152 Correlation between testicular and accessory sex glands biometric characteristics in Nellore and Caracu bulls

Abstract

The objective of this study was to determine the correlation between testicular and accessory sex gland measurements in Nellore (Bos taurus indicus) and Caracu (Bos taurus taurus) bulls. Bulls (n = 282, including 203 Nellore from 12 to 61 months and 79 Caracu from 12 to 48 months) had their reproductive organs measured. Scrotal circumference was measured with a tape. Length (dorso-ventral) and diameter (mid-lateral) of testes were measured using a graduated ruler. Testicular volume (V) was calculated by the cylinder formula: V = 2[(R2) × π × L], where R = radius (diameter/2), L = testicular length and π = 3.14 (Fields et al. 1979 J. Anim. Sci. 48, 1299-1304). B-mode ultrasonographic examinations with a 7.5-MHz transrectal linear-array transducer were performed to obtain the mean of 3 vertical dimensions of the vesicular glands, disseminated prostate, ampulla of vas deferens, and lumen of ampulla, and cranio-caudal and dorso-ventral dimensions of the prostate body and bulbourethral glands. For paired organs, the mean was calculated and used in analyses. Biometry data of testes and accessory sex glands were analysed by the PROC CORR (Pearson correlation) of the SAS program (SAS Institute Inc., Cary, NC, USA; P < 0.05). Testicular measurements (scrotal circumference, diameter and length) were positively correlated with each other (r = 0.69 to 0.92). Similarly, biometrics of the accessory sex glands had positive correlations with testes. The vesicular glands had correlations of r = 0.62, 0.43, 0.58 and 0.59 with testes length, diameter, and volume and scrotal circumference, respectively. Correlations testicular biometry characteristics and ampulla of vas deferens ranged from 0.52 to 0.68, whereas those between testicular characteristics and lumen of ampulla were much lower (r = 0.28 to 0.37), perhaps due to bulls riding penmates and ejaculating before the ultrasonographic examination. The dorso-ventral measure of the prostate body had positive correlations with size of testes (r = 0.13 to 0.28), whereas cranio-caudal measurement of this gland was not correlated with size of testes. Finally, there were positive correlations between testes and disseminated prostate (0.28 to 0.36), and testes and bulbourethral glands, both in the dorso-ventral and cranio-caudal dimensions (0.17 to 0.42). In conclusion, testicular biometry in bulls was correlated with measurements of accessory sex glands, perhaps due to testosterone synthesis, which is essential for accessory sex gland development.