Abstract. This study aimed at screening genetic diversity and differentiation in four horse breeds raised in Tunisia, the Barb, Arab-Barb, Arabian, and English Thoroughbred breeds. A total of 200 blood samples (50 for each breed) were collected from the jugular veins of animals, and genomic DNA was extracted. The analysis of the genetic structure was carried out using a panel of 16 microsatellite loci. Results showed that all studied microsatellite markers were highly polymorphic in all breeds. Overall, a total of 147 alleles were detected using the 16 microsatellite loci. The average number of alleles per locus was 7.52 (0.49), 7.35 (0.54), 6.3 (0.44), and 6 (0.38) for the Arab-Barb, Barb, Arabian, and English Thoroughbred breeds, respectively. The observed heterozygosities ranged from 0.63 (0.03) in the English Thoroughbred to 0.72 in the Arab-Barb breeds, whereas the expected heterozygosities were between 0.68 (0.02) in the English Thoroughbred and 0.73 in the Barb breeds. All F ST values calculated by pairwise breed combinations were significantly different from zero (p < 0.05) and an important genetic differentiation among breeds was revealed. Genetic distances, the factorial correspondence, and principal coordinate analyses showed that the important amount of genetic variation was within population. These results may facilitate conservation programs for the studied breeds and enhance preserve their genetic diversity.

Stakeholders place great emphasis upon rationalizing the management and rearing techniques which are utilized within sheep farms. The present study aimed to investigate factors which may improve the reproductive performance of melatonin-treated Sardinian sheep via a series of three trials. The first trial (n = 100) investigated the effect of melatonin treatment alongside body condition score (BCS), the second trial (n = 150) investigated the effect of treatment alongside the date of treatment (treatment period) and the third trial (n = 150) investigated the effect of treatment alongside the previous lambing of the ewes. The findings indicated that melatonin is an effective tool for anticipating and improving the reproductive activity of in Sarda breed sheep during the springtime. Furthermore, to obtain optional results, melatonin implantation should be conducted in April, in ewes that have a BCS of >2.5 and that have passed their third month of lactation.

The genetic characterization of Tunisian donkeys with microsatellite markers led to the identification of a total of 214 alleles, with an average of 14.27 alleles per locus. The number of effective alleles per locus (Ne) indicates a rich genetic polymorphism for the used markers. The number of alleles per locus (Na) is higher than Ne,confirming the high genetic diversity in the investigated population. Observed heterozygosis(Ho) for all the studied loci inthe entire population equals 0.744. The FIS index was significantly different from zero, pointing toan excess of heterozygotes. The mean of the number of effective migrants exchanged per generation (Nm) was 3.05 indicating a high level of gene exchange. Genetic distances and the principal coordinate analysis showed three distinct population groups/breeds, with a commongenetic structure for all the individuals. This genetic characterization of the Tunisian donkey population constitutes a valuable basis for further investigations, and to the elaboration of adequate conservation strategies.

Diversity of Arabian stallions distributed throughout the territory of Tunisia has been evaluated. Seventeen microsatellite markers were used for the determination of genetic variation. A total of 95 alleles were detected in the 50 stallions studied. The number of alleles per locus ranged from 2 to 9 with an average of 5.6. The observed mean number of genetically diverse alleles (Na) was 5.6 (0.44). The mean number of expected alleles (Ne) was 3.42 (0.28). The average expected and observed heterozygosity was approximately 0.675 (0.026) and 0.593 (0.044), respectively. Principal component analysis showed the presence of 2 subpopulations in the studied sample set. These findings demonstrate the potential of microsatellites as a tool for designing and controlling animal breeds. Results show that the population under study has sufficient levels of genetic variations, which can be used as a foundation for developing plans for species conservation and long-term sustainability.

The aim of the study is to investigate the effects of age, sex, running distance and origin of horse on racing speed for Thoroughbred Arabian horse in Tunisia. Although the occidental type is known to be more successful in racing than the Tunisian type, we undertook this study to try to confirm or deny this supremacy for a sample of racehorses born in Tunisia from occidental father. A total of 333 racing records were considered for race performance. The effects of environmental factors on (sex, age, father’s origin, race distance, number of race seasons) race performance were analyzed using the least-squares method(LSM).The racehorses studied were all Arabian Thoroughbred horses in operation at the racecourse of Ksar Said from 2010 to 2020. They are 180 horses, 90 horses born of a Tunisian father, and 90 horses born in Tunisia ofthe occidentalfather. These horses are the best and most successful in their category. The study revealed that the gender and age effectswere statistically insignificant onracingperformance. Race performance was significantly influenced by the distance and the origin of the father which affirms the improving role of the occidentalhorse in the Tunisian population.