1Gabor G, 2Szasz F,
1Dept. Cattle Breeding, Res. Inst. Anim. Breed. Herceghalom,
2 Dept. Gynec. and Obstet. Univ. Vet. Sci. Budapest, Hungary

Comparative study of the bull's testicular echotexture (ET) and tonometry (TM) with the semen production and the non-return rate (NRR)

The objectives were to determine relationships among ultrasonographic ET of the testis, testicular consistency, the semen production and the 56 days non return rate in bulls. Holstein-Friesian (HF, n=78, average age, 16.5 mo) and Austrian Fleckvieh (AF, n=16, average age, 25.9 mo) bulls were used. The ET was measured by a B-mode echograph and a 7.5 MHz linear transducer (the gain and pressure were standardized). Pixel analysis was performed with custom software on the ultrasonic images in an area 1 cm high x 6.5 cm wide (just under the tunica albuginea). The average ET of the ultrasonograms were indicated on a 64 gray scale (0=black, 63=white). The consistency of the testis was measured by an electronic (auto-freeze function at a standard pressure) tonometer. Semen was collected by artificial vagina twice a week 10 wks apart and total sperm number per ejaculate was determined (TSN). Pearson correlation coefficients (SAS) were determined for these data. Older bulls, expected to have greater seminiferous tubule activity and bigger testis, have a lower ET (age vs. ET: r=-0.61; P<0.001). Lower ET suggests a greater seminiferous tubule lumenal space and fluid content within testicular parenchyma. In HF group also negative correlation were found between ET and TSN (r=-0.29; P<0.01), and in the AF group the ET correlated with the NRR (r=-0.51; P<0.05). The TM positively correlated with the age (r=0.71; P<0.001) and the TSN (r=0.27; P<0.05) but negatively with the ET (r=-0.43; P<0.01). No correlation was found between TM and NRR (r=0.06). These results suggest that there are associations among the ET, TM and semen characteristics and ET may be used to predict semen production and/or the non return rate in young bulls. Although TM should be typical at an exact age of the bull, at this stage using of it on practical level is not recommendable.