1,720,967 research outputs found
Genome- wide analyses reveal population structure and identify candidate genes associated with tail fatness in local sheep from a semi- arid area
Full text linkUnder a climate change perspective, the genetic make-up of local livestock breeds showing adaptive traits should be explored and preserved as a priority. We used genotype data from the ovine 50 k Illumina BeadChip for assessing breed autozygosity based on runs of homozygosity (ROH) and fine-scale genetic structure and for detecting genomic regions under selection in 63 Tunis ia n sheep samples. The average genomic inbreeding coefficients based on ROH were estimated at 0.017, 0.021, and 0.024 for Barbarine (BAR, n = 26), Noire de Thibar (NDT, n = 23), and Queue fine de l'Ouest (QFO, n = 14) breeds, respectively. The genomic relationships among individuals based on identity by state (IBS) distance matrix highlighted a recent introgression of QFO into the BAR and a genetic differentiation of NDT samples, possibly explained by past introgression of Europe an gene pools. Genome-wide scan for ROH across breeds and within the BAR sample set identified an outstanding signal on chromosome 13 (46.58–49.61 Mbp). These results were confirmed using FST index, differentiating fat vs. thin-tailed individuals. Candidate genes under selection pressure (CDS2, PROKR1, and BMP2) were associated to lipid storage and probably preferentially selected in fat-tailed BAR animals. Our findings suggest paying more attention to preserve the genetic integrity and adaptive alleles of local sheep breeds
Genetic structure of Tunisian sheep breeds as inferred from genome-wide SNP markers
Full text linkAssessing the status of genetic variability of native sheep breeds could provide important clues for research and policy makers to devise better strategies for the conservation and management of genetic resources. In this study, a genetic investigation of Tunisian sheep breeds using a genome-wide scan of approximately 50,000 SNPs was performed. To reconstruct genetic structure and relationships among four sheep breeds, 40 samples belonging to fat-tailed Barbarine, Queue Fine de l'Ouest, Noire de Thibar and D'Man breeds were genotyped using Illumina Ovine SNP50 BeadChip. Tunisian breeds averaged 96 % polymorphic loci with an expected heterozygosity (He = 0.36). Genetic analysis of relationship between breeds using Bayesian clustering, MDS and Neighbor-Network analysis, and estimation of FST genetic structure, highlighted the genetic differentiation of Noire de Thibar breed from the other local breeds, reflecting the effect of past events of introgression of European gene pool. The Queue Fine de l'Ouest breed showed a genetic heterogeneity and was close to Barbarine and D'Man breeds, as evidenced by MDS and the lowest level of differentiation with Barbarine breed (FST = 1.8 %). The D'Man breed shared a considerable gene flow with the thin-tailed Queue Fine de l'Ouest breed. Possible factors explaining the genetic patterns observed, such as considerable gene flow probably due to anthropogenic activities in the light of population management and conservation programs
Sequencing and Characterization of αs2-Casein Gene (CSN1S2) in the Old-World Camels Have Proven Genetic Variations Useful for the Understanding of Species Diversification
No full textThe CSN1S2 gene encodes αs2-casein, the third most abundant protein in camel milk. Despite its importance in foals, human nutrition, and dairy processing, the CSN1S2 gene in camels has received little attention. This study presents the first complete characterization of the CSN1S2 gene sequence in Old-World camels (Camelus bactrianus and Camelus dromedarius). Additionally, the gene promoter, consisting of 752 bp upstream of exon 1, was analyzed. The entire gene comprises 17 exons, ranging in length from 24 bp (exons 4, 8, 11, and 13) to 280 bp (exon 17). Interesting was the identification of the exon 12 in both species. The promoter analysis revealed 24 putative binding sites in the Bactrian camel and 22 in dromedary camel. Most of these sites were typical elements associated with milk protein, such as C/EBP-α, C/EBP-β, Oct-1, and AP1. The SNP discovery showed relatively high genetic diversity compared to other camel casein genes (CSN1S1, CSN2, and CSN3), with a total of 34 polymorphic sites across the two species. Particularly noteworthy is the transition g.311G>A in the CSN1S2 promoter, creating a new putative consensus binding site for a C/EBP-β in the Bactrian camel. At the exon level, two novel variants were found. One was detected in exon 6 of the Bactrian camel (g.3639C>G), resulting in an amino acid replacement, p.36Ile>Met. The second variant was found in noncoding exon 17 of dromedary CSN1S2 (g.1511G>T). Although this mutation occurs in the 3'-UnTranslated Region, it represents the first example of exonic polymorphism in the CSN1S2 for this species. This SNP also affects the binding sites of different microRNAs, including the seed sequence of the miRNA 4662a-3p, highlighting its role as a regulatory factor for CSN1S2 gene. A PCR-RFLP was set up for genotyping a dromedary Tunisian population (n = 157), and the minor allele frequency was found to be 0.27 for the G allele, indicating a potential yield improvement margin. The interspersed elements (INEs) analysis revealed 10 INEs covering 7.34% and 8.14% of the CSN1S2 sequence in the Bactrian and dromedary camels, respectively. Furthermore, six elements (A, B, F, H, I, and L) are shared among cattle and camels and are partially found in other ruminants, suggesting a common ancestral origin of these retrotransposons. Conversely, elements C, D, E, and G are specific to camels
Refining the genomic profiles of North African sheep breeds through meta-analysis of worldwide genomic SNP data
No full textIntroduction: The development of reproducible tools for the rapid genotyping of thousands of genetic markers (SNPs) has promoted cross border collaboration in the study of sheep genetic diversity on a global scale. Methods: In this study, we collected a comprehensive dataset of 239 African and Eurasian sheep breeds genotyped at 37,638 filtered SNP markers, with the aim of understanding the genetic structure of 22 North African (NA) sheep breeds within a global context. Results and discussion: We revealed asubstantial enrichment of the gene pool between the north and south shores of the Mediterranean Sea, which corroborates the importance of the maritime route in the history of livestock. The genetic structure of North African breeds mirrors the differential composition of genetic backgrounds following the breed history. Indeed, Maghrebin sheep stocks constitute a geographically and historically coherent unit with any breed-level genetic distinctness among them due to considerable gene flow. We detected a broad east–west pattern describing the most important trend in NA fat-tailed populations, exhibited by the genetic closeness of Egyptian and Libyan fat-tailed sheep to Middle Eastern breeds rather than Maghrebin ones. A Bayesian FST scan analysis revealed a set of genes with potentially key adaptive roles in lipid metabolism (BMP2, PDGFD VEGFA, TBX15, and WARS2), coat pigmentation (SOX10, PICK1, PDGFRA, MC1R, and MTIF) and horn morphology RXFP2) in Tunisian sheep. The local ancestry method detected a Merino signature in Tunisian Noire de Thibar sheep near the SULF1gene introgressed by Merino’s European breeds. This study will contribute to the general picture of worldwide sheep genetic diversity
Modelling heat stress effects on milk production traits in Tunisian Holsteins using a random regression approach
No full text15 PágProduction data and climatological data supporting the results of this study are available on request from the Tunisian Livestock and Pastures Office (OEP: 30, Rue Alain Savary 1002 Tunis Belvédère Tunisie, Tél: +21,671,844 791, Fax +21,671,793,603, e-mail: [email protected], URL: http://www.oep.nat.tn) and the National Meteorological Institute (INM: 1, Avenue Mohamed Ali Akid, Cité Olympique—El Khadhra 1003—Tunis—Tunisie, Tél: +216 70 24 77 40, Fax: 71 77 26 09, e-mail: [email protected], URL:https://www.meteo.tn). The data are not publicly accessible due to legal restrictions.This study investigated the impact of temperature and humidity on milk production traits in Tunisian dairy cows, analysing population-level trends and individual cow responses using various modelling techniques and heat stress (HS) indices. Two distinct datasets were used for this purpose: the first included 551,139; 331,654 and 302,396 test-day records for milk, fat and protein yields, respectively. The second supplemented the production information with daily average (THIavg) and maximum (THImax) temperature-humidity index (THI) data. Three main parts of analyses were conducted simultaneously: classical least squares, identification of HS thresholds and associated production losses and assessment of individual cow responses using random regression models (RRM) fitting various continuous functions that include/exclude individual effects. The best model, determined by goodness-of-fit measurements, was a cubic polynomial function that accounted for individual variation and THIavg as a heat load measure. HS thresholds were established at THIavg/THImax of 70/74 for milk yield, 50/55 for fat percentage, 59/66 for protein percentage, 54/63 for fat yield and 56/66 for protein yield. According to the fitted polynomial models, daily milk production traits showed a curvilinear decline with accelerated loss rates beyond the established thermal thresholds. However, for all models and thermal indices, maximum daily production losses remained below 164 g/day, 4.4 g/day and 6.1 g/day for milk, fat and protein yields, respectively. Despite these losses, the relatively high thermal thresholds and lower associated production losses suggest that Tunisian dairy cows can tolerate high heat loads. Moreover, observed variations in response patterns indicate potential for selecting heat-tolerant individuals within this population.This research has no funding source.Peer reviewe
CA.RA.VA.N project: toward implementation of a modern camel selection system in Northern Africa?
No full textA project entitled “CA.RA.VA.N., Toward a CAmel tRAnsnational VAlue chain” (http://www.arimnet2.net/index.php/researchprojects/projects-2nd-call-2/ca-ra-va-n), involving research institutions from Spain, Italy, France, Algeria, Morocco, and Tunisia, has been recently financed by EU through the Arimnet2 instrument. Additional partners from eligible (Tunisia) and non-eligible areas (Mauritania and Austria) have been associated to the project due to relevant interest in, and expected contribution to, the topic of the project. General goals and activities planned within the CA.RA.VA.N. project, together with an overview of the already launched initiatives, known constraints and emerging opportunities for the development of the dromedary sector in Northern African countries will be discussed
Saving threatened native breeds by autonomous production, involvement of farmers organization, research and policy makers: The case of the Sicilo-Sarde breed in Tunisia, North Africa
No full textThe Sicilo-Sarde, the only native milking sheep in Tunisia and in North Africa has undergone a considerably population reduction from 200,000 ewes in 1995 to 25,000 ewes in the year 2000. Low sheep milk price and a shift to dairy cattle were among the reasons for this decline. The train objective of this study was to report on the impact of farmers organization, technology transfer and market on reversing the dramatic decline of this native dairy sheep breed to a promising livestock development model. Having at the grassroots a pioneer who chose to form the Sicilo-Sarde breed association in 2003 was a key ingredient in the process of saving this breed from disappearance. Quick steps were first taken: Selling milk through the association allowed doubling its price in one year. A new legislation benefiting dairy sheep was introduced. A trilogy principle was followed where breed owners, researchers and policy makers interacted together to find optimum solutions that fit expressed needs of breed owners. An applied multidisciplinary research program was established and tackled major constraints faced by the breed in nutrition, management, reproduction, health, breeding and product development. Encouraged by an unsatisfied market and good prices, small farmers with a few cows started shifting to dairy sheep and poor new ones managed to get loans to purchase dairy sheep breeding animals. Based on a total of 7937 lactations recorded during the period 1997-2002, average milk yield, days in milk and suckling period were 89 kg +/- 47 kg, 139 d +/- 47 d and 104 d +/- 22 d, respectively. Given the low producing ability of the breed and the impossibility of importing proven rams for health considerations, frozen semen from 17 Sarda rams was imported from Italy and 1600 ewes from 12 flocks were inseminated by intrauterine in 2005-2006. Fertility, prolificacy, and mortality rates varied from 47% to 63%, 157% to 184% and 0 to 34%, respectively. The decline of the breed was stopped and reversed and members of the association and small farmers in the region will benefit from the produced offspring. While currently the association is accessed by more organized producers, it provides an opportunity for the integration of smaller, poorer producers to improve their livelihoods. This case has inspired another group of farmers of a native sheep meat breed to form their own association to promote their breed. (C) 2008 Elsevier B.V. All rights reserved
Monitoring crossbreeding trends in native Tunisian sheep breeds
No full textImportant urban market changes have been noticed in Tunisia for animals that produce thin tail carcasses in contrast to carcasses of animals with a fat tail. In response to this trend, farmers are crossing the local Barbarin (a fat-tailed breed) with thin tailed breeds (Algerian Ouled Djellel and Black Thibar). This happens while the fat tail is known as a criterion of adaptation to harsh conditions and fat-tailed animals are preferred for religious practices. The objectives of this study were to identify hidden reasons for these changes and assess the degree of crossbreeding between the Barbarin sheep and thin tailed breeds. A total of 912 surveys were conducted in three major sheep regions covering the capital (Tunis) and five departments, and including 601 sheep owners, 158 butchers and 153 consumers. The main results showed that even though raising sheep is still as an activity by itself, fattening activities (breeding-fattening or only fattening) are becoming more and more dominant and they represented 75%, 53% and 65% of the sheep activities in the capital Tunis, South East and North West regions, respectively. While breeders and consumers still prefer, in their majority (55-75%), the Barbarin fat tail lambs, butchers tend to favor thin tailed sheep because of the difficulty of selling the fat of the tail that represents up to 15% of the carcass weight. To meet the butchers' demand, farmers are shifting to thin tail breeds and crosses and in the studied areas, market changes towards thin tailed breeds were dictated by butchers' and not consumers' preference. Sensory tests revealed little difference among the three studied genotypes but showed a superiority of the fat tail lambs in tenderness, flavour and smell. (c) 2007 Published by Elsevier B.V
Marker-assisted introgression of fecundity mutation into Barbarine sheep breed under low input production system
No full textFecundity gene introgression has become an economical method to improve sheep prolificacy in developing countries. The FecXBar and FecGH mutations are variants of the BMP15 and GDF9 sheep genes, respectively, identified in Tunisian Barbarine sheep prolific line “W-INRAT,” created through a prolificacy-based selection program. The first mutation caused increased prolificacy in heterozygous state and sterility in homozygous ewes. The aim of this work was to increase the number of effective carriers by the introgression of fecundity mutation into non-carrier conventional flocks based on a marker-assisted breeding program. The genotyping was carried out to follow up on the segregation of prolificacy mutation. The conventional ewes, raised in state farms of Tunisia and inseminated by “W-INRAT” rams, yielded 100% carriers females at heterozygous state. These females were selected to be inseminated with conventional rams and produced carriers’ lambs with 66.7% males and 33.3% females. The prolific males will be kept in breeding centers to disseminate the fecundity mutation in commercial flocks. This approach facilitates the dissemination of fecundity genes and contributes to livelihood improvement in communities raising Barbarine sheep
Marker-assisted introgression of fecundity mutation into Bar-barine sheep breed under low input production system
No full textThe interest for gene fecundity introgression becomes an interesting method to improve sheep litter size in developing countries. In Tunisia, the Barbarine sheep is low prolific breed. A new mutation (FecXBar) in (BMP15) gene causing increased prolificacy in heterozygous and sterility in homozygous ewes has been recently discovered in Barbarine prolific line (W), created through a prolificacy-based selection program. The aims of this study were to screen and disseminate the FecXBar mutation into non-carrier conventional flocks using artificial insemination (AI) technique and based on a three-tier breeding program. The genotyping was carried out to screen the prolific mutation in the parents and their offspring F1. The AI of 334 conventional ewes using four prolific carrier rams yielded 143 lambs of which 53.15% are females. The genotyping of FecXBar in F1 animals showed that the mutation segregated in 35% of the total offspring animals and 65.8% from produced females. At puberty age, these females will be mated with conventional rams to produce improved prolific males. The scale-out of the suggested breeding program presents a starting point to produce carriers’ males in order to disseminate the fecundity mutation into commercial flocks
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