissues associated in reproductive function. Eleven reproduction and production traits were analyzed.

Results

A total of 40 SNPs were associated (P < 0.05) with DPR. Among these were genes involved in the endocrine system, cell signaling, immune function and inhibition of apoptosis. A total of 10 genes were regulated by estradiol. In addition, 22 SNPs were associated with heifer conception rate, 33 with cow conception rate, 36 with productive life, 34 with net merit, 23 with milk yield, 19 with fat yield, 13 with fat percent, 19 with protein yield, 22 with protein percent, and 13 with somatic cell score. The allele substitution effect for SNPs associated with heifer conception rate, cow conception rate, productive life and net merit were in the same direction as for DPR. Allele substitution effects for several SNPs associated with production traits were in the opposite direction as DPR. Nonetheless, there were 29 SNPs associated with DPR that were not negatively associated with production traits.

Conclusion

SNPs in a total of 40 genes associated with DPR were identified as well as SNPs for other traits. It might be feasible to include these SNPs into genomic tests of reproduction and other traits. The genes associated with DPR are likely to be important for understanding the physiology of reproduction. Given the large number of SNPs associated with DPR that were not negatively associated with production traits, it should be possible to select for DPR without compromising production.

A polymorphism in the insulin-like growth factor 1 gene is associated with postpartum resumption of ovarian cyclicity in Holstein-Friesian cows under grazing conditions

Background

Insulin-like growth factor 1 (IGF-1) gene is considered as a promising candidate for the identification of polymorphisms affecting cattle performance. The objectives of the current study were to determine the association of the single nucleotide polymorphism (SNP) IGF-1/SnaBI with fertility, milk production and body condition traits in Holstein-Friesian dairy cows under grazing conditions.

Methods

Seventy multiparous cows from a commercial herd were genotyped for the SNP IGF-1/SnaBI. Fertility measures evaluated were: interval to commencement of luteal activity (CLA), calving to first service (CFS) and calving to conception (CC) intervals. Milk production and body condition score were also evaluated. The study period extended from 3 wk before calving to the fourth month of lactation.

Results and discussion

Frequencies of the SNP IGF-1/SnaBI alleles A and B were 0.59 and 0.41, respectively. Genotype frequencies were 0.31, 0.54 and 0.14 for AA, AB and BB, respectively. Cows with the AA genotype presented an early CLA and were more likely to resume ovarian cyclicity in the early postpartum than AB and BB ones. No effect of the SNP IGF-1/SnaBI genotype was evidenced on body condition change over the experimental period, suggesting that energy balance is not responsible for the outcome of postpartum ovarian resumption in this study. Traditional fertility measures were not affected by the SNP IGF-1/SnaBI.

Conclusion

To our knowledge this is the first report describing an association of the SNP IGF-1/SnaBI with an endocrine fertility measure like CLA in cattle. Results herein remark the important role of the IGF-1gene in the fertility of dairy cows on early lactation and make the SNP IGF-1/SnaBI an interesting candidate marker for genetic improvement of fertility in dairy cattle.