Cryptorchidism is a genital defect in which ram testicles fail to descend, causing azoospermia, while maintaining normal behavior towards females. We investigated whether cryptorchid rams can induce a ram-effect in ewes that would then be subjected to artificial insemination (AI). Therefore, ewes were isolated from any contact with rams for 6 weeks, then exposed to cryptorchid rams for 14 days. From day 15 to day 24, estrus was checked using a cryptorchid teaser four times daily (at 08:00, 12:00, 16:00, 20:00). Ewes detected in estrus were inseminated 24 h later. Experiment 1 included ewes (n = 31) all exposed to the cryptorchid ram-effect (CRE): 70.9% showed estrus, lambing rate after AI was 45.5%, and prolificacy was 1.40. Experiment 2 compared CRE (n = 80) with a control group with no prior exposure to males (n = 39). Estrus occurrence differed significantly (75.0% vs. 23.1%, respectively, p ≤ 0.001). Lambing rate from AI was 44.1% and prolificacy 1.27. These results show that cryptorchid rams effectively induce and synchronize estrus in Sarda ewes. AI fertility results on natural estrus following CRE yields outcomes comparable to those previously reported after hormonal synchronization for this breed.

Cryptorchidism is the most common non-lethal congenital defect of the male reproductive system in sheep, with potential economic consequences for flock management. This study investigated the incidence, testicular morphology, ultrasonographic characteristics, semen quality, and sexual behavior of bilateral cryptorchid Sarda rams. Slaughterhouse inspections of 2360 lambs showed an incidence of 0.87% cryptorchidism. Cryptorchid testes were significantly rounder and lighter than intact testes, indicating impaired development in affected animals. Ultrasonography of 15 adult bilateral cryptorchid rams showed that retained testes were markedly undersized and that the left testis was less frequently visualized. No significant association with age was detected within the studied age range. All ejaculates recovered from bilateral cryptorchid rams were azoospermic. Nevertheless, behavioral trials suggested that bilateral cryptorchid males retained sexual interest and the ability to identify estrous ewes. These findings confirm the infertility of bilateral cryptorchid Sarda rams while highlighting their preserved sexual behavior, suggesting a potential zootechnical use as teaser rams for heat detection. Repurposing cryptorchid males in this way could represent a potential alternative to surgically modified teaser rams or the use of aprons on intact rams.