Comparison of genetic response and inbreeding coefficient when the MOET technique and different proportions of proven and young bull semen were used in dairy herds

2005 ◽  
Vol 2005 ◽  
pp. 129-129
Author(s):  
M. Aminafshar ◽  
M. Moradi Shahrebabak ◽  
M. Sanjabi ◽  
A. Lavvaf
Keyword(s):  
Embryo Transfer ◽  
Genetic Improvement ◽  
Inbreeding Coefficient ◽  
Dairy Herds ◽  
Genetic Response ◽  
Young Bull ◽  
Bull Semen ◽  
Multiple Ovulation ◽  
Breeding Schemes ◽  
Potential Improvement

Breeding schemes with multiple ovulation and embryo transfer opens up a possibility to enhance genetic improvement through intense female selection and short generation intervals. The potential improvement in genetic response may increase when elite cows produce a number of embryos, instead of one calf per year. Also different ratio of proven bull and young bull semen may be used to inseminate cows in the herd. The objective of this project has been to investigate genetic response and coefficient of inbreeding, when elite cows produce number of embryos during a year, instead of reproducing one calf per year. Also genetic response and inbreeding coefficient were estimated when different ratio of proven bull and young bull semen were used to inseminate cows in the herd.

Combining clonal response and genetic response in dairy cattle improvement

1989 ◽  
Vol 49 (2) ◽  
pp. 163-169 ◽  
Author(s):  
G. Teepker ◽  
C. Smith
Keyword(s):  
Embryo Transfer ◽  
Genetic Response ◽  
Transfer Scheme ◽  
Multiple Ovulation ◽  
Selection Systems ◽  
Fixed Set ◽  
Commercial Population ◽  
Generation Cycle ◽  
Genetic Responses

ABSTRACTRepeated cloning of bovine embryos by nuclear transfer, producing large clones of monozygous animals, may be possible in the future. Initially, clones could be tested and the best one selected and spread over the commercial population by embryo transfer. Further genetic improvement could be obtained by rebreeding a number of the best clones to produce a new set of clones. However, the testing and selection systems to pick the best clone (for short-term clonal response) and to pick clones with the best breeding values (for long-term genetic response) are different. The objective of this study was to derive a system which achieves both high clonal and high genetic responses. An adult MOET (multiple ovulation and embryo transfer) scheme with 40 breeding males and 40 breeding females per generation (cycle) was used to maintain adequate genetic variation for continued genetic response. For a fixed set of testing facilities and a given family structure initial clonal response is maximized by testing several members per clone. Long-term genetic response is usually greatest when testing one member per clone. Compromises to obtain both high clonal response and high genetic responses were from 95 to 100% efficient.

Influence of age of donor ewe on MOET in Texel sheep

1994 ◽  
Vol 1994 ◽  
pp. 86-86
Author(s):  
B.T. Wolf ◽  
M.J.A. Mylne
Keyword(s):  
Embryo Transfer ◽  
Genetic Improvement ◽  
Follicle Stimulating Hormone ◽  
Selection Intensity ◽  
Female Reproduction ◽  
Sheep Breeding ◽  
Multiple Ovulation ◽  
Genetic Benefits ◽  
Chemical Products ◽  
Aged Donor

Smith (1986) identified the theoretical potential of multiple ovulation and embryo transfer (MOET) to increase the rate of genetic improvement within nucleus sheep breeding flocks by upto 100%. The likely genetic benefits of MOET arise from the potential to overcome limits to female reproduction thus allowing increased selection intensity and reduced generation intervals among females. The present study was conducted to evaluate the potential for MOET from 18 month-old maiden ewes (gimmers) in comparison with aged donor ewes.In October 1991, a group of twenty 18-month old ewes and twenty aged ewes (3.5 year-old) were synchronised into oestrus using intravaginal pessaries containing 45 mg Cronolone (Chronogest, Intervet Laboratories Ltd.) inserted for 12 days. Superovulation was achieved using 20 i.u. of ovine follicle stimulating hormone (Ovagen, Immuno-Chemical Products N.Z. Ltd) given in eight equal doses at 12-hourly intervals starting 58 hours before progestagen pessary withdrawal.

The importance of family sizes in adult multiple ovulation and embryo transfer (MOET) nucleus breeding schemes in dairy cattle

1991 ◽  
Vol 52 (1) ◽  
pp. 33-47 ◽  
Author(s):  
J. Ruane
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Dairy Cattle ◽  
Embryo Transfer ◽  
Sex Ratios ◽  
Survival Rates ◽  
Biological Factors ◽  
Multiple Ovulation ◽  
Breeding Schemes ◽  
Nucleus Breeding

ABSTRACTThe importance of family sizes in adult multiple ovulation and embryo transfer (MOET) nucleus schemes with discrete generations of single trait selection was examined using Monte Carlo simulation. Two areas were investigated. Firstly, the number of sons and daughters per dam was varied in schemes using hierarchical mating designs. With four or eight sires and 32 dams selected, increasing the number of sons per dam from one up to four achieved 1 to 8% higher rates of response but at the expense of increased variation in response and 10 to 56% higher rates of inbreeding. With four or eight sires and 16, 32 or 64 dams selected, the number of daughters was set to two, four or eight (with one son per dam in each case). For schemes transferring equal numbers of embryos, responses were lower with two daughters per dam but were fairly similar with four or eight daughters per dam while inbreeding rates increased as fewer sires and dams were selected. Secondly, the effects of variation in family sizes due to biological factors and chance were investigated with eight sires and 32 dams selected and with hierarchical or factorial (two or four sires per dam) mating designs. When all selected cows yielded embryos, changes in family sizes due to differences in sex ratios, in survival rates of embryos to selection and to variation in the number of embryos per donor reduced response by 1 to 4%. However, when 20% or 33% of the superovulated females yielded no embryos, thus requiring the use of genetically inferior replacements, response was reduced by a further 9 to 13%

Response to superovulation in Scottish Blackface ewes during seasonal anoestrus

1996 ◽  
Vol 1996 ◽  
pp. 187-187
Author(s):  
L D Dunne ◽  
J J Robinson ◽  
P J Broadbent ◽  
T G McEvoy ◽  
D F Dolman
Keyword(s):  
Embryo Transfer ◽  
Genetic Improvement ◽  
Embryo Production ◽  
Generation Interval ◽  
Multiple Ovulation ◽  
Biological Constraint ◽  
Selection Intensities

A major limitation to the success of genetic improvement programmes using multiple ovulation and embryo transfer is the failure to generate sufficient viable embryos per donor ewe to maintain selection intensities and sustain a low generation interval. Seasonal anoestrus imposes a biological constraint on embryo production in many breeds of sheep. The objective of this study was to investigate the response to superovulation during seasonal anoestrus (April - May) in Scottish Blackface ewes.

Superovulation in the ewe: the effects of source of gonadotrophin, season, breed and age

1993 ◽  
Vol 1993 ◽  
pp. 59-59
Author(s):  
K. Fernie ◽  
W.S. Dingwall ◽  
W.A.C. McKelvey ◽  
J. FitzSimons
Keyword(s):  
Treatment Period ◽  
Embryo Transfer ◽  
Genetic Improvement ◽  
Ovulation Rate ◽  
Pituitary Extract ◽  
Multiple Ovulation ◽  
The Mean ◽  
Chemical Products ◽  
Different Sources ◽  
Potential Rate

The potential rate of genetic improvement which can be achieved in sheep through the use of multiple ovulation and embryo transfer (MOET) is limited by the great variation in the response of ewes to superovulation treatments. Factors which have been shown to influence natural ovulation rate in the ewe include season, breed, age and the administration of exogenous gonadotrophins from different sources. The following study was conducted to examine the effects of these factors on the response of ewes to superovulation treatments, with a view to increasing the mean ovulation rate and to concurrently decrease the between-ewe variability.During the course of 4 experiments a total of 170 ewes (Suffolk and Texel) were treated with 45mg progestagen-impregnated intravaginal pessaries (Chronogest: Intervet Laboratories Ltd.) for a period of 12 days. Sixteen ewes had no further treatment and were used as controls. The remaining 154 ewes, were treated with one of two exogenous gonadotropin preparations on days 10, 11, 12 and 13 of the progestagen treatment period (day 0 = pessary insertion). One group (n = 76) was treated with a porcine pituitary extract (pFSH) and the second (n = 78) with a highly purified ovine FSH (Ovagen: Immuno-Chemical Products).

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