Growth Traits In Sheep Research Articles

Polymorphism of sheep PRKAA2 gene and its association with growth traits

Small ruminants farming plays an important role in the livelihood of a large part of the population. Herein we aimed to analyze the effects of single nucleotide polymorphisms in PRKAA2 gene on the growth-related traits of Hu sheep and Dorper sheep. The body weight and body type of 1254 sheep were measured at 80, 100, 120, 140, 160 and 180d, and 37620 phenotypic data were collected. RT-qPCR analysis was performed to test PRKAA2 gene expressed in different tissues of sheep, with the highest expression level in spleen, followed by kidney. In the present study, the PRKAA2 gene sequencing revealed one polymorphism located on Chr1 (Oar_rambouillet_v1.0), termed as chr1:32832382 G > A, and were significantly associated with growth traits of sheep (p < 0.05). The body weight, body length, chest circumference, and cannon circumference of individuals with AA genotype were significantly higher than those with the GG and GA genotypes (p < 0.05). Our findings reveal that PRKAA2 gene could be used as a marker-assisted selection to improve the growth-related traits of sheep.

Meta-analysis of performance and genetic parameter estimates for growth and body weight traits of sheep in the tropics

A meta-analysis on 68 articles was performed to combine the estimates of genetic parameters of growth traits in sheep from the tropics. 10 traits were included which met the quality control criteria. Weighted estimates were obtained by combining 275 means, 442 heritability estimates (255 direct, 98 maternal, and 62 common environmental), and 765 correlation estimates (381 phenotypic and 384 genetic). A random-effects model was used and the heterogeneity of parameter estimates was evaluated using the I2-statistic. Direct heritability increased with age from 0.196 at birth to 0.388 at 18-months of age while maternal and common environmental effects decreased with age and ranged between 0.116 to 0.186 and 0.060 to 0.115 respectively. Phenotypic correlations ranged from 0.233 to 0.944 and genetic correlations ranged from 0.356 to 0.922. Weighted least-squares analysis was done to study the effects of non-genetic factors where the distance from the equator was found to significantly affect all the heritability traits. Weighted estimates obtained from this study could be beneficial during the implementation phase of a breeding program which is designed for the genetic improvement of sheep breeds in the tropics.

Detecting Single Nucleotide Polymorphisms in MEF2B and UCP3 and Elucidating Their Association with Sheep Growth Traits.

Herein we detected single nucleotide polymorphisms in MEF2B and UCP3 by DNA sequencing and the KASPar technology and analyzed their association with sheep growth traits. Two synonymous mutations, g.1826 C > T and g.10266 G > C, were detected, respectively, and they were found to be significantly associated with sheep growth traits (p < 0.05). In case of MEF2B g.1826 C > T, the average body weight and chest and cannon circumference of sheep with the CC genotype were significantly higher than those of sheep with the CT and TT genotypes (p < 0.05). Moreover, in case of UCP3 g.10266 G > C, the average body weight and chest and cannon circumference of sheep with the GG genotype were significantly higher than those of sheep with the GC and CC genotypes (p < 0.05). Moreover, the average body weight of sheep with the CC/GG genotype was higher compared with those of other genotype combinations. We also assessed MEF2B and UCP3 expression in different sheep tissues, confirming their expression in all examined tissues. To summarize, we believe that the polymorphisms identified in MEF2B and UCP3 can serve as molecular markers for sheep growth traits.

The InDel variants of sheep IGF2BP1 gene are associated with growth traits

Insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) plays positive roles in the growth, proliferation of cells and early embryos development by binding mRNA targets. Recently, it had been shown that some polymorphic loci within IGF2BP1 gene were associated with growth traits in animals, especially in goats. Therefore, it has been hypothesized that some variants within IGF2BP1 gene may be also involved in growth traits of sheep. Nine insertion/deletion (InDel) mutations within IGF2BP1 were identified and three loci were polymorphic. Meanwhile, the association analyses between three InDels and growth traits were carried out in 745 sheep. The results showed that all InDels included 5 bp InDel in downstream region, 9 bp InDel in intron 4 and 15 bp InDel in intron 2 within IGF2BP1 were significantly associated with growth traits (p<.05). Furthermore, at 5 and 9 bp InDel loci, the individuals of heterozygous genotype (ID) had superior growing performance especially at body weight (BW). In all, three InDels were crucial variants correlated with growth traits and could be applied in marker-assisted selection (MAS) in sheep.

Mutations in FGFR1 were associated with growth traits in sheep (Ovis aries)

For its role in the mediation of myoblast proliferation, fibroblast growth factor receptor 1 (FGFR1) was considered a functional candidate gene for growth performance in Tibetan sheep. Via the polymerase chain reaction-restriction fragment length polymorphism (PCR-PFLP) approach, four single nucleotide polymorphisms (SNPs) including g.14752C > T (intron 1), g.45361A > G (intron 7), g.49400A > G (3’UTR region) and g.49587A > T (3’UTR region), were identified in 422 ewes. The association analysis demonstrated that individuals carrying the AA genotype of g.49400A > G had significantly greater withers height, length than those with GG genotype (p < 0.05). Individuals with genotype AA of g.49587A > T had significantly greater weight and chest circumference than those with genotype TT (p < 0.01). Additionally, the individuals with Hap1/1 diplotypes (CAAA-CAAA) were highly significantly associated with weight and chest circumference than Hap1/2 diplotypes (CAAA-CAAT) (p < 0.05). The quantitative real-time polymerase chain reaction (qPCR) analysis revealed that the FGFR1 was detectable expressed in muscle tissues within three different age stage. Remarkably higher mRNA expression was detected at fetal lamb stage as compared with adult ewes (p < 0.01). The outcome of this research confirmed that both g.49400A > G and g.49587A > T of FGFR1 were involved in growth-related traits, which may be considered to be genetic markers for improving the growth traits of Tibetan sheep.

Genetic variations in the Myostatin gene affecting growth traits in sheep.

Background and Aim:Sheep productivity in developing countries is crucial, as this animal is an essential source of meat and wool. Myostatin (MSTN) plays an important role in the regulation of muscle mass through the regulation of muscle growth, differentiation, and regeneration. The present study sought to investigate genetic variation in the first intron of the MSTN gene and the association of variants with growth traits in major sheep breeds in Egypt (Barki, Ossimi, and Rahmani) and Saudi Arabia (Najdi) using polymerase chain reaction (PCR) and sequencing.Materials and Methods:Blood samples were collected, and DNA was extracted from 75 animals. A 386 bp fragment in the first intron of the MSTN gene was amplified using PCR. Polymorphic sites were detected using direct sequencing and then correlated with growth traits using a general linear model.Results:Sequence analysis of the first intron of MSTN gene identified six single-nucleotide polymorphisms (SNPs) in the studied breeds. Four mutual SNPs were determined: c.18 G>T, c.241 T>C, c.243 G>A, and c.259 G>T. In addition, two SNPs c.159 A>T and c.173 T>G were monomorphic (AA and TT, respectively) in the Ossimi, Rahmani, and Najdi breeds and polymorphic in the Barki breed. The association analysis revealed that the c.18 G>T and c.241 C>T significantly associated (p<0.05) with birth weight and average daily weight gain, respectively.Conclusion:Our results strongly support MSTN as a candidate gene for marker-assisted selection in sheep breeding programs. Furthermore, the identified variants may be considered as putative markers to improve growth traits in sheep.

An insertion/deletion within the CREB1 gene identified using the RNA-sequencing is associated with sheep body morphometric traits

In a previous study, the cyclic AMP response element-binding protein 1 (CREB1) gene, which is likely involved in the regulation of fat metabolism in sheep adipose tissue, was identified using RNA sequencing. CREB1 is a transcription factor that participates in the regulation of cell proliferation, differentiation, and survival as well as energy metabolism. Therefore, based on preliminary studies, this study aimed to reveal the correlation between the insertion/deletion (indel) polymorphism of the CREB1 gene and sheep growth traits. One insertion variation of the ovine CREB1 gene, C3-ins-26bp, was investigated in 1847 Chinese and Mongolian sheep breeds. The minor allele frequencies in the CREB1 gene varied from 0.021 to 0.938. Further, statistical analyses indicated that the C3-ins-26bp indel in the CREB1 gene was significantly related to various body measurements (body length, height, and index; chest width, depth, and width index; cannon circumference index; and height at the hip cross) in a Tan sheep population (p<0.05). Collectively, these findings may provide important insights into marker-assisted selection of sheep.

Effect of maternal haemoglobin variants and lamb genotype on pre-weaning growth rate of sheep of Northern Nigerian and their crosses

&#x0D; &#x0D; &#x0D; &#x0D; Pre-weaning growth trait of sheep of Northern Nigerian (Balami, Uda and Yankasa) subjected to diallel crossing were estimated using 127 lambs. The study was conducted at National Animal Production Research Institute (NAPRI), Zaria, Nigeria. Blood (5ml) samples were collected from ewes and rams that produce the lambs to evaluate the effect of parental haemoglobin (Hb) variant on the pre-weaning growth rate of lambs. Weight and average daily gain (ADG) of lambs were obtained at 2 weeks interval to 12th week. The data obtained were subjected to analysis of variance using General Linear Model Procedure of SAS. Pair-wise difference was used to separate the mean. Frequency of ewes’ Hb genotype in relation to lambs was sorted and tested with Chi Square Procedure of SAS. The result showed that HbAB was the predominant (P&lt;0.01) variant in the studied population, observed in 60% of the ewes and 100% of the sires. Allele A had the highest frequency (62%) in the dam population. The genotypic distribution of Hb variants in the population significantly deviated from Hardy Weinberg equilibrium (χ2 = 50.8, P&lt;0.01). HbAB and HbBB dams gave birth to lambs that were heavier (P&lt;0.01) than lambs from HbAA from birth to 12 weeks of age. Crossbred lambs from Balami rams and Uda ewes (BL x UD) recorded the highest weight (4.47±0.20 kg) at birth while the least weight (1.73±0.20 kg) at birth was obtained from crossbred lambs given birth to by Yankasa rams and Balami ewes (YK X BL). Pure Balami lambs (BL X BL) was outstandingly superior (P&lt;0.05) to lambs from other genotypes starting from the second week of age up to weaning (12th week). BL X BL also recorded the highest (238.09±12.42 g) average daily gain from birth to 2 weeks of age (ADG2). The ADG decreased linearly as the lambs advanced in age from birth to weaning. Balami sheep are capable of expressing their genetic potentials (better growth than others) in the Northern Guinea Savannah zone of Nigeria. Genetic improvement of growth traits of Nigerian sheep using indigenous stock should focus on the exploitation of genetic potentials in terms of faster growth rate of Balami sheep.&#x0D; &#x0D; &#x0D; &#x0D;

Hierarchical cluster analysis of yearling body weight and linear body measurementsof sheep of Northern Nigeria and their crosses

This study was conducted at the Sheep Project Unit of Small Ruminant Research Programme (SRRP) of National Animal Production Research Institute (NAPRI), Ahmadu Bello University, Shika, Zaria. Balami, Uda and Yankasa breeds (sheep of Northern Nigeria) were crossed . A total of 65 Yankasa, 23 Uda and 16 Balami ewes were served by 4 Yankasa, 3 Uda and 3 Balami rams. The diallel breeding pattern produced 192 lambs. However, only the 65 yearling that survived up to 12 months of age (yearling) were used for this study. The yearling body weight and linear body measurement data were analysed using General Linear Model (GLM) procedures of SAS with model that incorporated lamb genotype as fixed effects. Pairwise difference was used to separate the mean (SAS, 2003). Distances were used to construct dendrogram using the Unweighted Pairs Group Method Analysis implemented in R 2.13.0 package. TREE procedure that prints the dendrogram based on the distances between the clusters was introduced in PROC CLUSTER procedure. Yearling genotype affected body weight and all the linear body measurements considered in this study (P&lt;0.05). The pure Balami yearling (BL X BL) had the highest birth weight at 12 months of age (29.10±4.02kg). Clumping structure of yearling body weight among sheep of Northern Nigeria and their crosses were grouped into two clusters at distance 2.656. Pure Balami (BL X BL) formed the first cluster while the rest of the genotypes belong to the second cluster. The second cluster was further divided into two sub-groups at 0.796. The first sub-group had yearlings from pure Uda (UD X UD), Uda ram and Yankasa ewe (UD X YK), Uda ram and Balami ewe (UD X BL), Balami ram and Uda ewe (BL X UD) and Yankasa ram and Uda ewe (YK X UD) at 0.514. Similar clumping structures with two clusters share among the nine genotypes at varied distances were recorded for all the linear body measurements studied. Patterns of similarities were established for yearling body weight and linear body measurements among sheep of Northern Nigeria and their crosses. Improvement plans for yearling growth traits of sheep in Nigeria should consider the genotypes with divergent genetic distances as sires and dams. This will ensure the best exploration of positive heterosis.&#x0D;

Association of GnRH1 Gene with Growth Traits in Two Breeds of Sheep

The present study was conducted to identify the associations between the genetic polymorphisms of GnRH1 gene and growth traits in Awassi and Karakul breeds of sheep. Two GnRH1 amplicons of 313 bp and 323 bp were designed to cover exon 1, exon 2, and their flanking regions, respectively. Genotyping experiments were performed using PCR-SSCP and DNA sequencing. No polymorphism was observed in 323 bp amplicons, while two SSCP-banding patterns were detected in 313 bp amplicons with the presence of two genotypes (AA and AB). Two novel mutations in AB genotype were observed, namely 5′-UTR:50 A > C and intron1:264 G > C. In addition to these detected genotypes, results indicated that several growth traits were significantly associated with breed, sex, and dam-age in the first 6 months of birth. However, a tendency of individuals with AA genotype to exert better performance in the majority of measured growth traits than individuals with AB genotype was also observed. With the advent of the month-9 and onward, this tendency developed to be significant (P < 0.05), in which the association of all growth traits with the GnRH1 genotypes was dominated over other factors. Furthermore, more significant associations were observed in the month-12, in which individuals with AA genotype had higher growth traits measurements than individuals with AB genotype (P < 0.01). In conclusion, we detected a tight linkage between the polymorphisms of the GnRH1 gene and growth traits at sexual maturity. Therefore, this study strongly suggests the GnRH1 gene as a new candidate in marker-assisted selection for growth traits in sheep.

Novel InDels of GHR, GHRH, GHRHR and Their Association with Growth Traits in Seven Chinese Sheep Breeds.

Simple SummaryIt is advantageous to find the potential molecular markers which are associated with the growth and development of mutton sheep through molecular breeding. In this study, four molecular markers were selected from growth hormone receptor (GHR), one was found on growth hormone releasing hormone (GHRH) and growth hormone releasing hormone receptor (GHRHR), respectively. The purposes of this paper were to screen molecular makers in the related genes of the growth hormone (GH) axis and provide theoretical basis for molecular breeding and genetic selection of mutton sheep. In this study, six molecular markers were selected from the genes for growth hormone receptor (GHR), growth hormone releasing hormone (GHRH), and growth hormone releasing hormone receptor (GHRHR). The three molecular markers in GHR and one in GHRHR could potentially be used for marker assisted selection of growing-related traits in mutton sheep.The GH growth axis plays an important role in the growth and development of animals and runs through the whole life of animals. Many studies have shown that molecular mutations in key genes of the GH axis will affect the growth and development of animals. The purpose of this study was to explore the distribution characteristics of InDels of GHR, GHRH, and GHRHR in seven Chinese sheep populations, and to further explore the relationship between InDels and sheep growth traits. GHR showed high variation in Chinese sheep, and GHR-53 showed the highest minimum allele frequency (MAF). There was only one InDel mutation site in both GHRH and GHRHR. The genotype frequencies of Hu sheep (HS), Tong sheep (TS), and Lanzhou fat-tail sheep (LFTS) were quite different from other breeds. The association between GHR, GHRH, and GHRHR InDels and body size traits in seven varieties were analyzed. The results showed that there was no significant relationship between GHRH and body size traits in the seven sheep populations. There was a positive association between GHR-21 and hip height of LFSH (p < 0.05). GHR-43 reduced body height and chest depth of Small tail han sheep (STHS) and hip width of TS. GHR-44 significantly affected the body weight of HS, the body height of STHS and the head depth of TS. GHR-53 significantly reduced cannon girth of HS, chest of STHS and forehead width of TS. GHRHR-2 significantly reduced the body weight of LFHS. To sum up, this study revealed the effects of GHR, GHRH, and GHRHR InDels on sheep phenotypic traits, which indicated their potential application prospects in the genetic improvement of mutton sheep.

A genome-wide association study revealed five SNPs affecting 8-month weight in sheep.

Lamb weight at 8 months of age is an important trait in the sheep industry in terms of the onset of puberty around this age; however, knowledge of its effective genetic factors is limited. Therefore, a GWAS using the 50K SNP-Chip was performed on 96 Baluchi sheep to identify the genomic regions associated with 8-month weight. The results of the present study revealed five SNPs on chromosomes 4, 14 and 16 at 5% chromosome-wide significance level, jointly accounting for 0.95% of total genetic variance. Four genes - MTPN, HYDIN, LRGUK and ZFP90 - were found in 50kb intervals around the significant SNPs, of which MTPN is involved in regulation of skeletal muscle growth. Our results may provide a new vision to identify the genomic regions affecting growth traits in sheep.

A Deletion Downstream of the CHCHD7 Gene Is Associated with Growth Traits in Sheep.

Simple SummaryThe genes CHCHD7 and PLAG1 are located on the same growth-related major quantitative trait locus of sheep. PLAG1 affects sheep growth, but no corresponding studies have been conducted on CHCHD7. However, polymorphisms in the CHCHD7 gene are associated with carcass weight and muscle formation in cattle, body height in cattle and humans, and weaning weight in Duroc pigs. In this study, the mathematical expectation method was used to analyze an 8-bp deletion mutation located downstream of the CHCHD7 gene in 2350 individuals from seven sheep breeds. The associations between wild-type and deletion genotypes and growth traits in Tan sheep were also analyzed. The 8-bp deletion locus was significantly associated with body length (p = 0.032), chest depth (p = 0.015), and chest width (p = 0.047) of Tan sheep. Additionally, wild-type genotype carriers were more numerous than those heterozygous for the deletion genotype. Thus, the genotyped 8-bp deletion downstream of the CHCHD7 gene may be associated with growth and development traits in sheep.In sheep, the coiled-coil-helix-coiled-coil-helix domain containing 7 (CHCHD7) gene and the pleiomorphic adenoma gene 1 (PLAG1) are on the same growth-related major quantitative trait locus, positioned head-to-head approximately 420 bp apart on chromosome 9. PLAG1 affects sheep growth, but the effects of CHCHD7 have not been determined. In this study, an 8-bp deletion downstream of CHCHD7 was analyzed in 2350 sheep from seven breeds. The associations between the deletion and growth traits of Tan sheep were also determined. Both genotypes (homozygous wild-type and heterozygous) for the 8-bp deletion were found in Tan (TS), Luxi Blackhead (LXBH), Small-Tail Han (STHS), and Lanzhou Fat-Tail (LFTS) sheep. However, there were no polymorphic sites for the mutation in Hu (HS), Sartuul (SS), and Australian White (AUW) sheep. In TS, LXBH, STHS, and LFTS sheep, the deletion genotype was less frequent than the wild-type genotype, and the allele frequencies of the deletion variant were 0.007 (TS), 0.011 (LBXH), 0.008 (STHS), and 0.010 (LFTS). The 8-bp deletion was significantly associated with body length (p = 0.032), chest depth (p = 0.015), and chest width (p = 0.047) in Tan sheep. Thus, the 8-bp deletion downstream of the CHCHD7 gene might be associated with growth and development traits of sheep.

A novel 17 bp InDel polymorphism within the PPARGC1A gene is significantly associated with growth traits in sheep

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) is a member of transcriptional coactivator of the peroxisome proliferator-activated receptor. It is involved in lipid metabolism, energy metabolism, adipocyte differentiation and regulation of mitochondrial biogenesis. Therefore, the genetic variation of PPARGC1A gene will be of great value. The purposes of this study were to detect novel InDels within the PPARGC1A gene and analyze the effects of genetic polymorphisms on growth traits. We detected a novel 17 bp insertion polymorphism within the eleventh intron of the sheep PPARGC1A gene. Experimental results revealed that the InDel (insertion/deletion) genotypes distribution of the seven breeds of sheep was significant differences, of which three genotypes were detected. After correlation analysis, there were many significant phenotypic differences between the body size traits of the three genotypes. Interestingly, the dominant genotype was different in body weight both in STHS sheep and HS sheep. In summary, the 17 bp insertion polymorphism within the PPARGC1A gene had a great influence on the growth traits of sheep, which may provide a potential theoretical basis for marker-assisted selection in sheep genetic breeding.

Integrating Genome-Wide CNVs Into QTLs and High Confidence GWAScore Regions Identified Positional Candidates for Sheep Economic Traits.

Copy number variations (CNVs) are important source of genetic variation, which can affect diverse economic traits through a variety of mechanisms. In addition, genome scan can identify many quantitative trait loci (QTLs) for the economic traits, while genome-wide association studies (GWAS) can localize genetic variants associated with the phenotypic variations. Here, we developed a method called GWAScore which collected GWAS summary data to identify potential candidates, and integrated CNVs into QTLs and high confidence GWAScore regions to detect crucial CNV markers for sheep growth traits. We got 197 candidate genes which were overlapping with the candidate CNVs. Some crucial genes (MYLK3, TTC29, HERC6, ABCG2, RUNX1, etc.) showed significantly elevated GWAScore peaks than other candidate genes. In this study, we developed the GWAScore method to excavate the potential value of candidate genes as markers for the sheep molecular breeding.

Association analysis of KMT2D copy number variation as a positional candidate for growth traits.

Copy number variations (CNVs) are an important source of genetic variation, which can affect a wide range of economic traits by diverse mechanisms. KMT2D (Lysine methyltransferase 2D) is an important positional candidate for growth traits. Quantitative trait loci (QTLs) with large effects on economically important traits cover the KMT2D gene. The KMT2D gene overlays a CNV within its exons, hence it was chosen as a crucial candidate gene to study the association between CNV and growth traits. Further, KMT2D, a major mammalian histone H3K4 mono-methyltransferase, plays a critical role in regulating development, differentiation, metabolism, and tumor suppression. Therefore, we proposed the hypothesis that KMT2D CNV may have phenotypic effects on sheep growth traits. In our study, KMT2D CNVs in three Chinese sheep breeds were detected by quantitative polymerase chain reaction (qPCR), and the loss copy was found to be the dominant genotype. Association analysis between growth traits and KMT2D CNV was also performed, which revealed that individuals with the median copy showed better performance than those with the loss copy in all three breeds. This research suggested that KMT2D CNV can be used as a promising marker for sheep molecular breeding.

Copy Number Variation of the PIGY Gene in Sheep and Its Association Analysis with Growth Traits.

Simple SummaryThe PIGY (phosphatidylinositol glycan anchor biosynthesis class Y) gene is a member of the PIG gene family and encodes the glycosylphosphatidylinositol-N-acetylglucosaminyltransferase (GPI-GnT) complex. It initiates the biosynthesis of GPI and plays an important role in cell–cell interactions. Sequencing has revealed a 3600 bp copy number variation (CNV) in exon 2 of the PIGY gene in sheep, potentially altering a functional part of the protein. The CNV overlaps 28 quantitative trait loci that are relevant to some economic traits like muscle density and carcass weight. We screened for this CNV of the PIGY gene in 569 individuals, namely, 240 Chaka sheep (CKS), 168 Hu sheep (HS), and 161 small-tailed Han sheep (STHS), and analyzed the association between the presence of this CNV and sheep body size traits. The results showed that the loss-type CNV was more prevalent than other types in these three breeds, and there were significant effects of the PIGY gene CNV on body weight, chest circumference, and circumference of cannon bone of sheep. The results showed that sheep with gain-type CNV had better growth traits than those with other types. The findings reveal the relationship between the CNV of the PIGY gene and growth traits of sheep, suggesting that CNV could be utilized for improved molecular breeding of sheep.Copy number variation (CNV) is a type of genomic variation with an important effect on animal phenotype. We found that the PIGY gene contains a 3600 bp copy number variation (CNV) region located in chromosome 6 of sheep (Oar_v4.0 36,121,601–36,125,200 bp). This region overlaps with multiple quantitative trait loci related to phenotypes like muscle density and carcass weight. Therefore, in this study, the copy number variation of the PIGY gene was screened in three Chinese sheep breeds, namely, Chaka sheep (CKS, May of 2018, Wulan County, Qinghai Province, China), Hu sheep (HS, May of 2015, Mengjin County, Henan Province, China), and small-tailed Han sheep (STHS, May of 2016, Yongjing, Gansu Province, China). Association analyses were performed on the presence of CNV and sheep body size traits. We used real-time quantitative PCR (qPCR) to detect the CNV for association analysis. According to the results, the loss-type CNV was more common than other types in the three breeds (global average: loss = 61.5%, normal = 17.5%, and gain = 21.0%). The association analysis also showed significant effects of the PIGY gene CNV on body weight, chest circumference, and circumference of the cannon bone of sheep. Sheep with gain-type CNV had better growth traits than those with other types. The results indicate a clear relationship between the PIGY gene CNV and growth traits of sheep, suggesting the use of CNV as a new molecular breeding marker.

Inbreeding affected differently on observations distribution of a growth trait in Iranian Baluchi sheep.

ObjectiveInitial consequence of inbreeding is inbreeding depression which impairs the performance of growth, production, health, fertility and survival traits in different animal breeds and populations. The effect of inbreeding on economically important traits should be accurately estimated. The effect of inbreeding depression on growth traits in sheep has been reported in many breeds. Based on this, the main objective of the present research was to evaluate the impact of inbreeding on some growth traits of Iranian Baluchi sheep breed using quantile regression model.MethodsPedigree and growth traits records of 13,633 Baluchi lambs born from year 1989 to 2016 were used in this research. The traits were birth weight, weaning weight, six-month weight, nine-month weight, and yearling weight. The contribution, inbreeding and co-ancestry software was used to calculate the pedigree statistics and inbreeding coefficients. To evaluate the impact of inbreeding on different quantiles of each growth trait, a series of quantile regression models were fitted using QUANTREG procedure of SAS software. Annual trend of inbreeding was also estimated fitting a simple linear regression of lamb’s inbreeding coefficient on the birth year.ResultsAverage inbreeding coefficient of the population was 1.63 percent. Annual increase rate of inbreeding of the flock was 0.11 percent (p<0.01). The results showed that the effect of inbreeding in different quantiles of growth traits is not similar. Also, inbreeding affected differently on growth traits, considering lambs’ sex and type of birth.ConclusionQuantile regression revealed that inbreeding did not have similar effect on different quantiles of growth traits in Iranian Baluchi lambs indicating that at a given age and inbreeding coefficient, lambs with different sex and birth type were not equally influenced by inbreeding.

Novel copy number variation of the BAG4 gene is associated with growth traits in three Chinese sheep populations

Copy number variation (CNV) as an important source of genetic phenotypic and variation is related to complex phenotypic traits. The aim of this study was to investigate the potential associations of BAG4 (Bcl-2-associated athanogene 4) copy numbers variations with sheep growth traits in three Chinese sheep breeds (CKS, STHS, and HS). BAG4 is located within the stature and udder attachment quantitative trait loci (QTL) in sheep. Expression profiling revealed that the BAG4 gene was widely expressed in the tissues of sheep. The distribution of BAG4 gene copy number showed that the loss of copy number was more dominant in CKS and HS which was different from that in STHS. Statistical analysis revealed that the BAG4 CNV was significantly associated with body height in CKS (p < 0.05), with body slanting length in HS (p < 0.05), and with body height and hip cross height in STHS (p < 0.05). The χ2 values showed significant differences in the BAG4 CNV distribution frequency between varieties. In conclusion, the results establish the association between BAG4 CNV and sheep traits and suggest that BAG4 CNV may be a promising marker for the molecular breeding of Chinese sheep.

Associations of ORMDL1 gene copy number variations with growth traits in four Chinese sheep breeds.

Copy number variations (CNVs) are gains and losses of genomic sequence of more than 50 bp between two individuals of a species. Also, CNV is considered to be one of the main elements affecting the phenotypic diversity and evolutionary adaptation of animals. ORMDL sphingolipid biosynthesis regulator 1 (ORMDL1) is a protein-coding gene associated with diseases and development. In our study, the polymorphism of ORMDL1 gene copy numbers in four Chinese sheep breeds (abbreviated CK, HU, STH, and LTH) was detected. In addition, we analyzed the transcriptional expression level of ORMDL1 gene in different tissues of sheep and examined the association of ORMDL1 CNV with growth traits. The statistical analysis revealed that ORMDL1 CNV was remarkably correlated with body height, heart girth, and circumference of cannon bone in HU sheep (), and there are significant effects on body weight, body height, body length, chest depth, and height of hip cross in STH sheep (). In conclusion, our results provide a basis for the relationship between CNV of ORMDL1 gene and sheep growth traits, suggesting that ORMDL1 CNV may be considered a promising marker for the molecular breeding of Chinese sheep.