Hedi HAMMAMI (2009). Genotype by Environment Interaction for Production Traits of Holsteins Using Two Countries as Model: Luxembourg and Tunisia (Doctoral thesis). Gembloux, Belgium, Gembloux Agricultural University, 170 p., 30 tabl., 16 fig. Summary. Under globalization, breeding organizations are selecting animals and exchanging germplasm across various environments. Ignoring genotype by environment interaction (G x E) may affect the efficiency of breeding strategies and limit outcomes from cooperation between breeding programs. Quantifying the effectiveness of indirect selection and effects of G x E for different breeds is therefore necessary. The objective of this thesis was to evaluate the magnitude of G x E for milk yield using Luxembourg and Tunisian Holstein populations. In fact, these two countries rely considerably on importation of superior genes from diverse origins for their breeding programs. This study needed records on both the genotype and the environment. In the first part of this thesis, genetic ties between the two populations were studied. Additive relationships and genetic similarity were important and genetic links have been strengthened with time which allowed the analysis of the phenotypic expression of daughters of common sires under each of these tow production environments. In the second part, genetic parameters for production traits of Tunisian Holsteins were estimated by a test-day random regression model (RRTD). Heritability estimates for 305-d milk, fat and protein yields were low to moderate (0.12 to 0.18) suspecting difficulties of high-producing cows to express their potential under limiting production conditions. In the third part, G x E for milk yield and persistency were investigated using character state models, where milk yield in each country was considered as a separate trait, and where the country border delimitation was designed as an environmental character state. A RRTD sire model was applied and was extended to a RRTD animal model. Significant G x E was detected for milk yield and persistency by both models. Large differences in genetic and permanent environmental variances between the two countries were observed. Genetic correlations for 305-d milk yield and persistency between Luxembourg and Tunisian Holsteins were 0.50 and 0.43 (sire model) and 0.60 and 0.36 (animal model). Moreover, low rank correlations obtained between estimated breeding values of common sires translate a significant re-ranking between the two environments. At the end of this thesis, a herd management (HM) parameter reflecting feeding and management intensity was defined. Three HM levels were identified in each country and G x E was investigated within- and across-environments. Significant G x E was detected between the Tunisian HM levels, whereas, only heterogeneous genetic variance for milk yield with limited re-ranking of sires across the three Luxembourg environments was observed. Overall, this thesis shows that under constraining environmental effects, selection for adaptive traits among economically valuable traits under their specific conditions is needed for low-input systems. When satisfactory feeding resources, management and husbandry practices are available, high degree environmental sensitivity is desired and the use of a high yielding breed may be encouraged.

本研究的主要目的，在於探討中國大陸的得獎基金之績效持續性是否存在？本研究利用晨星與理柏兩家國際專業評級機構於2004年至2012年所頒發的中國大陸得獎基金為研究樣本（前者的樣本為41檔基金，後者的樣本為53檔基金），資料來源分別為晨星資訊（深圳）有限公司及新浪網。在分別採用累計淨值報酬率、Sharpe指標作為績效衡量指標，並使用Spearman等級相關檢定、績效二分法與迴歸分析，以驗證中國大陸得獎基金在頒發前後不同期間的績效表現是否具有持續性。研究結果發現，前兩種檢定方法皆呈現基金績效在短期（三個月及六個月）具有持續性，而在長期甚至出現績效反轉的現象。而迴歸模型分析的主要發現為，在控制其他變數後，獲得晨星中國基金獎之基金在短期才具持續性，在一年時出現績效反轉。而獲得理柏中國基金奬之基金，在六個月的評估期間就可能出現績效反轉的現象。 / The purpose of this study is to investigate whether the persistence of awarded funds’ performance exist in China. This study employs awarded funds of MorningStar award and Lipper award in China as the sample provided by Morningstar website in China and Sina website. Using accumulated rate of return and Sharpe index as the measurements of awarded funds’ performance and Spearman’s rank correlation coefficient, two-way table constructed by Goetzmann and Ibbotson (1994) and regression analysis as methodologies to analyze this issue in different before-and-after periods, the primary finding of this study is that the former two methodologies show that the performance persistence of awarded funds exist only in three- and six-month periods, and performance reversal appears in the long-run. According to regression analysis, this study suggests that MorningStar awarded funds might have persistent performance in the short-run, but performance reversal after 1-year period. However, Lipper awarded funds do not have persistent performance, but performance reversal after six-month period.

As novas biotecnologias em reprodução, como a transferência de embriões e a fecundação in vitro, de certo modo, despertaram nos produtores e pesquisadores da área de melhoramento animal o interesse na seleção de fêmeas, antes pouco explorada dada a grande ênfase empregada na seleção e avaliação de reprodutores machos. A cada ano é percebido que a pecuária de corte funciona como uma empresa e, como tal, deve-se preocupar com todos os detalhes e não enfocando apenas um, como o mais importante, e é com isso que o Programa de Melhoramento Genético da Raça Nelore (PMGRN-USP) estuda cada vez mais um número maior de características como, stayability e suas possíveis aplicações à seleção das vacas Nelore, pois tem grande importância econômica. Com o objetivo de analisar a característica stayability sob enfoque Bayesiano, em registros de produção de vacas da raça Nelore, inicialmente foram implementados dois tamanhos de cadeia de Gibbs (225 ou 550 mil), dois períodos de descarte amostral (25 ou 50 mil) e duas formas de tomadas de amostra (a cada 1000 ou 250 rodadas). Os registros foram codificados como 0 (fracasso, ou menos de três partos até os 6 anos de idade) ou 1 (sucesso, ou pelo menos três partos até os 6 anos de idade) e os arquivos sofreram restrição ou não para NEP (Número Efetivo de Progênie), para número de touros dentro do grupo de contemporâneos (GC) e exclusão de grupos inteiros com média para a característica igual a 0 ou 1 (ou seja, sem variabilidade dentro do GC). Testaram-se três definições para GC. Utilizou-se o software MTGSAM for threshold (Multiple-Trait Gibbs Sampler for Animal Models), sob modelo unicaráter de touro-avô materno, para obtenção de componentes de (co)variância, estimativas de herdabilidade e soluções para cada touro (que originam as Diferenças Esperadas na Progênie - DEPs). As análises resultaram em amostras com baixa correlação serial, mostraram pequenas diferenças entre as estimativas pontuais de herdabilidade e alta correlação de rank para as DEPs dos 4180 touros avaliados. Adotou-se a implementação tamanho da cadeia/descarte amostral/amostragem como 225mil/25mil/1000 para as análises subseqüentes. A comparação entre estimativas de herdabilidade obtidas sob modelo de limiar e sob modelo linear não mostrou vantagens do primeiro, sendo que análises sob modelo linear, que têm reduzido tempo de processamento, poderiam ser preferidas quando houver muitos registros de produção, bastando transformar as estimativas de herdabilidade para escala subjacente. As comparações, sob modelo linear ajustadas para escala subjacente, entre a stayability padrão (0 ou 1) e a alternativa (considerando o número de partos até os seis anos de idade para aquelas vacas antes codificadas com valor 1), mostraram que podem ocorrer alterações na classificação de um número significativo de touros avaliados, mesmo sendo nas posições intermediárias do rank, talvez pela ligeira capacidade da característica alternativa em detectar variabilidade entre touros. Classificaram-se os 4180 touros em ordem decrescente e foram estudadas as genealogias dos 42 melhores (também chamados de TOP 1% ou aqueles que apresentam DEP para stayability superior a 57,6%) para identificar famílias importantes e avaliar a variabilidade genética da stayability. Além do touro Karvadi Imp. (essencialmente presente como avô, bisavô ou tataravô das mães dos touros TOP1%), outros genearcas com grande representatividade entre os TOP1% foram os touros Godhavari Imp. (via Kurupathy e Neofito), Rolex (via Cardeal), Rastã e Falo da BV (estes últimos pela via materna). / The new reproduction technologies like embryo transfer and in vitro fertilization brought to animal breeding researchers, and producers, a growing interest in the selection of females, which was a subject not well explored before, when the focus used to be only on evaluation and selection of males. The beef cattle industry is becoming more competitive each year, and the producers must think about all the aspects and details that can affect the production process. The PMGRN-USP (Nelore Breeding Program of the São Paulo University) studies a large number of traits to be used as selection criteria. Among these traits, there is stayability, which has a great economic importance. The aim of this project was to analyze the trait stayability, with a Bayesian approach, in a Nelore cattle population. Firstly, the implementation used two lengths of Gibbs chain (225 or 550 thousand), two periods of burn-in (25 or 50 thousand) and two thinning intervals (at each 1000 or 250 rounds). The cows were classified as 0 (failure, or less than three calves until six years of age), or 1 (success, or at least 3 calves until six years of age). The data were, or were not, restricted for NEP (Effective Number of Progeny), for number of sires in the contemporary group (GC), and for lack of variability in the contemporary group. Three different definitions of GC were tested. The software MTGSAM for threshold (Multiple-Trait Gibbs Sampler for Animal Models) was used, under an univariate sire-maternal grandsire model to get the (co)variance components, the heritability estimate and the solutions to each sire (that are used to get the Expected Progeny Differences - EPD). The results showed a low serial correlation in the samples, small differences among heritability estimates and a high rank correlation among the EPD estimates of the 4180 sires evaluated. The implementation 225000/25000/1000 was adopted to the subsequent analysis. The comparison between the heritability estimates obtained under the threshold model and the linear model didn’t show any advantage to the first. The analysis under linear models could be preferred because of its reduced processing time in large data sets, needing only a transformation of the heritability estimates to the underlying scale. The comparisons, under linear model adjusted to the underlying scale, between the standard stayalility (0 or 1) and the alternative (obtained from the perception of the fertility differences among the cows classified as 1) showed a variation in the position of a considerable number of sires in the rank, maybe because the alternative trait gets some additional variation among sires. 4180 sires were classified in a rank and the genealogies of the 42 best sires (or TOP 1%, or the ones with stayability EPD greater than 57,6%) were studied to identify major families and evaluate the genetic variation of stayability. Besides of Karvardi Imp (a bull very present as an ascendant (2, 3 or 4 generations) of the dams of the TOP1% sires), another founder sires with influence among the TOP1% were Godhavari Imp (via Kurupathy and Neofito), Rolex (via Cardeal), Rastã, and Falo da BV (the last two via maternal).

The work occupy by inverse analysis based on artificial neural network. This identification algorithm enable correct determine parameters of applied material model on creation of numerical model of construction so it's possible that the results of computerized simulation correspond with experiments. It look's like suitable approach especially in cases with complicated problems and complex models with many material parameters.