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

scholarly journals Sheep breeding schemes utilising artificial insemination; large-scale simulation with a complex breeding goal

animal ◽  
2011 ◽  
Vol 5 (3) ◽  
pp. 367-377 ◽  
Author(s):  
L.S. Eikje ◽  
L.R. Schaeffer ◽  
T. Ådnøy ◽  
G. Klemetsdal
Keyword(s):  
Artificial Insemination ◽  
Large Scale ◽  
Sheep Breeding ◽  
Large Scale Simulation ◽  
Breeding Goal ◽  
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 Genetic and economic benefits of selection based on performance recording and genotyping in lower tiers of multi-tiered sheep breeding schemes

2017 ◽  
Vol 49 (1) ◽  
Author(s):  
Bruno F. S. Santos ◽  
Julius H. J. van der Werf ◽  
John P. Gibson ◽  
Timothy J. Byrne ◽  
Peter R. Amer
Keyword(s):  
Economic Benefits ◽  
Sheep Breeding ◽  
Breeding Schemes

Assessing connectedness in across-flock genetic evaluations

1999 ◽  
Vol 1999 ◽  
pp. 121-121 ◽  
Author(s):  
R. M. Lewis ◽  
R. E. Crump ◽  
G. Simm ◽  
R. Thompson
Keyword(s):  
Stochastic Simulation ◽  
Prediction Error ◽  
Error Variance ◽  
Breeding Values ◽  
Prediction Error Variance ◽  
Selection Decisions ◽  
Breeding Schemes ◽  
Estimated Breeding Values ◽  
Genetic Evaluations

With across-flock genetic evaluations, the extent of genetic links or connectedness between animals in separate flocks affects the reliability of selection decisions. As connectedness improves, error in comparing breeding values among flocks falls. Connectedness is thought more important when founder animals (i.e. unknown parentage) of separate flocks differ genetically. The prediction error variance (PEV) of differences in estimated breeding values (EBV) between animals is considered an appropriate measure of connectedness (Kennedy and Trus, 1993). In this study the level of connectedness, and its consequence, in breeding schemes that differ in the extent of ancestral relationships between flocks, and in which founder animals of these flocks differ genetically, was assessed by stochastic simulation.

Opportunities for breeding for disease resistance in British sheep

2005 ◽  
Vol 2005 ◽  
pp. 49-49
Author(s):  
G.J. Nieuwhof ◽  
S.C. Bishop
Keyword(s):  
Disease Resistance ◽  
Disease Incidence ◽  
Selection Index ◽  
Economic Values ◽  
Sheep Breeding ◽  
Sheep Scab ◽  
Internal Parasites ◽  
Breeding Schemes

Recently, the costs of eight sheep diseases were calculated by Bennett and IJpelaar (2003). The highest annual costs were estimated for enzootic abortions in ewes (EAE) £20 M and toxoplasmosis £12M. In a survey among its members, the Moredun Foundation (1997) identified internal parasites (GI parasites), sheep scab and footrot as the most important sheep diseases, but these three diseases were not analysed by Bennett and IJpelaar (2003). The aim of this study is to estimate the benefits of reductions in the incidence or severity of these diseases, using the methodology of Bennett et al. (1999), and the benefits of reductions in disease incidence or severity. From this, marginal economic values for resistance are calculated and applied in selection index scenarios that mimic current sheep breeding schemes.

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.

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