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

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).

1999 ◽  
Vol 1999 ◽  
pp. 119-119 ◽  
Author(s):  
A. A. Aslaminejad ◽  
R. M. Lewis ◽  
J. A. Roden ◽  
V.R. Fowler

The CAMDA group breeding scheme was established in 1976. Its objective is to increase lamb growth rate, mature size and maternal ability of the Welsh Mountain sheep while retaining their hardiness and breed type. The opportunity to achieve this goal depends on the extent of genetic variation within the breed for these traits. The objective of this study was to estimate the amount of variation in 18-week live weight attributable to the lamb genotype (direct) and dam maternal ability, both genetic and environmental, in Welsh Mountain sheep within this scheme.A total of 12954 records of 18-week live weight of Welsh Mountain lambs collected between 1976 and 1995 from 4 flocks of the CAMDA scheme were considered. The data were edited for small contemporary groups and for incomplete performance or pedigree recording.


Author(s):  
G.E. Pollott ◽  
D. Croston ◽  
D.R. Guy

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.


2013 ◽  
Vol 56 (1) ◽  
pp. 564-572 ◽  
Author(s):  
F. Ghafouri-Kesbi

Abstract. The aim of the present study was to estimate (co)variance components and genetic parameters for average daily gain from birth to weaning (ADGa), weaning to 6 months (ADGb), weaning to 9 months (ADGc), 6 months to 9 months (ADGd) and corresponding Kleiber ratios (KRa, KRb, KRc and KRd) in Mehraban sheep. A derivative-free algorithm combined with a series of six univariate linear animal models was used to estimate phenotypic variance and its direct, maternal and residual components. In addition, bivariate analyses were done to estimate (co)variance components between traits. Estimates of direct heritability (h2) were 0.10, 0.11, 0.16, 0.09, 0.13, 0.13, 0.15 and 0.08 for ADGa, ADGb, ADGc, ADGd, KRa, KRb, KRc and KRd, respectively and indicate that in Mehraban sheep genes contribute very little to the variance of the growth rate and Kleiber ratio. Estimates of maternal heritability (m2) were 0.10, 0.08 and 0.05 for ADGa, KRa and KRb, respectively. Direct additive genetic correlations ranged from −0.32 (KRa-KRd) to 0.99 (ADGb-KRb) and phenotypic correlations ranged from −0.53 (ADGa- ADGd) to 0.99 (ADGa-KRa). Estimates of direct heritability and genetic correlations show that genetic improvement in efficiency of feed utilization through selection programmes is possible, though it would generate a relatively slow genetic progress.


1996 ◽  
Vol 1996 ◽  
pp. 113-113 ◽  
Author(s):  
M. Araghi ◽  
M.K. Curran ◽  
G.E. Pollott

In 1989, ten Suffolk breeders co-operated to establish a nucleus flock at Wye College. The group is known as the Wye Suffolk Improvement Group (WSIG). The members each contributed 5-10 pedigree ewes to use as the initial nucleus flock. Eighty-nine ewes were delivered to the College by the various participants. The objective of this study was to obtain estimates of the heritabilities of live animal traits, used to improve carcass traits, and phenotypic and genotypic correlation estimates between them in the Suffolk lambs in the south of England.


1996 ◽  
Vol 1996 ◽  
pp. 113-113
Author(s):  
M. Araghi ◽  
M.K. Curran ◽  
G.E. Pollott

In 1989, ten Suffolk breeders co-operated to establish a nucleus flock at Wye College. The group is known as the Wye Suffolk Improvement Group (WSIG). The members each contributed 5-10 pedigree ewes to use as the initial nucleus flock. Eighty-nine ewes were delivered to the College by the various participants. The objective of this study was to obtain estimates of the heritabilities of live animal traits, used to improve carcass traits, and phenotypic and genotypic correlation estimates between them in the Suffolk lambs in the south of England.


1995 ◽  
Vol 1995 ◽  
pp. 131-131
Author(s):  
G.E. Pollott ◽  
D.R. Guy ◽  
D. Croston

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.


2020 ◽  
pp. 31-35
Author(s):  
В.М. Габидулин ◽  
С.А. Алимова ◽  
Х.Х. Тагиров

Представлены результаты исследования по выявлению хозяйственно-биологических особенностей и селекционно-генетических параметров селекционируемых признаков коров стада абердин-ангусской породы австралийской репродукции. По результатам исследования выявлено, что генетический потенциал продуктивности максимально выражен в возрасте пяти лет (у полновозрастных коров) и перманентно сохраняется до девятилетнего возраста. Рост основных селекционируемых признаков с двух до пяти лет составил по живой массе 15,1%, по молочности – 5,1%. С увеличением возраста маток отмечен стабильный рост показателя «выход деловых телят» на 2,3%. Селекционный дифференциал за три поколения у коров в трёхлетнем возрасте по живой массе составил 23 кг и по молочности – 7,4 кг, коэффициент наследуемости составил 0,42 по живой массе и 0,36 – по молочности коров, эффект селекции по живой массе за поколение составил 9,7 кг, за год – 1,9 кг, по молочности – 2,7 кг и 0,5 кг соответственно. У генотипированных коров по схеме мать-дочь эффект селекции за поколение был выше у гетерозиготных генотипов дочерей, рождённых в Курганской области. Знание и рациональное использование традиционных и новых по ДНК маркерных методов селекции на производстве позволит выявить, а также реализовать генетический резерв животных и управлять селекционным процессом при совершенствовании племенного стада абердин-ангусской породы. The results of research on detecting of commercial-biological features and selection-genetic parameters of cows’ features under selection of the Australian reproduction Aberdeen-Angus breed herd of are presented. According to the results of the research it was revealed that the genetic potential of productivity is maximally expressed at the age of 5 years (in mature cowbanes) and persists permanently until the age of nine. The growth of the main features under selection from two to five years amounted to 15.1% by live weight, 5.1% by milking capacity. With an increase in the age of the dams a stable increase in the "calf crop percent" by 2.3% was noted. The selection differential for three generations in cows at the age of three years in living weight was 23 kg and in milking capacity – 7.4 kg, the inheritance coefficient was 0.42 in living weight and 0.36 - in milking capacity of cows, the effect of selection by live weight per generation was 9.7 kg, for the year – 1.9 kg, in milking capacity – 2.7 kg and 0.5 kg, respectively. In genotyped cows according to the dam-daughter scheme genetic progress through selection per generation was higher in heterozygous genotypes of daughters born in the Kurgan region. Knowledge and rational use of traditional and new DNA marker methods of selection at the place of production will allow identifying, as well as unlocking the genetic reserve of animals and managing the selection process while improving the breeding herd of the Aberdeen-Angus breed.


Author(s):  
Е.V. Arlimova ◽  
◽  
Е.А. Smotrova ◽  

Actuality of research data is in contribution rate of growth of genetic progress according to main economic traits in Ayshire populations at the cost of conducting correlative- regression analysis and study of influence factors, as a preparatory phase in development of selection index for selection of animal units into selected groups. Study sample of cow heifers (n=12821), which are offsprings of 232 servicing bulls from 13 farms, is modified to normal distribution with the help of R-studio program (on control of events, emergence, removal of empty and impossible values). Calculation and analysis of selective- genetic parameters of economic traits are conducted, and also impact assessment of genetic and paratypic factors on realization of economic traits of local cattle population of Ayshire breed in Leningrad region for the period from 2014 to 2018. Animal milk production was 6848 kg with fat mass percentage and protein 4,07 and 3,29 %. We established lowering of MOP duration and reproductivity coefficient and fertility index (RC and FI). Multiregressional model was formed including into formula percentage of fat, protein, live weight and service period. It was established that with fat increase for 1 % milk yield will decrease by 15,3 kg, but with increase of protein on the same value- for 107,8 kg of milk. The most accurate influence on studied economic traits had father factor (14,97 – 41,58% ***). Consequently, with the aim to achieve positive result in population development of Ayshire cattle it is necessary to use bulls, having high genetic potential of milk yield and reproductive qualities.


1996 ◽  
Vol 63 (3) ◽  
pp. 423-428 ◽  
Author(s):  
S. C. Bishop ◽  
K. Bairden ◽  
Q. A. McKellar ◽  
M. Park ◽  
M. J. Stear

AbstractFaecal egg counts and live weights were measured on approximately 200 predominantly twin-born Scottish Blackface lambs each year for 3 years, from 1 to 6 months of age. Measurements were made at 4-week intervals following anthelmintic treatment. Heritability estimates (with s.e.s) of log transformed faecal egg count at each age were 0·01, 0·00, 0·12 (0·10), 0·14 (0·12), 0·15 (0·07) and 0·22 (0·13), for ages 1 to 6 months respectively. Therefore, genetic variation exists for acquired but apparently not for innate resistance to infection. Maternal common environmental effects (with s.e.s) were 0·36 (0·11), 0·20 (0·05), 0·27 (0·09), 0·06 (0·08), 0·15 (0·09) and 0·16 (0·08), for ages 1 to 6 months respectively. Genetic correlations between faecal egg counts in lambs older than 3 months were not significantly less than 1·0, indicating that faecal egg counts at different ages are expressions of the same trait. Phenotypic correlations between faecal egg counts were generally positive but small. Measurement error contributed one-third of the observed variation for individual egg counts. The heritability of mean faecal egg count from 3 to 6 months was 0·33 (s.e. 0·15), indicating that selection decisions can be made more accurately using multiple egg counts per animal. Phenotypic correlations between faecal egg counts and live weight were generally negative but close to zero. However, genetic correlations between faecal egg counts and live weight in lambs older than 3 months were close to -1·0, indicating that resistance to gastrointestinal parasites may be an important genetic determinant of growth rate in this environment.


Author(s):  
Shahabodin Gharahveysi ◽  
Hadi Ghezelsoflou

From the past to now, body conformation is an instrument for the Iranian horse judging. This research aimed to study and estimate the genetic and nongenetic parameters of limb conformation traits in the Iranian Turkoman horses. Therefore, body conformation traits, specifically limb conformation, of 1273 horses were measured. Among the horses studied, 357 stallions and 916 mares were included. For studying the nongenetic (such as sex, province and birth year) and genetic effects (such as additive genetic effect), the LSMEANS procedure and the restricted maximum likelihood method (REML) were used by SAS and MATVEC software, respectively. Birth year had a significant effect on most of the traits, especially scapula length and arm length (P < 0.05). The lowest and the highest heritability was estimated for femur length (0.11 ± 0.03) and forearm length (0.40 ± 0.09), respectively. Overall, considering the heritability estimations, the expectation is that limb conformation traits will have a good response to the selection and genetic progress. Farmers can choose the best stallions and mares based on the traits mentioned, so that their foals can have good body conformation.


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