Breeding programmes for smallholder sheep farming systems: II. Optimization of cooperative village breeding schemes

Abstract This 484-paged book is an extensively updated and expanded edition of the previous book by Simm, which focused on cattle and sheep. It has 14 chapters, the first chapter in the book sets the scene for modern livestock breeding, by looking at the origins and roles of today's livestock breeds. The next four chapters deal with the scientific principles of livestock improvement. Chapter 2 outlines some of the basic principles in genetics and attempts to illustrate the link between genes and the performance of individual farm animals, or populations of them. In Chapter 3 the main strategies for genetic improvement are discussed. The factors which affect responses to within-breed selection, and some of the tools and technologies used, especially for more effective within-breed selection, are discussed in Chapters 4 and 5. Chapter 6 explores in more depth how we analyse variation in farm animals. Chapter 7 discusses approaches to predicting breeding values. Chapters 8 to 13 deal with the application of these principles in practical breeding programmes in dairy cattle, beef cattle, sheep and goats, poultry, pigs and aquaculture. Finally, Chapter 14 discusses some of the key societal, technical and ethical challenges facing farm animal production in general, and animal breeding and genetics in particular. It discusses how livestock breeders, scientists and others might respond to ensure wide societal and animal benefits from future breeding schemes. There is a glossary of technical terms at the end of the book.

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Opportunities for genetic improvement of sheep and cattle in the hills and uplands

BSAP Occasional Publication ◽

10.1017/s0263967x00001506 ◽

1994 ◽

Vol 18 ◽

pp. 51-66

Author(s):

G. Simm ◽

J. Conington ◽

S. C. Bishop

Keyword(s):

Genetic Improvement ◽

Livestock Industry ◽

Current Structure ◽

Livestock Species ◽

Selection Experiments ◽

Breeding Programmes ◽

Breeding Schemes ◽

Breeding Goals

AbstractThe principles of genetic improvement apply to hill sheep and cattle in just the same way as they apply to other livestock species. However, the breeding goals often differ, and will continue to change in the light of new economic and political circumstances. Also, there are particular problems of implementing breeding programmes in some of these areas, which do not apply to other livestock species. In this paper we aim to review or discuss (i) the current structure of the livestock industry in the hills and uplands, (ii) strategies for genetic improvement, (iii) the results of relevant selection experiments and industry breeding schemes, (iv) some of the difficulties of implementing breeding programmes and possible solutions, and (v) new opportunities for the genetic improvement of animals in the hills and uplands.

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Sesbania sesban (sesban).

10.1079/fc.49466.20210115097 ◽

2021 ◽

Author(s):

John Peter Thompson

Keyword(s):

Alley Cropping ◽

Land Reclamation ◽

Farming Systems ◽

Soil Improvement ◽

Marginal Lands ◽

Traditional Medicines ◽

Germplasm Collections ◽

Short Rotation ◽

Tropical America ◽

Breeding Programmes

Abstract S. sesban is a fast-growing leguminous shrub or small tree, up to 8 m tall and 12 cm in diameter. Although its geographical origin is not known, it is widely distributed and cultivated throughout tropical Africa and Asia, and has been introduced into tropical America. It is found both in the humid tropics and in more arid and semiarid regions of the world. It is often utilized as a short rotation tree on fallow and marginal lands, or as an agroforestry tree within farming systems - in alley-cropping, as a shade tree, as a support tree for horticultural plants and for planted fallows. It is mostly grown for production of highly nutritive and digestible leaf fodder for which it is repeatedly coppiced. The leaves are also used as a green manure. Other uses include: soil conservation, erosion control, soil improvement, land reclamation, shelterbelts/windbreaks and hedges. The wood is used as fuelwood, for light construction purposes, and for the manufacture of pulp. The leaves and flowers are edible; they are also utilized, along with a gum from the seeds and bark, for traditional medicines. It can easily be grown from seed and nursery seedlings. There are no reports of breeding programmes for the species (the most widely collected of the genus) although most accessions originate from Africa. Germplasm collections are available in Ethiopia, Australia and Hawaii (USA).

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Asymptotic rates of response from index selection

Animal Science ◽

10.1017/s0003356100032347 ◽

1989 ◽

Vol 49 (2) ◽

pp. 217-227 ◽

Cited By ~ 67

Author(s):

Naomi R. Wray ◽

W. G. Hill

Keyword(s):

Genetic Variance ◽

Additive Genetic Variance ◽

Index Selection ◽

Selection Intensity ◽

Response To Selection ◽

Multiple Trait ◽

Breeding Values ◽

Breeding Programmes ◽

Breeding Schemes ◽

Rate Of Response

ABSTRACTThe reduction in additive genetic variance due to selection is investigated when index selection using family records is practised. A population of infinite size with no accumulation of inbreeding, an infinitesimal model and discrete generations are assumed. After several generations of selection, the additive genetic variance and the rate of response to selection reach an asymptote. A prediction of the asymptotic rate of response is considered to be more appropriate for comparing response from alternative breeding programmes and for comparing predicted and realized response than the response following the first generation of selection that is classically used. Algorithms to calculate asymptotic response rate are presented for selection based on indices which include some or all of the records of an individual, its full- and half-sibs and its parental estimated breeding values. An index using all this information is used to predict response when selection is based on breeding values estimated by using a Best Linear Unbiased Prediction (BLUP) animal model, and predictions agree well with simulation results. The predictions are extended to multiple trait selection.Asymptotic responses are compared with one-generation responses for a variety of alternative breeding schemes differing in population structure, selection intensity and heritability of the trait. Asymptotic responses can be up to one-quarter less than one-generation responses, the difference increasing with selection intensity and accuracy of the index. Between family variance is reduced considerably by selection, perhaps to less than half its original value, so selection indices which do not account for this tend to place too much emphasis on family information. Asymptotic rates of response to selection, using indices including family information for traits not measurable on the individuals available for selection, such as sex limited or post-slaughter traits, are found to be as much as two-fifths less than their expected one-generation responses. Despite this, the ranking of the breeding schemes is not greatly altered when compared by one-generation rather than asymptotic responses, so the one-generation prediction is usually likely to be adequate for determining optimum breeding structure.

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Optimization of breeding programmes under index selection and constrained inbreeding

Genetics Research ◽

10.1017/s0016672397002656 ◽

1997 ◽

Vol 69 (2) ◽

pp. 145-158 ◽

Cited By ~ 18

Author(s):

B. VILLANUEVA ◽

J. A. WOOLLIAMS

Keyword(s):

Environmental Effects ◽

Selection Index ◽

Index Selection ◽

Mass Selection ◽

Optimum Number ◽

Time Horizons ◽

Breeding Programmes ◽

Breeding Schemes ◽

Males And Females ◽

Single Objective

A method for finding optimum breeding schemes which maximize genetic gain under index selection with constraints on the rate of inbreeding is derived. The selection index includes information on the candidate and its sibs. Optimization is for the numbers of males and females to be selected and for the index weights when fixed numbers of offspring per generation, heritabilities and time horizons are considered. The expected rate of gain after a number of generations of selection is combined with the expected asymptotic rate of inbreeding (ΔF) in a single objective function which is maximized for finding the optimum solutions. Under restricted inbreeding, optimum designs are very similar for maximizing gains at different time horizons. The optimum number of selected males (for giving maximum gains) increases with the size of the scheme and with the severity in restricting ΔF and decreases with the heritability. Low heritability, less severe restrictions on ΔF and large schemes lead to increases in the relative weights given to performance of relatives in the index. The presence of common environmental effects leads to increases in optimum mating ratio when the heritability is low, to increases in the number of selected males and to more intense selection within families. Gains from index selection are compared with gains from mass selection. Under restricted inbreeding the advantage of optimized index selection over mass selection is only notable when the heritability is low and the scheme is large (in which case indices put more emphasis on family information than mass selection) and when the heritability is high and the scheme is small (in which case indices put less emphasis on family information).

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Adaptability to organic farming of lentil (Lens culinaris Medik.) varieties developed from conventional breeding programmes

The Journal of Agricultural Science ◽

10.1017/s002185961000050x ◽

2010 ◽

Vol 149 (1) ◽

pp. 85-93 ◽

Cited By ~ 12

Author(s):

D. N. VLACHOSTERGIOS ◽

A. S. LITHOURGIDIS ◽

D. G. ROUPAKIAS

Keyword(s):

Organic Farming ◽

Organic Agriculture ◽

Lens Culinaris ◽

Farming Systems ◽

Direct Selection ◽

Conventional Farming ◽

Organic System ◽

Conventional Breeding ◽

Breeding Programmes ◽

Organic Farming Systems

SUMMARYThe development of organic agriculture has raised the demand for crop varieties well-adapted to organic farming systems. Most of the varieties presently cultivated in organic agriculture were developed from conventional breeding programmes. The objective of the present work was to study the adaptability to organic farming systems of lentil (Lens culinaris Medik.) varieties developed from conventional breeding programmes. Twenty varieties were evaluated over five environments under organic and conventional farming systems from 2005 to 2007. Genotype×system interactions (GSI) for grain yield were significantly different in four out of the five environments and GSI explained 0·03–0·17 of the variance. Spearman's rank correlation index of the 20 varieties between the conventional and organic system ranged from 0·27 to 0·93 in the five environments. Direct selection of the top five varieties in organic systems resulted in significantly higher grain yields than indirect selection in one out of the five environments. However, among the top five varieties, the highest yielding varieties under conventional farming systems were not always the highest yielding varieties under organic farming systems. These results indicate that the demands of organic agriculture for yield performance could be only partially satisfied by varieties developed under conventional breeding programmes.

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Are there any Advantages of Genetically Diverse Material in Cereal Breeding Programmes for Organic Farming?

Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences ◽

10.2478/v10046-012-0022-z ◽

2012 ◽

Vol 66 (4-5) ◽

pp. 152-162

Author(s):

Vija Strazdiṇa ◽

Indra Beinaroviča ◽

Linda Legzdiņa ◽

Arta Kronberga

Keyword(s):

Winter Wheat ◽

Organic Farming ◽

Farming Systems ◽

Breeding Lines ◽

Wheat Genotypes ◽

Cereal Breeding ◽

Breeding Programmes ◽

Variety Mixtures ◽

Growing Conditions ◽

Pure Lines

Employing cereal genetic variation in breeding programmes for organic farming is one of the ways to create varieties with higher stability and adaptability. The aim of the study was to compare and evaluate grain yield, quality and other traits of barley pure lines, hybrid populations, variety mixtures, as well as winter wheat hybrid populations and parental varieties, in organic and conventional farming systems. Significant evidence for advantages of using barley mixtures and populations under organic and conventional management systems was not observed. More advantages with respect to yield, adaptability to unfavourable environments and TGW were observed for breeding lines selected for suitability to organic conditions. Combination of distinctive genotypes may result in a fairly stable mixture with average yield above the components. The study confirmed that resistance of winter wheat genotypes to abiotic stress is one of the significant traits that is closely connected with limitation of the wheat productivity in both growing conditions. Yield and grain quality value of winter wheat genotypes was lower under organic conditions compared to a conventional growing system. Advantages of populations were not observed under organic conditions, but significantly higher yield, in comparison to parental varieties, was obtained for two populations in conventional conditions. In general, the yield of populations was intermediate to that of the parents.

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