Semen quality and freezability analysis during breeding and non‐breeding seasons in heavy draft stallions in southern Chile

Abstract

The aim of this study was to evaluate seasonal changes in basic parameters of sperm quality and freezability behaviour of ejaculates from 10 fertile heavy draft stallions. A total of 140 ejaculates were collected, processed and evaluated during both the breeding (September–November) and non‐breeding seasons (April–June). Fresh semen was evaluated for volume, concentration, total spermatozoa per ejaculate, plasma membrane integrity and total sperm motility. Cryopreserved samples were evaluated for plasma membrane integrity and sperm motility by the CASA system, and for the freezability index (FI), which was defined as the decreased ratio of viability after freezing–thawing. In fresh ejaculates, only viability showed significantly higher values in the breeding than in the non‐breeding season (64.0% ± 15.0% vs. 58.6% ± 12.0%, respectively; p < .05). The sperm post‐thawing analysis of viability and total motility parameters showed no significant changes linked to the season. However, the FI analysis showed that the ejaculates collected in the non‐breeding season had higher cryoresistance characteristics than those collected in the breeding season. Results suggest that the presence of some cryoprotective factor/s in heavy draft horse ejaculates could be modulated by seasonality, with higher protective effects in the non‐breeding season.

Kinematic and Morphometric Assessment of Fresh Semen, before, during and after Mating Period in Brahman Bulls

“…Also, it is believed that the adverse conditions within the uterus and oviduct are essential for selecting the most suitable sperm for fertilization [ 60 ]. Reports on stallions did not register differences in sperm TM during breeding and resting seasons [ 61 ], thus agreeing with the results obtained in this study. Several authors describe a positive effect of collection frequency in bull sperm TM [ 4 ], but, in our study, during the mating period, in which there is a higher ejaculation frequency, the opposite effect was observed, with bulls showing the lowest TM, which can be related to a high renewal rate and no adequate maturation of spermatozoa.…”

Temporal trends in equine sperm progressive motility: a systematic review and meta-regression

“…Whilst breed is not a direct measure of inbreeding, it was accounted for within the statistical model. Considering the method of breed categorisation, stallions were grouped using recognised methods (Ebel et al, 2020). However, differences in sperm trends may be on a more specific level, indicating a potential limitation of broad categorisation methods required in this data set.…”

Kallikrein proteoforms and reproductive parameters in stallion are conditioned by climate

“…Morte et al 8 reported differences in spermatic concentration, vitality and morphology, but the progressive motility did not differ among seasons. Recently, Ebel et al 9 evaluated seasonal changes in the quality of sperm from fertile stallions, and only viability showed higher values during the breeding season; Johannisson et al 10 found minor variations in kinematics and morphology of sperm among seasons.…”

“…Groups of proteins have been reported as associated with mammalian 19 and stallion reproductive capacity, such as fibronectin type II modules, cysteine-rich secretory proteins (CRISPs) and spermadhesins 16 , albumins and kallikreins 9 . In horses, different semen proteins have been reported for the breeding and non-breeding seasons 9 , 10 .…”

“…Groups of proteins have been reported as associated with mammalian 19 and stallion reproductive capacity, such as fibronectin type II modules, cysteine-rich secretory proteins (CRISPs) and spermadhesins 16 , albumins and kallikreins 9 . In horses, different semen proteins have been reported for the breeding and non-breeding seasons 9 , 10 . Few two-dimensional electrophoresis (2-DE) proteomics studies have added information about the mapping of seminal plasma proteoforms of mammals, including equines 18 , 20 .…”