TITLE:
Liquid Storage of Ram Semen: Associated Damages and Improvement
AUTHORS:
Serge Leugoué Kameni, Félix Meutchieye, Ferdinand Ngoula
KEYWORDS:
Antioxidants, Lipid Peroxidation, Liquid Storage, Ovine, Oxidative Stress, Reactive Oxygen Species
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.11 No.3,
July
16,
2021
ABSTRACT: The successful application of assisted reproductive techniques (ARTs) in
ovine as in other mammal species relies on many factors among which the quality
of the semen used. After collection, semen samples are generally processed for
storage (liquid storage or cryoconservation) before being used for insemination
or in vitro embryo
production. During the liquid storage process, sperm cells are exposed to
artificial conditions which lead to oxidative stress—the imbalance between
pro-oxidants and antioxidants (AO), following overproduction of reactive oxygen
species (ROS)—resulting in ultrastructural, biochemical
and functional damages of spermatozoa. Especially, viability, motility,
mitochondrial activity, membrane integrity, and acrosome integrity are reduced while morphological
abnormalities, DNA fragmentation, and lipid peroxidation (LPO) are increased,
affecting the fertilizing ability and subsequent early embryonic development
when using standard extenders. Indeed, an optimal semen extender must not only
regulate and support an environment of adequate pH and buffering capacity to
protect spermatozoa from osmotic and cooling stresses, but, also prevent the
generation and/or scavenge excess ROS. To improve ram semen liquid storage,
several methods have been developed with the supplementation of extenders with
antioxidants or antioxidant like-compounds (enzymes, amino-acids, vitamins,
plant extracts), seminal plasma, sugars, fatty acids, and nanoparticles being a
relevant approach. Promising results have been registered with the
supplementation of extenders with these compounds, confirming they can be used
to preserve ram semen quality and fertility. Therefore, the present review
provides an updated overview of the damages and associated mechanisms that ram
spermatozoa undergo during liquid storage. Moreover, the supplementation of
extenders with different compounds as a tool to improve semen storage is also
discussed as well as their efficiency to reduce and/or prevent sperm damages
during storage.