Identifying QTL and candidate genes for prolificacy in maize

In maize,prolificacy,the number of ears per plant,is a trait of interest to maize breeders for breeding high grain-yielding cultivars or specialty corn,as well as being a model trait for decoding the molecular mechanism of maize evolution.Its genetic basis remains largely unknown.We identified a stable quantitative trait locus,qEN7,for ear number on chromosome 7 in both F2 and F2:3 populations derived from a single cross between the nonprolific inbred line Mo17 and the prolific inbred line LAN404 derived from the landrace PI217404.qEN7 explained 10.7%-11.9%of phenotypic variation,and the LAN404 allele at this locus was associated with an increase of around one ear per plant.qEN7 was confined by fine-mapping to a 0.56-Mb region containing eight annotated genes.Analysis of selection,gene expression patterns in various maize tissues,and sequence polymorphisms between the two parental lines suggested that Zm00001d020683,which encodes a putative INDETERMINATE DOMAIN(IDD)transcription factor,is the most likely candidate gene underlying qEN7.Zm00001d020683 is expressed mainly in the vegetative meristem,immature ears,and internodes and has undergone selection during maize improvement.The identification of qEN7 and the prediction of its candidate gene sheds some light on the evolution of maize ear number and provides a novel resource for breeding of multi-ear maize cultivars.

Genetic Parameters Evaluation of Main Reproductive Traits for the New Yorkshire Dam Line with High Prolificacy

The genetic parameters of main reproductive traits for the new Yorkshire line with high prolificacy were evaluated by multiple animal model DFREML The re- suits showed that the heritability evaluates of the total number of born （TNB）, alive number of born （ANB）, litter weigh at birth （LWB） and litter weight at age of 21 days were 0.10, 0.15, 0.09 and 0.14, respectively. The genetic correlations between these traits, for example, the correlations between TNB/ANB, NB/LWB, TNB/LW21, ANB/LWB, ANB/LW21 and LWB/LW21 were 0.87, 0.74, 0.43, 0.69, 0.59 and 0.51, respectively.

Combined Selection Index for New Yorkshire Dam Line with High Prolificacy

The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /：2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding.

Serum Esterase Polymorphisms and Their Associations with Prolificacy in Small Tail Han Sheep

[ Objective] The aim of this research was to provide a theoretical basis for the.breeding and identification of multiparous Small Tail Han sheep. [ Method] The polymorphisms of serum esterase （Es） locus in Small Tail Han sheep were detected by vertical discontinuous polyacrylamide gel electrophoresis （PAGE）. According to the statistical analysis of different genotypes and their litter size, the correlation between Es polymor- phisms and litter size was analyzed. [ Result] There were three genotypes in Es locus, and Es^＋- was the dominate genotype. The differences of ewe litter size in the 1 ,t parity among these three genotypes were nonsignificant （ P 〉 0.05）, As far as the 2^nd and 3rd parity was considered, the litter size of genotype Es＋＋ was significantly （P〈0.05） higher than that of Es-- and Es^＋- ; the average litter size of Es＋＋ was extremely significant （ P 〈 0.01 ） higher than that of Es - - and Es ＋ - while there was no significant difference （ P 〉 0.05） between the latter two. [ Conclusion] The Es lo- cus could be regarded as a genetic marker locus for early selection of high-yielding ewes and Es ＋＋ is the high-yielding genotype of Small Tail Han sheep.

Bone Morphogenetic Protein 15 as a Candidate Gene for Prolificacy of Jining Grey Goat

On the basis of the ovine bone morphogenetic protein 15(BMP15)gene,two pairs of primers(PI and P2)were designed to amplify exons 1 and 2 of the BMP15 gene in five randomly selected does of both Angora and Jining Grey goats.The sequences of BMP15 exon 1(P1 amplification)of Angora and Jining Grey goats were identical.There was a 3-nucleotide(CTT)insertion in positions 268 to 270 of goat BMP 15 exon1 compared with that of sheep(GenBank accession number AF236078),which caused a leucine insertion in the 12th position of amino acid sequence.Sequence length of goat BMP 15 exon 2(P2 amplification)was identical with that of sheep(AF236079),but there were seven nucleotide and four amino acid changes between goat and sheep.The nucleotide in the 963rd position of BMP15 exon 2 was A for Angora goat and sheep,and G for Jining Grey goat.Based on this A963G mutation,primer pair P3 was designed to detect single nucleotide polymorphism of BMP15 exon 2 in breeds of high prolificacy(Jining Grey),moderate prolificacy(Boer)and low prolificacy(Angora and Inner Mongolia Cashmere)by polymerase chain reactionsingle strand conformation polymorphism(PCR-SSCP).Three genotypes(AA,AG and GG)were detected in Jining Grey goats,two genotypes(AG and GG)in Boer,and only the AA genotype in Angora and Inner Mongolia Cashmere goats.Sequencing revealed one mutation(A963G)in genotype GG compared with genotype AA,and this mutation resulted in an amino acid change of serine→glycine(S300G).In Jining Grey goats,frequencies of AA,AG and GG genotypes were 0.008,0.059 and 0.933,respectively.Genotypic distributions of the BMP 15 gene were significantly different(P<0.05 or P<0.001)between Jining Grey and Boer,Angora,and Inner Mongolia Cashmere goats.In Jining Grey goats,the does with the GG genotype had 0.71(P<0.05)or 1.57(P<0.05)additional kids than did those with AG or AA genotypes,and does with the AG genotype had 0.86(P<0.05)more kids than did those with the AA genotype.These results tentatively indicate that the BMP15 gene is either a major gene that affects prolificacy in Jining Grey goats,or may be a molecular marker in close linkage with such a gene.

Production Systems, Genetic Diversity and Genes Associated with Prolificacy and Milk Production in Indigenous Goats of Sub-Saharan Africa: A Review

Goats are one of the oldest domesticated animal species widely distributed in the world playing an important role in the food production system in Sub-Saharan African Region (SSAR). Due to their multiple uses (milk production, meat, fiber and hides) and adaptation aptitudes to ecological conditions, goats produce and contribute positively to farmers’ socio-economy status in various production systems. This review aimed at giving a summary overview on the goat’s production systems characteristics, the genetic diversity and the candidate genes affecting reproductive and milk production performances in goat breeds in SSAR. It has been observed that traditional livestock production system with communal grazing system is the most used in goat keeping in SSAR. The geographical locations play an important role in the relationships between goat’s distributions in the region. At the same time, goats might have been differentiated and isolated one to others due to the wide geographic range, the diversify climate and the topography in the region. Among the six worldwide known haplogroups of goat (A, B, C, D, G and F), haplogroup A is the most representative in SSAR. However, haplogroup G and B can be found in some goat populations in some countries in east (Kenya and Ethiopia) and south parts of Africa. This review reveals that little is known on the candidate genes associated with prolificacy and milk production traits in indigenous goat breeds in the region. That observation suggests the importance of assessing candidate genes associated with economic traits in the populations of goat in SSAR.

Impact of dietary L-arginine supply during early gestation on myofiber development in newborn pigs exposed to intra-uterine crowding

Background: Intra-uterine crowding(IUC) observed in hyperprolific sows impairs myofiber hyperplasia and overall fetal growth. Arginine supplementation(ARG) in gestation diets has been shown to positively affect litter and muscle development. The study objective was to assess whether the effect of ARG on offspring characteristics, with special emphasis on myofiber hyperplasia, differs under IUC conditions from these responses,because in that situation growth retardation is particularly prevalent due to reduced fetal nutrient supply.Unilateral oviduct ligation(OL) was used as a model for an uncrowded and hyperprolificacy(IN) as a model for a crowded intra-uterine environment.Methods: Five OL and five IN sows were fed a diet supplemented daily with either 43 g L-alanine(Ctrl) or 25 g L-arginine from d 14 to 28 of gestation in a cross-over design(two periods: 5^( th) and 6^( th) parity). At farrowing, two male and two female offspring, respectively, with a low and intermediate birth weight(BtW) were selected. After euthanization, the Semitendinosus muscle(STM) was removed and weighed, and the light and dark portions(STM_d and STM_l) were prepared for myofiber histochemistry using ATPase staining and the entire STM for gene expression analysis of myogenesis-related genes using RT-qPCR. In addition, various organs were removed and weighed. Data were analyzed using the MIXED model in SYSTAT.Results: No effect of either IUC or dietary treatment was found in litter characteristics. Offspring of ARG sows displayed a greater muscle area in STM(P < 0.01) as a result of the greater myofiber hyperplasia(P < 0.01). The increase was more distinct in the STM_l(P < 0.05) than in the STM_d(P = 0.131). Offspring of OL sows were heavier at birth(P < 0.01), had a heavier STM(P < 0.05), liver(P < 0.01) and kidney(P < 0.05), but when expressed relative to birth weight, these differences were absent. In addition, IUC had an effect(P < 0.05) on the expression of one of the myogenesis-related genes investigated.Conclusions: Independent from the extent of IUC, ARG improved Bt W, muscle and organ weights and myofiber hyperplasia in offspring.

Detection of the FecX^R Mutation of BMP15 Gene in Sheep and Goats

PCR-SSCP was used to detect mutations of bone morphogenetic protein 15(BMP15) gene in both high prolificacy(Small Tail Han sheep,Hu sheep,Jining Grey goat and Boer goat) and low prolificacy breeds(Dorset sheep,Texel sheep,Inner Mongolia Cashmere goat and Angora goat).Both the nucleotide sequences and the amino acid sequences were compared in amplification fragments of both Small Tail Han sheep and Jining Grey goat.The results indicated that none of the four sheep and the four goat breeds carried the same FecXR mutation of the BMP15 gene as do Rasa Aragonesa sheep.The nucleotide sequence of Small Tail Han sheep was completely identical with that of the sheep BMP15 sequence(GenBank AF236079,NM001114767).Three base substitutions(T529G,C530G and T576C) and two amino acid changes(V155G and S171P) were found in Jining Grey goat compared with Small Tail Han sheep.The FecXR mutation of the BMP15 gene had no significant effect on high prolificacy of Small Tail Han sheep, Hu sheep,Jining Grey goat and Boer goat.

The Use of Melengestrol Acetate as a Strategy to Improve Production Efficiency of Sheep in Rural Areas in Mexico

The aim of this study was to evaluate the use of melengestrol acetate （MGA） as a strategy to improve the production efficiency in ewes of rural areas in Mexico. Twenty ewes of breeds （Dorper and Dorper with Pelibuey） non-pregnant and with ovarica activity were used. The treatment consisted of the administration of 0.22 mg MGA/ewe/d for 17 d. The MGA efficiency was measured once the treatment finalized, and the producer was responsible for the registration of the estrus presentation and prolificacy rate. 95% of the sheep presented estrus in a period of 14 d after stopping treatment. The prolificacy percentage was of 1.2 lambs born by ewe during a period of six months （including treatment and period of gestation）. In conclusion, the use of MGA represents an alternative to improve the efficiency of sheep production in rural areas in Mexico, since it can increase the number of lambs by 30% in a period of 12 months.