FecB基因在9个绵羊品种中的多态性及其与产羔数和羔羊生长发育的相关性

以绵羊BMPR-IB基因为候选基因,应用PCR-RFLP方法通过分析湖羊、夏洛来、陶赛特、萨福克、罗米丽、中国美利奴羊、中国美利奴肉用多胎品系以及陶赛特×中国美利奴羊和萨福克×中国美利奴羊杂交后代共615只个体的FecB基因多态性,以及BMPR-IB基因多态性对产羔数、体尺和体重的影响.结果表明,BMPR-IB基因在不同品种(系)绵羊中共有3种基因型(BB、B+和++),但基因型频率分布在各品种(系)间差异极显著(P<0.01).在湖羊中仅有BB基因型;在中国美利奴肉用多胎品系中BB、B+和++基因型频率分别为51%、30%和19%;而其他品种(系)羊中则仅有++基因型.对中国美利奴羊肉用多胎品系研究,发现BB和B+基因型群体平均产羔数分别为2.8和2.3,显著高于++基因型群体(1.2,P<0.01).在90日龄时,BB和B+基因型群体的体重分别为18.6±3.70 kg和18.0±3.31 kg,显著高于++基因型群体(15.6±2.22kg,P<0.05);此外,90日龄时,BB和B+基因型群体比++基因型群体胸围、胸宽较大(P<0.05);但这些差异在120日龄时消失.另外,我们还发现不同地区群体的第一胎产羔数存在明显差别.这些结果表明,BMPR-IB基因为影响绵羊产羔数的主效基因,并首次证明该基因对后代羔羊出生后生长发育具有加性效应.     

Polymorphism of FecB gene in nine sheep breeds or strains and its effects on litter size, lamb growth and development

Nine sheep breeds or strains, including 615 individuals were screened with forced PCR RFLP method for the FecB gene to study the polymorphism and its effects on litter sizes, body weights and body sizes. Results show that the polymorphism frequencies of FecB gene are significantly imbalanced in these breeds or strains. The Hu sheep were all homozygous carriers (BB). In the Chinese Merino prolific meat strain, the genotype frequencies of BB, B+ and ++ are 51%, 30% and 19%, respectively, whereas all the other flocks had only the wild-type (++) genotype. Results within Chinese Merino prolific meat strain showed that mean litter sizes of ewes with genotype BB and B+ are 2.8 (+/-0.74) and 2.3 (+/-0.63) (P > 0.05), whereas ++ ewes had a litter size of only 1.2 (+/-0.68) (P < 0.01). At 90 days after birth, the body weights of BB/B+ lambs were higher than that of ++ lambs (18.6 +/- 3.70 kg, 18.0 +/- 3.71 kg versus 15.6 +/- 2.22 kg, P < 0.05). In addition, the heart girth and chest width of BB/B+ lambs were significantly longer than ++ lambs (P < 0.05). No significant differences were observed in either body weight or body size at day 120. Litter size at first lambing from Hu at Natural Source Conservative Region was found to be significantly higher than that from the other two regions sampled (P < 0.05). In addition to the additive effect on litter size, these findings show for the first time that the FecB gene had a positive effect on early postnatal body growth.     

A review of the effects of the Booroola gene (FecB) on sheep production

Booroola Merino (B^oM) ewes have a high ovulation rate and litter size which in 1980 was postulated to be due to the effects of a major gene (FecB). This was confirmed in breeding experiments and FecB was subsequently shown to be due to a mutation (BMPR-1B) on chromosome 6. The B^oM originated from an Australian commercial fine wool Merino flock (Booroola) and has been used in crossing experiments and for introgression of FecB into many breeds around the world to improve fecundity. The mutation has recently been found in native sheep breeds in India, China and Indonesia and it is likely that FecB in the Australian B^oM was derived from importations of Garole sheep from India in 1792 and 1793.The effects on production traits of the FecB mutation in a range of genetic comparisons, environments and production systems are reviewed. Comparisons involving B^oM crosses with various other breeds and contrasts of FecB homozygous (BB), heterozygous (B+) and non-carrier (++) genotypes in comparable background genotypes, including non-B^oM, have been summarised from 45 reports. The weighted mean effect for ewes carrying one copy of FecB (B+) was +1.3 (range +0.8 to +2.0) for ovulation rate and +0.7 (range +0.4 to +1.3) for litter size. The effect of a second copy (BB) was generally additive for ovulation rate, with little or no increase in litter size for BB ewes among B^oM crosses. However there was generally a further increase in litter size for BB ewes of about half the effect of one copy (B+) in the Indian and Chinese breeds. Poor lamb survival and lamb growth reduced the number of lambs weaned and total weight of lamb weaned by B+ ewes. Most studies still showed a small advantage for B+ ewes, although several reported negative effects. While embryo survival declines at higher ovulation rates, the effects of FecB per se are equivocal. There is some evidence of a higher non-pregnancy rate among homozygous BB ewes. Most studies reported lower birth weight and growth rate from B^oM cross lambs and lambs from crossbred ewes introgressed with FecB. However it is difficult to separate the effects of low background genetic merit for growth of the B^oM and the lower birth weight and growth rate of lambs from larger litters from the genetic effect of carrying FecB. There was little or no difference in growth rate between BB, B+ and ++ genotype lambs. For other traits including, seasonal oestrous activity, carcass and meat quality and wool production, there was no evidence of major effects of FecB. The opportunities for management and nutritional modification of FecB expression and implications for industry adoption are briefly discussed.     

Effect of Genetic Variations of the POU1F1 Gene on Growth Traits of Nanyang Cattle

PCR-RFLP was applied to analyze the effect of the genetic variations of the POU1F1 gene on growth traits of 100 Nanyang cattle. The results showed that the 451 bp PCR product digested with Hinf I demonstrated polymorphism in the population, which was at Hardy-Weinberg equilibrium. Moreover, the frequencies of alleles A/B in the Nanyang population were 0.465/0.535. The association of the variations of the POU1F1 gene with the growth traits in the population was analyzed. The following parameters were greater in individuals with a genotype BB than in those with an genotype AB: birth weight, average weight increase before ablactation, body height at 12 months, body weight, body length, and chest girth at 6 months and 12 months (P<0.05). The body weight at 12 months was higher in the BB individuals than in the AA individuals (P <0.05). The body weight and body sizes also showed a trend of allele B> allele A in the other age groups. Therefore, the genotype BB maybe a dominant genotype and the allele B may be a dominant allele. These results imply that the allele B of the POU1F1 gene is likely to positively affect the growth traits.     

Ovulation response to pregnant mares' serum gonadotrophin in prepubertal ewe lambs of different Booroola genotypes

Ovulation rates following treatment with PMSG were measured in prepubertal ewe lambs of known Booroola genotype to evaluate the technique as a method of early identification of Booroola genotypes. Two experiments were conducted with homozygous (FF), heterozygous (F+) and non-carrier (++) interbred $\text{1}\text{2}$ Merino $\text{1}\text{2}$ Romney breed type ewe lambs and a third experiment compared first cross F+ $\text{1}\text{2}$ Merino $\text{1}\text{2}$ Coopworth breed type with contemporary Coopworths (++). The ewe lambs aged 5–6 months were injected with 400 or 600 i.u. PMSG. The percentage of ewe lambs ovulating following treatment with PMSG was similar in all experiments (75–77%) but in Experiment 1 the FF and F+ lambs had a significantly higher proportion ovulating than the ++ lambs (P<0.05). The mean ovulation rate of FF ewe lambs treated with PMSG was 1.03 (Expt 1) and 1.69 (Expt 2) higher than ++ lambs (P<0.05). In Experiment 1 the mean ovulation rate of F+ ewe lambs was 0.33 higher than ++ ewe lambs but this difference was not significant. However, in Experiments 2 and 3 the mean ovulation rate of F+ ewe lambs treated with 600 i.u. PMSG was 1.06 and 0.45 higher than ++ ewe lambs respectively (P< 0.05). These results show that PMSG treatment is a promising technique for identifying the Booroola genotype of ewe lambs at an early age but further experiments with different dose rates of PMSG and different ages and liveweights of lambs are required to determine optimum dose rates and time of treatment.     

Polymorphisms of KiSS-1 and GPR54 genes and their relationships with litter size in sheep

The KiSS-1 and GPR54 genes were studied as candidate genes for the prolificacy in sheep. Four pairs of primers were designed to detect single nucleotide polymorphisms of exon 1 of KiSS-1 gene and exon 1, exon 2 and partial exon 5 of GPR54 gene in high fecundity breeds (Small Tail Han and Hu sheep) and low fecundity breeds (Dorset, Texel and Corriedale sheep) by PCR-SSCP. Polymorphisms in exon 1 of KiSS-1 gene were detected in prolific Small Tail Han sheep (AA, AB and BB genotypes) and Hu sheep (AA and CC genotypes), no polymorphism was found in low fecundity sheep breeds (only AA genotype). Polymorphisms in exon 2 of GPR54 gene were detected in prolific Hu sheep (DD and EE genotypes) and no polymorphism was found in prolific Small Tail Han sheep and low fecundity sheep breeds (only DD genotype). No polymorphism was detected in exon 1 and partial exon 5 of GPR54 gene in five sheep breeds. The polymorphic genotypes were sequenced. While compared the BB genotype with the AA genotype, one nucleotide mutation (G1035A) was detected, which resulted in amino acid change, Val25Met. Five nucleotide mutations were detected from AA to CC genotype (C981T, C996T, T997C, C1034G, C1039T), and among them four caused amino acid changes, that is, Arg7Trp, Phe12Leu, Asn24Lys, Ala26Val. While compared the EE genotype with the DD genotype, two nucleotide mutations (T2360C, A2411C) were detected, which gave rise to amino acid changes, Met90Thr and Asp107Ala, respectively. Genotype frequencies of AA, BB and AB were 0.62, 0.05 and 0.33 in Small Tail Han sheep, respectively. The Small Tail Han sheep ewes with genotype BB or AB had 0.88 (P?<?0.05) or 0.51 (P?<?0.05) lambs more than those with genotype AA; the Small Tail Han sheep ewes with genotype BB had 0.37 (P?>?0.05) lambs more than those with genotype AB. These results preliminarily indicated that the KiSS-1 gene may have some association with prolificacy in sheep.     

Effects of joining at 7 months,and ewe genotype,on the performance of ewes to 19 months of age and that of their progeny to slaughter

Two ways of reducing the cost of replacements are increasing litter size and number of litters produced; thus, the total weight of lamb carcass output per ewe lifetime. The effects of ewe genotype on the performance of ewes lambing at 1 year and of their progeny to slaughter, and the effect of age at first joining (7 or 19 months) on BW at ~19 months and survival to joining at 19 months were evaluated over two consecutive years, using 460 ewe lambs from three genotypes: Belclare (Bel), Suffolk × Belclare (Suf × Bel) and ≥ 75% Suffolk ancestry (Suf75). Lambs from the three genotypes were at a similar proportion of mature BW and half of the lambs, within genotype, were allocated to be joined for the first time at 7 or 19 months. The ewe lambs were managed in a grass-based rotational-grazing system, except when housed from December to March on a grass silage-based diet. Belclare ewes had larger litters (P < 0.001), reared more lambs per ewe joined (P < 0.01), were lighter at lambing and at 19 months (P < 0.01), were of smaller body size at 19 months (P < 0.001) and their progeny were lighter at weaning (P < 0.05) relative to Suf75 genotype; the Suf × Bel ewes were intermediate for most traits but had a significantly lower litter size (P < 0.05) than Bel ewes. Progeny from Suf × Bel ewes were 17 days younger at slaughter (P < 0.01) relative to those from Bel ewes. Ewe genotype had no effect (P > 0.05) on lamb mortality (born dead, total mortality to weaning), lambing assistance, number of ewes that failed to lamb, or on ewe survival to 19 months of age. Increasing ewe BW at joining increased the probability (P < 0.001) of rearing at least one lamb and this effect was consistent across genotypes. There were significant relationships (P < 0.001) between ewe BW at lambing and lamb BW at birth and at weaning of 0.053 (SE 0.0089) kg and 0.29 (SE 0.049) kg, respectively. Ewes that lambed at 1 year were 2 kg lighter (P < 0.001) at 19 months of age and had a smaller body size (P < 0.01) relative to those not joined. It is concluded that ewe genotype had a significant effect on number of lambs reared, and thus lamb carcass output. Whilst lambing at 1 year reduced BW by 2 kg when joined at 19 months, it did not affect ewe survival to that stage.     

Polymorphism of 5′ regulatory region of ovine FSHR gene and its association with litter size in Small Tail Han sheep

Single nucleotide polymorphisms of 5?? regulatory region of follicle-stimulating hormone receptor (FSHR) gene were detected in two high prolificacy sheep breeds (Small Tail Han and Hu sheep) and two low prolificacy sheep breeds (Corriedale and Chinese Merino sheep) by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). The results indicated that there were three genotypes (AA, AB and BB) detected by primer 1 in Hu sheep while only one genotype (AA) in other three sheep breeds, and frequencies of AA, AB and BB genotypes in Hu sheep were 0.700, 0.225 and 0.075, respectively. There were three genotypes (EE, EF and EG) detected by primer 3 in Small Tail Han sheep while only EE genotype occurred in other three sheep breeds, and frequencies of EE, EF and EG genotypes in Small Tail Han sheep were 0.775, 0.200 and 0.025, respectively. No polymorphism was detected in four sheep breeds by primer 2 and primer 4. The sequencing results showed that there were two nucleotide mutations (g. ?681T>C and g. ?629C>T) in genotype BB compared with AA for primer 1. As for primer 3, two mutations (g. ?197G>A and g. ?98T>C) in genotype EF compared with EE and two mutations (g. ?200G>A and g. ?197G>A) in genotype EG compared with EE. The heterozygous ewes with EG or EF had 0.89 (P?<?0.05) or 0.42 (P?<?0.05) lambs more than homozygous ewes (EE genotype) in Small Tail Han sheep, respectively, while there was no significant difference on litter size between EG and EF ewes.     

Polymorphism in exon 3 of follicle stimulating hormone beta (FSHB) subunit gene and its association with litter traits and superovulation in the goat

The polymorphism in follicle stimulating hormone beta (FSHB) subunit gene was detected by PCR-SSCP and PCR-RFLP methods in 780 does from four goat breeds including Boer, Matou, Black and Boer-Matou crossbred (BM). The associations of FSHB genotypes with litter size (LS), litter weight at birth (LWB) and gestation length (GL) as well as superovulation performances were analyzed in relatively lower-prolific Boer and higher-prolific Matou breeds. A 1514 bp linear DNA sequence of goat FSHB gene covering the complete 3 exons was cloned by four pairs of primer. A new mutation (A2645G, GenBank Accession no: S64745) locating in exon 3 causing an amino acid change from glutamine (Gln) to arginine (Arg) at residue 115 was identified, which resulted in three genotypes named AA, AB and BB. The three genotypes were detected in the four studied goat breeds. The higher-prolific Matou breed had the highest frequency of genotype AA. Association analysis showed that Boer and Matou does with AA genotype have the largest LS both in average and in parities from first to fourth (P < 0.05). Furthermore, Boer does with AA genotype had the heaviest LWB compared to other two genotypes (P < 0.05). Matou does with AA genotype have more numbers of ova harvested, large follicles and corpus lutea on ovaries after superovulation than those with BB genotype (P < 0.05). Therefore, these results suggest that the FSHB gene is a candidate gene that affects reproduction traits in goats.     

中国美利奴羊H-FABP基因多态性及其与部分肉质性状的相关性

利用聚合酶链式反应-单链构象多态（PCR-SSCP）技术检测中国美利奴羊（Ovis aries var. Merino）心型脂肪酸结合蛋白基因（H-FABP）外显子2的单核苷酸多态性（SNPs）和遗传多态性,分析其与肌内脂肪（IMF）含量、肌纤维直径和肌纤维密度的相互关系,为该品种绵羊的分子标记辅助选择提供理论依据。结果显示,H-FABP基因外显子2有AA、AB和BB 3种基因型,AA型和BB型在778位均发生了C缺失,939位均发生了A→G转换,BB型还在789位发生了T→C转换,该突变导致所编码氨基酸发生了缬氨酸→丙氨酸的替换;BB型为IMF的优势基因型,与AB型相比差异显著（P<0.05）,与AA型相比差异极显著（P<0.01）;BB型对肌纤维直径存在负相关。结果提示,中国美利奴羊H-FABP基因外显子2具有多态性,该基因可能是中国美利奴羊肉质性状的主效基因,或者与控制肉质性状的主效基因相连锁。     

The effect of a SNP in ESR gene on the reproductive performance traits in Polish sows

The aim of the experiment was to detect polymorphism in the ESR gene to determine associations between the genotype and litter size in Polish Large White and Landrace sows. Reproductive traits investigated were: total number of piglets born (TNB), number of piglets born alive (NBA) and number of piglets weaned (TW). The polymorphism in ESR gene was detected using the PCR-RFLP method, with specific primers and the restriction enzyme AvaI. Two different alleles of ESR gene were identified: alleles A (0.71) and B (0.29). The relationship between the ESR genotypes and TBN, NBA and NW were analyzed. The analysis showed in first parity sows statistically significant (P < 0.01) differences between sows carrying different ESR genotypes. The analysis of ESR gene showed that sows with BB genotype had the largest litter size compared to AB and BB sows, but the difference was statistically not significant.     

On-station comparative analysis of reproductive and survival performance between Red Maasai,Dorper, and Merino sheep breeds

The reproductive performance of ewes and the survivability of lambs to weaning have a critical economic impact on sheep farming worldwide. Further, knowledge of major mortality causes allows an opportunity for improved flock management to evade financial losses. The maximum likelihood estimates for generalised linear mixed models and chi-square test methods were used to examine 971 mating records, 839 and 763 lambs born and weaned (singles or twins) from the Naivasha Sheep and Goats station in Kenya for the years 2011 to 2020 consisting of Dorper, Red Maasai (RedM), and Merino breeds. The RedM (P < 0.05) outperformed Dorper and Merino in weaning rate, whereas reproductive performance between the three breeds was not significantly different (P > 0.05) in litter size and multiple lambings per ewe lambing. On the one hand, Dorper significantly (P < 0.05) outperformed the other two breeds only in weaning weight per lamb born. In addition, among all the major causes of death, pneumonia appeared to be the one to which Dorper breeds were most susceptible (chi-square test, P < 0.05). According to the findings of this study, neither the Dorper nor the Merino sheep breeds were reproductively superior to the RedM in an extensive semi-arid production environment. In addition, Dorper's susceptibility to the leading causes of mortality, particularly pneumonia and sheep pox, were relatively high compared to other breeds and could be a precursor to massive economic losses for Dorper sheep producers. In contrast to the indigenous RedM breed, imported sheep breeds appeared to be more susceptible to major mortality-related under an extensive production system. Therefore, regardless of weaning weight, RedM breed production appears to be a more viable investment for small-scale farmers, particularly in semi-arid regions.     

Effects of the MyoG Gene on the Partial Growth Traits in Pigs

Single-nucleotide polymorphisms of the MyoG gene were tested using PCR-SSCP in different pig breeds including Landrace, Large White, Duroc, Shanxi Black, and Mashen pigs, and the effects of the MyoG gene on the birth weight, the weaning weight, the 6-month body weight, and the backfat thickness were also analyzed. On the basis of the published sequence of the porcine MyoG gene, ten pairs of primers were designed, and one polymorphism was found in the PCR product amplified with In2-3 primers. The results showed that: (1) the Landrace, the Large White, and the Duroc breeds differ significantly (P < 0.05) in genotype distribution from the Shanxi Black and the Mashen breeds; (2) On the basis of the fixed effect model, significant differences were found in the birth weight and the backfat thickness among the different MyoG genotypes, whereas no significant differences existed in the weaning weight and the 6-month body weight; (3) Using least square analysis, it was seen that individuals of the BB genotype had significantly less (P < 0.01) birth weight than those of the AA and AB genotypes, with the order being AA>AB>BB; the pigs of the AA genotype had significantly lower (P < 0.01) backfat thickness than those of the AB and BB genotypes, with the order being AA<AB<BB. These results suggest that the genotype has significant effects on the individual birth weight and the backfat thickness, and that the selection of the A allele is favored with regard to the birth weight and the backfat thickness.     

Lambing rates and litter size following carazolol administration prior to insemination in Kivircik ewes

The effect of carazolol on the ease of penetrating the cervix during artificial insemination, lambing rate and litter size was studied using 1.5–4.0-year old Kivircik ewes in an incomplete 3 × 2 × 2 experimental design. All of the ewes in this study were synchronized for oestrus by insertion of a progesterone impregnated vaginal sponge for 12 days and administration of 400 IU PMSG at sponge withdrawal. Three methods of service were compared: natural service, artificial insemination (AI) with fresh semen, or AI with frozen semen. Two times of insemination (fixed time AI versus AI at observed oestrus) were compared on the fresh and frozen AI treatments. The absence (control) or use of carazolol (carazolol; 0.5 mg/ewe i.m. 30 min before mating) was the third factor in the design and penetration of the cervix by the insemination pipette was assessed as shallow (<10 mm), middle (10–20 mm) or deep (>20 mm). Natural service ewes were only mated at observed oestrus. Consequently, the factorial design was incomplete and there were a total of 10 treatments each represented by 30 ewes. Natural service resulted in a significantly (P < 0.05) higher lambing rate and litter size (86%; 2.0 ± 0.05 lambs/ewe) than AI using fresh (65%; 1.6 ± 0.1 lambs/ewe) or frozen (40%; 1.4 ± 0.14 lambs/ewe) semen. For AI animals the lambing rate and litter size were not significantly different when service was at a fixed time (50%; 1.5 ± 0.12 lambs/ewe) or at observed oestrus (56%; 1.5 ± 0.12 lambs/ewe). Carazolol did not permit complete cervical penetration in any ewe. Deep penetration of the cervix at AI was achieved in 33% of untreated (control) and 48% of carazolol treated ewes (P < 0.05). However, the proportion of ewes in which penetration of the cervix and semen deposition was greater than shallow was similar for control (82%) and carazolol (85%), and lambing rate and litter size were similar for both treatments. Over the three service methods, the lambing rate was 56% for control and 63% for carazolol (NS) and litter size was similar for both treatments. It was concluded that the carazolol treatment used prior to natural mating or AI in this experiment did not improve lambing rate or litter size in Kivircik ewes.     

绵羊产羔性状主效基因检测研究

以绵羊BMP15基因和BMPR-IB基因为候选基因,以湖羊、中国美利奴单胎品系、中国美利奴肉用和毛用多胎品系为研究对象,采用PCR-RFLP方法对候选基因进行单核苷酸多态性（SNP）位点检测和基因型分析,同时研究基因对绵羊产羔数的影响。对BMP15基因进行SNP检测,结果未发现多态性位点;对BMPR-IB基因进行多态性检测,结果发现了一个A746 G SNP位点。依据A746 G SNP位点进行基因型分析,结果在各品种（系）羊中发现了3种基因型,即BB、B+和++。等位基因型频率在各品种（系）间差异极显著（P<0.001）,在湖羊中以BB基因型为主,在中国美利奴单胎品系中以++基因型为主, 而在中国美利奴肉用和毛用多胎品系中以B+基因型为主。BMPR-IB A746G位点的变异明显影响绵羊的产羔数,与++基因型母羊相比, BB和B+基因型母羊产羔数明显较多。研究结果同时表明,利用BMPR-IB基因型可以很好的预测母羊的产羔数。研究获得的这些结果强烈表明BMPR-IB为影响绵羊的产羔数的主效基因,可以用于对绵羊产羔数的选择。Abstract: The current study was designed to detect SNPs within BMP15 and BMPR-IB gene and investigate the effect of the genes on sheep litter size. Four sheep lines, HU-Yang, Chinese M erino monotocous, Chinese Merino multiparous for wool production and Chinese Merino multiparous for mutton production, were used in this study. Litter sizes were recorded for each ewe in the four lines. Primers for BMP15 and BMPR-IB gene were designed from database sheep sequence and polymorphisms were detected by PCR-RFLP method. The results showed that there was no polymorphism with BMP15 gene among the four lines, and there was an A / G SNP with BMPR-IB gene at base 746 among the four lines. Three types of genotype (BB, B+ and ++), based on A / G locus, were found within each line. The frequencies of genotypes were significantly different among the lines (P<0.001), with BB genotype primarily existing in HU-Yang, ++ genotype in Chinese Merino monotocous line, and B+ genotype in Chinnese Merino multiparous lines. The A / G mutation influence significantly the sheep litter sizes, and the BB and B+ ewes had significant higher litter sizes than ++ ewes. The results of present study showed simultaneously that the genotype of BMPR-IB was a perfect predictor of the sheep litter sizes. These results intensively indicated that BMPR-IB is a major gene to affect litter size in sheep, and could be used as the molecular genetic marker to select litter size in sheep.     

Correlation Analysis Between Single-Nucleotide Polymorphism of Malate Dehydrogenase Gene 5′-Flanking Region and Growth and Body Composition Traits in Chicken

Malate dehydrogenase (MD) is a key enzyme that plays an important role in energy metabolism. It catalyzes the oxidative decarboxylation of L-malate to yield CO₂ and pyruvate, while simultaneously generating NADPH from NADP⁺. The NADPH generated can be utilized in de novo synthesis of palmitate, which is the precursor molecule for the formation of other long-chain fatty acids. And high levels of MD will also activate muscle development. The current study was designed to investigate the effects of MD gene on growth and body-composition traits in chicken. The eighth generation population of Northeast Agricultural University broiler lines divergently selected for its abdominal fat and Northeast Agricultural University F₂ resource population were used in the research. Polymorphisms were detected by DNA sequencing and PCR-RFLP method was then developed to screen the population. A single mutation at the position of the 235 bp (Accession No. U49693) of MD 5′-flanking region was found. The correlation analysis between the polymorphism of the MD gene and growth and body composition traits was carried out using the appropriate statistic model. Least-square analysis showed that the BB genotype birds had much higher pectoralis major weight and percentage of pectoralis major than AA genotype birds (P<0.05). The abdominal fat weight, percentage of abdominal fat, the liver weight and percentage of liver weight of the AA genotype birds were much higher than those of BB genotype birds (P<0.05). These results indicate that MD gene is the major gene or is linked to the major gene that affects the growth and body composition traits in chicken.     

三种绵羊BMP15基因第二外显子多态性及与产羔数的相关性分析

绵羊存在影响多胎性状的不同主效基因,选择影响Romney Hanna绵羊和Cambridge绵羊高繁殖力的骨形态发生蛋白15 (bone morphogenetic protein 15, BMP15)为候选基因,采用PCR-SSCP的方法检测BMP15基因外显子Ⅱ第747位点(T747→C)和755位点(T755→C)在蒙古羊、甘肃高山细毛羊、小尾寒羊三种绵羊母羊中的多态性,同时还研究了上述两处突变对三种绵羊产羔数的影响。表明:(1)一共检测到野生纯合型AA、突变杂合型AB (T747→C)、AC (T755→C)三种不同的基因型,AA为优势基因型,A为优势等位基因;(2)三种基因型在甘肃高山细毛羊中均被检测到,而蒙古羊和小尾寒羊中未检测出AB基因型;(3)突变杂合型蒙古羊(AC)比野生纯合型(AA)的平均产羔数多0.27只(p<0.05)。(4)AC的基因型频率,双羔母羊和多羔母羊均高于单羔母羊。根据以上实验推测,BMP15第755位点发生的T→C突变(AC型)对蒙古羊一胎产双羔影响十分显著,甘肃高山细毛羊中AC基因型的绵羊其产羔数有比AA基因型和AB基因型多的趋势,因此该位点可能是一个影响绵羊高繁殖力潜在的DNA标记。     

Effect of polymorphism in the peroxisome proliferator-activated receptor gamma gene on litter size of pigs

The association of polymorphisms in peroxisome proliferator-activated receptor γ (PPARγ) gene with litter size was studied in Large White and Landrace pig. Three SNP loci (P1, P2 and P7) on PPARγ₂ gene were determined by PCR–SSCP and the results showed that there were A → G mutations at 220 and 324 bp in 5′-regulator region and at 147 bp in exon 6, respectively. Allele frequencies were analysed in two breeds. Information on 2341 litter records from 564 sows was used to analyse the trait total number born (TNB) and number born alive (NBA). In Large White, TNB and NBA of genotype BB for P2 locus were the lowest, and the TNB and NBA of third and following parities and all parities were 0.74 and 0.51 piglets per litter less (P < 0.001) than those of the highest genotype AB, respectively, but for P1 and P7 locus the beneficial genotype AA were more 0.4–0.8 piglets per litter (P < 0.05) than the inferior genotype AB. In landrace, TNB and NBA of the first parity of genotype BB for P1 locus were 2.0 piglets per litter higher than AA (P < 0.05), but for all parities the TNB and NBA of genotype BB were 0.66 and 0.97 piglets per litter (P < 0.05) higher than AA, respectively. At P2 locus, the TNB and NBA of the second parity of genotype AA were obviously higher than those of AB (P < 0.05). And at P7 locus, the TNB and NBA of each parity of genotype AA were both about 2 piglets per litter more than those of BB (P < 0.05). The results indicated that PPARγ gene was significantly associated with litter size in pigs.     

BMPR-IB和BMP15基因作为小尾寒羊多胎性能候选基因的研究

以控制BooroolaMerino羊多胎性能的BMPR IB基因 ,以及影响Invedale和Hanna羊排卵数的BMP15基因作为候选基因 ,从分子水平上对小尾寒羊的多胎机制进行研究 ,分析突变位点的特性 ,并通过大规模的群体检测统计推断其遗传效应。实验结果表明 :多胎品种小尾寒羊在BMPR IB基因的相应位置上发生了与BooroolaMerino羊相同的突变 (A74 6G) ,该基因的BB基因型在小尾寒羊群体内为优势基因型 ,且小尾寒羊初产和经产母羊的BB基因型比 ++基因型分别多产 0 97羔 (P <0 0 5 )和 1 5羔 (P <0 0 1) ,推测BMPR IB基因与控制小尾寒羊多胎性能的主效基因存在紧密的遗传连锁。而BMP15基因在小尾寒羊中不存在V31D或Q2 3Ter突变 ,说明小尾寒羊的多胎遗传机制与Romney羊不同 ,因此排除了BMP15突变影响小尾寒羊排卵数的可能性。     

Plane of nutrition during the rearing phase for replacement ewes of four genotypes: II - effects on performance during first pregnancy and to weaning,and of their progeny

Plane of nutrition (PN) offered to ewe replacements during the rearing phase (8 to 17 months) and first pregnancy may affect reproductive and progeny performance when replacements are joined at ~19 months. The effects of PN offered to spring-born ewe replacements during their first winter (winter_1), second summer (summer_2) and subsequent winter (mid and late pregnancy; winter_2) were evaluated, over 3 consecutive years, using 287 ewe lambs of four genotypes: Charmoise×Scottish Blackface (C×SBF), Belclare×SBF (Bel×SBF), Belclare (Bel) and Belclare×SBF (heterozygous for a gene, either FecG^H or FecX^G mutations, that increases ovulation rate: BelMG×SBF). Ewe lambs were offered, daily, a deferred-grazed herbage allowance (HA) of either 0.75 or 1.75 kg dry matter during winter_1. During summer_2 the replacements were set-stocked to maintain sward heights of 4 or 6 cm. Ewes were housed during mid and late pregnancy (winter_2) and offered either medium or high-feed-value grass silage, thus yielding a 2×2×2 factorial design. Increasing HA during winter_1 and residual sward height during summer_2 increased ewe BW post joining (P<0.001) and at lambing (P<0.01), but had no effect (P>0.05) on number of lambs reared. Increasing HA during winter_1 increased lamb BW at birth (P<0.05) and reduced carcass fat score (P<0.05). There was a significant interaction between PN offered during winter_1 and summer_2 for average daily gain (ADG) from birth to 5 weeks (P<0.01) and from 5 to 10 weeks (P<0.05): progeny of replacements that experienced either a high or low PN throughout the rearing phase had lower ADG than lambs born to the replacements that experienced a low PN only during winter_1 or summer_2. Increasing PN during winter_2 increased ewe BW (P<0.001), lamb BW at birth (P<0.001) and weaning (P<0.05) and reduced the proportion of ewes that failed to lamb (P<0.01). Ewe genotype had a significant (P<0.001) effect on litter size (1.48 to 2.45), number of lambs reared, lamb BW at birth and weaning, lamb ADG and age at slaughter. It is concluded that, among the nutrition treatments examined, increasing PN during mid and late pregnancy had the greatest effect on ewe and progeny performance. Although increasing PN offered during winter_1 increased lamb birth BW, PN offered during summer_2 had no effect on lamb performance. There were no significant interactions between PN and ewe genotype.