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Periconceptional nutrition (PCN) can influence foetal hypothalamo-pituitary adrenal (HPA) axis function and alter cortisol secretion with possible consequences for maturation and growth of major organs, gestation length and behaviour. We examined effects of PCN on phenotype and survival of the neonatal lamb in 466 Merino ewes allocated to treatments providing 70%, 100% and 150% respectively, of maintenance requirements for 17 days prior and 6 days after insemination. Gestation length and birth weight for lambs in PCN treatment groups was similar (P > 0.05) but low PCN decreased the size of the neonate (crown-rump-length and metacarpal length P < 0.05). A subset of lambs euthanased at 5 days of age further showed that low PCN decreased the amount of peri-renal fat (P < 0.05) and increased liver mass (P < 0.05) while high PCN increased neck thymus and ovary mass (P < 0.05). Neonatal lambs from low PCN ewes returned faster to their mothers after release (P < 0.05) and contacted the udder in the shortest time (P < 0.05). Significant interactions between PCN treatment and sex (P < 0.05) and between PCN treatment and ewe age (P < 0.05) were also observed for time lambs took to follow the ewe. Survival of lambs was similar but potential differences may have been masked by favourable weather conditions. In conclusion, this study provides evidence of significant changes in lamb growth and development dependent on PCN and, for the first time, links these changes with significant changes in behaviour of the neonate. The impact of these effects on lamb survival and potential reproductive capacity of female offspring remains to be determined., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Five haplogroups have been identified in domestic sheep through global surveys of mitochondrial (mt) sequence variation, however these group classifications are often based on small fragments of the complete mtDNA sequence; partial control region or the cytochrome B gene. This study presents the complete mitogenome from representatives of each haplogroup identified in domestic sheep, plus a sample of their wild relatives. Comparison of the sequence successfully resolved the relationships between each haplogroup and provided insight into the relationship with wild sheep. The five haplogroups were characterised as branching independently, a radiation that shared a common ancestor 920,000 ± 190,000 years ago based on protein coding sequence. The utility of various mtDNA components to inform the true relationship between sheep was also examined with Bayesian, maximum likelihood and partitioned Bremmer support analyses. The control region was found to be the mtDNA component, which contributed the highest amount of support to the tree generated using the complete data set. This study provides the nucleus of a mtDNA mitogenome panel, which can be used to assess additional mitogenomes and serve as a reference set to evaluate small fragments of the mtDNA.

Complete mitochondrial DNA (mtDNA) control regions (CR) were sequenced and analysed in order to investigate wild sheep taxonomy and the origin of domestic sheep (Ovis aries). The dataset for phylogenetic analyses includes 63 unique CR sequences from wild sheep of the mouflon (O. musimon, O. orientalis), urial (O. vignei), argali (O. ammon) and bighorn (O. canadensis) groups, and from domestic sheep of Asia, Europe and New Zealand. Domestic sheep occurred in two clearly separated branches with mouflon (O. musimon) mixed into one of the domestic sheep clusters. Genetic distances and molecular datings based on O. canadensis CR and mtDNA protein-coding sequences provide strong evidence for domestications from two mouflon subspecies. Other wild sheep sequences are in two additional well-separated branches. Ovis ammon collium and O. ammon nigrimontana are joined with a specimen from the transkaspian Ust-Urt plateau currently named O. vignei arkal. Ovis ammon ammon, O. ammon darwini and O. vignei bochariensis represent a separate clade and the earliest divergence from the mouflon group. Therefore, O. musimon, O. vignei bochariensis and Ust-Urt sheep are not members of a 'moufloniform' or O. orientalis species, but belong to different clades. Furthermore, Ust-Urt sheep could be a hybrid population or an O. ammon subspecies closely related to O. ammon nigrimontana.

A medium-density linkage map of the ovine genome has been developed. Marker data for 550 new loci were generated and merged with the previous sheep linkage map. The new map comprises 1093 markers representing 1062 unique loci (941 anonymous loci, 121 genes) and spans 3500 cM (sex-averaged) for the autosomes and 132 cM (female) on the X chromosome. There is an average spacing of 3.4 cM between autosomal loci and 8.3 cM between highly polymorphic [polymorphic information content (PIC) > or = 0.7] autosomal loci. The largest gap between markers is 32.5 cM, and the number of gaps of > 20 cM between loci, or regions where loci are missing from chromosome ends, has been reduced from 40 in the previous map to 6. Five hundred and seventy-three of the loci can be ordered on a framework map with odds of > 1000 : 1. The sheep linkage map contains strong links to both the cattle and goat maps. Five hundred and seventy-two of the loci positioned on the sheep linkage map have also been mapped by linkage analysis in cattle, and 209 of the loci mapped on the sheep linkage map have also been placed on the goat linkage map. Inspection of ruminant linkage maps indicates that the genomic coverage by the current sheep linkage map is comparable to that of the available cattle maps. The sheep map provides a valuable resource to the international sheep, cattle, and goat gene mapping community.

A full-sib mapping population was typed for Taql Southern blot RFLPs at the ovine alpha-inhibin (INHA), beta(A)-inhibin/activin (INHBA), and beta(B)-inhibin/activin (INHBB) loci. The most likely positions were found by genetic linkage analysis. INHA was placed on ovine chromosome 2q, between microsatellite markers BM6444 and INRA135, while INHBB was located 39 cM proximal to INHA between markers BMS1126 and BMS2626. The INHBA gene, a comparative mapping anchor locus, mapped to chromosome 4, between microsatellites OARCP26 and BMS719. These data confirm and refine previous chromosomal assignments by in situ hybridization, provide comparative mapping information, and identify microsatellite markers suitable for QTL association studies with inhibin/activin genes in ruminants.

Two major Ovis aries mitochondrial DNA (mtDNA) haplogroups have been described in independent studies. HinfI RFLP data of mitochondrial genomes from a large sample set (n = 239) indicated an ancient mutation which differentiates between the two mtDNA types. A completely determined sheep mtDNA sequence was used to assign this mutation to the COI gene and to develop a PCR based assay discriminating between the two phylogenetic branches. The haplogroup specificity of the mutation was further investigated in 26 randomly selected individuals. The animals were unequivocally assigned to their respective groups on the basis of the developed test and their complete control region sequences. The assay provides a rapid and economic means of discriminating between both major domestic sheep mtDNAs.

The complete mitochondrial DNA (mtDNA) molecule of the domestic sheep, Ovis aries, was sequenced, together with part of the mtDNA of a specimen representing the other major O. aries haplotype group. The length of the complete ovine mtDNA presented is 16,616 nucleotides (nt). This length is not absolute, however, due to heteroplasmy caused by the occurrence of different numbers of a 75-nt-long tandem repeat in the control region. The sequence data were included in analyses of intraspecific ovine molecular differences, molecular comparisons with bovine mtDNAs, and phylogenetic analyses based on complete mtDNAs. The comparisons with bovine mtDNAs were based on the central domains of the ovine control regions, representing both major ovine haplotype groups, and the corresponding domains of Bos taurus and B. indicus. The comparisons showed that the difference between the bovids was 1.4 times greater than the intraspecific ovine difference. These findings suggest that the strains of wild sheep from which domestic sheep originated were more closely related than were the B. primigenius subspecies which gave rise to B. indicus and B. taurus cattle. Datings based on complete mtDNAs suggest that the bovine and ovine lineages diverged about 30 million years before present. This dating is considerably earlier than that proposed previously.

Two mitochondrial DNA molecules which represent major Ovis aries mtDNA haplogroups were cloned and comparatively sequenced to assess the degree of intraspecific variation. A total of 9623 bp that correspond to 58% of both mitochondrial genomes were determined. The control region, the Cytb, ND2, ND3, ND4L, COIII and 12 tRNA genes, including the origin of L-strand replication, were completely characterized. Partial sequence information was obtained from the 12S and 16S rRNA and an additional six protein coding and six tRNA genes. The control regions of the two mtDNAs showed a nucleotide divergence of 4.34% while coding regions differed by 0.44%. The number of sheep coding region substitutions was similar to values observed in intraspecific comparisons of mitochondrial DNAs that represent remote points in genealogical trees of mice and humans. However, replacement substitutions were only observed at approximately 30% of the rate in mice and approximately 20% of the rate in humans. Nucleotide substitutions with a potential for phenotypic effects were found in the 12S and 16S rRNA and in the ND1 and COIII genes.

To investigate the origins and phylogenetic relationships of domestic sheep, mitochondrial DNA (mtDNA) from 243 sheep of five European, one African, and four Asian breeds and several mouflon (Ovis musimon), urial (O. vignei bochariensis), and argali (O. ammon nigrimontana, O. a. collium) were assayed for restriction fragment length polymorphisms (RFLP). Twenty haplotypes were identified which occurred in three major phlogenetic groups: urial/argali, mouflon/domestic, and domestic sheep. From the branches that contain mouflon and domestic sheep, two major domestic sheep lineages are apparent. One lineage, termed European lineage, contains the majority of haplotypes detected among European domestic sheep. These mtDNAs resemble mouflon haplotypes. The other lineage, termed Asian lineage, consists of haplotypes found in central Asian and some European domestic sheep. The mean sequence difference between these two lineages (0.72%) is of similar magnitude as that between two argali subspecies. To accurately estimate sequence differences between the European and Asian mtDNA types, the mitochondrial control region of one animal from each lineage and of one mouflon and urial were completely sequenced. Sequence comparisons show that Asian and European domestic sheep lineages differ by 4.43%. The mouflon sequences diverges from the Asian type by 4.52%, but by only 1.36% from the European type. Our data supports the hypothesis that some modern domestic sheep and European mouflon derive from a common ancestor and provide evidence of an additional wild ancestor, other than the urial and argali groups, which has yet to be identified.

A cosmid clone containing the complete sheep inhibin subunit beta B gene (INHBB) was assigned to sheep and cattle homologous chromosome bands 2q31-q33 by fluorescence in situ hybridization. The assignment of INHBB in sheep excludes another candidate gene as the site of the FecB mutation.

A total of 419 individuals of four breeds with differing fecundity (Rhoenschaf, Merinolandschaf, East Friesian Milksheep, Romanov) and several wild sheep of the Ovis musimon, O. orientalis, O. vignei and O. ammon groups were screened for genetic variation at the beta A-inhibin (INHBA) locus with up to 11 enzymes. The four breeds differed significantly (P < 0.001) in TaqI allele frequencies. The frequency of the TaqI A allele coincided with the average litter size in each breed.

Restriction endonuclease fragment patterns of mitochondrial DNA (mtDNA) in sheep were analysed with 11 enzymes. Four breeds (Merinolandschaf, Rhoenschaf, Schwarzkoepfiges Fleischschaf and Skudde) of domestic sheep and European Mouflon were examined. A restriction map with 28 cleavage sites of seven enzymes was established. KpnI and PstI do not cut ovine mtDNA. Two EcoRI fragments of Merinolandschaf, Rhoenschaf and Mouflon each were cloned and partially sequenced. Intraspecific nucleotide sequence differences within 1.101 kb ranged from 0.09 to 0.27%. Hybridization analysis with a fragment of porcine mtDNA along with sequencing data from cloned fragments was used for orientation of the restriction map along the bovine sequence. Ovine mtDNA sequences encompassing parts of the Cyt.b-, ND5-, CoIII- and ATPase6 genes were compared with the corresponding sequences of the bovine mtDNA.

Poor lamb survival pre-weaning is a major source of reproductive inefficiency in Australian sheep flocks. While nutrition and management options have been extensively researched and promoted to improve lamb survival, the present review focuses on the prospects for obtaining genetic gain and helps identify selection strategies for boosting such gains to improve overall reproductive efficiency in the Australian sheep industry. Estimated heritability for lamb survival using linear model analysis is low, although use of threshold models suggests that heritability could be higher, which, if true, could help explain the substantial genetic gains obtained in long-term selection experiments. Epigenetic mechanisms may hinder selection and quantitative trait-loci identification through confounding and/or masking genetic variances and co-variances. With sufficient information, these effects could be considered in genetic evaluations by identifying those components that are amenable to selection. Regarding indirect selection, finding effective criteria for improving lamb survival has proved elusive. Most measures of maternal behaviour, temperament and lambing difficulty researched are poorly correlated genetically with lamb survival. Of lamb behaviours and thermo-genic indicators studied, latency to bleat following handling by humans is moderately genetically correlated with lamb survival, as is neonatal rectal temperature. Industry application remains to be adequately explored for the more promising of these measures. Finally, in lieu of direct selection for lamb survival, there is merit in selecting for multiple-rearing ability or its equivalent, possibly with additional selection criteria for lamb survival and reproductive efficiency. Poor lamb survival limits the achievement of good reproductive efficiency of sheep in many countries. The opportunities for genetic improvement of lamb survival are reviewed, with the prospects found to be better than previously thought. Notwithstanding the importance of good nutrition and management, combinations of direct and indirect selection may ultimately make a valuable contribution to improving lamb survival. [ABSTRACT FROM AUTHOR]