Polymorphisms in the IGF1 gene and their effect on growth traits in Mexican beef cattle

The association of gene polymorphisms with milk production and mastitis resistance phenotypic traits in dairy cattle

The aim of this study was to evaluate the association between gene polymorphisms (SNPs) and mastitis indicators and their relationship with milk production profitability in dairy herd.A functional analysis was also performed of five genes containing the studied SNPs and those located close by. DNA was isolated from the hair bulb of 320 dairy cows kept in three herds and SNP-microarray analysis was performed. The data on 299 cows was subjected to final statistical analysis using AI-REML method with one-trait repeatability test-day animal model and pedigree information using the DMU4 package. Five from 35 SNPs significantly associated with mastitis indicators or production traits and located within a gene or no more than 500,000 nucleotides from the gene were selected for the functional and economic analysis. A questionnaire was also developed to collect associated economic data of 219 cows from three herds, such as the value of milk production and direct costs incurred over three years; this allowed the gross margin, direct profitability index and direct costs incurred to produce one liter of milk to be determined, among others. None of the five studied SNPs were related to protein content. The rs110785912(T/A), found near CXCR4, and rs136813430(T/C), located in the TLR4 gene exon, were associated with lnSCC, while rs110455063(C/G), located near IGFI, was associated with milk yield, fat and total solid contents. rs109421300(T/C), associated with fat/protein content ratio, as well as fat and total solid content, is located in the DGAT1 gene intron. rs41587003(A/C), located in the DLG2 gene intron, was associated with lactose content. The economic analysis revealed differences between the variants of the three tested SNPs. The T/C variant of the rs136813430(T/C) SNP was characterized by the highest gross margin, the highest direct profitability index and the lowest costs incurred to produce 1 liter of milk. The T/A variant of rs110785912(T/A) was related to low lnSCC and was characterized by the highest direct profitability index. In turn, the C/C variant of the rs41587003(T/C) was related to the lowest level of lactose and the highest costs of milk production. It appears that rs136813430(T/C) may be the most promising of the tested SNPs for increasing the profitability of milk production. To our knowledge, it is the first effort to assess directly a correlation between the DNA polymorphism and economic output of a dairy enterprise.

Influence of single nucleotide polymorphism in the IGF-1 gene on performance and conformation traits in Munjal sheep

Genetic polymorphism research in livestock species aims to assess genetic differences within and among breeds, primarily for conservation and development objectives. The aim of the present study was to determine the point mutation in the IGF-1 gene (g.855G>C and g.857G>A) and its association with performance traits in Munjal sheep. In total, 50 Munjal sheep were selected and the genomic DNA was isolated using the Automated Maxell RSC DNA/RNA purification system and the Maxwell RSC whole blood DNA kit. A reported set of primers was used to amplify the 294-bp fragment encompassing the targeted region, i.e. the 5' flanking region of the IGF-1 gene. The polymerase chain reaction product of 294-bp size harbouring the g.857G>A mutation in the 5' flanking region of the IGF-1 gene was digested with HaeII enzyme. Three possible genotypes were defined by distinct banding patterns, i.e. GG (194, 100 bp), GA (294, 194, 100 bp) and AA (294 bp) in the studied population of Munjal sheep. The genotypic and allelic frequencies of g.857G>A single nucleotide polymorphism of the IGF-1 gene indicated that the frequency of the A allele was higher in the studied population, i.e. 0.59 and the GA genotype was found to be the predominant genotype (0.66). Allele A of the IGF-1 gene was found to be associated with higher body weights and can be used in selection criteria for improving the performance of Munjal sheep. The positive effect of the IGF-1 gene on several conformational traits as observed in this study suggests that this area of the ovine IGF-I gene is particularly important and warrants further investigation on a larger population size.

Genetic Polymorphisms of IGF1 and IGF1R Genes and Their Effects on Growth Traits in Hulun Buir Sheep

The identification of candidate genes and genetic variations associated with growth traits is important for sheep breeding. Insulin like growth factor 1 (IGF1) and insulin like growth factor 1 receptor (IGF1R) are well-accepted candidate genes that affect animal growth and development. The current study attempted to assess the association between IGF1 and IGF1R genetic polymorphisms and growth traits in Hulun Buir sheep. To achieve this goal, we first identified three and ten single nucleotide polymorphisms (SNPs) in exons of IGF1 and IGF1R in Hulun Buir sheep and then constructed six haplotypes of IGF1R based on linkage disequilibrium, respectively. Association studies were performed between SNPs and haplotypes of IGF1 and IGF1R with twelve growth traits in a population encompassing 229 Hulun Buir sheep using a general linear model. Our result indicated three SNPs in IGF1 were significantly associated with four growth traits (p < 0.05). In IGF1R, three SNPs and two haplotype blocks were significantly associated with twelve growth traits (p < 0.05). The combined haplotype H5H5 and H5H6 in IGF1R showed the strong association with 12 superior growth traits in Hulun Buir sheep (p < 0.05). In conclusion, we identified SNPs and haplotype combinations associated with the growth traits, which provided genetic resources for marker-assisted selection (MAS) in Hulun Buir sheep breeding.

Exploring the relationship between polymorphisms of leptin and IGF-1 genes with milk yield in indicine and taurine crossbred cows

Leptin an adipokine plays a significant role in several physiological processes and has been indicated as a candidate gene for marker-assisted selection for high-yielding cows. Insulin-like growth factor-1 (IGF-1) hormone plays an important physiological role in growth, development, metabolism, and lactation in bovines. It is believed to be one of the main mediators of energy balance effects on the reproductive performance of dairy cows after calving. The present investigation was carried out to identify the novel polymorphisms in exon 3 region of leptin and exon 3 partial intron 3 of IGF-1 genes and their association with the milk production performance in indicine and taurine crossbred (Karan Fries) cows. Blood samples were collected from 160 apparently healthy Karan Fries (KF) cows. Four SNPs (single-nucleotide polymorphisms) at positions rs29004508 (C > T), rs29004509 (C > T), rs29004510 (T > C), and rs29004511 (T > C) in leptin gene and two SNPs at positions rs133251968 (C > A) and rs137289661 (C > T) in IGF-1 gene were found in KF cows; however, rs29004509 (C > T) had a positive correlation (r = 0.376; P < 0.05) with milk yield. The genetic variants observed in exon 3 region of leptin gene and their association with milk yield traits revealed the importance of CT genotype, which had been useful for genetic improvement of KF cow for milk production traits and can also be utilized as a potential genetic marker to select appropriate animals.

Associations between genetic variants of the insulin-like growth factor I (IGF-I) gene and growth traits in European sea bass (Dicentrarchus labrax, L.)

The IGF-I is a significant peptide hormone to cell growth, development, reproduction, and metabolism of teleost fish. This study was conducted to investigate the IGF-I gene polymorphism and to reveal the association between the genotypes of IGF-I gene and growth traits in 80 harvest size European sea bass (Dicentrarchus labrax, L.) reared in İzmir region of Turkey. The 821 bp long exon 1 and 5' UTR regions of IGF-I gene were amplified, and PCR products were analyzed via DNA sequencing method. Two novel single nucleotide polymorphisms (SNPs) such as g.46672A > G and g.46749C > T in the 5' UTR region of IGF-I gene in the European sea bass were detected for the first time with this study. Associations between the genotypes of IGF-I g.46749C > T locus and body weight were found statistically significant (p < 0.05). The genotypes of IGF-I g.46749C > T and g.46672A > G loci were found significantly associated with total length (p < 0.05). However, both loci did not show significant associations with body width. The studied gene region sequences were entered to NCBI GenBank database with the accession numbers: MK621680-MK621682. Thus, these polymorphisms have a significant effect on the body weight and total length which could be useful for sea bass selection and breeding for marker-assisted selection (MAS) program.

Possible relationship between IGF-1/SnaBI genotypes and milk yield of Holstein-Friesian cows

The correlation between polymorphisms in the IGF-1 gene and production traits in beef cattle is well known. The effect of insulin-like growth factor on the value of milk traits is not yet adequately understood. The aim of the study was to attempt to describe the effect of IGF-1/SnaBI substitution on selected milk performance parameters of the Black-and-White variety of Holstein-Friesian cows. Three genotypes were identified: CC, CT and TT. The results showed a correlation between IGF-1/SnaBI genotypes and milk yield (highest for CC homozygotes and lowest for CT heterozygotes). No relationship could be established between the genotype and the quality characteristics of milk.

The non-synonymous mutation in bovine SPP1 gene influences carcass weight

Meat quality in beef cattle is controlled by genetic factors. SPP1 (secreted phosphoprotein 1) gene, coding a multifunctional cytokine with diverse biological functions, is the candidate gene influencing carcass traits. In this study, we tried to discover DNA polymorphisms associated with beef quality in bovine SPP1 gene, so that two SNPs (single nucleotide polymorphisms) in the promoter region and one SNP in the CDS (coding sequence) region were identified. Although the formers were predicted to alter SPP1 expression, they did not show any effects on the traits. On the contrary, statistical analysis revealed that g.58675C > T, a non-synonymous mutation from threonine to methionine in the conservative region, had a significant effect on carcass weight. Carcass weight of the animals with C/T allele (473.9 ± 6.0 kg) was significantly heavier than that of the C/C homozygotes (459.2 ± 2.8 kg). Because SPP1 gene functions in skeletal muscle cells as a positive regulator, the non-synonymous mutation might influence muscle development and remodeling, resulting in increased carcass weight of the C/T animals. Our results indicate that the SNP can be applied as a DNA marker for the improvement of beef cattle.

Polymorphism of insulin-like growth factor 1 gene and its relationship with reproductive performances and milk yield in Sarda dairy sheep

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IGF-1 gene plays an important role in regulating reproduction in ruminants.

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Here three SNPs were found in the IGF-I gene in Sarda sheep.

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The found SNPs were related to reproductive performance and milk yield.

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This results could be used to improve the reproductive performances and milk yield in Sarda sheep.

The aim of this research was to detect polymorphisms within the IGF-I gene in dairy sheep and to verify their influence on milk yield and reproductive performances. Four hundred Sarda ewes in their second lactation were selected from 2 farms. Their reproductive traits (fertility rate, interval in days from ram introduction to lambing and litter size) and milk yield were recorded, from the second to the fourth lactation. DNA was extracted from individual blood samples and subjected to amplification and sequencing of the IGF-I gene 5′ UTR and Exon 3 regions. Three polymorphic sites were recorded at positions g184028491C>G and g184028489C>T of the 5′UTR, and g184023223G>A of the Exon 3. The C allele at position g184028491 showed a significant association with higher fertility rate (P < 0.05) and a shorter interval in days from ram introduction to lambing (P < 0.01). In addition, a significant effect of the CC genotype was found with higher milk yield for P < 0.05 in the second and third lactation, and P < 0.01 in the fourth lactation compared to the other genotypes. Even, AA genotype at position g184023223 of the exon 3 showed a positive significant effect on milk yield for P < 0.05, in the second and third lactation, and for P < 0.01 in fourth lactation compared to the other genotypes. In conclusion the found SNPs showed a significant influence on reproductive performances and milk yield in Sarda sheep breed suggesting a possible application in sheep selection plans.

Interaction between CA repeat microsatellites and HIF1α regulated the transcriptional activity of porcine IGF1 promoter

Insulin-like growth factor 1 (IGF1) is pivotal in the regulation of animal growth. Highly polymorphic CA repeat microsatellites have been identified in the IGF1 promoter region of different breeds of pigs. Previous studies showed that CA repeat microsatellites are associated with circulating IGF1 level. However, the mechanisms by which CA repeat microsatellites regulate IGF1 expression remain unclear. This study aimed to detect the association of CA repeat microsatellites with the transcriptional regulation of porcine IGF1 and the possible mechanisms. Results revealed that the number of CA repeats in porcine IGF1 promoter was 14-18, and a promoter with 14 or 15 CA repeats had a higher transcriptional activity (P < 0.01). Transcription factor hypoxia-inducible factor 1 subunit alpha (HIF1α) was confirmed to bind to the binding site upstream of CA repeat microsatellites. The microsatellites with 14 or 15 CA repeats were more sensitive to changes in the HIF1α expression level (P < 0.01). These results suggested that CA repeat microsatellites and HIF1α affected the transcriptional activity of each other in the regulation of IGF1 expression, thereby implying an interaction between them. Overall, this study provided novel evidence for elucidating the effects of CA repeat microsatellites on the transcriptional regulation of porcine IGF1.

Signatures of selection in Charolais beef cattle identified by genome-wide analysis

Charolais cattle are one of the most important breeds for meat production worldwide; in México, its selection is mainly made by live weight traits. One strategy for mapping important genomic regions that might influence productive traits is the identification of signatures of selection. This type of genomic features contains loci with extended linkage disequilibrium (LD) and homozygosity patterns that are commonly associated with sites of quantitative trait locus (QTL). Therefore, the objective of this study was to identify the signatures of selection in Charolais cattle genotyped with the GeneSeek Genomic Profiler Bovine HD panel consisting of 77 K single nucleotide polymorphisms (SNPs). A total 61,311 SNPs and 819 samples were used for the analysis. Identification of signatures of selection was carried out using the integrated haplotype score (iHS) methodology implemented in the rehh R package. The top ten SNPs with the highest piHS values were located on BTA 4, 5, 6 and 14. By identifying markers in LD with top ten SNPs, the candidate regions defined were mapped to 52.8-59.3 Mb on BTA 4; 67.5-69.3 on BTA 5; 39.5-41.0 Mb on BTA 6; and 26.4-29.6 Mb on BTA 14. The comparison of these candidate regions with the bovine QTLdb effectively confirmed the association (p < 0.05) with QTL related to growth traits and other important productive traits. The genomic regions identified in this study indicated selection for growth traits on the Charolais population via the conservation of haplotypes on various chromosomes. These genomic regions and their associated genes could serve as the basis for haplotype association studies and for the identification of causal genes related to growth traits.

Polymorphisms of the IGF1 gene and their association with growth traits, serum concentration and expression rate of IGF1 and IGF1R in buffalo

The insulin-like growth factor 1 (IGF1) gene is a member of the group of somatotropin axis genes that play a significant role in cell proliferation and growth of muscles. Here, we searched for polymorphisms in buffalo IGF1 and found two novel single nucleotide polymorphisms (SNPs), G64A and G280A, in the noncoding sequences of exon 1 and exon 4, respectively. Statistical analysis of different genotypes showed that the individuals with GG genotypes had significantly (P<0.05) higher body weight (BW) and average daily gain (ADG) than those with other genotypes at ages of 3-6 months in G64A SNP and 6-9 months in G280A SNP. The combined genotypes of these two SNPs produced three haplotypes, GG/GG, AG/AG, and AA/AA, which were significantly associated (P<0.0001) with BW and ADG at an age from 3 to 12 months. Buffaloes with the homozygous GG/GG haplotype showed higher growth performance than other buffaloes. The two SNPs were correlated with mRNA levels of IGF1 and IGF1 receptor (IGF1R) in semitendinosus muscle as well as with the serum concentration level of IGF1. Also, buffaloes with GG/GG haplotype showed higher mRNA and serum concentration levels. The data revealed that these two SNPs could be valuable genetic markers for selection of Egyptian buffaloes for better performance in the population.

Effect of the <i>IGF-I</i> gene polymorphism on growth, body size, carcass and meat quality traits in Coloured Polish Merino sheep

Abstract. Insulin-like growth factor I, encoded by the IGF-I gene, plays a role in cell growth and differentiation, embryogenesis, metabolism regulation, skeletal growth, and protein synthesis. The aims of this study were to investigate the polymorphism in the 5′ flanking region of the IGF-I gene and evaluate associations between the single-nucleotide polymorphism (SNP) in this gene and growth, body size, carcass and meat quality traits in Coloured Polish Merino sheep. In total 78 live and post mortem traits were investigated. Polymorphism in the IGF-I gene was identified with the use of the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method in 305 Coloured Polish Merino sheep. In association studies, traits of interest were analysed with the use of the MIXED and GENMOD procedures of the SAS statistical package. Two alleles named A and B, and two IGF-I genotypes – AA and AB – were detected. The A allele and the AA genotype were predominant, with the frequencies of 91.6 and 83.3 %, respectively. The IGF-I genotype was found to have a highly significant effect on fore shank weight (P  =  0.006), kidney fat class (P  =  0.002) and EUROP fat class (P  =  0.005). Furthermore, the IGF-I genotype significantly affected external fatness of carcass class (P  =  0.038), drip loss (P  =  0.049), and subjective assessment of meat colour (P  =  0.043), and it tended to be associated with longissimus dorsi (LD) muscle width (P  =  0.063) and flavour (0.067). Concluding, the IGF-I gene could be considered as a candidate gene of selected carcass and meat quality traits in sheep.

Association of a Cac8I polymorphism in the IGF1 gene with growth traits in Indian goats

The Insulin-like Growth Factor 1 (IGF1) gene is a member of somatotropic axis and plays a key role in proliferation of cells, mitosis, myogenesis, meiosis, differentiation in foetal development and post natal growth. The objectives of this study were to verify the single nucleotide polymorphisms (SNPs) in IGF1 gene and their association with growth traits in two indigenous native goat genetic groups of Kerala, viz., Malabari and Attappady Black. A total of 277 goats were genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using the restriction enzyme Cac8I. One SNP, A224G was detected in the 5′ non-coding region of the IGF1 gene, and accordingly two genotypes were revealed, GG and AG. This SNP was significantly associated with growth traits in Attappady Black goats, which is maintained as meat breed in Kerala. Results from this study demonstrated higher performance of GG animals for growth traits. The association of IGF1 gene with these traits emphasizes the importance of caprine IGF1 as a candidate gene for growth traits in goat breeding.

The effect of polymorphism in gene of insulin-like growth factor-I on the serum periparturient concentration in Holstein dairy cows

OBJECTIVE

To investigate the relationship between polymorphism within the 5'-untranslated region (5'-UTR) of IGF-I gene and its periparturient concentration in Iranian Holstein dairy cows.

METHODS

Blood samples (5 mL, n = 37) were collected by caudal venipuncture from each animal into sample tubes containing the EDTA and DNA was extracted from blood. In order to measure IGF-I concentration the collection of blood samples (n = 111) was also done at 14 d before calving (prepartum), 25 and 45 d postpartum.

RESULTS

We found evidence for a significant effect of C to T mutation in position 512 of IGF-I gene on its serum concentration in dairy cows in Iran. Cows with CC genotype had significantly higher concentration (Mean±SD) of IGF-I at 14 d prepartum (91.8±18.1) µg/L compared to those with TT genotype (73.3±14.4) µg/L (P=0.04). A significant trend (quadratic) was found for IGF-I concentration, as higher in CC cows compared to ones with TT genotype, during the 14 d before calving to 45 d postpartum (P=0.01).

CONCLUSIONS

We concluded that C/T transition in the promoter region of IGF-I gene can influence the serum concentration of IGF-I in periparturient dairy cows.

PCR-SSCP Variation of IGF1 and PIT1 Genes and Their Association with Estimated Breeding Values of Growth Traits in Makooei Sheep

Molecular biology techniques genetic improvement by facilitating identification, mapping and analysis of polymorphism of genes by encoding proteins that act on metabolic pathways involved in economically interesting traits. This use of genetic markers can aid identification of those animals with the highest breeding values in sheep. On the basis of sheep genome mapping, information was examined on the ovine IGF1 and PIT1 genes as a possible genetic marker for growth traits in sheep. The current study was designed to estimate the frequencies of putative IGF-1 and PIT-1 genes SNPs and investigate associations with calculated EBVs of growth traits in Makooei sheep. PCR-SSCP analysis of the exon1 of IGF-I gene and include a part of intron2, exon3 and a part of intron3 and PIT-1 gene revealed the following banding patterns; three (AA, AG, GG) and four AA (p1), AB (p2), CC (p3), CD (p4), banding patterns respectively. Results from this study demonstrated higher performance of AA animals in BW and GBW, and AG animal in WW and W6 that may be related to the role of IGF-1 at the pre-puberty and puberty stages. Also higher performance of p3 animals in W9, YW and GSN, and p1 animal in GNY may be related to the PIT-1 role in post-puberty.

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.

Effect of the IGF-1/PTEN/Akt/FoxO signaling pathway in the duodenal mucosa of rats subjected to water immersion and restraint stress

The insulin growth factor 1/phosphatase and tensin homologue deleted on chromosome 10/Akt/forkhead box (IGF-1/PTEN/Akt/FoxO) signaling pathway reportedly exhibits gastroprotective effects by reducing water immersion and restraint stress (WRS)-induced gastric mucosal cell apoptosis. We examined the expression and localization of IGF-1, PTEN, Akt, and FoxO proteins, caspase-3 activity, and the number of apoptotic cells in the duodenal mucosa of rats subjected to WRS to confirm whether the IGF-1/PTEN/Akt/FoxO signaling pathway has a role in the duodenal mucosa. The results indicated that WRS enhanced cell apoptosis in the duodenal mucosa. In addition, in normal rats, PTEN was found mainly in the cellular cytoplasm of the duodenal glands and lamina propria of villi. IGF-1 and total Akt were observed in the cellular cytoplasm of the duodenal glands. In addition, total Akt was found in the cellular cytoplasm of the myenteric plexus. FoxO3a and FoxO4 were primarily concentrated in the cellular cytoplasm of the lamina propria. Specifically, PTEN, FoxO3a and FoxO4 were also localized in the cellular cytoplasm of lamina propria of restituted villi in the duodenal mucosa of rat subjected to WRS. In addition, messenger RNA transcript levels of IGF-1, PTEN, Akt1, Akt2, FoxO3, and FoxO4 were upregulated in the duodenal mucosa, with a peak between the 4th and 8th day after 7 h of WRS. Furthermore, the results also suggested that Akt3 messenger RNA transcript levels in the duodenal mucosa of rats after WRS showed no significant differences compared with those in the non-WRS group. Collectively, our results implied that the IGF-1/ PTEN/Akt/FoxO signaling pathway was effective in regulating cellular apoptosis in the duodenal mucosa of rats after WRS.

Association between GNRHR, LHR and IGF1 polymorphisms and timing of puberty in male Angus cattle

Background

In bovines, there are significant differences within and among beef breeds in the time when bulls reach puberty. Although the timing of puberty is likely to be a multigenic trait, previous studies indicate that there may also be single genes that exert major effects on the timing of puberty within the general population. Despite its economic importance, there are not many SNPs or genetic markers associated with the age of puberty in male cattle. In the present work, we selected three candidate genes, GNRHR, LHR and IGF1, and associated their polymorphisms with the age of puberty in Angus male cattle.

Results

After weaning, 276 Angus males were measured every month for weight (W), scrotal circumference (SC), sperm concentration (C) and percentage of motility (M). A total of 4 SNPs, two within GNRHR, one in LHR and one in IGF1 were genotyped using the pyrosequencing technique. IGF1-SnaBI SNP was significant associated (P < 0.01) with age at SC 28 cm, but it were not associated with age at M 10% and C 50 million. Genotype CC exhibited an average age at SC 28 cm of 7 and 11 days higher than CT (p = 0.037) and TT (p = 0.012), respectively. This SNP explained 1.5% of the genetic variance of age of puberty at SC28. LHR-I499L, GNRHR-SNP5 and GNRHR-SNP6 were not associated with any of the measurements. However, GNRHR haplotypes showed a suggestive association with age at SC 28 cm.

Conclusions

The findings presented here could support the hypothesis that IGF1 is a regulator of the arrival to puberty in male calves and is involved in the events that precede and initiate puberty in bull calves. Given that most studies in cattle, as well as in other mammals, were done in female, the present results are the first evidence of markers associated with age at puberty in male cattle.