Comparative analysis of the effects of long and short-term intravaginal progestagen applications on milk components and oxidative stress index in goats for estrus synchronization with the natural mating process

In this study, the effects of long- and short-term intravaginal progestagen protocols on milk components and oxidative stress index (OSI) were investigated in Saanen goats during the breeding season. and the results were compared with natural mating. A total of 60 healthy goats, aged between 2 and 4 years, in mid-lactation and with at least one previous parturition, were used. The animals were randomly assigned to three groups. Group 1 (n=20) received an intravaginal sponge for 12 days, Group 2 (n=20) for 7 days, while Group 3 (n=20) was subjected to natural mating without any hormonal intervention. Throughout the study, milk samples were evaluated for fat, protein, lactose, density, solid-not-fat (SNF), salt, pH, and freezing point. Blood samples were analyzed for total antioxidant capacity (TAS), total oxidant capacity (TOS), and oxidative stress index (OSI). Pregnancy diagnoses were performed on day 30 using ultrasonography. According to the findings, milk components in Group 1 exhibited a more stable pattern over time. In Group 2, some parameters initially showed a rapid increase, but a fluctuating pattern was observed in the following weeks. In Group 3, a tendency toward a decrease was detected in several milk components. A statistically significant increase in OSI was observed only in Group 2, whereas the increase observed in Group 1 was not statistically significant. Pregnancy rates were determined as 80% in Group 1, 85% in Group 2, and 75% in Group 3 (p>0.05). No clinical mastitis cases were observed in any of the groups during the study period. However, transient signs of vaginitis were noted in some animals in sponge-treated groups, which resolved spontaneously without the need for treatment. In conclusion, long-term progestagen application appeared to provide more stable results in milk components and a more controlled course of oxidative stress levels compared to the short-term protocol. This approach may offer advantages in preserving milk quality parameters. Nevertheless, to increase the generalizability of these findings, further studies involving a larger number of animals and different seasonal conditions are recommended.