The aim of the present study was to establish the normal sonographic parameters for the Yankasa ram‟s testes and epididymides; and to observe their relationship with the semen parameters and reproductive hormones (testosterone, luteinizing and follicle-stimulating hormone LH and FSH, respectively). Fifteen clinically healthy Yankasa rams were acquired from reputable livestock markets (Makarfi, Makarfi LGA and Tudun Sebu, Soba LGAs Kaduna State, Nigeria. The testicular length (TL), testicular width (TW) and testicular circumference (TC) were measured by using a vernier caliper and flexible tape after clinical assessment for breeding soundness. B-mode Sonostar ultrasound scanner with a 5MHz probe was used to scan the testisticular and epididymal echo texture. Semen samples were collected from each ram using electro-ejaculator and two mls, of blood sample was collected via jugular puncture every hour from each ram over a period of 6 hours (6:00 am to 11:00 am) on the day of sampling for reproductive hormone assay. The mean values of ultrasound measurement of the left and right testicular length were 130.4 ± 2.73 mmand 125.5 ±2.57 mm respectively, the left and right testicular breadth were 42.15 ±2.53 mm and 44.85 ±2.14 mm respectively, the left and right heights were 52.25 ± 2.10
- and 53.02 ± 2.20 mm respectively, while the volumes were 280,340 ± 12,780 mm3 and 296,432 ± 17,549 mm3. The mean value for the left epididymal head volume using ultrasound was 6,480.0 ± 620mm3 while that of the right was 4,490.0 ± 420 mm3 and the mean value for the left epididymal tail volume was 2,830.0 ± 300 mm3, while that of the right was 3,010.0 ± 500 mm3. The mean left testicular length (15,700.0 ± 550 mm) and that of the right (15,900 ± 610mm) using vernier caliper was greater than the value obtained with ultrasound machine (13,040.0 ± 270mm and 12,550.0 ± 270mm respectively). Similarly, the mean left and right
testicular volumes obtained using vernier caliper were 1,482,000 ± 64,370 mm3 and 1,503,000 ± 74,270 mm3 respectively, and were also higher than the ultrasound measurements. The testicular parenchyma of Yankasa rams was an isoechoic structure (midgray echo texture) with uniform echogenicity which was surrounded by an hyper-echoic structure (Tunica albugina and Tunica vaginalis). The mediastinum testis was seen as a point of hyperechoic area in the center oftesticular parenchyma when scanned in the transverse plane, while the echogenicity of the epididymides was similar to that of the echogenicity of the testes, but with some hypoechoic area of echogenicity in the epididymal head. From the normal Doppler evaluation of testicular arteries, the velocity, pressure and resistance to blood flow in the left testes of Yankasa rams were higher than in the right testes. The sperm concentration, reaction time and normal sperm cells correlated positively(r = 0.05) and insignificantly with the testicular volume using vernier caliper or ultrasound, while the sperm motility correlated negatively(r = -0.05) with the left and right vernier caliper measurements of the testicular volumes but positively with the left and right ultrasound measurements of the testicular volumes (r = 0.05). The testosterone and luteinizing hormone correlated negatively and insignificantly, with the right and left testicular length, circumference, volumes and weight (r= -0.05). None of the reproductive hormones studied had effects on the epididymides of Yankasa rams. Evaluation of echotexture and biometry of the Yankasa rams testes and epididymides using ultrasound is essential for maximum and rational utilisation of the breeding stock and can be used to predict future semen parameters.
1.1 Background of the Study
There is constant economic pressure for highly efficient lamb production, produced through natural breeding and artificial insemination (AI). Research has shown that, for over three decades, the ram is responsible for nearly 87.5% of the genetic contribution to a flock (Falconer, 1976). Ultrasonographic examination of the testes, epididymides and accessory sex glands has proved to be a valuable, non- invasive technique for the assessment of genital macroscopic morphology and pathology in several mammalian species of veterinary interest, (Kahn, 2004), including the ram (Gouletsou et al., 2003). Accessory sex glands are all found along the length of the pelvic urethra (Anonymous1, 2013). They produce secretions containing different components which facilitate movement of the sperm as well as providing a physiological buffer against the acidic environment of the female genital tract. One of the most important substances of the secretion is fructose which is an energy source for sperms (Anonymous1, 2013).
Ultrasonographic imaging has been used in measuring size and structure of the testis in bulls and rams (Cartee et al., 1990; Ahmad et al., 1991; Chandolia et al., 1997a). Several studies have been used to determine the changes in structure of the testis using ultrasound imaging in pathological conditions (Ahmad and Noakes 1995a; Karaca et al., 1999) and clinically healthy animals (Ahmad et al., 1991; Evans et al., 1996; Aravindakshan et al., 2000a, 2000b; Gouletsou et al., 2003).