Mass selection in livestock using limited testing facilities

This paper considers the problem of maximizing the expected annual response to mass selection when testing facilities are limited and so do not allow testing of all potential candidates. In such situations, there is room for variation both in the proportion of breeding animals selected on the basis of the test result and in the allocation of testing places between male and female candidates. When testing facilities are very limited (case 1), males have priority in testing and the maximum proportion to select based on test results is 27%. This means that it is then better to use untested males, i.e. taken at random, than males which are in the lower 73%. This situation holds until the ratio (k) of tested to potential candidates reaches k1 = 1.85/c(4aλ + 1), where c is the degree of polygyny (mating ratio), a the age at first offspring (yr) and λ, the annual fecundity (i.e. half the dam progeny crop). As k increases above k1 (case 2), all replacement males should be tested and testing space should be entirely devoted to males, with random choice of females. This situation holds until k reaches a critical value, k2, above which testing space should be equally distributed between the 2 sexes (case 3). The value of k2, obtained iteratively for any given set of parameters c, a and λ, as defined above, is shown to increase when c increases and when aλ decreases. The strategies recommended, which imply contrasting turn-over rates between selected candidates and candidates chosen at random, are compared to those aimed at maximizing selection intensity for a fixed value of the generation interval. Numerical examples are provided, covering the range of situations prevailing in farm livestock species.Cet article traite de la maximisation du gain génétique annuel attendu en sélection massale quand la capacité de contrôle est limitée et ne permet pas de contrôler tous les candidats potentiels à la sélection. Dans une telle situation, on peut faire varier à la fois la proportion des reproducteurs sélectionnés sur leur résultat de contrôle et la répartition des places de contrôle entre les 2 sexes. Quand la capacité de contrôle est restreinte (cas 1), les mâles ont la priorité et le taux de sélection maximal à l’issue des contrôles est de 27%. Il vaut mieux alors utiliser des mâles non controlés, c’est-à-dire choisis au hasard, que des mâles se trouvant dans les 73% inférieurs. Cette situation prévaut tant que le rapport (k) des candidats contrôlés aux candidats potentiels ne dépasse pas k1 = 1, 85/c(4aλ+1), où c est le degré de polygynie (nombre de reproducteurs femelles/nombre de reproducteurs mâles), à l’âge au le 1er descendant (an) et ) λ la fécondité annuelle (c’est-à-dire la moitié du nombre de descendants produits annuellement par femelle). Quand k dépasse k1 (cas 2) tous les mâles de renouvellement doivent être contrôlés et toutes les places de contrôle doivent être réservées aux mâles, les femelles étant choisies au hasard. Cette situation prévaut jusqu’à une valeur critique k = k2, au-dessus de laquelle les places doivent être également réparties entre les 2 sexes (cas 3). On montre que cette valeur k2, qui est obtenue par itération pour tout ensemble donné des paramètres c, a et λ, définis ci-dessus, augmente avec c et diminue quand aλ augmente. Les stratégies recommandées, qui impliquent des taux de renouvellement très différents entre les candidats sélectionnés et les candidats choisis au hasard, sont comparées à celles qui visent à maximiser l’intensité de sélection à intervalle de génération fixé. Des exemples sont donnés pour illustrer le cas des diverses espèces animales domestiques

Observed response to individual selection of boars over a period of eleven years

International audienc

Premiers résultats d'une expérience de sélection réalisée dans un centre d'insémination artificielle porcine

International audienc

Efficacité économique des programmes de sélection porcine: Introduction

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Theoretical aspects of applying sib-pair linkage tests to livestock species

The Haseman-Elston (HE) sib-pair linkage test in its original form is computationally simple but suffers from low power. With the advent of highly polymorphic markers, the exclusive use of fully informative matings (ie matings where the number of genes identical by descent for any sib pair can be inferred without error) for the HE test becomes feasible. This article examines the influence of highly polymorphic marker systems (5 alleles), large family sizes (6 full-sibs) and hierarchical breeding structures (mating ratio of 25) on the power of the HE test by means of simulation studies. Simulations are performed under the assumption that the costs of marker genotyping are a limiting factor for marker-QTL linkage studies. Consequently, the total number of individuals (parents and offspring) typed is fixed at 5 000 in each of the situations compared. The results show that the power of the HE test is considerably increased when both highly polymorphic markers and large full-sib families are available. For example, for a locus explaining 8% of the phenotypic variance the power of the test increases from 14 to 74% if the locus has 5 alleles instead of 2 and sibship size is 6 instead of 2. Hierarchical breeding structures tend to further increase the power of the test, for the example given from 74 to 79%.Dans sa forme originelle, le test de liaison génétique de Haseman-Elston (HE), basé sur les couples de germains, est simple à calculer, mais statistiquement peu puissant. Avec des marqueurs hautement polymorphes, l’utilisation exclusive d’accouplements totalement informatifs (ie des accouplements permettant d’établir avec certitude le nombre de gènes d’origine identique pour n’importe quel couple de germains) peut être envisagée. Cet article examine, à l’aide de simulations, l’effet d’un système génétique hautement polymorphe (5 allèles également fréquents), d’une grande taille de fratrie (6 germains) et d’une structure d’élevage polygynique (25 femelles accouplées à chaque mâle) sur la puissance du test HE. Les simulations sont faites en supposant que le coût des typages génétiques est le facteur limitant des études de liaisons entre gènes marqueurs et locus de caractères quantitatifs. En conséquence, le nombre total d’individus typés (parents et descendants) est fixé à 5 000 dans chacune des situations comparées. Les résultats montrent que la puissance du test HE est considérablement accrue quand on dispose à la fois de marqueurs hautement polymorphes et de grandes fratries. Ainsi, pour un locus expliquant 8% de la variance phénotypique du caractère, la puissance du test au seuil de 5% est de 0,74 au lieu de 0, 14 quand on passe de 2 à 5 allèles au locus marqueur et de 2 à 6 frères par fratrie. Les structures d’élevage-polygyniques tendent à accroître encore la puissance du test, qui, dans l’exemple ci-dessus, passe de 0,74 à 0,79 avec une structure de 25 fratries issues du même père, par rapport à des couples de parents indépendants

Synchrony, Amalgam and Communion: Erico Verissimo\u27s O Tempo E O Vento as Symbolic Complex

Erico Verissimo\u27s O Tempo e o Vento has long been considered his masterpiece more, it would seem, by dint of its quantity than its quality, since relatively little research has been done on this novel. The attitudes reflected in O Tempo e o Vento concerning the relationship of time and space and man\u27s affiliation thereto have been previously ignored and only through a structuralist analysis of this novel have these determinations been discovered. The structuralist approach comprises certain inherent assumptions of an a priori system of knowledge. One assumption is reflected in the structure of language which presupposes for all mankind a common system of perceiving reality. Another assumption is the unconscious or collective mentality as explicated by Carl Gustav Jung. Finally, the acausal relationship of time and space and man\u27s compatibility with these realms are taken into consideration

RAZVOJ REGIONALNE SREDIŠNJICE ZA ŽIVOTINJSKE GENETSKE RESURSE: EUROPSKI PRIMJER

This paper describes the process that lead to the creation of the European Regional Focal Point (ERFP). The action was suggested by FAO Global Strategy (1995) aimed to assist countries to stop animal diversity erosion by helping them with a better use and preservation of their livestock resources. In 1997, France accepted the responsibility of developing an ERFP though its Bureau des Ressources Genetiques (BRG). During the first year, the ERFP held meaningful discussions with the different European countries with the objective of finding a general agreement for an organisational structure as well as a medium-term work programme. The following step was settled during the Annual Meeting of the European Association for Animal Production (EAAP) in Warsaw where it was agreed that the new body had to have a light structure and respect national sovereignty regarding the AnGR. In February 2000, following a difficult internal debate involving the establishment of a basic strategy and further steps, an enquiry was launched among the National Coordinators in order to have an overall picture and to evaluate the usefulness of the proposed organisation to be established. In 2000 during the 6th workshop of the European NCs. The ERFP was created. The new structure is based on: a) an Annual Meeting of National Focal Points; b) a Steering Committee; and c) a Secretariat to be elected among the National Focal Points to serve for a limited period.U radu se opisuje proces za stvaranje Europske središnjice (ERFF). Cilj je globalne strategije FAO-a (1995.) pomoći zemljama u zaustavljanju propadanja životinjske raznolikosti te u boljem iskorištavanju i očuvanju životinjskih resursa. Francuska je 1997. prihvatila odgovornost za razvijanje ERFF-a kroz svoj Bureau des Ressources Genetiques (BRG). U prvoj godini ERFF je održao svrhovite debate u raznim europskim zemljama s ciljem pronalaženja općeg sporazuma za organizacijsku strukturu kao i srednjoročni program rada. Na godišnjem sastanku Europskog udruženja za proizvodnju životinja (EAAP) u Varšavi, utvrđen je sljedeći korak i dogovoreno da novo tijelo mora imati laganu strukturu i poštivati nacionalni suverenitet u vezi AnGr. U veljači 2000. nakon naporne interne rasprave u vezi sa stvaranjem temeljne strategije i daljnjih koraka pokrenuta je anketa među nacionalnim koordinatorima kako bi se dobila opća slika i procijenila korisnost osnivanja predložene organizacije. Godine 2000. na šestoj Radionici europskog NCs-a, osnovan je ERFF. Nova se struktura temelji na: a) godišnjem sastanku Središnjice b) upravljačkom komitetu c) sekretarijatu izabranom među članovima Središnjice na određeno vrijem

Expectation of variance due to mitochondrial genes from several mating designs

Genetic variation due to non-nuclear DNA has been generally ignored by animal breeders. Recent evidence has confirmed that mitochondrial inheritance is predominantly of maternal origin in mammals. Advances in biotechnology make manipulation of non-nuclear and nuclear material in embryos likely in the future. Estimation of the relative importance of direct, matemal and mitochondrial genetic variation would help in assessing the value of these new technologies. Expectations of causal components of variance from previously used mating and crossfostering designs are modified to include variation due to mitochondrial (cytoplasmic) material. The efficiencies of the designs are compared, as well as the statistical consequences of adding the mitochondrial component to the original models. The designs presented have limitations due to possible confounding of maternal, grand-maternal and mitochondrial effects and to their being not adequate for all animal species and traits. However techniques such as embryo transfer can circumvent those difficulties. Possibilities of using improved designs clearly depend on biotechnological advances and on the cost of implementing those new techniques