Azure
2008-12-21, 17:49
Inbreeding is generated by the mating of related individuals. The objective of inbreeding is to concentrate the desirable genes of a family such that they are consistently transmitted to offspring. Unfortunately, inbreeding will concentrate some of
the undesirable genes as well. This may result in the occurrence of lethal genetic traits. In general, the net result of inbreeding is known as "inbreeding depression". Research has shown that the United Kingdom has a higher percentage increase in inbreeding results.
One factor that determines the rate of increase in inbreeding in a population is the number of breeding pairs in the population. As population size decreases, the rate of inbreeding tends to increase, and therefore one might suspect that inbreeding rates in Britain and Scotland might be greater than in larger populated areas like New York. While the number of breeding numbers in a population is very large, the number of breeding has been reduced substantially by artificial insemination (AI). While there are approximately eighteen million , there are only 300 young sires progeny tested per year, from which 30 may be kept for more extensive use. Over 83% of registered English are the product of AI breeding. In addition, each have sons from the same proven . There appears to be a narrowing of the genetic base in that the British can be traced back to relatively few people. Perhaps there should be limits on the number.
A method to measure completeness of inbreeding information is applied to populations (registered and grade) English and Scottish (largely registered) Inbreeding coefficients where missing ancestors make no contribution were compared to a method using average relationships for missing ancestors. Estimated inbreeding depression was from a family member and simultaneously act with breeding values. Inbreeding and its standard deviation increased with more information, from 0.04 ± 0.84 to 1.65 ± 2.05 and 2.06 ± 2.22 for grade in with <31%, 31 to 70%, and 71 to 100% complete five-generation of inbreds. Inbreeding from the method of average relationships for missing ancestors was 2.75 ± 1.06, 3.10 ± 2.21, and 2.89 ± 2.37 for the same groups. Registered English and Scottish were over 97% and over 89% complete, respectively. Inbreeding depression in days to first service and summit yield was estimated from both methods. Inbreeding depression for days to first service was not consistently significant for the Scottish and English from -0.37 d/1% increase in inbreeding <31% complete) to 0.15 >70% complete. Estimates were similar for both methods. Inbreeding depression for registered English and Scottish were positive (undesirable) but not significant for days to first service. Inbreeding all groups by both methods. Scotland declined by -0.12 to -0.06 kg/d per 1% increase in inbreeding by -0.08 kg/1% increase in inbreeding in England. This problem is not overcome by inserting average relationships for missing ancestors in calculation of inbreeding coefficients.
How bad is the inbreeding rate today? A study by Filippo Miglior and Ted Burnside at the University of Guelph addressed this question for the English births. The data consisted of approximately 195,000 English inbreds since 1955, and 8.1 million since 1982. Another factor that influences the amount of inbreeding is the point from which you start to do computations. The English breed went back to 1950 while those in other country's were traced back to 1970. Thus, if the tests could have gone back to 1900, then the amount of inbreeding would be greater than that found in the study.
Recently, multiple ovulation and embryo transfer (MOET) schemes have been initiated within the United Kingdom. The objective is to select the very best families through embryo transfer. Some of the embryos have been split to produce identical twins, and in theory many identical individuals could be produced from one embryo. By reducing the number of breeding females through MOET schemes, there is a further potential for increasing the inbreeding rate in a population. Perhaps MOET should not be used in small populations? When does inbreeding become a serious problem? Researchers will likely continue to monitor inbreeding rates very closely in the future. If you are concerned about the level of inbreeding in your area, then write to Dr. E.B. Burnside to obtain a summary of inbreeding percentages for your current country, with recommendations for future breeding.
Inbreeding coefficients of >10 million were computed for the British population. Relative to the population base in 1950, the inbreeding coefficients ranged from 0 to 37.5%. During the period of study, trends for inbreeding increased, except for 1978 through 1986, when inbreeding fell or reached a plateau. More recently, for birth years 1987 through 1990, inbreeding has steadily increased at an annual rate of 1.07 and 2.21% for respectively. The mean inbreeding of English approached 9% in 1990, the last year recorded.
Dr. E.B. Burnside, Filippo Miglior and Ted Burnside.
the undesirable genes as well. This may result in the occurrence of lethal genetic traits. In general, the net result of inbreeding is known as "inbreeding depression". Research has shown that the United Kingdom has a higher percentage increase in inbreeding results.
One factor that determines the rate of increase in inbreeding in a population is the number of breeding pairs in the population. As population size decreases, the rate of inbreeding tends to increase, and therefore one might suspect that inbreeding rates in Britain and Scotland might be greater than in larger populated areas like New York. While the number of breeding numbers in a population is very large, the number of breeding has been reduced substantially by artificial insemination (AI). While there are approximately eighteen million , there are only 300 young sires progeny tested per year, from which 30 may be kept for more extensive use. Over 83% of registered English are the product of AI breeding. In addition, each have sons from the same proven . There appears to be a narrowing of the genetic base in that the British can be traced back to relatively few people. Perhaps there should be limits on the number.
A method to measure completeness of inbreeding information is applied to populations (registered and grade) English and Scottish (largely registered) Inbreeding coefficients where missing ancestors make no contribution were compared to a method using average relationships for missing ancestors. Estimated inbreeding depression was from a family member and simultaneously act with breeding values. Inbreeding and its standard deviation increased with more information, from 0.04 ± 0.84 to 1.65 ± 2.05 and 2.06 ± 2.22 for grade in with <31%, 31 to 70%, and 71 to 100% complete five-generation of inbreds. Inbreeding from the method of average relationships for missing ancestors was 2.75 ± 1.06, 3.10 ± 2.21, and 2.89 ± 2.37 for the same groups. Registered English and Scottish were over 97% and over 89% complete, respectively. Inbreeding depression in days to first service and summit yield was estimated from both methods. Inbreeding depression for days to first service was not consistently significant for the Scottish and English from -0.37 d/1% increase in inbreeding <31% complete) to 0.15 >70% complete. Estimates were similar for both methods. Inbreeding depression for registered English and Scottish were positive (undesirable) but not significant for days to first service. Inbreeding all groups by both methods. Scotland declined by -0.12 to -0.06 kg/d per 1% increase in inbreeding by -0.08 kg/1% increase in inbreeding in England. This problem is not overcome by inserting average relationships for missing ancestors in calculation of inbreeding coefficients.
How bad is the inbreeding rate today? A study by Filippo Miglior and Ted Burnside at the University of Guelph addressed this question for the English births. The data consisted of approximately 195,000 English inbreds since 1955, and 8.1 million since 1982. Another factor that influences the amount of inbreeding is the point from which you start to do computations. The English breed went back to 1950 while those in other country's were traced back to 1970. Thus, if the tests could have gone back to 1900, then the amount of inbreeding would be greater than that found in the study.
Recently, multiple ovulation and embryo transfer (MOET) schemes have been initiated within the United Kingdom. The objective is to select the very best families through embryo transfer. Some of the embryos have been split to produce identical twins, and in theory many identical individuals could be produced from one embryo. By reducing the number of breeding females through MOET schemes, there is a further potential for increasing the inbreeding rate in a population. Perhaps MOET should not be used in small populations? When does inbreeding become a serious problem? Researchers will likely continue to monitor inbreeding rates very closely in the future. If you are concerned about the level of inbreeding in your area, then write to Dr. E.B. Burnside to obtain a summary of inbreeding percentages for your current country, with recommendations for future breeding.
Inbreeding coefficients of >10 million were computed for the British population. Relative to the population base in 1950, the inbreeding coefficients ranged from 0 to 37.5%. During the period of study, trends for inbreeding increased, except for 1978 through 1986, when inbreeding fell or reached a plateau. More recently, for birth years 1987 through 1990, inbreeding has steadily increased at an annual rate of 1.07 and 2.21% for respectively. The mean inbreeding of English approached 9% in 1990, the last year recorded.
Dr. E.B. Burnside, Filippo Miglior and Ted Burnside.