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J Veterinar Sci Technolo
Journal of Veterinary Science & Technology - Open Access
www.omicsonline.org
Review Article
OPEN ACCESS Freely available online
doi:10.4172/2157-7579.1000101
Volume 1• Issue 1•1000101
Recent Advances in Reproductive Biotechnologies in Sheep
and Goat
Basil Alexander
1,2
*, Gabriela Mastromonaco
1,3
and W. Allan King
1
1
Department of Biomedical Sciences, Ontario Veterinary College (OVC), University of Guelph, Ontario, Canada
2
Department of Farm Animal Production and Health, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Sri Lanka
3
Reproductive Physiology, Toronto Zoo, 361A Old Finch Avenue, Scarborough, ON, M1B 5K7
Keywords: Reproductive biotechnologies; In vitro/in vivo
fertilization; Artificial insemination; Somatic cell nuclear transfer;
Transgenesis
Contents
This review focuses on the platform of recent advances in
reproductive biotechnologies in sheep and goat. Here, we discuss
some aspects of veterinary and biomedical importance in artificial
insemination using sexed semen, in vitro/in vivo fertilization,
interspecies in vitro fertilization, multiple ovulation and embryo
transfer (MOET), somatic cell nuclear transfer and transgenic animal
production in sheep and goat. Some of these technologies are already
widely used in the cattle industry, and some are new to the goat and
sheep industry.
Introduction
The world sheep and goat populations in 2006 were recorded as
416 and 489 million, respectively [1]. Reproductive biotechnologies
are playing an increasingly important role in the production and
management of these species. Animal biotechnology encompasses
the application of science and engineering principles to the processing
or production of materials to provide services or goods for human
use [2]. Examples of current animal biotechnologies include artificial
insemination using fresh, frozen or sexed semen, embryo transfer
using fresh or frozen in vivo or in vitro produced embryos, cloning
using somatic cell nuclear transfer procedures and production of
transgenic animals. Recent advances in reproductive biotechnologies
have shown important developments in the technologies and their
delivery that promise to yield significant benefits for their application
within the livestock industry as well as in biomedical sciences. This
review focuses on the recent advances of biotechnologies in sheep
and goats.
Artificial Insemination (AI)
Artificial insemination is the procedure involving the mechanical
deposition of pre-collected semen into the uterus of an estrous
female by a technician. The widespread commercial application
of AI, a robust tool in livestock breeding, began in earnest in the
1950’s after researchers developed methods to successfully freeze
cattle semen [3]. This technology, which is the most extensively
applied reproductive biotechnology in the world, has many valuable
advantages such as reducing venereal diseases, rapidly increasing
genetic merits of the production animals through selective breeding
and eliminating lethal alleles. The potential to pass high genetic
merits of a selected male to thousands of females, makes this a far
more efficient technology for producing large numbers (1.5 x 10
8
) of
offspring per year compared to female based technologies, such as
embryo transfer (ET), which can only produce a few progeny from a
selected female. More recently, the advent of separation of sperm
into X- and Y-chromosome fractions using flow cytometry has added
a new dimension to livestock production [4].
*Corresponding author: Dr. Basil Alexander, Department of Farm Animal
Production and Health, Faculty of Veterinary Medicine and Animal Science,
University of Peradeniya, Peradeniya, Sri Lanka Fax: 0094 81 238 9136; Email:
baalexan@uoguelph.ca or pabda@pdn.ac.lk
Accepted September 23, 2010; Published September 29, 2010
Citation: Alexander B, Mastromonaco G, King WA (2010) Recent Advances in
Reproductive Biotechnologies in Sheep and Goat. J Veterinar Sci Technol 1:101.
doi:10.4172/2157-7579.1000101
Copyright: © 2010 Alexander B, et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
Since the first report of live rabbit pups of predetermined sex
using X and Y-enriched sorted semen over 20 years ago [5], there
have been more than 40,000 births of live animals resulting from the
so- called Beltsville sperm sexing technology [4]. This sperm sexing
technology has proven to be a reliable and more efficient method of
obtaining predetermined sex in animals compared to other relatively
wasteful methods of embryo sexing and pre-implantation genetic
diagnosis [6 - 8]. Live offspring born from fresh sex- sorted semen
have been reported in many species including cattle [9], pigs [10,11],
horses [12,13] and sheep [14,15]. As the sorting procedure can
separate sperm only at a speed of approximately 10 million per hour,
inseminations have to be carried out using limited numbers of sperm
in each insemination dose compared to the conventional standards
for AI. To obtain high success rates with sorted semen AI, most trials
have been carried out using fresh sorted semen, nevertheless, use
of frozen sorted semen is ultimately more beneficial to the livestock
industry as it can be stored for long duration and easy to transport
anywhere in the world.
Semen sexing technology
Semen sexing is the process of separating spermatozoa into
two subpopulations containing X-chromosome and Y-chromosome
bearing spermatozoa. In theory, use of the X-bearing spermatozoa
fraction for insemination will result in female progeny, while the
Y-bearing spermatozoa fraction will give male progeny. Considerable
efforts have been made in this area over the past 30-40 years, but
only recently has there been considerable progress, particularly in
cattle [16]. The most commonly applied technique for the separation
of a fresh semen sample into X and Y-chromosome bearing fractions
is fluorescence activated cell sorting (FACS). The concept behind this
technique is described below:
Fluorescence activated cell sorting (FACS)
This technique involves the separation of X- and Y- bearing
spermatozoa in small quantities based on the DNA content of the
spermatozoa so that they can then be used in in vitro fertilization
and AI programs [17]. The procedure is relatively slow and requires
expensive infrastructure at least for mass scale commercial
application. The technique is based on the biological principle that the
ISSN:2157-7579 JVST, an open access journal