Multivariate models for estimating jackass semen production and quality

Abstract

The purpose of this study was to analyse the effects of season, age, gonad and accessory sex glands on semen characteristics of jackass and to construct multivariate regression models to predict semen quality. In autumn, spring and summer, semen characteristics of 30 sexually mature donkeys (1,014 ejaculations) were analysed to investigate the effect of seasons on semen quality, and gonad and accessory sex gland parameters of 12 jackasses were measured immediately after ejaculation by ultrasonography to investigate the effect of seasons on reproductive organ size. Semen (598 ejaculates), gonad and accessory sex gland parameters of 40 jackasses aged between 3 and 7 years were analysed in autumn to investigate the effects of age and reproductive organ size on semen quality and to construct multivariate models. To verify the accuracy of the models, semen (476 ejaculates), gonad and accessory sex gland parameters of 20 jackasses were measured from March to June. Results revealed that semen, gonad and accessory sex gland parameters were not affected by season and age. Progressive motility (PM) was positively correlated with long axis of the spermatic cord (LASC) and negatively correlated with percentages of sperm abnormality (PSA). Total sperm count (TSC) was positively correlated with testis circumferences (TC) and cross‐sectional area of cauda epididymis (CSACE). TC, CSACE, LASC and PSA were included into multivariate models to predict PM, TSC and functional sperm count (FSC) in 20 jackasses (PM = 72.332 + 0.428 LASC − 0.441 PSA; TSC = −169.929 + 8.728 TC + 0.253 CSACE; FSC = −206.645 + 8.788 TC + 0.258 CSACE). The predicted and observed values corresponded well. In conclusion, the tested models can be used for predicting semen quality of donkey.

Age-related linear and nonlinear modelling of semen quality parameters in Miranda donkeys

“…Additionally, azoospermia stages have been described in donkeys due to plugged ampullae causing total ampullae obstruction (Segabinazzi et al 2018) or after immunocastration procedures (Rocha et al 2018), but also may be physiologically mediated by undifferentiated embryonic cell transcription factor 1 (UTF 1) and deleted in azoospermia-like (DAZL) expression in donkey testis (Lee et al 2017;Choi et al 2020) and has been suggested to be an effect derived from ageing (Liu et al 2021) which was supported by our results as shown in Figure 3. Figure 8 also describe a decrease in total spermatozoa motility which is concomitant with the azoospermia stage detected in Figure 3.…”

Evaluation of Testicular Volume and Correlation with Sperm Production in Martina Franca Donkeys: A Parameter to Consider When Approving Breeding Jacks

“…Based on our previous studies, at these latitudes, the TSN should not vary significantly over the seasons even if, in the winter months, the reduction in daylight hours leads to a reduction in testosterone concentrations, resulting in a slight decrease in testicular volume and sperm concentration [18,23]. Liu et al [1] also reported no significant changes in testicular volume and sperm concentration throughout the year.…”

“…Conservation and breeding programs should involve healthy, in line with standards, and highly fertile subjects. A method that has been used in the livestock sector for estimating fertility is the evaluation of testicular size and its correlation with daily sperm production [1]. Recently, such studies have also been carried out on the donkey population, both in breeds bred for commercial purposes, such as the Dezhou donkey [2], and in those at risk of extinction, such as the Ragusano donkey [15] and Miranda's donkey [16].…”

“…Regarding testicular measurements, in the past, the caliper was considered the instrument of choice, also for the donkey species [31]. In recent years, however, studies have focused mainly on measurements carried out with ultrasound [1,2,15,16], as this tool is more accurate in measurement, allowing the evaluation of only the testicular parenchyma [14]. Furthermore, in the equine stallion, studies comparing the measurements obtained with the two different instruments highlighted that 2D ultrasound measurements are more accurate than those performed with the caliper [14] in estimating the volume of isolated testicles after orchiectomy.…”

“…Donkey breeding has been gaining interest all over the world for several decades, as it has zoo-technical value both for the production of milk and meat; in some cultures, donkey derivatives (particularly from the Dezhou donkey) are also used in traditional medicine [1,2]. Furthermore, in areas characterized by high animal biodiversity, protecting endangered native breeds, such as the Martina Franca donkey, is of paramount importance to preserve genetic variability [3,4].…”