Vascular morphology and expression of angiogenic factors in sheep ovaries and their relation with the lambing rate.

The study aims to present the vascular anatomy of ovarian arterial system in sheep and to explore its relation with the angiogenic factors vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2), environmental factors and the lambing rate. Small-tailed Han sheep, Hu sheep, Aohan finewool sheep and Tibetan sheep who are from different habitats in China and with different lambing rates were investigated. The vascular corrosion casting technique and scanning electron microscopy were used to understand arterial architecture, and real-time quantitative PCR (qRT-PCR) and Western blotting were used for assessing VEGF and Ang-2 expression. Results showed that high-prolificity breeds had significantly larger vessel diameters in ovaries than low-prolificity ones. VEGF gene transcript and protein expression were related with the lambing rate, while Ang-2 gene transcript was negatively related with the lambing rate. Results indicated that high-prolificity breeds have more abundant arterial blood supply, which is associated with VEGF expression.

Ruminal and histological characteristics and nitrogen balance in lamb fed diets containing cactus as the only roughage.

This study examined rumen fermentation, histological, blood, and urinary characteristics as well as ammoniacal nitrogen concentration, pH, nitrogen balance, and microbial protein in lamb fed diets containing spineless cactus as the sole roughage source plus levels of wheat bran (WB) in comparison with a control diet based on spineless cactus and buffelgrass. Twenty-eight uncastrated, crossbreed lambs with an average initial weight of 22.6 ± 2.37 kg were used in the experiment. The treatments consisted of a standard diet (control) containing buffelgrass and spineless cactus and three diets containing cactus as the only roughage source plus varied concentrations of WB (30, 37, and 44%, on a dry matter basis). Results were evaluated by analysis of variance, and contrasts were applied at the 5% probability level for mean comparison. Rumen villus height and width were greater and musculature was lower in the lamb fed diets containing 37% and 44% WB compared with those fed control diet. In the intestine, the crypts were smaller in the animals which consumed the diets with 30, 44, and 37% WB. All WB levels resulted in lower nitrogen intake and retention. Microbial protein concentration, microbial protein efficiency, microbial nitrogen, urea, and glucose were not significantly affected. Feeding lamb with diets containing levels of wheat bran, with cactus as the only roughage source, does not negatively affect their ruminal-fermentation, blood, and urinary characteristics; ammoniacal nitrogen concentration; pH; or microbial protein. However, nitrogen balance and ruminal and intestinal morphometric characteristics are impaired.

The Basal Radial Glia Occurs in Marsupials and Underlies the Evolution of an Expanded Neocortex in Therian Mammals.

A hallmark of mammalian brain evolution is the emergence of the neocortex, which has expanded in all mammalian infraclasses (Eutheria, Marsupialia, Monotremata). In eutherians, neocortical neurons derive from distinct neural stem and progenitor cells (NPCs). However, precise data on the presence and abundance of the NPCs, especially of basal radial glia (bRG), in the neocortex of marsupials are lacking. This study characterized and quantified the NPCs in the developing neocortex of a marsupial, the tammar wallaby (Macropus eugenii). Our data demonstrate that its neocortex is characterized by high NPC diversity. Importantly, we show that bRG exist at high relative abundance in the tammar indicating that this cell type is not specific to the eutherian neocortex and that similar mechanisms may underlie the formation of an expanded neocortex in eutherian and marsupial mammals. We also show that bRG are likely to have been present in the therian ancestor, so did not emerge independently in the eutherian and marsupial lineages. Moreover, our data support the concept that changes in multiple parameters contribute to neocortex expansion and demonstrate the importance of bRG and other NPCs for the development and expansion of the mammalian neocortex.

Two linked TBXT (brachyury) gene polymorphisms are associated with the tailless phenotype in fat-rumped sheep.

T-box transcription factor T (TBXT), encoding the brachyury protein, is an embryonic nuclear transcription factor involved in mesoderm formation and differentiation. Previous studies indicate that TBXT mutations are responsible for the tailless or short-tailed phenotype of many vertebrates. To verify whether the tailless phenotype in fat-rumped sheep is associated with TBXT mutations, exon 2 of the TBXT gene for 301 individuals belonging to 13 Chinese and Iranian sheep breeds was directly sequenced. Meanwhile, 380 samples were used to detect the genotypes of the candidate variations by mapping to their reads databases in the Sequence Read Archive repository of GenBank. The results showed that one missense mutation, c.334G>T (GGG>TGG) with a completely linked synonymous variant c.333G>C (CCG>CCC) was found to be associated with the 'tailless' characteristic in typical fat-rumped sheep breeds. The c.334G>T transversion led to the conversion of glycine to tryptophan at the 112th amino acid in the T-box domain of the brachyury protein. In addition, crossbreeding experiments for long-tailed and tailless sheep showed that CT/CT allele of nucleotides (nt) 333 and 334, a recessive mutation, would cause sheep tails to be shorter, suggesting that these two linked variants at nucleotides 333 and 334 in TBXT are probably causative mutations responsible for the tailless phenotype in sheep.

Current challenges in sheep artificial insemination: A particular insight.

Ovine artificial insemination (OAI) is not commonly performed because of specific problems related to semen application techniques, leading to highly variable results. The ideal methodology (frozen-thawed semen/vaginal route) is unfeasible under field conditions due to the cervix morphology of the ewe, which prevents the process of intrauterine insemination necessary to obtain acceptable results. Currently, OAI commercial programmes use superficial cervical insemination, CAI (vaginal), with chilled semen (15°C) and intrauterine insemination, LAI (laparoscopic), with frozen-thawed semen. The ability to improve upon these contrasting techniques may be derived from examining certain poorly studied factors such as insemination time, productive state of females and alternatives of seminal preservation, some of which we reviewed in this work. This interim solution will remain in use until AI by the vaginal route with frozen-thawed semen is developed, but it poses new challenges in optimizing the freezing of the sperm and adapting the cervical (CAI) and/or transcervical intrauterine AI (TCAI). In this review, we address the current problems and evaluate their methodological (mechanical) and chemical (dilation) alternatives. Currently, TCAI is a methodologically complex technique with poor fertility results, so further studies are needed to improve the logistics of this procedure and the results of its application.

The pay-off of hypsodonty - timing and dynamics of crown growth and wear in molars of Soay sheep.

BACKGROUND: Several lineages of herbivorous mammals have evolved hypsodont cheek teeth to increase the functional lifespan of their dentition. While the selective drivers of this trend and the developmental processes involved have been studied in greater detail, thus far no quantitative information is available on the relationship between additional investment into tooth growth and the resulting extension of the functional period of these teeth. To achieve this, we performed a detailed analysis of molar crown growth in known-age Soay sheep repeatedly injected with different fluorochromes. RESULTS: Our study revealed that in sheep molars especially the formation of the crown base portion is prolonged in comparison with other herbivorous artiodactyl species. Our results demonstrate that growth of the crown base accounted for more than half of the total crown formation time (CFT) of the anterior lobes of the first (approx. 220 days of total CFT of 300 days), second (approx. 260 of 460 days) and third (approx. 300 of at least 520 days) molars, and that the formation of this crown portion occurred largely after the teeth had already reached functional occlusion. By combining data on wear-related changes in crown morphology from the literature with the reconstructed additional investment into the crown base portion, it was possible to relate this additional investment to a prolongation of the functional periods of the molars ranging from 4 years in the M1 to 6 years in the M3. CONCLUSIONS: Our results allow to establish a quantitative link between an additional investment into molar crown growth of sheep and the extension of the functional period of these teeth. The reported findings enable an assessment of the adaptive value, in terms of increased longevity, of an additional investment into crown elongation in a mammalian herbivore.

Genetic variants in fat- and short-tailed sheep from high-throughput RNA-sequencing data.

The identification of genetic variations underlying desired phenotypes is one of the main challenges of current livestock genetic research. High-throughput transcriptome sequencing has been recognized as an efficient way to unravel the rich genetic variants across various species. The Lanzhou Fat-Tail sheep is an endangered sheep breed in China with a notable feature of an exaggerated fat tail that also independently occurs in other sheep breeds. However, the genetic mechanism underlying this particular trait has not been fully elucidated yet. In this study, we used RNA-seq on tissue samples (longissimus dorsi muscle, perinephric fat and tail fat) from three sheep breeds with either fat or thin tails and characterized the genetic variation in Lanzhou Fat-Tail sheep with the ultimate goal of identifying the causal genes and genetic networks responsible for the fat tail in this rare sheep breed. In total, 7 122 920 SNPs and 901 518 indels were detected in the nine individual sheep investigated, of which 606 952 SNPs (8.5%) and 77 633 indels (8.6%) overlapped with QTL associated with fat traits in sheep. Furthermore, we detected 26 613 specific SNPs in Lanzhou Fat-Tail sheep and 44 SNPs located in the same genomic position reported in another sheep breed with fat tails. Interestingly, 33 SNPs are selectively distributed on a chromosome 3 region (39.58-40.91 Mb) that was reported as a strong candidate genomic region for fat deposition in tails of sheep. Our research has also suggested that three genes (CREB1, WDR92 and ETAA1) may be associated with fat tail development. In summary, the resultant genetic variants data in this study provide a valuable resource for marker-assisted selection of the trait in Lanzhou Fat-Tail sheep populations.

Do carcasses of lambs finished on commercial production systems meet market standards?

This study aimed to characterize a commercial lamb finishing system using animals of undefined breed from production to slaughter by analyzing performance, carcass traits, yield of commercial cuts, and the quality and meat acceptance of different slaughter groups, as to evaluate whether this system provides the market with a standardized product. The lots were not homogeneous for yield of commercial cuts and performance and morphometric traits evaluated in vivo. The groups were heterogeneous to 75% of the 13 carcass traits evaluated, among them, hot and cold carcass weights, hot and cold carcass yields, carcass grade finishing and biological yield. There was also no uniformity for the proportion of non-carcass components, morphometry of carcass, visual appraisals, and loin traits. On the other hand, homogeneity was achieved in physico-chemical and sensory traits, except for hardness and proportion of saturated, monounsaturated and polyunsaturated fatty acids. We conclude that the commercial finishing system with the use of undefined crossbred lambs does not produce carcass and cuts standardized to the market.

Qualitative and quantitative ultrasound attributes of maternal-foetal structures in pregnant ewes.

The aim of this study was to examine foetal organs and placental tissue to establish a correlation between the changes in the composition of these structures associated with their maturation and the ultrasonographic characteristics of the images. Twenty-four pregnant ewes were included in the study. Ultrasonography assessments were performed in B-mode, from the ninth gestational week until parturition. The lungs, liver and kidneys of foetuses and placentomes were located in transverse and longitudinal sections to evaluate the echogenicity (hypoechoic, isoechoic, hyperechoic or mixed) and echotexture (homogeneous and heterogeneous) of the tissues of interest. For quantitative evaluation of the ultrasonographic characteristics, it was performed a computerized image analysis using a commercial software (Image ProPlus® ). Mean numerical pixel values (NPVs), pixel heterogeneity (standard deviation of NPVs) and minimum and maximum pixel values were measured by selecting five circular regions of interest in each assessed tissue. All evaluated tissues presented significant variations in the NPVs, except for the liver. Pulmonary NPVmean, NPVmin and NPVmax decreased gradually through gestational weeks. The renal parameters gradually decreased with the advancement of the gestational weeks until the 17th week and later stabilized. The placentome NPVmean, NPVmin and NPVmax decreased gradually over the course of weeks. The hepatic tissue did not show echogenicity and echotexture variations and presented medium echogenicity and homogeneous echotexture throughout the experimental period. It was concluded that pixels numerical evaluation of maternal-foetal tissues was applicable and allowed the identification of quantitative ultrasonographic characteristics showing changes in echogenicity related to gestational age.

How maturity influences annulus-endplate integration in the ovine intervertebral disc: a micro- and ultra-structural study.

The annulus-endplate anchorage system plays a vital role in structurally linking the compliant disc to its adjacent much more rigid vertebrae. Past literature has identified the endplate as a region of weakness, not just in the mature spine but also in the immature spine. The aim of this structural study was to investigate in detail the morphological changes associated with annulus-endplate integration through different stages of maturity. Ovine lumbar motion segments were collected from two immature age groups: (i) newborn and (ii) spring lamb (roughly 3 months old); these were compared with a third group of previously analysed mature ewe samples (3-5 years). Sections from the posterior region of each motion segment were obtained for microstructural analysis and imaged in their fully hydrated state via differential interference contrast (DIC) optical microscopy. Selected slices were further prepared and imaged via scanning electron microscopy (SEM) to analyse fibril-level modes of integration. Despite significant changes in endplate morphology, the annular fibre bundles in all three age groups displayed a similar branching mechanism, with the main bundle splitting into several sub-bundles on entering the cartilaginous endplate. This morphology, previously described in the mature ovine disc, is thought to strengthen significantly annulus-endplate integration. Its prevalence from an age as young as birth emphasizes the critical role that it plays in the anchorage system. The structure of the branched sub-bundles and their integration with the surrounding matrix were found to vary with age due to changes in the cartilaginous and vertebral components of the endplate. Microscopically, the sub-bundles in both immature age groups appeared to fade into the surrounding tissue due to their fibril-level integration with the cartilaginous endplate tissue, this mechanism being particularly complex in the spring lamb disc. However, in the fully mature disc, the sub-bundles remained as separate entities throughout the full depth of their anchorage into the cartilaginous endplate. Cell morphology was also found to vary with maturity within the cartilaginous matrix and it is proposed that this relates to endplate development and ossification.

Selection signature analysis reveals genes associated with tail type in Chinese indigenous sheep.

Fat-tailed sheep have commercial value because consumers prefer high-protein and low-fat food and producers care about feed conversion rate. However, fat-tailed sheep still have some scientific significance, as the fat tail is commonly regarded as a characteristic of environmental adaptability. Finding the candidate genes associated with fat tail formation is essential for breeding and conservation. To identify these candidate genes, we applied FST and hapFLK approaches in fat- and thin-tailed sheep with available 50K SNP genotype data. These two methods found 6.24 Mb of overlapped regions and 43 genes that may associated with fat tail development. Gene annotation showed that HOXA11, BMP2, PPP1CC, SP3, SP9, WDR92, PROKR1 and ETAA1 may play important roles in fat tail formation. These findings provide insight into tail fat development and a guide for molecular breeding and conservation.

A genome-wide association study reveals candidate genes for the supernumerary nipple phenotype in sheep (Ovis aries).

Genome-wide association studies (GWASs) have been widely applied in livestock to identify genes associated with traits of economic interest. Here, we conducted the first GWAS of the supernumerary nipple phenotype in Wadi sheep, a native Chinese sheep breed, based on Ovine Infinium HD SNP BeadChip genotypes in a total of 144 ewes (75 cases with four teats, including two normal and two supernumerary teats, and 69 control cases with two teats). We detected 63 significant SNPs at the chromosome-wise threshold. Additionally, one candidate region (chr1: 170.723-170.734 Mb) was identified by haplotype-based association tests, with one SNP (rs413490006) surrounding functional genes BBX and CD47 on chromosome 1 being commonly identified as significant by the two mentioned analyses. Moreover, Gene Ontology enrichment for the significant SNPs identified by the GWAS analysis was functionally clustered into the categories of receptor activity and synaptic membrane. In addition, pathway mapping revealed four promising pathways (Wnt, oxytocin, MAPK and axon guidance) involved in the development of the supernumerary nipple phenotype. Our results provide novel and important insights into the genetic mechanisms underlying the phenotype of supernumerary nipples in mammals, including humans. These findings may be useful for future breeding and genetics in sheep and other livestock.

Choosing sheep (Ovis aries) as animal model for temporomandibular joint research: Morphological, histological and biomechanical characterization of the joint disc.

Preclinical trials are essential to the development of scientific technologies. Remarkable molecular and cellular research has been done using small animal models. However, significant differences exist regarding the articular behavior between these models and humans. Thus, large animal models may be more appropriate to perform trials involving the temporomandibular joint (TMJ). The aim of this work was to make a morphological (anatomic dissection and white light 3D scanning system), histological (TMJ in bloc was removed for histologic analysis) and biomechanical characterization (tension and compression tests) of sheep TMJ comparing the obtained results with human data. Results showed that sheep processus condylaris and fossa mandibularis are anatomically similar to the same human structures. TMJ disc has an elliptical perimeter, thinner in the center than in periphery. Peripheral area acts as a ring structure supporting the central zone. The disc cells display both fibroblast and chondrocyte-like morphology. Marginal area is formed by loose connective tissue, with some chondrocyte-like cells and collagen fibers in diverse orientations. Discs obtained a tensile modulus of 3.97±0.73MPa and 9.39±1.67MPa, for anteroposterior and mediolateral assessment. The TMJ discs presented a compressive modulus (E) of 446.41±5.16MPa and their maximum stress value (σmax) was 18.87±1.33MPa. Obtained results suggest that these animals should be considered as a prime model for TMJ research and procedural training. Further investigations in the field of oromaxillofacial surgery involving TMJ should consider sheep as a good animal model due to its resemblance of the same joint in humans.

A novel TaqI polymorphism in the coding region of the ovine TNXB gene in the MHC class III region: morphostructural and physiological influences.

The tenascin-XB (TNXB) gene has antiadhesive effects, functions in matrix maturation in connective tissues, and localizes to the major histocompatibility complex class III region. We hypothesized that it may influence adaptive physiological response through an effect on blood vessel function. We identified a novel g.1324 A→G polymorphism at a TaqI recognition site in a 454 bp fragment of ovine TNXB and genotyped it in 150 Nigerian sheep using PCR-RFLP. The missense mutation changes glutamic acid (GAA) to glycine (GGA). Among SNP genotypes, significant differences (P < 0.05) were observed in body weight and fore cannon bone length. Interaction effects of breed, SNP genotype, and geographic location had a significant effect (P < 0.05) on chest girth. The SNP genotype was significantly (P < 0.05) associated with physiological traits of pulse rate and skin temperature. The observed effect of this novel polymorphism may be mediated through its role in connective tissue biology, requiring further association and functional studies.

Pelvic magnetic resonance imaging in the ewe: a model for experimental gynecologic research.

AIM: Our goal was to demonstrate the feasibility of pelvic magnetic resonance imaging (MRI) in the ewe. MATERIAL AND METHODS: Two ewes underwent a pelvic 3 Tesla MRI scan, under light anesthesia, with T2-weighted fast spin-echo images and T1-weighted spoiled gradient-echo images. Multiplan T1 weighted images were also obtained after the intravenous injection of a contrast product. One ewe was anestrous and the other one had undergone ovarian stimulation. RESULTS: No incident occurred during the examination. Both the uterus (with two horns) and the ovaries were identified. The intensity of the endometrial, myometrial and ovarian signals was similar to that encountered in women. The uterus and ovaries could be enhanced in both cases. Pelvic vasculature was also studied. In the case of hormonal stimulation, the endometrium was thicker, follicular growth was identified and enhancement seemed greater. CONCLUSION: MRI in the ewe is feasible and could be helpful in experimental gynecologic research, especially in uterus transplantation.

[Structure and venous vascular bed of the rectum in Stavropol breed sheep].

This investigation was aimed at the study of macromorphology of the rectum, including its intramural and extraorgan venous vascular bed in 18-month-old sheep of Stavropol breed. The methods used included anatomical preparation, morphometry, contrast mass intravascular injection, separation of an intestinal wall into the individual layers and preparation of total samples. The thickness of rectal muscular coat in 18-month-old sheep was found to increase in the caudal direction which is interpreted as an adaptation of the intestine for the evacuation of condensed fecal masses through the anal canal lumen. Intramural rectal venous vascular bed included three plexuses: submucosal, muscular and subserosal. The prevalence of the veins of wide-field type with an index of 90-120 in the rectal wall of a sheep results in the deceleration of the venous blood flow in the organ. At the same time, rectal intramural venous vascular bed possesses higher adaptive capacity in the cases of occlusion of the basic roots due to the well developed collateral network located between the roots of wide-field veins. The major extraorgan venous vessel of sheep rectum is a cranial rectal vein. Presence of its terminoterminal anastomoses with caudal rectal and left colonic veins may provide a bypass rectal venous blood flow in the cases of a the obstruction of one of its major vessels of various etiology.

Geometric morphometric evaluation of mandibles of four sheep breeds: Bardoka, Ivesi, Polish Mountain sheep and Turcana.

The enduring relationship between humans and domestic sheep has evolved over millennia, showcasing diverse uses such as meat, milk, wool, leather and fur, shaped by geographical, historical, cultural and social factors. The sheep breeds discussed include the Ivesi from Southeastern Anatolia, known for its varied animal products; the resilient Turcana breed of Romania; Kosovo's Bardoka, valued for its triple-purpose characteristics; and Poland's Polish Mountain Sheep, uniquely utilized for milk production in cheese making. Sheep, with their enduring relationship with humans and significant economic importance, have attracted scientific interest in morphometric studies of their mandibles, yielding valuable data applicable across various fields including basic anatomy, veterinary clinical anatomy, zooarchaeology and veterinary forensic medicine. Traditional morphometric studies rely on statistical methods to compare length, depth and angular ratios between anatomical formations, often highlighting differences between specific points but not fully revealing shape variations between distinct groups. Geometric morphometric analysis has emerged as a preferred method in recent years, enabling shape analyses using coordinate data from various imaging techniques, facilitating a comprehensive examination of mandibular morphometrics among sheep breeds across different countries. This study involved four sheep breeds from different countries, namely Ivesi from Turkey, Bardoka from Kosovo, Polish Mountain Sheep from Poland and Turcana from Romania, with a total of 70 mandibles sourced from various veterinary faculties. Mandibular photographs were meticulously captured, focusing on the right side of mandible pairs and placing landmarks and semi-landmarks along the entire edge, enabling geometric morphometric analysis using tpsUtil, tpsDig2 and MorphoJ software. The analysis included principal component analysis, canonical variate analysis and discriminant function analysis for pairwise comparisons, facilitating a comprehensive examination of mandibular shape variations among the different sheep breeds. Using geometric morphometric methods, this study analysed mandibles from four distinct sheep breeds sourced from different countries, revealing notable variations in regions such as the ramus mandibula, angulus mandibula and incisive areas, attributed to genetic, geographical and dietary influences, highlighting the importance of continued research to better comprehend these shape differences.

Multivariate analysis of heat tolerance characteristics in Santa Inês and crossbred lambs in the Federal District of Brazil.

Heat tolerance is an important trait for deciding on which genetic resource to use on farms in tropical regions. Three genetic groups of lambs were evaluated by physical and physiological parameters related to adaptation and multivariate analyses used to test if these traits were efficient in separating the genetic groups and which traits were more important in this separation. Crossbred lambs were more similar to each other than to Santa Inês, in general; but individually there was an overlap between Ile de France and Santa Inês lambs. Size traits had higher canonical correlation with physiological variables, while rectal temperature, heart rate, and hemoglobin were more highly correlated with physical traits. Error rates using only physiological traits were high, suggesting that these are inefficient in separating groups of lambs for heat tolerance, while separation with physical traits was more efficient.

Estimation of mature live weight using some body measurements in Karya sheep.

The aim of this study was to determine models which will be used for the estimation of adult live weights based on some body measurements using multiple regression model in Karya sheep of different age groups. Animal material of the study consisted of a total of 215 Karya sheep. Least squares means for live weight, body length, rump height, withers height, back height, chest depth, chest girth, and chest width of Karya sheep in Adnan Menderes University Group Sheep Breeding Program elite flock and breeder flocks were found as 47.24 kg, 67.08, 68.29, 68.58, 66.97, 30.04, 93.24, and 18.29 cm, respectively. Karya ewes were put into five categories according to ages (2-6 years). High positive phenotypic correlation coefficients were observed between live weight and body measurements of animals in different age groups (2-6 years). Among the formed multiple regression models, the highest coefficients of determination (R(2)) were obtained from the models formed for body length or body length and chest girth together (R(2) = 0.79, R (2) = 0.87). It is concluded that live weight of Karya sheep can be estimated with a high accuracy using some body measurements and statistical methods.