Porcine circovirus 4 (PCV4) was first discovered in 2019 in a herd of pigs with porcine respiratory disease, dermatitis and nephropathy syndrome in Hunan Province, China. It has subsequently been detected in other provinces and in South Korea. In consideration of the potential of the virus to cause an epidemic, rapid, sensitive, and specific detection of PCV4 is needed, as is the facilitation of further epidemiological research through elucidation of the whole genome of PCV4. This study had those two aims. Fifty-five blood samples, two pig tissue samples, nine saliva swabs and one semen sample which all originated from Sichuan province pig farms were analysed. The virus’ genome of 1,770 bp was synthesised artificially based on a Chinese reference strain and primers and probes for the ORF2 gene were designed. Then, the amplified target fragment was cloned into the pMD19-T vector and a series of diluted recombinant plasmids were used to generate a standard curve. An optimised real-time TaqMan PCR method was established. The results of this study showed that the established method is specific for PCV4 but not for other viruses, and has amplification efficiency of 99.6%, a regression squared value (R²) of 1.000 and a detection limit of 2.2×10 DNA copies. This method was shown to be analytically specific and sensitive with a low intra- and inter-assay coefficient of variation (<1.67 %). Of a total of 67 clinical samples tested using the established method, three were shown to be positive (4%). This study confirms the existence of PCV4 in Sichuan and provides a promising alternative tool for rapid detection of PCV4.

This study aimed to determine testicular blood flow with semen imaging and describe accompanying variations in mediastinal thickness (MT), serum testosterone, and semen characteristics in Baladi bucks approaching puberty and sexual maturity. From 5–10 months of age, Baladi bucks (n = 5) underwent B-mode imaging, Doppler scanning, and blood sampling for testosterone assaying once a month. From 7 months, semen was collected and evaluated. The first semen was collected at a mean age of 7.2 months, while the first spermatozoa appeared at 8.3 months, and the mean age of sexual maturity was 9.4 months. The highest semen volume (1.02 ± 0.09 mL), motility (mass score = 5 and individual = 78.00 ± 1.58%), morphology (94.74 ± 1.99%), alive% (85.21 ± 1.32), and semen concentrations (5.24 ± 0.32 109/mL) were noted in buck 4 (9.5 months; 25.0 kg) followed by others. Testicular width (TW) and MT were positively correlated (r = 0.71; P = 0.03) and increased from 8–10 months (P < 0.05). The spectral graph of young bucks revealed an absent end velocity point. Testicular flow expressed by colored area/pixels was positively correlated with age (r = 0.855), accompanied by increased testosterone levels. Semen characteristics and Doppler parameters were not significantly correlated, except Doppler indices negatively correlated with progressive motility percentage. In conclusion, only the testicular Doppler indices are useful for evaluating testicular function and selecting bucks for breeding since these were the only variables negatively correlated with progressive motility percentage. The spectral Doppler velocities are not useful in estimating the full picture of semen quality in sexually mature bucks. These values should be assessed cautiously since many alterations could lead to the elevation or decline of testicular Doppler parameters.

This study aimed to compare the testicular morphometry, mediastinum thickness, hormonal levels, hemodynamic, echogenicity, and heterogeneity in Baladi bucks at prepubertal and postpubertal stages. Five bucks (Capra hircus) were evaluated in two different stages of growth: prepubertal (age 4.5± 0.6 months; 15.0 ± 3.0 kg) and post-pubertal stages (age 13.0 ± 1.3 months; 33.0 ± 2.5 kg). Scrotal circumference, testicular dimensions, mediastinum thickness, echogenicity, heterogeneity, Doppler parameters, semen collection, testosterone, estradiol, follicle-stimulating hormone (FSH), luteinizing hormones (LH), and nitric oxide metabolites (NOMs) were measured. There was an (P<0.05) elevation of the testicular length, width, and scrotal circumference. Mediastinum thickness and colored areas toward and away from probe were increased (P<0.05) in post-pubertal age (2.18±0.01, 6556±32.58, and 7845±65.44) compared to pre-pubertal one (1.27±0.96, 4290±42.12, and 5144±54.24). The spectral graph was characterized by low resistance (RI), moderate pulsatility (PI) with high peak velocity, and low endpoints in the post-pubertal stage while the endpoint was equal to zero in young bucks. The post-pubertal age was associated with a marked decline (P<0.05) in echogenicity, heterogeneity, and RI, while estradiol, testosterone, and NOMs levels were increased (P<0.05). It could be concluded that the post-pubertal stage in Baladi bucks is associated with changes in testicular width, length, mediastinum thickness, RI, scrotal circumference, echogenicity, pixel heterogeneity, testicular colored area away and toward the probe, end-diastolic point, testosterone, nitric oxide, and estradiol levels, as all those variables are considered an accurate markers for the onset of sexual maturity in Baladi bucks.