REPRODUCTIVE MANAGEMENT AND ASSISTED REPRODUCTIVE TECHNOLOGIES IN SARDA DAIRY SHEEP: ADVANCED DIAGNOSTICS, SEMEN QUALITY INDICATORS AND EMBRYO PRODUCTION

The present PhD thesis focused on the reproductive management of dairy sheep systems, with particular emphasis on the breeding soundness evaluation (BSE) of rams, the identification of predictive indicators of semen quality, and the application of reproductive biotechnologies in Sarda sheep. The work was developed within the context of Mediterranean dairy sheep farming systems, particularly in Sardinia, where reproductive efficiency represents a major challenge due to the strong seasonality of the species and the increasing intensification of production systems. A major component of the research focused on the annual reproductive dynamics of intensively managed Sarda rams housed in a semen collection center. Circannual changes in testicular morphometry, echotexture, spectral Doppler assessment of the testicular and internal pudendal arteries, endocrine and metabolic profiles, and semen characteristics assessed by computer-assisted sperm analysis (CASA) were investigated. The results demonstrated marked seasonal variations in testicular size, reproductive hemodynamics, testosterone concentrations, metabolic activity, and semen quality. In particular, late summer and autumn were characterized by increased scrotal circumference, testicular volume, circulating testosterone concentrations, and improved progressive sperm kinematic parameters, whereas winter and spring were associated with lower values of these reproductive traits, consistent with seasonal reductions in reproductive function. Moreover, the study also highlighted that reproductive function in semen collection centers is not exclusively driven by the photoperiod but rather by the interaction between endogenous seasonal physiology and management-related factors, particularly semen collection frequency and workload. These findings emphasize the importance of seasonally adjusted reproductive management strategies and support the combined application of reproductive ultrasonography and computer-assisted semen analysis (CASA) as complementary approaches for monitoring reproductive function and fertility in intensively managed rams. The thesis further investigated the application of reproductive biotechnologies in lactating Sarda ewes subjected to a superovulation and embryo transfer protocol based on decreasing doses of PLUSET (pFSH+pLH). We evaluated ovarian dynamics through serial transrectal ultrasonography and assessed the influence of ovarian status, follicular populations, and milk production on ovulatory responses and embryo yields. Significant associations were identified between medium follicle counts during hormonal treatment and superovulatory outcomes, as well as between milk yield and embryo recovery rate. These findings contribute to improving the understanding of factors influencing the variability of superovulatory responses in dairy sheep and may support the optimization of embryo transfer programs under commercial farming conditions. Overall, the thesis highlights the central role of the ram in reproductive efficiency and demonstrates the potential application of advanced reproductive diagnostics and ultrasonographic techniques in small ruminant reproduction. The results provide practical and scientific insights for improving reproductive management, semen collection strategies, and assisted reproductive technologies in Mediterranean dairy sheep systems.