New Approaches to Assess Fertility in Domestic Animals: Relationship between Arterial Blood Flow to the Testicles and Seminal Quality

Abstract

The early identification of infertile males improves reproduction efficiency at a production level and is essential to secure high production rates. Before entering a breeding program, males must pass an initial breeding soundness examination (BSE) which consist of several diagnostic exams whose end point is to estimate their future fertility. There is ongoing research to find new markers that allow better identification of fertile males. Doppler mode allows the quantitative and qualitative evaluation of the irrigation of organs. When evaluating the reproductive system, Doppler mode has been successfully used for the evaluation of the uterine and ovarian irrigation. In males, it is gaining relevance for the evaluation of testicular irrigation. Researchers have found a relationship between pulsed-wave Doppler velocimetric parameters and seminal quality in various domestic animal species. This suggests Doppler ultrasound parameters should be considered as objective parameters to evaluate testicular function. In this review, we analyze the results in the main domestic animal species and discuss the differences and similarities among the results. We also discuss the effect of the location of the measurements, breed, season and laterality in the measurement of Doppler velocimetric parameters as well as the impact and limitations of this method of assessing breeding soundness.

Ageing affects plasma steroid concentrations and testicular volume, echotexture and haemodynamics in rams

“…In the current study, the pulsed-wave Doppler indices (RI and PI) were significantly lower in the mature and aged rams compared to the young ones. In various species, RI and PI considered were important parameters to assess reproductive performance (Velasco & Ruiz, 2021).…”

“…In the current study, the pulsed‐wave Doppler indices (RI and PI) were significantly lower in the mature and aged rams compared to the young ones. In various species, RI and PI considered were important parameters to assess reproductive performance (Velasco & Ruiz, 2021). Interestingly, the reduction in their values was obviously associated with superior semen quality and quantity characteristics, as well as testosterone concentrations in camels (Kutzler et al, 2011), dogs (Zelli et al, 2013) and rams (Batissaco et al, 2013).…”

“…In the last few years, testicular functions were strictly depending on the vascular perfusion within the testicular artery (Velasco & Ruiz, 2021). Several studies confirmed that the fluctuations in testicular blood flow were accompanied with severe changes in semen quality parameters, plasma testosterone levels, seminal oxidative status and reproductive performance in farm animals (El‐Shalofy & Hedia, 2021a; Hedia et al, 2020b; Kastelic et al, 2018).…”

Exogenous oxytocin administration improves the testicular blood flow in rams

“…Practitioners used to conduct a general physical examination, scrotal circumference estimation and semen analysis to determine the reproductive soundness in male farm animals (Karaca et al., 2016; Kridli et al., 2007). Recently, the application of pulsed wave Doppler ultrasonography has become a useful noninvasive practice to assess the reproductive performance in male animals through the analysis of the blood flow dynamics within the testicular artery (Hedia & El‐Belely, 2021; Samir et al., 2015; Velasco & Ruiz, 2021). Several measurements of the testicular blood flow can be recorded using the pulsed wave Doppler, including parameters like peak systolic velocity, PSV; end‐diastolic velocity, EDV; time average maximum velocity, TAMV and Doppler indices like pulsatility index, PI; resistive index, RI (Viana et al., 2018).…”

Effect of body condition score on the testicular biometrical measures, semen characteristics and testosterone level in jackass

“…Therefore, body condition score (BCS) is an effective method to monitor the energy intake and assessment of live animal energy reserves (Reneau and Linn, 1989). In addition, testicular biometry is used as an indicator of reproductive status and its characterization has been well documented in farm animals (Velasco & Ruiz, 2021) and horses (Rau et al, 2017). Testis's size and sperm production are highly correlated which imply that the larger the testes, the greater the sperm production for stallions (Blanchard et al., 2001).…”