Field Studies on Immunization of Goat Kids Against Coccidiosis Using X-Radiation-Attenuated Oocysts of Different Eimeria Species

Background/Objectives: Caprine coccidiosis caused by Eimeria spp. is an important parasitic disease affecting goat health and production, with current control strategies relying mainly on anticoccidial drugs. The emergence of drug resistance and the need for sustainable alternatives highlight the importance of developing effective immunoprophylactic approaches. This study aimed to evaluate the immunoprotective effect of X-ray-attenuated Eimeria oocysts against caprine coccidiosis under field conditions and to determine the influence of vaccination on parasite burden, clinical outcomes, and productive performance. Methods: A field study was conducted using attenuated oocysts obtained from naturally infected goats from the same farm. The main Eimeria species identified were E. christenseni, E. arloingi, and E. ninakohlyakimovae. Three sequential trials were performed to optimize vaccination protocols. Goat kids aged 1–6 weeks received different immunization treatments consisting of doses ranging from 5 × 103 to 6 × 104 sporulated oocysts attenuated by X-ray irradiation at 10–30 kRad (100–300 Gy). Animals were monitored weekly through the evaluation of body weight, faecal consistency, health status, faecal oocyst shedding, and Eimeria species composition. Results: Vaccination with radiation-attenuated oocysts reduced parasite replication and faecal oocyst shedding, particularly affecting highly pathogenic species such as E. ninakohlyakimovae, while maintaining overall Eimeria species diversity. Clinical protection was mainly reflected in reduced parasite pressure rather than the complete prevention of mild diarrhoea. Productive parameters were not markedly improved, suggesting that the main benefit of vaccination was improved parasite control and reduced environmental contamination. Conclusions: Early administration of X-ray-attenuated Eimeria oocysts represents a promising strategy for controlling caprine coccidiosis. Vaccine efficacy depends on appropriate timing and optimization of attenuation conditions. Further studies investigating immune mechanisms, species-specific protection, and performance under commercial farming conditions are required to support the development of sustainable vaccines for goat production.