Economic Selection Index Research Articles

Economic selection index using different milk production traits of Holstein and its crossbreds

The study was conducted to estimate the Best Linear Unbiased Prediction (BLUP) breeding values of different milk production traits for Holstein and its crossbreds and to construct an economic selection index or total merit for individual cows from 2 different dairy farms in Chittagong, Bangladesh. The BLUP-estimated breeding values were obtained by AIREML, and an economic selection index was constructed as the sum of the product of the estimated breeding value with the economic value for each trait (lactation milk yield, calving interval, and liveweight). The Holstein × Sahiwal crossbred showed better phenotypic performance in both farms while the same cows showed variable performance when compared to each other. It can be postulated that comparatively better performance might be due to good management and proper feeding, as well as the lactation stage and age of the cows. According to the economic selection index value, the Holstein × Local scored higher when compared to other genotypes. Therefore, the selection of cows of top index value would be beneficial for the production of offspring in the next generation.

Development of an economic selection index for Australian tea tree

This study has developed the first formal breeding objective for the Australian tea tree plantation industry. Significant gains in profitability of Australian tea tree (Melaleuca alternifolia) could be made through selection for biomass and oil yield, while maintaining oil quality at acceptable levels. Economic values or weights (EWs), for breeding-objective traits were estimated based on a bio-economic model of a typical production system in Australia. Sensitivity of EWs to the production-system parameters was analysed by what-if scenarios. Selection indices and genetic responses were derived and sensitivity of selection index coefficients to variation in EWs and genetic parameters were analysed by Monte Carlo simulation. The EW for average leaf biomass (LB) and oil content (OC) had the net present value of AU$29.53/kg and AU$2059 per mg/g, respectively. Among the production system parameters studied, discount rate and oil price had large impact on the two EWs, while operating costs changed the EW of LB but did not affect the that of OC. Using optimal selection index, positive expected responses in objective traits LB (36.2 kg/ha/year), OC (4.64 mg/g), and in all selection traits (i.e. juvenile OC, height, leafiness, and 1,8-cineole) were obtained except for terpinen-4-ol, at a 10% selection intensity (i = 1.76). Use of restricted selection index resulted in zero change in either 1,8-cineole or terpinen-4-ol content, but also in an opportunity cost especially in OC. The most important factor affecting the sensitivity of the selection index was the EW for OC.

Proposed economic selection indices for the Simmentaler breed in South Africa

The development of economic selection indices for an integrated Simmentaler production system was described. The breeding objective was defined in terms of production-, functional- and product quality traits. Criteria included in the total index were birth- and weaning weight (direct and maternal), final weight, mature cow weight, days-to-calving, backfat thickness, tenderness and marbling. The total merit index was termed as IT = – 1.60 BWD – 1.95 BWM + 2.23 WWD + 1.75 WWM – 0.54 FW – 2.01 MCW – 13.21 CD + 4.97 BF – 2.36 T + 12.66 M. The correlation between this index and the aggregate breeding objective was 0.988. The economic superiority of the progeny from the top 40% of animals selected on their ranking in the total index, relative to the average progeny, is expected to be R 119.51. South African Journal of Animal Science Vol. 37 (2) 2007: pp. 122-131

Development of a maternal breeding goal and tools to select for this goal in UK beef production

AbstractA maternal breeding goal for the UK beef industry is described and economic selection indexes are developed to assist in the selection of animals for the goal. The breeding objective is made up of general maternal ability traits, cow size, calving and carcass traits. The general maternal ability traits include calving interval, age at first calving, lifespan, maternal weaning weight and maternal calving difficulty. The calculations of economic values for the traits are outlined and discounted genetic expression coefficients are presented. Three selection indexes are illustrated. The first provides a general dualpurpose index for the selection of bulls to produce replacement heifers in most situations. The second, the hardy breed index, is designed to allow selection for improved maternal performance in extensive and hardy environments. The third, the fertile herd index, allows producers who do not have herd fertility problems to place more selection emphasis on objectives other than fertility. A sample of data from the Limousin breed was used to calculate estimated breeding values (EBVs) which were used to investigate response to the three indexes when the top 20% of sires were selected from either sires with 50 or more grand-maternal progeny or bulls with no recorded progeny. Approximately two thirds of the economic response seen in the selection of heavily used bulls was observed in bulls with no progeny for the hardy and dual-purpose indexes. Bulls were also selected using the existing UK terminal sire index and the resulting bulls assessed in the dual-purpose maternal index. There was found to be a negative economic response to the maternal aspect of the index, though a positive response was seen in the carcass objective. The indexes are presented as the sum of four subindexes emphasizing the contribution of maternal ability, cow size, calving and carcass, respectively to the total index. This further assists commercial producers in selection decisions.

Índices de seleção para um rebanho Caracu de duplo propósito

Neste trabalho, objetivou-se determinar índices de seleção para um rebanho da raça Caracu de duplo propósito, cujo objetivo de seleção (H) incluiu a venda de bezerros desmamados e a produção de leite. As características que compuseram H foram: produção total de leite, idade ao primeiro parto, período de serviço, peso à desmama e duração da vida produtiva. Foram propostos dois índices de seleção para H. Os critérios de seleção adotados no índice 1 foram: produção de leite na primeira lactação, primeiro período de serviço, peso à desmama (PD) e perímetro escrotal. No índice 2, foram consideradas as mesmas características, sendo, entretanto, o ganho médio diário do nascimento à desmama empregado como critério de seleção para PD. As análises estatísticas para a obtenção dos componentes de (co)variâncias e das estimativas dos parâmetros genéticos e fenotípicos foram realizadas pelo método da máxima verossimilhança restrita livre de derivada, por um modelo animal (uni e bi-característica). As informações zootécnicas e genealógicas, os preços e as quantidades dos insumos e dos produtos foram obtidos no escritório da empresa estudada. Os custos de produção e as receitas da atividade pecuária foram determinados para o período de 1994 a 2000. A equação de lucro foi tomada em base anual, usando-se valores médios para número de animais por categoria, características biológicas e preços..¹ O valor econômico para cada característica foi obtido pela derivada parcial da função de lucro em relação à característica em questão. Os dois índices econômicos de seleção trariam considerável resposta para o objetivo proposto. Entretanto, o índice 1, que incluiu PD, seria um pouco mais eficiente em termos de resposta à seleção total.

Effects of Errors in Genetic Parameter Estimates on Accuracy of Selection Index for Relative Desired Genetic Changes in Pigs

The effects of errors in estimates of genetic parameters on genetic response to selection in pigs were investigated when the selection was based on selection index for relative desired genetic changes (DC-index). The effects of errors on gains based on economic selection index (Smith-Hazel index: SH-index) were also investigated to compare with DC-index. Information on individual phenotype of candidate for selection (SIC) and on family (SIF) of the candidate was used in selection index. Average daily gain (DG), backfat thickness (BF) and litter size at birth (LS) were considered as traits for breeding objective and selection criteria. The respective heritabilities of 0.3, 0.5 and 0.1 for DG, BF and LS, with genetic and phenotypic correlations between DG and BF of 0.2, and no correlations between LS and DG and BF were assumed. A distinction is drawn between the response [E(_??_H0)] possible with use of the optimum index based on exact parameters and that achieved [E(_??_ H1)] with an index which uses the estimates of the genetic parameters in SH-index. We also draw a distinction between the response [E(_??_g0i)] possible with use of the optimum index and that achieved [E(_??_g1i)] of each ith trait with an index which uses the estimates of the parameters in DC-index. The efficiencies of selection in SH-index and DC-index were defined as RH[=E(_??_H1)/E(_??_H0)] and RD[the minimum value of E(_??_g1i)/E(_??_g0i) in all selected traits], respectively. Errors in estimates of genetic correlation had smaller effect for RH and RD than errors in estimates of heritability per unit. Expected loss in efficiency in DC-index was more sensitive than SH-index to incorrect estimates of heritability or genetic correlation. Errors in phenotypic correlation scarcely affect both RH and RD. For response to selection, the effect of error in estimate of heritability for LS was the largest in three traits. If there is no confirmation of accurate estimates of genetic parameters (e. g. genetic parameters in literature are used in selection programs) and if absolute of relative desired change for LS per genetic standard deviation unit is larger than that for both DG and BF, a higher heritability for LS should be used to construct selection index.

A bio-economic approach to estimating economic values for UK hill sheep

Profitability of sheep production systems depends on several different animal characteristics rather than a single trait. Economic selection indexes combine information from more than one trait into an overall score, to maximise genetic gain. Economic values (EVs) are required for each trait in the breeding goal so that selection emphasis is proportional to the economic importance of each trait. Defining clear breeding goals is more complex for hill breeds than for other sectors of the sheep industry because they provide breeding females in addition to lambs for slaughter. The aims of this paper are to i) describe how EVs for breeding goal traits suitable for UK hill sheep were derived for a combination of carcass, maternal and ‘sustainability’ traits using a bio-economic model, and ii) show how these EVs vary between different production systems as a result of the differences in the physical constraints of farm size, pasture availability and the biological limits of sheep in extensive rearing environments.

Potential for selection to improve efficiency of feed use in beef cattle: a review

Evidence for genetic variation in feed efficiency of beef cattle is reviewed in this paper, and ways in which this variation might be used in selection programs to improve beef cattle in Australia are discussed. Efficiency of beef production systems is determined by feed and other inputs of all classes of animals in the production system as well as outputs in terms of slaughter progeny and cull cows. Different indices have been used to express aspects of efficiency on cattle over certain periods of the production cycle. Use of these indices is discussed, and then evidence for genetic variation in both growing animals and mature animals is reviewed. Genetic variation in feed efficiency exists in both growing and mature cattle, although information is lacking to determine whether variation in total production system efficiency exists. The physiological basis for observed variation in feed efficiency is discussed, with differences in requirements for maintenance, body composition, proportions of visceral organs, level of physical activity, and digestion efficiency identified as possible sources of variation. Selection to improve efficiency might be achieved by measuring feed intake of growing animals and utilising genetic correlations that are likely to exist between efficiency of growing animals and mature animals. Measurement of feed intake might occur in central test stations, or methods may be developed to measure feed intake on-farm. Ways of utilising information generated in genetic evaluations are discussed, and it is concluded that estimated breeding values for feed intake after a phenotypic adjustment for growth performance would be most practical, although not theoretically optimal. Such estimated breeding values would best be used in an economic selection index to account for genetic correlations with other traits, including feed intake of the breeding herd, and the economic value of feed in relation to other traits. Future research should be directed towards understanding the genetic relationships between feed intake and other traits in the breeding objective, and to find ways to reduce the cost of measurement of feed intake, including a search for genetic markers.

Shortcomings of current genetic evaluation systems.

Genetic evaluation, as the term is used today in the beef cattle and sheep industries, refers to the calculation and dissemination of genetic predictions for individual traits. If genetic predictions are to be used wisely, however, genetic evaluation should be broadened to include multiple-trait selection technology, preferably technology that is customized for individual commercial and seedstock producers. Most of the recent research in the area of genetic prediction/multiple-trait selection has focused on the use of economic selection indexes that incorporate genetic predictions produced within breeds. This approach is complicated by genotype x genotype, genotype x environment, and more complex interactions, and the changing correlations they create. The use of a mechanistic technology, bioeconomic simulation, to calculate economic weights can avoid some of the problems caused by interactions, but to implement this technology, academic animal breeders must accept the mechanistic concept of genetic potential and devise ways to translate current within-breed genetic predictions to predictions of this new measure. Sire selection by simulation, a multiple-trait selection technology described in detail in this article, uses bioeconomic simulation in a way that offers advantages over traditional selection indexes in terms of both functionality and appeal. For any customized technology to be applied on a meaningful scale, research priorities must change, and the business relationships between research groups and animal breeding industries must be restructured.

Selection for carcass and feedlot traits considering alternative slaughter end points and optimized management.

Profit was defined as a function of the genotype of animals and variables controlled by management. Alternative parameterizations of management variables were examined to compare the effect of controlling age at slaughter, weight at slaughter, or fat depth at slaughter. The various parameterizations are shown to result in equivalent economic weights for genetic variables, provided management variables are optimized for the current genotype. The implication is that economic weights and selection indexes can be conveniently calculated for age constant end points even though commercial production may involve weight or backfat depth constant slaughter points. An example of selection for profit in the feedlot phase of beef production is presented. Three genotype-management combinations were considered. Economic weights and subsequent selection index weights were shown to depend on both average genotypic means and management (feeding and marketing program) factors.

Are economic selection indices always superior to a desired gains index?

The comparison of different selection indices is justified only if the indices are constrated to achieve the same profit function, even when each index is not optimized with respect to that profit function.When a profit function is known and is non-linear, the desired gains index may be more efficient than the economic index. The optimum desired gains index should be determined by iterative techniques over several generations to compare the genetic progress with the economic index, because gains by the economic index are not linear and the changes observed in the initial generations of selection are not the same rates in future generations, although those changes are linear in the case of the desired gains index.

Selection indexes for production traits of Canadian dairy sires

It would be of benefit to the dairy industry to have sires evaluated for the net economic value of their genetic potential for milk-production traits. Economic weights and selection indexes were derived for a variety of production circumstances, taking into account all returns and costs of dairy production and allowing for the existence of quotas. A single index designed for the average farmer in Ontario under a multiple-component pricing system was highly efficient (>98% of maximum gains) for most situations. Changes in pricing of milk caused the largest changes in the index. An index based on the current volume payment with fat correction would cause a 24% loss in efficiency of selection if protein eventually becomes twice the price of fat. A single index was proposed as highly efficient for farmers across Canada irrespective of their production circumstances, provided payment for milk is based on a multiple-component pricing system giving roughly equal value to fat and protein and low value to milk volume. Key words: Selection indexes, economics, milk production, sire selection

Selection on fat and protein to maximise profit in dairy herds

The possibilities of modifying milk composition by breeding and the consequences of use of indices for selection in dairy cattle were studied. Selection indices, based on sires' breeding values for milk, fat and protein yield, were derived both by desired gain and by calculating net economic values. When a maximum positive genetic response of fat and protein concentration or its ratio was desired, genetic responses were relatively low for milk, fat and protein yield. When selection achieves a maximum genetic response of one of the three yield traits (milk, fat, protein), the correlated responses of the other yield traits were high. Net economic values for milk, fat and protein yield were estimated to derive economic indices. Economic selection indices were influenced by the method of restriction of milk production per herd. When milk output per herd was fixed, concentrate price and herd production level influenced the ranking of bulls, based on economic selection indices. However, when milk production was not restricted per herd, or when both milk yield and fat concentration were restricted, only the scale of the index was influenced by varying prices for concentrates or herd production levels. The price ratios paid for fat: protein yield did, generally, have little influence on the ranking of bulls based on economic indices. A selection index for milk, fat and protein yield, using net economic values, is very useful to farmers to improve their income.

An economic selection index for lean meat production in New Zealand sheep

ABSTRACTAn economic selection index was derived for terminal sire sheep breeds or strains, using physical and financial results from New Zealand export lamb-producing flocks. The aggregate breeding value of the index comprised carcass lean weight and carcass total fat weight. Index measurements were live weight, ultrasonic fat depth and ultrasonic muscle depth. Economic values used for lean and fat weights (NZ$5·65 and NZ$–1·2 per kg, respectively) were the change in profit per kg increase in lean or fat weight from that in the average carcass of lambs slaughtered in 1984/85. The s.d. of the aggregate breeding value was NZS3·20, and the correlation between the full index and the aggregate breeding value was 0·23. This correlation fell to 0·18, 0·15 and 0·07, respectively, when muscle depth or fat depth or muscle and fat depths were omitted from the index. Selection on the full index, or on the index omitting muscle depth was expected to lead to an increase in carcass lean weight and a slight decrease in carcass fat weight. Selection on the index omitting fat depth, or selection on live weight alone, was expected to lead to an increase in both fat and lean weights.

The use of product traits such as lean growth rate as selection criteria in animal breeding

ABSTRACTIn meat animals there is some interest in lean growth rate or lean food conversion efficiency as selection criteria. These traits may be estimated as the product of growth rate (or efficiency), killing-out proportion and carcass lean proportion. When used as selection criteria these product traits do not require estimates of genetic parameters or economic values for component traits. Hence, they may be more stable, and of longer-term use than classical economic selection indices. The purpose of this study is to compare expected responses to selection on product traits with expected responses from selection, either on individual component traits, or on an economic selection index. Formulae were derived for predicting the phenotypic and genetic correlations between a product and one component, and for predicting the heritability of the product trait; these depend on the coefficients of variation and heritabilities of components, and on the genetic correlations among them. When the coefficient of variation of one component is much higher than that of the other, (× 3), this component will tend to dominate the product trait. In cattle and sheep, and to a lesser extent in pigs, killing-out proportion and leanness are usually less variable than growth rate or efficiency. Thus, in many cases, there is little loss in response in lean growth (or lean efficiency) from selection solely on growth rate (or efficiency) regardless of leanness. Although product traits do not require derivation of economic values, their component traits do have implied economic values. Often more appropriate weightings will be given to components by using an economic selection index, even when economic values and genetic parameters are not estimated precisely.

An economic selection index for sugar cane breeding

For decision-making about varietal release, plant breeders use yield-trial data supplemented by intuitive selection indices based on secondary characters. It is suggested that they could be replaced by explicit economic indices. Profitability is taken as the function to be maximised. An example drawn from sugar cane in Barbados, West Indies shows that secondary characters can indeed reasonably be given weights which turn out to be economically substantial. In principle, similar economic indices could be developed for any crop. All such equations are essentially local in application.

Selection indices for terminal sire beef breeds

Rising living standards and an increasing awareness of the health risks of a diet high in saturated fats have led to strong consumer discrimination against animal fats. Additionally the surplusses of animal products in Europe suggest that more attention should be paid to the inputs in animal production, rather than solely increasing output. Improving the efficiency of lean meat production is therefore an important consideration in all meat animal systems. In 1976 Fowler, Bichard and Pease proposed the ‘biological indices’ lean growth rate and lean food conversion as selection criteria in pigs. These traits may be estimated as the product of growth rate (GR) or food conversion efficiency (FCE), and in vivo estimates of killing out and carcass lean proportions. However, in cattle and sheep the relatively low coefficient of variation of estimated killing out and of lean proportions, means that the biological indices are frequently dominated by GR and FCE. In such cases there may be little difference in response from selection solely on GR and FCE (Simm, 1983). The objective of the present study was to derive economic selection indices for terminal sire beef breeds, which might give appropriate economic weighting to the components of efficient lean meat production.

SELECTION INDEX WHEN GENETIC GAINS OF INDIVIDUAL TRAITS ARE OF PRIMARY CONCERN

A new procedure for constructing economic weight free selection index, based on exclusively breeder's intention, is presented. In its derivation the aggregate genotype which is absolutely required in the conventional method was ignored. In this sense this method is completely new and is applicable to the case in which the relative economic weight of each trait is unknown or difficult to assess because of no available standard for the assessment.The use of the technique to evaluate the breeder's objective whether it is attainable within a given period of time with a given selection intensity is described.This selection index has a wide application to practical breeding operations, since it includes several conditions of constraints proposed by other workers. The formula for predicting genetic gains in those traits which are not of the breeder's primary objective is also presented.