Читать книгу Bovine Reproduction - Группа авторов - Страница 75

Infrared thermograms of the scrotum of bulls with apparently normal scrotal thermoregulation were symmetrical left to right, with temperature at the top 4–6 °C warmer than at the bottom [24, 25]. More random temperature patterns, including a lack of horizontal symmetry and areas of increased scrotal surface temperature, were interpreted as abnormal thermoregulation of the testes or epididymides. Nearly all bulls with an abnormal thermogram had reduced semen quality [24, 25]; conversely, not every bull with poor quality semen had an abnormal thermogram. Consequently, infrared thermography is a useful tool for breeding soundness evaluation of bulls, although it does not replace collection and evaluation of semen. In one study, 30 yearling beef bulls, all deemed breeding sound on a standard breeding soundness examination, were individually exposed to approximately 18 heifers for 45 days [26]. Pregnancy rates 80 days after the end of the breeding season were similar (83 vs 85%) for bulls with a normal or questionable scrotal surface temperature pattern, respectively, but were higher (P < 0.01) than pregnancy rates for bulls with an abnormal scrotal surface temperature pattern (68%).