Advances in Reproductive Technologies; Impact for Genetic Improvement.
Advances in Reproductive Technologies;
Impact for Genetic Improvement
A. Anang
Faculty of Animal Husbandry
Padjadjaran University
ABSTRAK
Kemajuan teknologi di bidang reproduksi mempunyai peranan yang sangat penting
terhadap pemuliaan ternak, karena dapat mempercepat kemajuan genetik dengan
memperpendek interval generasi dan lebih akurat dalam melakukan seleksi. Tujuan dari
makalah ini adalah untuk membahas dampak-dampak kemajuan teknologi di bidang
reproduksi terhadap kemajuan genetik dan pola pemuliaan. Pola pemuliaan yang
mungkin bisa digunakan adalah pola MOET, pola pejantan unggul, dan pola masa
depan. Aplikasi teknologi ini juga akan membawa dampak terhadap animal walfare
dan etika. Peranan pemerintah oleh karena itu sangat penting untuk meyakinkan bahwa
produk-produk bioteknologi ini dapat diterima oleh masyaraka
t dan tidak
membahayakan.
Kata kunci : Teknologi Reproduksi, Kemajuan Genetik, Pola pemuliaan
ABSTRACT
Advances in reproductive technologies have become increasingly important in livestock
breeding, as they are able to accelerate genetic changes due to shorter generation
interval and improving accuracy in selection program. This paper addressed to
highlight the possibly impacts of reproductive technologies on genetic changes and
breeding schemes. Application of reproductive technologies in animal breeding
programs accelerates genetic changes, because of reducing generation interval and more
accurate in selection. However, the rate of inbreeding tends to increase due to reducing
number of animals in the breeding selection. The breeding schemes, which may be used
in the future are: MOET scheme and superior sire scheme and future scheme. The
application of reproductive technologies leads to animal welfare dilemmas and ethical
consideration. Involvement of Government, therefore, is very important to ensure that
the their products are publicly acceptable and do not cause harm impairment.
Key words: Reproductive Technology, Genetic Changes, Breeding Schemes
INTRODUCTION
Advances in reproductive technologies are becoming increasing important for livestock
breeding. The aim of these technologies is to improve the quality of the products as well
as animal genetic. Artificial insemination (AI), for example, can be expected to
contribute in improving the efficiency of livestock production and it has genetically a
major impact on livestock breeding.
Reproductive technologies will also have a significant effect on livestock breeding in
the future. An increase in the rate of reproduction will lead to a decrease in generation
interval. In cattle, for example, a single cow by natural reproduction yields 6-10 calves
for its life, by using multiple ovulation and embryo transfer (MOET) it can yield up to
100 calves (Kruip and Spaan, 1992). In addition, the increase of offspring per cow leads
to enhancing genetic gain per year and leads to increased accuracy of selection, due to
shorter generation interval and more records. Further development in this area will
definitely has a major impact on future animal breeding strategies.
A long with development of these technologies, the analysis of individual ethnic and
animal welfare are being debated. It will be interesting to highlight the recent advances
in reproductive technologies in livestock improvement, also human’s judgments. The
purposes of this paper are to discuss the likely impacts of reproductive technologies in
improving livestock production, genetic changes, breeding schemes, animal welfare,
and ethical consideration.
REPRODUCTIVE TECHNOLOGY
Advances in reproductive technologies during 20 years have been phenomenal and it
will continue to expand to the next decade. Started with artificial insemination (AI) in
1930s these technologies led to embryo transfer (MOET) in 1980s. More advanced
technologies have been developed recently. These include invitro maturation (IVM),
and invitro fertilization (IVF) of oocyte, semen sexing, and asexual multiplication of
embryos by splitting and nuclear transfer (Brand, 1992).
Moet
Making greater use of the egg cells, in the ovaries of the genetically superior livestock
is still the main purpose of research in livestock reproduction. One successful method is
MOET (Kruip and Spaan, 1992). MOET allows females to produce more offspring in a
single season, possibly more than it will be produced in life time (Anonymous, 1993).
The first stage of MOET is superovulation by reproductive hormones, such as Follicle
Stimulating Hormone (FSH) to stimulate development of follicles and oestrus. In cattle,
the donor can be expected to come into oestrus 2 days later and then, it can be
inseminated. The second stage is recovery of embryos. The embryos can be recovered
by non-surgical using catheter, introduced via cervix. The next stage is transfer of
embryos to recipient animals. The recipients are selected either by detection of natural
oestrus or by synchronization (Kruip and Spaan, 1992).
The advantages of MOET are those: (1) multiple offspring from genetically superior
parent can be produced, (2) selection of bull in AI program is more accurate, (3) it can
produce disease-free livestock for export/import, and (4) embryos are much cheaper to
transport than live animals (Kruip and Spaan, 1992). However, the success of MOET
depends on (1) controlling of oestrus and ovulation, (2) inducing the animal to
superovulation, and (3) recovering the embryos by passing sterile medium through the
uterine tracts (Woolliams and Wilmut, 1989).
Ivm/Ivf
IVM/IVF are based on technique of gaining access to the very large numbers of
immature eggs (oocyte), present within the ovaries female animals. Typically, 20-30
oocyte can be collected from a pair of ovaries (Anonymous, 1992). The oocytes can
also be collected from animal after slaughter (Anonymous, 1993). The method
developed is transvaginal ultrasound gained puncture of follicles, which uses ultrasound
to guide a hollow needle via vagina into the follicle to extend to the oocyte. Immature
oocyte can be matured in laboratory within 24 hours culture period and subsequently
fertilized (Kruip and Spaan, 1992). This method has become possible to improve
animal production and animal breeding. The future progress will rely on development
of synthetic media or growth factor for cultivation oocyte (Robinson and Mc Evoy,
1993).
Semen Sexing
One of the major goals in animal production and breeding is separation of X and Y
chromosome-bearing spermatozoa (Robinson and Mc Evoy, 1993). The basis of the
separation is by DNA probes, which can match to specific genes on Y chromosomes
(Anonymous, 1993). In rabbit semen, X and Y chromosomes can be purified over 80%.
In insemination of them with X-rich or Y-rich samples to females produced male sex
ratio of 94:6 and 19:81 respectively. This revolutionary system could be 0,1 to 0,5 more
efficient than the best conventional system because energy cost of dam maintenance is
dramatically reduced (Robinson and Mc Evoy, 1993). In addition, the application will
lead to intensifying future selection, animal breeding programmes and animal
production strategies (Robinson and Mc Evoy, 1993).
Asexual Multiplication of Embryos by Splitting and Nuclear Transfer
All the reproductive techniques above are different genetically, even embryos carry the
best inherited qualities. Splitting generates more identical embryos from single desired
one. The embryo is cleaved into two, four or eight embryos, which are genetically
identical (Kruip and Spaan, 1992). Splitting will be of benefit in commercial
production because it allows: (1) production of animal of desired sex, (2) increase
uniformity, and (3) rapid repopulation and dissemination (Seidel, 1980). However, the
recent problems are still in development of embryos, especially if it is split more than
four embryos, and reducing the ability of embryos to survive freezing and thawing
(Woolliams and Wilmut,1989).
Nuclear transfer technology is able to overcome the weakness of embryo splitting.
General scheme of nuclear transfer is that oocytes are collected from an animal and
embryo from another. The embryo is cleaved and the cells of embryo are placed into
unucleated oocytes. The fusion of the embryo cells and the oocytes is by means of
electrical pulse. The fused products are transferred into animal. Moreover, the transfer
of nuclei to unucleated oocytes reconstitutes embryo to develop. The problem of this
technique is that the embryos have lower viability than normally-collected and
transferred intact embryos (Wooliams and Wilmut, 1989). In spite of the difficulties, the
commercial-nuclear transferred embryos will be a reality in the near future, and it will
be an enormous commercial value in beef and dairy cattle industry (Kruip and Spaan,
1992).
GENETIC CHANGES
As mentioned, the reproductive technologies can increase the rate of genetic response,
this is based on reducing generation interval and more accurate in selection. Shorter
generation interval is due to an increase in offspring per animal and using an animal in
shorter time than natural reproduction. Whereas, the increase in accuracy of selection is
because in the structure of the breeding scheme has a small number of population.
Comparison among contemporaries are balanced, and environment and management
can be better controlled.
In embryo splitting, selection accuracy increase because the records on genetically
identical individuals are available. However, selection intensity among males and
females has not been increased, because this leads to the use of genetically identical
males and females (Nicholas and Smith, 1983).
One of the problems in operation of MOET scheme is the rate of inbreeding because of
reducing the number of males in breeding selection (Woolliams and Wilmut, 1989).
With increased inbreeding, production may decline and make it difficult to evaluate the
progress in the future.
REPRODUCTIVE TECHNOLOGIES IN THE FUTURE BREEDING SCHEME
Conventional Scheme
In a conventional breeding scheme, the genetic improvement is separated into: sires of
sons, sires of replacements, dams of sons and dams of replacements. Annual genetic
improvement depends on the accuracy of selection intensity and generation interval.
However, the main problem is the low reproductive rate, which may lead to low
selection intensity.
In most developing countries, the use of this method with progeny testing will continue
for many years. The advantage of this scheme is its accurate and strong selection of
males to be replacement stock. However, the disadvantage are the low selection
intensity and long generation interval. The existence of reproductive technology, for
example MOET, can help to improve low reproduction, especially in reducing
generation interval and accuracy of selection.
MOET Scheme
An alternative to conventional schemes is a MOET scheme. The purpose of this scheme
is to increase the rate of genetic progress by minimizing the generation interval for both
male and female. In cattle, for example, all genetic improvement should take place in a
nucleus herd and afterward, be spread throughout to the whole population by using sires
bred in the nucleus.
Outstanding population should be selected to get very high genetic merit. When the
females reach puberty, they should be flushed and subsequently mated. In cattle,
approximately 21 months after flushing, the new generation of MOET males and
females are 12 months old. The pubertal offspring should be selected for the next
generation or replacement in the nucleus.
The main advantage of this selection is that the nucleus gets a high genetic
improvement due to the increase of response to selection. The small population makes it
possible to record and select for traits that are difficult to measure in field conditions,
for example feed efficiency. Furthermore, in the nucleus also increases the possibility to
develop and use expensive reproductive technologies (Christensen, 1991).
The Superior Sire Scheme
This scheme is created to maximize efficiency from conventional and MOET schemes.
In dairy cattle, for example, the yearling daughters of sires are superovulated and
flushed, and subsequently mated. The embryos are transferred immediately. Two years
later a new generation of males and females are sexually mature and ready for MOET.
The yearling males from the scheme are used for AI to serve all recorded cows in the
population. Subsequently, the genetic merit of the sires is accurately estimated based on
the performance of large daughter in the field. Moreover, the best male is used to serve
the donor in the breeding unit. Yet the scheme may be difficult because the farmers
prefer to use proven males than young males (Christensen, 1991).
Future Scheme
To get high genetic progress future schemes should consider:
(1) The nucleus establishes an advanced genetic research on superior females.
(2) Selected embryos are transferred to recipients that may be ordinary herd.
(3) The young males are performance tested for growth, muscularity, feed efficiency,
functional fitness, etc.
(4) The young females should also be performance tested in the rearing period, and the
test should be extended to include production records.
(5) The population has 3 sub-populations:
a. includes in which MOET and other new technologies are applied to breed young
animals with high genetic merit.
b. includes other recorded and makes up the basis for progeny stations.
c. Includes non-recorded population.
(6) The highly selected progeny tested males are used to serve the females in the
nucleus.
(7) Both the nucleus and population should be kept open for use of semen and embryos
from foreign populations (Christensen, 1991).
ANIMAL WELFARE
Animal possesses few welfare dilemmas, defined as a state of complete mental and
physical health where the animal at harmony with its environment. Reproductive
technology may be beneficial for the farmer or breeder, but it hurt the animal.
Therefore, the causes of unnecessary pain or distress to farmed livestock may be an
offence. In embryo transfer, for example, the major problem arises when embryos,
obtained from large breeds are placed in recipients that cannot give birth to them, and
they finally require surgery to deliver the fetus (Murray and Ward, 1993).
Recently in Europe, the whole procedures of a veterinary surgeon must be done by
veterinarian or authorized-trained persons who work led by veterinarian. Bovine
Embryo Collection and Transfer Regulation 1993 implement a European directive
89/556/EEC also controls the collection of invivo fertilized embryos destined for trade
within the community and transfer embryos for domestic market (Anonymous, 1993).
ETHICAL CONSIDERATION
Animal biotechnology will raise ethical issues. Some are common to scientific research
in general or to the human exploitation of animals. Analysis of individual ethical
consideration is based on ethical principles and, ultimately, on ethical theories. The
ethical theories, which inform our consideration on individual issues. Whereas ethical
principles comprise elements of freedom; fairness; harmlessness and kindness. Thus, in
application of biotechnology is necessary to ensure that freedom is not diminished,
justice not impaired, that no harm is caused, and that real benefit is achieved (Melphan,
1993)
Finally, public acceptability is the final purpose of the viability of technology
innovations, particularly those effect so vital and universal a need as food. In other
word, public attitudes are an important aspect of the ethics of animal biotechnology
(Melphan, 1993).
CONCLUSION
Advances in reproductive technologies cause genetic changes. The rate of genetic
response increases because of reducing generation interval and more accurate in
selection. However, the rate of inbreeding tends to increase due to reducing number of
animals in the breeding selection.
The genetic changes in the population tend to create future breeding schemes. The
breeding schemes that may be used in the future are: conventional scheme, MOET
scheme and superior sire scheme and future scheme.
The application of reproductive technologies leads to animal welfare dilemmas and
ethical consideration. Involvement of Government, therefore, is very important to solve
these dilemmas. In addition, to have public acceptability, it must be ensured that these
technologies do not cause harm impairment.
REFERENCES
Anonymous, 1992. Biotechnology. New Answer to Old Question. Reproductive
Technology. Meat and Livestock Commition, Milton Keynes. MLC Beef Year Book:
118-127.
Anonymous, 1993. New Rules on Embryo Transfer. Animal Welfare. The Veterinary
record. December edition: 582-583.
Brand, A. 1992. Animals In Biotechnology – State and Art. in Biotechnological
Innovation in Animal Productivity. Butterworth-Heinemann: 1-10.
Christensen, L.G. 1991. The use of Embryo Transfer in Future Cattle Breeding Scheme.
Theriogenology. January, Vol. 35: 141-149.
Kruip, A.M. and W.J.M. Spaan, 1992. In vitro Embryo Production and Manipulation. in
Biotechnological Innovation in Animal Productivity. Butterworth-Heinemann: 56-66.
Melphan, T.B. 1993. Approaches to the Ethical Evaluation of Animal Biotechnology.
Anim. Prod 57: 353-359.
Murray, R.D. and W.R. Ward. 1993. Welfare Implication of Modern Artificial Breeding
Technique for Dairy Cattle and Sheep. The Veterinary Record, September Edition: 283286.
Nicholas, F.W. and C. Smith. 1983. Increased rate of Genetic Change in Dairy Cattle
Because of Embryo Transfer and Splitting. Anim. Prod 36: 341-353.
Robinson, J.J. and Mc. Evoy. 1993. Biotechnology Possibilities. Anim. Prod 57: 335352.
Seidel, G.E., Jr. 1980. Potential Application of Cloning in Animal Industry. Cong.
Anim. Repr. And Artificial Insemination. Madrid: 363-370.
Woolliams, J.A. and I. Wilmut. 1989. Embryo manipulation in Cattle Breeding and
Production. Anim Prod. 48: 3-30.
Impact for Genetic Improvement
A. Anang
Faculty of Animal Husbandry
Padjadjaran University
ABSTRAK
Kemajuan teknologi di bidang reproduksi mempunyai peranan yang sangat penting
terhadap pemuliaan ternak, karena dapat mempercepat kemajuan genetik dengan
memperpendek interval generasi dan lebih akurat dalam melakukan seleksi. Tujuan dari
makalah ini adalah untuk membahas dampak-dampak kemajuan teknologi di bidang
reproduksi terhadap kemajuan genetik dan pola pemuliaan. Pola pemuliaan yang
mungkin bisa digunakan adalah pola MOET, pola pejantan unggul, dan pola masa
depan. Aplikasi teknologi ini juga akan membawa dampak terhadap animal walfare
dan etika. Peranan pemerintah oleh karena itu sangat penting untuk meyakinkan bahwa
produk-produk bioteknologi ini dapat diterima oleh masyaraka
t dan tidak
membahayakan.
Kata kunci : Teknologi Reproduksi, Kemajuan Genetik, Pola pemuliaan
ABSTRACT
Advances in reproductive technologies have become increasingly important in livestock
breeding, as they are able to accelerate genetic changes due to shorter generation
interval and improving accuracy in selection program. This paper addressed to
highlight the possibly impacts of reproductive technologies on genetic changes and
breeding schemes. Application of reproductive technologies in animal breeding
programs accelerates genetic changes, because of reducing generation interval and more
accurate in selection. However, the rate of inbreeding tends to increase due to reducing
number of animals in the breeding selection. The breeding schemes, which may be used
in the future are: MOET scheme and superior sire scheme and future scheme. The
application of reproductive technologies leads to animal welfare dilemmas and ethical
consideration. Involvement of Government, therefore, is very important to ensure that
the their products are publicly acceptable and do not cause harm impairment.
Key words: Reproductive Technology, Genetic Changes, Breeding Schemes
INTRODUCTION
Advances in reproductive technologies are becoming increasing important for livestock
breeding. The aim of these technologies is to improve the quality of the products as well
as animal genetic. Artificial insemination (AI), for example, can be expected to
contribute in improving the efficiency of livestock production and it has genetically a
major impact on livestock breeding.
Reproductive technologies will also have a significant effect on livestock breeding in
the future. An increase in the rate of reproduction will lead to a decrease in generation
interval. In cattle, for example, a single cow by natural reproduction yields 6-10 calves
for its life, by using multiple ovulation and embryo transfer (MOET) it can yield up to
100 calves (Kruip and Spaan, 1992). In addition, the increase of offspring per cow leads
to enhancing genetic gain per year and leads to increased accuracy of selection, due to
shorter generation interval and more records. Further development in this area will
definitely has a major impact on future animal breeding strategies.
A long with development of these technologies, the analysis of individual ethnic and
animal welfare are being debated. It will be interesting to highlight the recent advances
in reproductive technologies in livestock improvement, also human’s judgments. The
purposes of this paper are to discuss the likely impacts of reproductive technologies in
improving livestock production, genetic changes, breeding schemes, animal welfare,
and ethical consideration.
REPRODUCTIVE TECHNOLOGY
Advances in reproductive technologies during 20 years have been phenomenal and it
will continue to expand to the next decade. Started with artificial insemination (AI) in
1930s these technologies led to embryo transfer (MOET) in 1980s. More advanced
technologies have been developed recently. These include invitro maturation (IVM),
and invitro fertilization (IVF) of oocyte, semen sexing, and asexual multiplication of
embryos by splitting and nuclear transfer (Brand, 1992).
Moet
Making greater use of the egg cells, in the ovaries of the genetically superior livestock
is still the main purpose of research in livestock reproduction. One successful method is
MOET (Kruip and Spaan, 1992). MOET allows females to produce more offspring in a
single season, possibly more than it will be produced in life time (Anonymous, 1993).
The first stage of MOET is superovulation by reproductive hormones, such as Follicle
Stimulating Hormone (FSH) to stimulate development of follicles and oestrus. In cattle,
the donor can be expected to come into oestrus 2 days later and then, it can be
inseminated. The second stage is recovery of embryos. The embryos can be recovered
by non-surgical using catheter, introduced via cervix. The next stage is transfer of
embryos to recipient animals. The recipients are selected either by detection of natural
oestrus or by synchronization (Kruip and Spaan, 1992).
The advantages of MOET are those: (1) multiple offspring from genetically superior
parent can be produced, (2) selection of bull in AI program is more accurate, (3) it can
produce disease-free livestock for export/import, and (4) embryos are much cheaper to
transport than live animals (Kruip and Spaan, 1992). However, the success of MOET
depends on (1) controlling of oestrus and ovulation, (2) inducing the animal to
superovulation, and (3) recovering the embryos by passing sterile medium through the
uterine tracts (Woolliams and Wilmut, 1989).
Ivm/Ivf
IVM/IVF are based on technique of gaining access to the very large numbers of
immature eggs (oocyte), present within the ovaries female animals. Typically, 20-30
oocyte can be collected from a pair of ovaries (Anonymous, 1992). The oocytes can
also be collected from animal after slaughter (Anonymous, 1993). The method
developed is transvaginal ultrasound gained puncture of follicles, which uses ultrasound
to guide a hollow needle via vagina into the follicle to extend to the oocyte. Immature
oocyte can be matured in laboratory within 24 hours culture period and subsequently
fertilized (Kruip and Spaan, 1992). This method has become possible to improve
animal production and animal breeding. The future progress will rely on development
of synthetic media or growth factor for cultivation oocyte (Robinson and Mc Evoy,
1993).
Semen Sexing
One of the major goals in animal production and breeding is separation of X and Y
chromosome-bearing spermatozoa (Robinson and Mc Evoy, 1993). The basis of the
separation is by DNA probes, which can match to specific genes on Y chromosomes
(Anonymous, 1993). In rabbit semen, X and Y chromosomes can be purified over 80%.
In insemination of them with X-rich or Y-rich samples to females produced male sex
ratio of 94:6 and 19:81 respectively. This revolutionary system could be 0,1 to 0,5 more
efficient than the best conventional system because energy cost of dam maintenance is
dramatically reduced (Robinson and Mc Evoy, 1993). In addition, the application will
lead to intensifying future selection, animal breeding programmes and animal
production strategies (Robinson and Mc Evoy, 1993).
Asexual Multiplication of Embryos by Splitting and Nuclear Transfer
All the reproductive techniques above are different genetically, even embryos carry the
best inherited qualities. Splitting generates more identical embryos from single desired
one. The embryo is cleaved into two, four or eight embryos, which are genetically
identical (Kruip and Spaan, 1992). Splitting will be of benefit in commercial
production because it allows: (1) production of animal of desired sex, (2) increase
uniformity, and (3) rapid repopulation and dissemination (Seidel, 1980). However, the
recent problems are still in development of embryos, especially if it is split more than
four embryos, and reducing the ability of embryos to survive freezing and thawing
(Woolliams and Wilmut,1989).
Nuclear transfer technology is able to overcome the weakness of embryo splitting.
General scheme of nuclear transfer is that oocytes are collected from an animal and
embryo from another. The embryo is cleaved and the cells of embryo are placed into
unucleated oocytes. The fusion of the embryo cells and the oocytes is by means of
electrical pulse. The fused products are transferred into animal. Moreover, the transfer
of nuclei to unucleated oocytes reconstitutes embryo to develop. The problem of this
technique is that the embryos have lower viability than normally-collected and
transferred intact embryos (Wooliams and Wilmut, 1989). In spite of the difficulties, the
commercial-nuclear transferred embryos will be a reality in the near future, and it will
be an enormous commercial value in beef and dairy cattle industry (Kruip and Spaan,
1992).
GENETIC CHANGES
As mentioned, the reproductive technologies can increase the rate of genetic response,
this is based on reducing generation interval and more accurate in selection. Shorter
generation interval is due to an increase in offspring per animal and using an animal in
shorter time than natural reproduction. Whereas, the increase in accuracy of selection is
because in the structure of the breeding scheme has a small number of population.
Comparison among contemporaries are balanced, and environment and management
can be better controlled.
In embryo splitting, selection accuracy increase because the records on genetically
identical individuals are available. However, selection intensity among males and
females has not been increased, because this leads to the use of genetically identical
males and females (Nicholas and Smith, 1983).
One of the problems in operation of MOET scheme is the rate of inbreeding because of
reducing the number of males in breeding selection (Woolliams and Wilmut, 1989).
With increased inbreeding, production may decline and make it difficult to evaluate the
progress in the future.
REPRODUCTIVE TECHNOLOGIES IN THE FUTURE BREEDING SCHEME
Conventional Scheme
In a conventional breeding scheme, the genetic improvement is separated into: sires of
sons, sires of replacements, dams of sons and dams of replacements. Annual genetic
improvement depends on the accuracy of selection intensity and generation interval.
However, the main problem is the low reproductive rate, which may lead to low
selection intensity.
In most developing countries, the use of this method with progeny testing will continue
for many years. The advantage of this scheme is its accurate and strong selection of
males to be replacement stock. However, the disadvantage are the low selection
intensity and long generation interval. The existence of reproductive technology, for
example MOET, can help to improve low reproduction, especially in reducing
generation interval and accuracy of selection.
MOET Scheme
An alternative to conventional schemes is a MOET scheme. The purpose of this scheme
is to increase the rate of genetic progress by minimizing the generation interval for both
male and female. In cattle, for example, all genetic improvement should take place in a
nucleus herd and afterward, be spread throughout to the whole population by using sires
bred in the nucleus.
Outstanding population should be selected to get very high genetic merit. When the
females reach puberty, they should be flushed and subsequently mated. In cattle,
approximately 21 months after flushing, the new generation of MOET males and
females are 12 months old. The pubertal offspring should be selected for the next
generation or replacement in the nucleus.
The main advantage of this selection is that the nucleus gets a high genetic
improvement due to the increase of response to selection. The small population makes it
possible to record and select for traits that are difficult to measure in field conditions,
for example feed efficiency. Furthermore, in the nucleus also increases the possibility to
develop and use expensive reproductive technologies (Christensen, 1991).
The Superior Sire Scheme
This scheme is created to maximize efficiency from conventional and MOET schemes.
In dairy cattle, for example, the yearling daughters of sires are superovulated and
flushed, and subsequently mated. The embryos are transferred immediately. Two years
later a new generation of males and females are sexually mature and ready for MOET.
The yearling males from the scheme are used for AI to serve all recorded cows in the
population. Subsequently, the genetic merit of the sires is accurately estimated based on
the performance of large daughter in the field. Moreover, the best male is used to serve
the donor in the breeding unit. Yet the scheme may be difficult because the farmers
prefer to use proven males than young males (Christensen, 1991).
Future Scheme
To get high genetic progress future schemes should consider:
(1) The nucleus establishes an advanced genetic research on superior females.
(2) Selected embryos are transferred to recipients that may be ordinary herd.
(3) The young males are performance tested for growth, muscularity, feed efficiency,
functional fitness, etc.
(4) The young females should also be performance tested in the rearing period, and the
test should be extended to include production records.
(5) The population has 3 sub-populations:
a. includes in which MOET and other new technologies are applied to breed young
animals with high genetic merit.
b. includes other recorded and makes up the basis for progeny stations.
c. Includes non-recorded population.
(6) The highly selected progeny tested males are used to serve the females in the
nucleus.
(7) Both the nucleus and population should be kept open for use of semen and embryos
from foreign populations (Christensen, 1991).
ANIMAL WELFARE
Animal possesses few welfare dilemmas, defined as a state of complete mental and
physical health where the animal at harmony with its environment. Reproductive
technology may be beneficial for the farmer or breeder, but it hurt the animal.
Therefore, the causes of unnecessary pain or distress to farmed livestock may be an
offence. In embryo transfer, for example, the major problem arises when embryos,
obtained from large breeds are placed in recipients that cannot give birth to them, and
they finally require surgery to deliver the fetus (Murray and Ward, 1993).
Recently in Europe, the whole procedures of a veterinary surgeon must be done by
veterinarian or authorized-trained persons who work led by veterinarian. Bovine
Embryo Collection and Transfer Regulation 1993 implement a European directive
89/556/EEC also controls the collection of invivo fertilized embryos destined for trade
within the community and transfer embryos for domestic market (Anonymous, 1993).
ETHICAL CONSIDERATION
Animal biotechnology will raise ethical issues. Some are common to scientific research
in general or to the human exploitation of animals. Analysis of individual ethical
consideration is based on ethical principles and, ultimately, on ethical theories. The
ethical theories, which inform our consideration on individual issues. Whereas ethical
principles comprise elements of freedom; fairness; harmlessness and kindness. Thus, in
application of biotechnology is necessary to ensure that freedom is not diminished,
justice not impaired, that no harm is caused, and that real benefit is achieved (Melphan,
1993)
Finally, public acceptability is the final purpose of the viability of technology
innovations, particularly those effect so vital and universal a need as food. In other
word, public attitudes are an important aspect of the ethics of animal biotechnology
(Melphan, 1993).
CONCLUSION
Advances in reproductive technologies cause genetic changes. The rate of genetic
response increases because of reducing generation interval and more accurate in
selection. However, the rate of inbreeding tends to increase due to reducing number of
animals in the breeding selection.
The genetic changes in the population tend to create future breeding schemes. The
breeding schemes that may be used in the future are: conventional scheme, MOET
scheme and superior sire scheme and future scheme.
The application of reproductive technologies leads to animal welfare dilemmas and
ethical consideration. Involvement of Government, therefore, is very important to solve
these dilemmas. In addition, to have public acceptability, it must be ensured that these
technologies do not cause harm impairment.
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