Ultrasonographic examination reduces the percentage of unsuccessful inseminations in dairy cows

The objective of this study was to investigate whether confirmation of suitability for service by traditional methods, observation and transrectal palpation, is improved in cattle by additional ultrasonographic examination of the uterus and ovaries. The data from 600 lactating cows from Southern Germany submitted for the first service and alternately assigned to manual (group M, n = 301) and manual and sonographic examination (group S, n = 299) were evaluated. Cows of group M with a large, soft follicle with an estimated diameter of 12.0 to 22.5 mm, without a palpable CL (>10 mm), and with a contractile uterus without palpable content were considered suitable for service and inseminated. Cows of group S with a soft follicle measuring 12.0 to 22.5 mm, without a CL (>10 mm), and with a contractile uterus and no echoic content were inseminated. Pregnancy was determined by ultrasonography at 28 to 35 days after the first service. In group S, 10.9% fewer cows (P = 0.003) were considered suitable for service than in group M. The main reason (29.6%) for exclusion from service in group S was the presence of a CL greater than 10 mm in addition to a preovulatory follicle (12.0-22.5 mm), which was diagnosed less frequently in group M (4.5%; P < 0.0001). The first-service conception rate tended to be higher in group S than in group M (62.7% vs. 54.9%; P = 0.10), and the percentage of open cows, based on all cows submitted for service, was higher in group M than in group S (35.2% vs. 25.1%; P = 0.007). We concluded that sonographic examination of cows submitted for service facilitates the exclusion from service of proestrous and diestrous cows and reduces the number of pointless services.