Improving lamb performance from Welsh Mountain Sheep breeding groups

2001 ◽  
Vol 2001 ◽  
pp. 223-223
Author(s):  
B M L McLean ◽  
O D Davies ◽  
D E Evans
Keyword(s):  
Performance Testing ◽  
Cooperative Groups ◽  
Sheep Breeding ◽  
Local Type ◽  
Group Breeding ◽  
Working Together ◽  
Breeding Schemes ◽  
Carcass Conformation ◽  
Breeding Groups ◽  
Genetic Pool

Sheep group breeding schemes have gained in popularity in recent years. The objectives of group breeding schemes are to improve desirable traits such as carcass conformation, weight and maternal ability whilst maintaining local type. However, if group breeding schemes were to work together then a larger genetic pool of performance recorded animals would be available to facilitate improvements. The objectives of this project were therefore twofold, 1.) was to improve traits such as weight and carcass conformation and 2.) to demonstrate the benefits of cooperative groups working together. In this project, group breeding schemes from North and Mid Wales have been working together with ram performance testing groups from North, South and Mid Wales to improve results from Welsh Mountain breeding schemes.

A comparison of the rate of genetic gain and inbreeding in open nucleus and closed flock breeding systems for sheep.

1993 ◽  
Vol 1993 ◽  
pp. 34-34
Author(s):  
Janet A. Roden
Keyword(s):  
Breeding Population ◽  
Best Linear Unbiased Prediction ◽  
Breeding Systems ◽  
Optimum Structure ◽  
Linear Unbiased Prediction ◽  
Sheep Breeding ◽  
Group Breeding ◽  
Breeding Schemes ◽  
Best Linear Unbiased ◽  
Open Nucleus

Open nucleus systems (ONS) have been used in sheep breeding for a number of years, usually in group breeding schemes. In the simplest form the population is divided into two tiers, the nucleus flock composed of elite individuals, while the base, which forms the majority of the population, is usually sub-divided into a number of individual flocks. Animals born in the nucleus may be selected as replacements in the base, while superior animals born in the base may become part of the breeding population of the nucleus. The optimum structure and genetic benefits of using an ONS under Australasian conditions have been extensively studied using deterministic predictions (James, 1977; Mueller and James, 1983). However, subsequent advances in genetic evaluation (e.g. the application of Best Linear Unbiased Prediction (BLUP)) and the smaller flock sizes typical in Europe, are likely to impact on the outcome and optimum structure of such systems.

scholarly journals Stochastic simulation of sheep breeding schemes for Iceland, with a focus on ewe trait improvement

2020 ◽  
Vol 2020 ◽  
pp. 25-33
Author(s):  
Eyjólfur Ingvi Bjarnason ◽  
Leiv Sigbjørn Eikje ◽  
Gunnar Klemetsdal
Keyword(s):  
Stochastic Simulation ◽  
Sheep Breeding ◽  
Trait Improvement ◽  
Breeding Schemes

The CAMDA sheep breeding scheme: I. Estimation of genetic parameters for 18-week weight

1999 ◽  
Vol 1999 ◽  
pp. 119-119 ◽  
Author(s):  
A. A. Aslaminejad ◽  
R. M. Lewis ◽  
J. A. Roden ◽  
V.R. Fowler
Keyword(s):  
Growth Rate ◽  
Genetic Parameters ◽  
Live Weight ◽  
Breeding Scheme ◽  
Sheep Breeding ◽  
Group Breeding ◽  
Incomplete Performance ◽  
Mature Size ◽  
Lamb Growth ◽  
Estimation Of Genetic Parameters

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.

scholarly journals Manipulated sex ratios alter group structure and cooperation in the brown-headed nuthatch

2019 ◽  
Vol 30 (4) ◽  
pp. 883-893 ◽  
Author(s):  
James A Cox ◽  
Jessica A Cusick ◽  
Emily H DuVal
Keyword(s):  
Cooperative Breeding ◽  
Group Structure ◽  
Sex Ratios ◽  
Cooperative Groups ◽  
Adult Males ◽  
Breeding Behavior ◽  
Single Male ◽  
Common Prior ◽  
Adult Sex Ratio ◽  
Breeding Groups

Abstract A biased adult sex ratio (ASR) can influence cooperative breeding behavior if the bias limits mating opportunities for the more abundant sex. We tested predictions associated with the ASR-cooperation hypothesis in the brown-headed nuthatch (Sitta pusilla). We manipulated ASR by cross-fostering known-sex nestlings within 2 large (≥100 ha) experimental plots for 5 years using a crossover design where each plot received an opposing male- or female-biased treatment for 2 consecutive years. A year with no manipulations followed before the bias was reversed on each plot for 2 additional years. Variation in ASR (adult males/total adults) was pronounced compared to background proportions (0.55) and ranged from a female bias in female-biased plots (0.47) to a strong male bias in male-biased plots (0.71). Sex ratios during the postbreeding period ranged more broadly (0.33 in female-biased plots vs. 0.74 in male-biased plots). Territory densities did not change significantly and allowed 6 predictions to be assessed. Consistent with predictions, the prevalence of cooperative breeding groups doubled under male-biased treatments and large cooperative groups appeared (≥2 male helpers vs. the single male helper most common prior to the experiment). These changes occurred despite increased dispersal of cross-fostered males in male-biased plots. Most juvenile females dispersed, but, consistent with predictions, the prevalence of female helpers increased under female-biased treatments. Manipulations did not alter the sex of nestlings produced nor extend the time that males served as helpers. Taken collectively, results support the ASR-cooperation hypothesis and the role that mate limitations play in cooperative breeding behavior.

The evaluation of selection in a crossing ram breed to improve litter size in sheep.

1986 ◽  
Vol 1986 ◽  
pp. 27-27
Author(s):  
S. Hoste ◽  
C. Smith
Keyword(s):  
Litter Size ◽  
Equal Weight ◽  
List Type ◽  
Testis Size ◽  
Type Number ◽  
Male And Female ◽  
Litter Weight ◽  
Group Breeding ◽  
Breeding Schemes ◽  
Selection Of

Five genotypes were compared as sires of crossbred ewes from Scottish Blackface dams. These included Border Leicester (BL), New Zealand Romney (R) (from two group breeding schemes where selection had emphasized litter size), and three lines from the composite A.B.R.O. Damline (DL). Selection of the male and female lambs in the purebred DL flock was: a)for an average of 5.5 years on a Ewe Index of eight week litter weight (Martin and Smith, 1980).b)for an average of 3.5 years on a Testis index, combining testis size (adjusted for body weight) and Ewe Index of eight week litter weight both components receiving approximately equal weight andc)a random bred control.These five genotypes (two rams per genotype per year for five years) were group mated (sires of individual ewes were not known) with Scottish Blackface ewes on an upland farm in Ayrshire.

Practical breeding developments and future prospects

1990 ◽  
Vol 14 ◽  
pp. 13-22
Author(s):  
M. K. Curran
Keyword(s):  
Best Linear Unbiased Prediction ◽  
Future Prospects ◽  
Population Changes ◽  
Linear Unbiased Prediction ◽  
Multiple Ovulation ◽  
Group Breeding ◽  
Breeding Schemes ◽  
Best Linear Unbiased ◽  
The Uk ◽  
Terminal Sire

AbstractThis paper is a review of practical sheep breeding improvement schemes and techniques in the UK. Recent breed population changes in each of the broad categories of hill, longwool/crossing, longwool ewe, terminal sire and shortwool ewe breeds are outlined. Current or planned improvement programmes are reported for Welsh Mountain, Beulah, Scottish Blackface, Border Leicester, Cambridge, Friesland, Romney, Texel, Suffolk, Lleyn and Merino breeds. The techniques of genetic improvement currently available are discussed including some costs and likely genetic gains; techniques include group breeding schemes, artificial insemination, multiple ovulation and embryo transplant, best linear unbiased prediction and transgenic methods. The application of these techniques and contribution they could make to future sheep improvement are assessed.

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.

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