Ultrasonographic evaluation of testicular and Pampiniform plexus characteristics in young bulls under different microclimatic conditions in a tropical environment

Abstract

This study aimed to evaluate the ultrasonographic characteristics of the testicles and pampiniform plexus of young bulls from 8 to 19 months of age under different microclimatic conditions. For this, 46 animals (8.0 ± 0.5 months and 211.0 ± 5.9 kg) were raised in two intensive rotational systems for 12 months, in which 24 animals (Nelore, n = 12; Canchim, n = 12) in a silvopastoral system and 22 animals (Nelore, n = 10; Canchim, n = 12) in a non-shaded pastoral system. Testicular biometric measurements, B-mode ultrasound assessments (echogenicity and heterogeneity of the testicular parenchyma and mediastinum), color Doppler (blood perfusion of the testicular parenchyma and pampiniform plexus), spectral Doppler of the supratesticular artery (pulsatility and resistance index), and blood collection from the jugular to determine testosterone concentration were performed monthly. Data were analyzed using the PROC MIXED procedure of SAS (p < 0.05), and possible interactions between production systems and animal age are presented. There was no difference in testicular volume variables (p = 0.4) between production systems over time. For parenchymal echogenicity (p = 0.3), a progressive increase was observed over time, with a maximum peak at 12 months of age, but without difference between systems. For the relative Doppler area of the testicular parenchyma (p = 0.4) and plexus (p = 0.1), values were decreased at 16 months of age, but without a difference between systems. For the velocimetric indices of the supratesticular artery, there were decreases in the pulsatility index (p = 0.3) and resistance index (p = 0.04), with no difference between the production systems. In conclusion, the variations observed in the present study are more related to age. Thus, there are no differences in the characteristics observed by ultrasound in young bulls kept in different microclimatic conditions under the circumstances studied.

Keywords: Animal andrology; Beef cattle; Color doppler; Microclimate; Production systems; Spectral doppler; Testicular hemodynamics.

Fig. 1

Monthly averages of (A) air temperature (AT; °C), (B) black globe temperature (BGT; °C), (C) relative humidity (RH; %), (D) wind speed (WS; m/s), (E) radiant heat load (RHL; W/m²) and (F) black globe temperature and humidity index (BGHI) over the experimental period in system non-shaded (NS) and silvopastoral system (SPS) between the 8:00 a.m. and 6:00 p.m. Superscript asterisks indicate differences between treatments for the times indicated (p < 0.05).

Fig. 2

Mean ± standard error of body weight, scrotal/testicular biometrics and testicular consistency of young bulls kept in non-shaded (NS) or silvopastoral (SPS) systems. (A) body weight (kg), (B) scrotal circumference (SC, cm), (C) testicular consistency (TS, 1–5), (D) testicular width (TW, cm), (E) testicular height (TH, cm) and (F) testicular volume (TV, cm³). Trat = NS or ILCF; age = from eight to 19 months.

Fig. 3

Mean ± error of the B-mode ultrasound variables of the testicular parenchyma and pampiniform plexus of young bulls kept in non-shaded (NS) or silvopastoral (SPS) systems. (A) parenchyma echogenicity (0–255), (B) parenchyma heterogeneity, (C) mediastinal echogenicity (0–255), (D) mediastinal heterogeneity, (E) vessel width of plexus (mm) and (F) mediastinal width (mm). Trat = NS or ILCF; age = from eight to 19 months. Superscript asterisks indicate differences between treatments for the ages indicated (p < 0.05).

Fig. 4

Mean ± error of the color Doppler mode ultrasound variables of the testicular parenchyma and pampiniform plexus of young bulls kept in non-shaded (NS) Mean ± error of the B-mode ultrasound variables of the testicular parenchyma and pampiniform plexus of young bulls kept in non-shaded (NS) or silvopastoral (SPS) systems. (A) relative area of color Doppler of parenchyma (RDA parenchyma, %), (B) color Doppler area of parenchyma (DA parenchyma, mm²), (C) relative to the high-speed Doppler pixels of parenchyma (HSP parenchyma, %), (D) relative of low-speed Doppler pixels of parenchyma (LSP parenchyma, %), (E) relative area of color Doppler of plexus (RDA plexus, %), (F) color Doppler area of plexus (DA plexus, mm²), (G) relative to the high-speed Doppler pixels of plexus (HSP plexus, %) and (H) relative of low-speed Doppler pixels of plexus (LSP plexus, %). Trat = NS or ILCF; age = from eight to 19 months. Superscript asterisks indicate differences between treatments for the ages indicated (p < 0.05).

Fig. 5

Mean ± error of the velocimetric variables of the supratesticular artery and hormonal concentrations of young bulls kept in non-shaded (SN) or Mean ± error of the B-mode ultrasound variables of the testicular parenchyma and pampiniform plexus of young bulls kept in non-shaded (NS) or silvopastoral (SPS) systems. (A) pulsatility index (PI), (B) resistance index (RI), and (C) serum testosterone (ng/mL). Different lowercase letters differ significantly (p < 0.05). Trat = NS or ILCF; age = from eight to 19 months. Superscript asterisks indicate differences between treatments for the ages indicated (p < 0.05).

Fig. 6

Experimental design of the study to evaluate the effect of production systems on testicular ultrasound characteristics and serum testosterone concentrations of young bulls. The animals were evaluated for 12 months in non-shaded (NS) or silvopastoral (SPS) systems. The present evaluations were performed once a month, measuring biometric variables (scrotal circumference, width, height and testicular volume) and testicular consistency. Blood samples were collected for serum testosterone levels. For ultrasonography, the following variables were evaluated: B-mode (echogenic values of the testicular parenchyma and mediastinum, width of the mediastinal vessels and plexus), color Doppler (blood perfusion and flow velocity of the testicular parenchyma and pampiniform plexus) and spectral Doppler (pulsatility and resistance indices of the supratesticular artery).

Fig. 7

Illustrative images of the ultrasound evaluation of the testicular parenchyma and pampiniform plexus of young bulls in non-shaded (NS) or silvopastoral (SPS) systems. (A) B-mode image of the testicular parenchyma, (B) B-mode image of the pampiniform plexus, (C) color Doppler mode image of the pampiniform plexus, (D) spectral Doppler mode image of the supratesticular artery.