Genetic progress in the lleyn group breeding scheme using a multitrait selection index

1995 ◽  
Vol 1995 ◽  
pp. 131-131
Author(s):  
G.E. Pollott ◽  
D.R. Guy ◽  
D. Croston
Keyword(s):  
Selection Index ◽  
Breeding Scheme ◽  
Genetic Progress ◽  
Group Breeding ◽  
North Wales ◽  
Group Members ◽  
Breeding Schemes ◽  
Set Up ◽  
Multitrait Selection ◽  
Made In

Group breeding schemes were introduced into Britain in the 1970s as a means of increasing the rate of genetic improvement in sheep and providing a vehicle for breeders to cooperate and pool resources. The Lleyn Group Breeding Scheme was set up in 1978 with the aim of improving several maternal traits in a breed known for its prolificacy. Although the breed originates from North Wales members of the group were drawn from different parts of Britain. Flocks in the scheme were all recorded by MLC and sheep had the possibility of being selected using MLC's selection index, appropriately weighted for the traits of interest to group members.This analysis was designed to investigate the genetic progress made in the scheme between 1979 and 1993. Three traits were analysed; adjusted early lamb weight (LW) (at eight weeks of age), mature weight (MW) (at 18-months) and litter size (LS) in the form Number of lambs born per ewe lambing (NLBEL). These three traits were investigated in ten flocks which participated in the scheme, at varying levels, during the 14-year period 1979-1993. However, only genetic progress in the nucleus flock is reported in this paper.

Genetic Progress in the Camda Group Breeding Scheme Nucleus

1994 ◽  
Vol 1994 ◽  
pp. 19-19
Author(s):  
G.E. Pollott ◽  
D. Croston ◽  
D.R. Guy
Keyword(s):  
Environmental Changes ◽  
Original Design ◽  
Breeding Scheme ◽  
Genetic Progress ◽  
Group Breeding ◽  
Set Up ◽  
Mature Size ◽  
Lamb Growth ◽  
Selection Of ◽  
Genetic Trends

A group breeding scheme was set up in 1976 by 10 Welsh Mountain breeders. The objective of the scheme was to improve lamb growth rate, mature size, mothering ability and litter size by selection in a nucleus flock. The original design of the scheme involved two control flocks. The Genetic Control flock was set up from the original base population and was used to monitor environmental changes in the nucleus flock. A Commercial Control flock comprised of a random selection of ewes mated to rams, which were purchased annually and represented the average animal available in the breed. An analysis of genetic progress in lamb growth in the first 9 years of the scheme was reported by Guy et al (1986). This paper presents genetic parameters and genetic trends for three traits recorded between 1977 and 1992.

The CAMDA sheep breeding scheme: II. Genetic progress over twenty years

1999 ◽  
Vol 1999 ◽  
pp. 120-120
Author(s):  
A. A. Aslaminejad ◽  
R. M. Lewis ◽  
J. A. Roden ◽  
V.R. Fowler
Keyword(s):  
Genetic Parameters ◽  
Genetic Effect ◽  
Live Weight ◽  
Maximum Likelihood Algorithm ◽  
Breeding Scheme ◽  
Genetic Progress ◽  
Group Breeding ◽  
Selection Decisions ◽  
Derivative Free ◽  
Lamb Growth

Two aspects of the CAMDA group breeding scheme is to improve lamb growth rate and the mothering ability of Welsh Mountain sheep. Genetic variation for these traits is present (Aslaminejadet al., 1999) but the rate of genetic progress depends on the selection decisions made within the scheme. The objective of this study was to estimate the genetic gain achieved in the nucleus and members’ flocks over the 20 years since the scheme began.A total of 31887 records of 12 and 18-week live weight of Welsh Mountain lambs collected between 1976 and 1995 in 7 flocks of the CAMDA scheme were used in this study. Each flock was analysed separately fitting a univariate animal model with a direct and maternal random genetic effect. Genetic parameters were estimated using a derivative-free restricted maximum likelihood algorithm (DFREML; Meyer, 1993).

Genetic assessment of the romney sheep group breeding scheme

1986 ◽  
Vol 1986 ◽  
pp. 28-28 ◽  
Author(s):  
S. Anderson ◽  
M. K. Curran
Keyword(s):  
Performance Test ◽  
Breeding Scheme ◽  
Common Environment ◽  
Ewe Lambs ◽  
Group Breeding ◽  
Independent Culling ◽  
Ram Lambs ◽  
Set Up ◽  
Genetic Assessment ◽  
Wye College

The Romney sheep group breeding scheme was initiated in 1979. Twelve pedigree breeders formed a Nucleus flock (N), at Wye College, each contributing ten “elite” ewes identified as prolific. The minimum entry requirement was that each ewe should have given at least twins at the previous lambing. The elite ewes were then performance tested in a common environment and those failing to give a multiple litter were replaced by other candidates from the flock of origin. The performance test was discontinued in 1982 when N was closed. Male and female replacements were chosen from the N-bred progeny. Replacements were selected on the basis of dam and sire's dam prolificacy record (live lambs born/ewe joined LLB/EJ)); ten ram lambs were chosen each year and thirty to forty ewe lambs. Ram lambs were used once as sires. Selection was for prolificacy with independent culling levels for tendency to prolapse, udder shape and breed type. A control flock (C) was set-up in 1982 by sampling at random within flock and age the twelve scheme member's flocks. Fifty pregnant ewes were assembled prior to the 1982 lambing. N and C were managed together apart from mating. No selection was applied to C.

Calculation of response and variance reduction due to multi-stage and multiple trait selection

1994 ◽  
Vol 58 (1) ◽  
pp. 1-9 ◽  
Author(s):  
S. Andersen
Keyword(s):  
Variance Reduction ◽  
Selection Index ◽  
Breeding Value ◽  
Multiple Trait ◽  
Multi Stage ◽  
Breeding Schemes ◽  
Unselected Population ◽  
Best Linear Unbiased ◽  
Selection Intensities ◽  
Set Up

AbstractIn deterministic comparisons of breeding schemes it is necessary to take account of variance reduction due to selection. This can take place as multi-stage selection within generations and it takes place across generations when offspring of selected parents are selected. A standard way to deal with this is to set up selection index equations where the parameters are altered as a consequence of selection. It is shown that if the breeding schemes use a univariate or multivariate best linear unbiased prediction (BLUP) animal model for prediction of breeding values this procedure can be simplified. This is done by modelling the distribution of estimated breeding value (EBV) utilizing that changes in EBV of an individual are independent of selection. In the univariate case the variance reduction and the resulting genetic gain can be calculated from the selection intensities and the accuracies in the unselected population. An expression is given for the response in each generation when selection is started in a base population with complete pedigree. This shows that a limiting value is obtained within three to four generations. The asymptotic response for several traits is described in the case where selection is on multitrait BLUP.

Utilization of the sex-determining region Y gene in beef cattle breeding schemes

1991 ◽  
Vol 53 (2) ◽  
pp. 157-164 ◽  
Author(s):  
S. C. Bishop ◽  
J. A. Woolliams
Keyword(s):  
Beef Cattle ◽  
Male Offspring ◽  
Biological Efficiency ◽  
Normal Male ◽  
Sry Gene ◽  
Breeding Scheme ◽  
Genetic Progress ◽  
Cattle Breeding ◽  
Breeding Schemes ◽  
Normal Males

AbstractIn mammals ‘maleness’, i.e. the presence of testes, is thought to be controlled by a single gene on the Y chromosome. Recently, a candidate gene termed the SRY (sex-determining region Y) gene has been located. If the SRY gene is the gene causing maleness then a transgenic male with the SRY gene on an autosome would produce a greater proportion of male offspring than a normal male. This would be advantageous in situations where male offspring are more valuable than females. Such transgenic males have a reduced probability of propagating their genotype and an effort has to be made to avoid their extinction. This is at the cost of genetic progress which must be made to enable the transgenics to remain competitive with normal males.In a simulated beef cattle breeding scheme if half of the annual matings were made to transgenics then after 15 years of selection the transgenic males fell the equivalent of 2·6 years of selection behind males in a traditional herd. If all matings were made to transgenics they fell over 9 years behind. Selection for lean food conversion ratio was considered as an example. After 15 years of selection the gain in biological efficiency from more male offspring outweighed the loss from reduced genetic progress only when more than 0·5 of the bulls used in the breeding scheme were normal males. In practice, the difficulty of maintaining a small population of transgenic males along with other costs not included in the calculations suggest that breeding schemes in beef cattle with an SRY transgene would not be practicable without further technology.

Controlling inbreeding in dairy MOET nucleus schemes

1995 ◽  
Vol 60 (3) ◽  
pp. 379-387 ◽  
Author(s):  
Z. W. Luo ◽  
J. A. Woolliams ◽  
R. Thompson
Keyword(s):  
Genetic Variance ◽  
Selection Index ◽  
Progeny Testing ◽  
Factorial Designs ◽  
Genetic Progress ◽  
Breeding Values ◽  
Embryo Recovery ◽  
Multiple Ovulation ◽  
Significant Difference ◽  
Breeding Schemes

AbstractA nucleus dairy population using multiple ovulation and embryo transfer (MOET) was stochastically modelled with overlapping generations. The aim was to investigate the feasibility of controlling inbreeding in MOET breeding schemes using more realistic parameters for embryo recovery and best linear unbiased prediction (BLUP) for genetic evaluation. Four different cases (involving the culling of donors, more donors and the use of organized progeny testing of nucleus bulls) were studied in combination with nested and factorial designs. Further studies involved modifications of the selection index, including subtracting parental breeding values, inflating the genetic variance in the BLUP evaluation and penalizing inbred animals; these options were examined both with and without organized progeny testing. The effects of applying these schemes on both genetic response and rate of inbreeding were investigated. The results stressed the importance of incorporating progeny testing into MOET schemes for value of reducing inbreeding whilst maintaining genetic progress. There was no significant difference between nested and factorial designs. In the absence of progeny testing the inflation of genetic variance was more effective than subtracting parental breeding values at controlling inbreeding; however incorporating progeny testing made the latter strategy more potent and the superiority of inflating the genetic variance was in this case much smaller and non-significant.

scholarly journals A Proposed Selection Index for Jersey Cattle in Zimbabwe

2013 ◽  
Vol 2013 ◽  
pp. 1-3 ◽  
Author(s):  
Edward Missanjo ◽  
Venancio Imbayarwo-Chikosi ◽  
Tinyiko Halimani
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Selection Index ◽  
Genetic Progress ◽  
Cattle Industry ◽  
Jersey Cattle ◽  
Breeding Objective ◽  
Multitrait Selection ◽  
Selection Of

A multitrait selection index for Zimbabwean Jersey cattle was constructed. The breeding objective was defined in terms of production and functionality traits. The production component of the index included milk yield , butterfat yield , protein yield , butterfat percent , and protein percent , while the functional component included the somatic cell count (SCC). The index was termed as . The accuracy of the index was 91.1%, and the correlation between this index and the aggregate breeding objective was 0.954. A selection index is more important in the selection of sires and cows. This leads to the greatest genetic progress and hence productivity in the dairy sector. Therefore, the application of the selection index developed is necessary if the dairy cattle industry is to maximise the exploitation of genetics and to improve its relative competitive position.

Majolica in the Early Colonial Andes: The Role of Panamanian Wares

2001 ◽  
Vol 12 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Ross W. Jamieson
Keyword(s):  
Spanish Colonial ◽  
Important Indicator ◽  
The Andes ◽  
Early Colonial ◽  
The Pacific ◽  
Elite Status ◽  
Set Up ◽  
The City ◽  
Made In

As one of the most common artifact categories found on Spanish colonial sites, the wheel-made, tin-glazed pottery known as majolica is an important chronological and social indicator for archaeologists. Initially imported from Europe, several manufacturing centers for majolica were set up in the New World by the late sixteenth century. The study of colonial majolica in the Viceroyalty of Peru, which encompassed much of South America, has received less attention than ceramic production and trade in the colonial Caribbean and Mesoamerica. Prior to 1650 the Viceroyalty of Peru was supplied with majolica largely produced in the city of Panama Vieja, on the Pacific. Panama Vieja majolica has been recovered from throughout the Andes, as far south as Argentina. Majolica made in Panama Vieja provides an important chronological indicator of early colonial archaeological contexts in the region. The reproduction of Iberian-style majolica for use on elite tables was symbolically important to the imposition of Spanish rule, and thus Panamanian majolicas also provide an important indicator of elite status on Andean colonial sites.

scholarly journals Novel Genes Associated with Dairy Traits in Sarda Sheep

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2207
Author(s):  
Michele Pazzola ◽  
Giuseppe Massimo Vacca ◽  
Pietro Paschino ◽  
Giovanni Bittante ◽  
Maria Luisa Dettori
Keyword(s):  
Association Analysis ◽  
Milk Yield ◽  
Dairy Traits ◽  
Breeding Schemes ◽  
Milk Coagulation ◽  
Set Up ◽  
A Minor ◽  
Daily Milk Yield ◽  
Breed Sheep ◽  
Daily Milk

The aim of the present research was to analyze the variability of 45 SNPs from different genes involved in metabolism and innate immunity to perform an association analysis with the milk yield, composition and milk coagulation traits. A population of 1112 Sarda breed sheep was sampled. Genotyping was generated by a TaqMan Open ArrayTM. Thirty out of the 45 SNPs were polymorphic, and 12 displayed a minor allele frequency higher than 0.05. An association analysis showed that the variability at genes PRKAG3 and CD14 was significantly associated with the daily milk yield. The variability at PRKAG3 was also associated with the protein and casein content, somatic cell score and bacterial score. The variation at the PRKAA2 gene was associated with the milk lactose concentration. The SNPs at CD14 were also associated with the traditional milk coagulation properties, while the SNPs at GHR and GHRHR were associated with kSR, a derived coagulation parameter related to the rate of syneresis. The information provided here is new and increases our knowledge of genotype–phenotype interactions in sheep. Our findings might be useful in appropriate breeding schemes to be set up for the Sarda sheep breed, but these should be confirmed by further studies, possibly performed on independent populations.

The incorporation of fertility indices in genetic improvement programmes

2001 ◽  
Vol 26 (1) ◽  
pp. 237-249 ◽  
Author(s):  
J.E. Pryce ◽  
R.F. Veerkamp
Keyword(s):  
Genetic Variance ◽  
Selection Index ◽  
Genetic Correlations ◽  
Live Weight ◽  
Parameter Estimates ◽  
Phenotypic Variance ◽  
Production Traits ◽  
Genetic Progress ◽  
Detection Rates ◽  
Days Open

AbstractIn recent years there has been considerable genetic progress in milk production. Yet, increases in yield have been accompanied by an apparent lengthening of calving intervals, days open, days to first heat and a decline in conception rates, which appears to be both at the genetic and phenotypic level. Fertility has a high relative economic value compared to production traits such as protein, making it attractive to include in a breeding programme. To do this there needs to be genetic variance in fertility. Measures of fertility calculated from service dates have a small genetic compared to phenotypic variance, hence heritability estimates are small, typically less than 5%, although coefficients of genetic variance are comparable to those of production traits. Heritabilities of commencement of luteal activity determined using progesterone profiles are generally higher, and have been reported as being from 0.16 to 0.28, which could be because of a more precise quantification of genetic variance, as management influences such as delaying insemination and heat detection rates are excluded. However, it might not be the use of progesterone profiles alone, as days to first heat observed by farm staff has a heritability of 0.15. The most efficient way to breed for improved fertility is to construct a selection index using the genetic and phenotypic parameter estimates of all traits of interest in addition to their respective economic values. Index traits for fertility could include measures such as calving interval, days open, days to first service, or days to first heat but there may also be alternative measures. Examples include traits related to energy balance, such as live weight and condition score (change), both of which have higher heritabilities than fertility measures and have genetic correlations of sufficient magnitude to make genetic progress by using them feasible. To redress the balance between fertility and production, some countries already publish genetic evaluations of fertility including: Denmark, Finland, France, Germany, Israel, The Netherlands, Norway and Sweden.

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