Statistical modeling for growth data in linear mixed models – Implications derived from an example of a population comparison of Golden Hamsters

Abstract. Using statistical modeling to determine the structure of expectation and covariance employed during analysis is a common feature of analytical research. This paper describes the necessary methodology for, and illustrates those techniques that are of special importance in, practical modeling and evaluation scenarios (likelihood ratio test, analytical criteria, residual analysis). Our approach is demonstrated upon a population comparison, taken on various measurement dates, that focuses on a wild population and a laboratory population of Golden Hamsters. The selected example is particularly suited due to the fact that – aside from the actual growth function of interest – additional fixed (e.g. effect of different mating periods, litter size) and random factors (e.g. maternal environment, repeated performances per animal) must be considered. The modeling shows significant efficiency regarding the improvement of the analytical criteria. The recommended evaluation model leads to a very close match of the observed ordinary least square residuals and of the variance and covariance functions, respectively, that have been derived from the estimated covariance structure.

Konstruktion von Indizes mit Restriktionen in Random Regression Modellen zur Veränderung der Wachstumskurve

Abstract. Title of the paper: Index construction with restrictions in random regression models to change the pattern of the growth curve Random regression models provide estimated breeding values (EBV) for the complete growth curve for any target age. The animal-specific curves can be described as the weighted sum of continuous covariates with random regression coefficients. By using the covariance matrix K of the additive genetic regression coefficients the response to index selection can be calculated for any age or time of the test period. In this study selection indexes with equality restrictions based on the eigenvectors of matrix K were used to modify the growth curve of the population. In order to demonstrate the index construction a matrix K was used, estimated from repeated measurements for body weight of bulls by using Legendre polynomials as covariates. Indexes for high and low growth rate until age at the reflection point were derived subject to the restriction of zero gain for initial and final body weight. Selection strategies for improving body weight at the end of the test period while holding the daily gain in a certain time interval on a desired level were compared. By using so-called "restrictive economic values", an aggregate breeding value for body weight was derived from EBV for individual growth curve.

Comparison of Breeding Values for Daily Gains of Bulls Estimated with Multi-Trait and Random Regression Models

Abstract. In this study, random regression models with Legendre polynomials of the 2nd, 3rd and 4th degree (RR2, RR3 and RR4) are compared with regard to the estimation of breeding values for the average daily gain of Czech Pied bulls (Simmental type). The data were prepared such that a multi-trait model (MTM) could be used as reference model. For each bull, 8 repeated records or fewer were available for the testing period from the 12th to the 420th day of life. For the modeling of the expected value structure, the fixed regression coefficients of the Legendre polynomials were subordinated hierarchically to the herd-year-season effects (HYS). For the comparison of the random regression models with the reference model, rank correlations between the estimated breeding values of various animal groups were calculated and a variety of top-lists were analyzed. In general, models RR3 and RR4 returned higher rank correlations with MTM in comparison to model RR2. Additionally, the number of common animals in the 1% and 10% top-lists showed that models RR3 and RR4 are to be preferred over RR2 when it comes to the estimation of breeding values.

Anpassung eines Fixed Regression Modells für die tägliche Zunahme von Fleckviehbullen mit Hilfe von Informationskriterien

Abstract. Title of the paper: Fitting a fixed regression model for daily gain of bulls using information criterion In this study the model choice is demonstrated exemplarily on data of 6405 Czech Simmental bulls using information criterion. Per bull up to 8 observations were available for the trait daily gain. Because the animals showed different age on control day, the expected gain curves were described in the population and within the herd*year*season-classes by second, third or fourth order Legendre polynomials of age. For optimization of the fixed effects and to choice the covariance structure of the repeated records the information criteria of Akaike (AIC), the Bayesian criteria (BIC) and the ICOMP-criteria, developed mainly from Bozdogan, were used. Within and over all covariance structures AIC selected generally the most complex model. On the other hand, BIC and ICOMP favoured a model with second order polynomials of age nested within the head*year*seasonclasses. All criterion selected models with nested second order polynomials within the herd*year*season-classes in comparison to models with non-nested polynomials of age.

Estimation of Genetic Parameters for Daily Gains of Bulls with Multi-Trait and Random Regression Models

Abstract. The average daily gains of 6,420 Czech Pied bulls (dual-purpose, Simmental type) from 7 breeding stations were analyzed using single-trait animal models, a multi-trait animal model and random regression models. The effects of station, year and season were taken into account by creating herd-year-season classes (HYS) with the season being defined as a 3-month class starting with December. Legendre polynomials of the 1st to the 4th degree were used to describe the daily gains within the HYS classes as well as to model bull-specific gain curves. The comparison of the h2-values estimated with single-trait models and those gained with a multi-trait model returned only insignificant differences. The comparison of genetic parameters based on the multi-trait model to those from different random regression models shows that polynomials of at least the 2nd degree are to be used for the genetic analysis of daily gains.

Estimation of Additive and Non-Additive Genetic Variances of Body Weight, Egg Weight and Egg Production for Quails (Coturnix coturnix japonica) with an Animal Model Analysis

Abstract. This study estimates the additive and non-additive variances for egg production and body weight traits of two lines of quails from a long-term selection with the help of the REML method. For the body weight of 42-day-old females (BW42f) and males (BW42m), a total of 7,934 records for line 1 and 7,214 records for line 2 from 21 generations were used in our analyses. Additionally, 1,717 records of females from line 1 and 1,671 records of females from line 2 contained information on their egg production at an age of 42 to 200 days (EN200), on the average egg weight for the first 11 weeks of their laying season (EW1), on the average egg weight from weeks 12 to 23 (EW2), and on their body weight at an age of 200 days (BW200f). A multivariate additive animal model and one-trait dominance models, which include the inbreeding coefficients as covariates, were fitted to the data. The estimates of the heritability gained from our dominance models were smaller than those from the additive model. For line 1, the heritability values decreased for EN200 from 0.35 to 0.32, for EW1 from 0.66 to 0.56, for BW200f from 0.42 to 0.38, and for BW200m from 0.51 to 0.49, respectively. For the first line, the respective ratio (d2) of the dominance variance to the phenotypic variance for EN200, EW1, BW200f and BW200m was 0.08, 0.22, 0.09 and 0.21, and the values for the second line were 0.12, 0.06, 0.001 and 0.23.

Untersuchungen zur Mortalität von Legehennen gehalten in Einzel- und Gruppenkäfigen

Abstract. Title of the paper: Mortality of laying hens housed in single and group cages This study provides genetic parameters for mortality of laying hens estimated with linear and threshold models. Records of one line from a commercial breeding programme of White Leghorns from three generations were available. Data included observations of 8636 hens from single and from 6908 hens of group cages. Mortality was defined as death in the first six months of lay with dead=1 and alive=0. The average mortality was 3.3% in single and 6.3% in group cages. The binary traits were analysed separately by linear animal (LAM), by threshold animal (TAM) and by threshold sire models. Further the two mortalities were analysed together by a linear-linear animal (LLAM) and threshold-threshold animal model (TTAM). The LLAM estimates of heritability were 1.5% for single and 3.2% for group cages. The heritability estimates of TTAM ranged from 9.6% to 9.9%. The rank correlations between breeding values of LAM and TAM were for all sires, the 10% best and the 5% best sires in the range 0.96 to 1.00. The analysis of rank correlations of the linear and threshold models showed: The LLAM provides a good (but only suboptimal) alternative for breeding value estimation of mortality in the investigated laying hen population.

Varianzkomponentenschätzung unter Berücksichtigung von Dominanz an simulierten Reinzuchtlinien

Abstract. Title of the paper: Estimation of variance components under dominance with simulated purebred lines A stochastic simulation based on a gene model was used to investigate the estimation of variance with dominance and additive animal models. For a heritability in broad sense of 0.5 three ratios of dominance variance (5, 10 and 25%) on the phenotypic variance were investigated under different degrees of dominance. No additionally biased estimations of the variance components as consequence of different dominance degrees were found. By using the dominance model for random mating as well as for selection the differences between true parameters and estimation values were small for all dominance degrees and ratios of dominance variance. Small, but significantly, differences can be explained by the change of the allele frequencies over the generations due to the influence of selection. By using the additive animal model, that ignores the dominance relationship, for high ratios of the dominance variance (25% or greater) important biased estimations of the variances were observed. For dominance ratios of 5% no significantly overestimation of the additive variances with the reduced model were found under selection and random mating.

Stichprobenumfang zur Schätzung der Dominanzvarianz bei hierarchischer Halb- und Vollgeschwisterstruktur

Abstract. Title of the paper: Sample size for estimation of dominance variance with hierarchical full- and half-sib structure The sampling size for the estimation of the ratio d2 of the dominance variance to the phenotypic variance is investigated for the case of hierarchical population structures corresponding to the relations in poultry and pig breeding. The standard error of the d2-estimation is calculated by using the Maximum-Likelihood method and the concept of parameter transformation. Estimation of the dominance variance requires much larger data sets than estimation of the additive variance. Assuming d2-values of 25, 17, 10 and 5% than the estimation of the ratio d2 required about 6, 10, 20 and 40 times more data than the estimation of the additive variance. For the case h2:d2=0.4:0.1 the estimation of d2 with 8320, 14720, 33040 and 58640 records yielded standard errors of 8, 6, 4 and 3%. In the situation of h2:d2=0.225:0.075 the same accuracies can be reached with records of 4400, 7760, 17520 and 31040 animals.

Optimierung von Zuchtstrukturen einer Zweilinienkreuzung – Eine Monte-Carlo Studie

Abstract. Title of the paper: Optimization of the population structure for a two-line crossbreeding scheme – a Monte-Carlo study A stochastic simulation was used to optimize the population structure in a two-line crossbreeding system under non-additive gene models. For different fixed test capacities, given number of offspring per dam and varying degrees of dominance the optimum number of selected sires was calculated. As criterions of the optimization the cumulative selection response on generation 10, the corresponding standard error of the response and the development of the inbreeding in the purebreds were used. If the trait was controlled by loci with partial and complete dominance, than the optimal number of selected sires was between 8 and 12 for given test capacities of 2304, 1152 and 1536 animals per generation and per the sire line. In the case of overdominance the number of selected sires increased on 24 to 48. Additionally, the level of the selection response in the three populations was affected by the difference of the allele frequencies in the initial generation and the economic weights of the additive purebred and crossbred effects. Under partial and complete dominance with corresponding purebred-crossbred genetic correlations of high and moderate level only small extra benefits were obtained from including crossbred information over pure line information.

Schätzung von Varianzkomponenten mit Gruppenmittelwerten am Beispiel von Legehennen, gehalten in Gruppenkäfigen

Abstract. Title of the paper: Estimation of variance components from group mean records of laying hens housed in group cages Two models are presented to estimate variance components if only group mean records are available. The first model accounts for additive genetic relationships and full-sib group effects (SIMIANER and GJERDE, 1991) and the second model contains the additive genetic effects of all animals from one cage by using modified design matrices. Estimates of the genetic parameters were obtained by the MIVQUE-method (RAO, 1971; LAMOTTE, 1973). The variances of the estimated heritabilities were derived from the information matrix. Estimations from individual records and from average records (cage average) were compared in a small application on laying hen data. The analysed trait was single egg weight measured on hens housed in group cages. It could be shown: If cage variance is negligible, than for the estimation of the heritabilities full-sib data can be used successfully. The application of the modified animal model is suggested, because this model can take into account more complex relationships between the animals of one cage.

The Use of HEL9 and INRA035 Microsatellites as Specific Markers for Bali Cattle

Abstract. Bali cattle are one of Indonesian native cattle’s that famous for their ability to adapt to tropical harsh conditions. For the last 25 years, indiscriminate crossbreeding using artificial insemination (AI) organizing mainly by government might be has contaminated the purity of Bali cattle. In order to utilize as well as to conserve Bali cattle it is necessary to develop an accurate and simples method to detect the purity of Bali cattle. This experiment is the continuation of a long term experiments in developing methods to detect the purity of Bali cattle i.e. phenotypic variations, blood protein polymorphisms, hair structure, chromosome and DNA microsatellite variation analyses. The specificity of HEL9 and INRA035 microsetellites in Bali cattle as well as in Banteng (Bos sondaicus) as their ancestor was tested. The results show that A and B alleles at INRA035 microsatellite locus are monomorphic and can be used for a specific markers for Bali cattle. Allele A at locus HEL9 that has high frequency (92.90%) in Bali cattle and 100% in Banteng can also be used as a supporting marker.

Genetische Parameter für Merkmale der Eiproduktion geschätzt mit additiven und Dominanzmodellen bei Legehennen

Abstract. Title of the paper: Genetic evaluation of egg production traits based on additive and dominance models in laying hens The study was conducted to estimate additive and dominance variances for egg production traits of two commercial purebred lines (A & D) of laying hens using an animal model analysis. Breeding values estimated from a dominance model were compared to those from an additive model. In total, 8625 records of line A and 8968 records of line D from three generations were used in the analysis. Every record contained information on the number of eggs laid between 20 and 28 (EN1-2), 28 and 48 (EN3-7) and between 20 and 48 (EN1-7) weeks of age. Further average egg weight (EW), egg weight at 28 (EW1), 33 (EW2) and 40 (EW3) weeks of age were available. An additive animal model and one- and three-trait dominance models including the inbreeding coefficients as covariates were fitted to the data. Simultaneous estimates of the additive and dominance variance components were obtained using the REML method. The estimates of h2 from the dominance models for EN1-2, EN3-7, EN1-7 and EW were 0.40, 0.15, 0.28 and 0.62 for line A and 0.38, 0.16, 0.26 and 0.53 for line D. The ratios d2 of the dominance variance to total variance were moderate for EN (0.12–0.13) and low for EW (0.04–0.07) within line A but relatively low for EN (0.03–0.12) and high for EW (0.12–0.21) within line D. Between the breeding values of the best 100 hens of each generation estimated with the additive and the dominance models for EN1-2, EN3-7, EN1-7 and EW high rank correlations (0.946, 0.896, 0.945 and 0.991 in line A and 0.996, 0.899, 0.971 and 0.951 in line D were found

Nutzung von QTL-Information bei der Langzeitselektion

Abstract. Title of the paper: Long-term selection by using QTL-information A quantitative trait is assumed to be genetically affected by a polygenic effect and a major effect of a single dialellic locus. Such an identified gene is denoted as quantitative trait locus (QTL). A population characterized by infinite population size, heritability equal to 0.4, ratio of QTL-variance and total genetic variance equal to 20 % and complete dominance at the QTL was considered. The objective of the study was to investigate the genetic changes in the population over 20 generations of selection in five different environmental situations. The scenarios differed in the environmental variation of the three QTL-genotypes and also in heritability level after the favourable allel being fixed. To selection over generations indexes were constructed including the breeding value for the known QTL, the genotypic value of the QTL and the estimated polygenic breeding value. Beside of selection on phenotype and standard-indexes a sub-optimal index contracted the environmental variances at the QTL was considered in the model. If the favourable QTL-genotype is highly affected by the environment than it can be of advantage to select against the favourable allel. Deterministic calculations confirmed greater long-term response for sub-optimal strategies over standard indexes and phenotypic selection, not only for the up-selection but for the down-selection as well. The results from the deterministic approach showed good agreements with the results obtained by stochastic simulation.

Genetic parameters for egg production and egg weight of laying hens housed in single and group cages

Abstract. The present study was conducted to estimate the heritability and genetic correlation of monthly egg production and egg weight of 2 lines White Leghorn hens in single and group cages. A total of 2289 records (line A) and 2596 records (line D) from single cages, 518 and 541 records (for line A and D, respectively) from group cages, were analysed. (Co) variance components of single cage data were analysed using the programme VCE4 applying the REML method and a multiple trait animal model. An EM-algorithm was used to obtain (co) variance components for group cage data. Genetic correlations between single and group cages were analysed using the programme VCE4 based on sire model. Heritability estimates for monthly egg production in single cages ranged from 0.08 to 0.44 (line A); 0.04 to 0.43 (line D) and those for group cages were 0.02 to 0.42 (line A); 0.02 to 0.19 (line D). Egg weight was highly heritable for single and group cages (heritability = 0.25 to 0.54). The genetic correlations between monthly and cumulative egg production were 0.25 to 0.95 (line A); 0.26 to 0.86 (line D) for single cage and 0.24 to 0.84 (line A); 0.26 to 0.96 (line D) for group cage. Cumulative egg production in single cage were highly correlated with those of group cages (0.89 and 0.63, respectively for line A and line D). Single cage records gave higher estimates of genetic parameter than group records. However, the trend of estimates is almost the same. High genetic correlations were found between single- and group cages in most of the production periods.

Monthly model for genetic evaluation of laying hens. II. Random regression

1. We investigated the use of monthly production records for genetic evaluation of laying hens, derived from a test day model with random regression in dairy cattle and compared it with other models. 2. Records of 6450 hens, daughters of 180 sires and 1335 dams, were analysed using a model with restricted maximum likelihood (REML): traits considered were monthly and cumulative egg production. Five models were studied: (1) random regression with covariates derived from the regression of Ali and Schaeffer (Canadian Journal of Animal Science, 67: 637-644, 1987) (RRMAS), (2) random regression with covariates derived from quartic polynomial (RRMP4), (3) fixed regression with covariates derived from Ali and Schaeffer (FRM), (4) multiple trait (MTM) and (5) cumulative (CM). 3. The models were compared on the basis of Spearman rank correlations of individual breeding values and sire breeding values estimated from subsets of full-sib split data. The hens (about 10% per generation) which ranked highest on their estimated breeding values from different models were compared phenotypically with their full records. 4. The estimates of heritability resulting from RRMP4 were biased upward from the estimates obtained from MTM, so this model was discarded. The heritabilities for monthly productions from RRMAS and MTM showed a similar pattern. They were high for the 1st month of production, decreased to their lowest value at about month 5 of production and increased again to the end of lay. 5. Spearman rank correlations between animal breeding values estimated by monthly models (RRMAS, FRM and MTM) were high, between 0.91 and 0.98, whereas those between estimates of monthly models and CM were lower, from 0.85 to 0.87. The correlations estimated either from intermittent months of measurements (odd vs even months) or full records were generally high, from 0.93 to 0.99. Information from odd months of production could be sufficient for cost-efficient recording schemes. The RRMAS generally had the highest correlation of sire breeding values between subsets of full-sib records, followed by MTM, RM and CM. Monthly models selected hens with higher productivity than the cumulative model. 6. In conclusion, genetic evaluation based on monthly production may be better than using cumulative production and RRMAS appeared to be the best among the models tested here.

Selection to improve birth and weaning weight of Javanese Fat Tailed Sheep

Abstract. In Indonesia, the Javanese Fat Tailed Sheep is a very popular domestic animal for its meat production However selection to increase body weight has never been done by local farmers. As a result the variability of body weight is high, and expected that application of a selection program can improve this trait Two Steps of selection were done in order to improve birth and body weight. In the first selection, the elite group was established by selecting the best 40 females and 3 males from 12500 sheep reared by local farmers based on their mature body weight and tail length. The control group was established by randomly selecting 40 females and 4 males In the second step of selection, the best 50 % females and 5 % males of the progeny of the elite group was selected based on their weaning weight and tail size. The first selection results indicate that there was a positive genetic progress in both birth and weaning weight. Selection had increased 7.17 % and 5.48 % of male and female birth weight respectively and 9.48 % and 9.78 % of male and female weaning weight, respectively. Positive genetic progresses of birth and body weight were also found after the second selection. Birth weights of males and females were 6.75 % and 7.20 % higher than those in the control group. Male and female weaning weights were 5.60 % and 8.19 % higher than those in the control group, however, selection for weaning weight did not affect reproductive traits.

Schätzung genetischer Parameter an einem Datenmaterial der Sächsischen Rinderpopulation

Abstract. Title of the paper: Estimation of genetic parameters in the dairy cattle population of Saxonia Population-genetic parameters of the dairy cattle population of Saxonia have been examined. The estimated heritabilities for milk quantity range between 0.35 and 0.42, for fat content between 0.48 and 0.55 and for protein content between 0.52 and 0.57. Higher heritabilities were found for 1st than for subsequent lactations. The genetic correlations between milk quantity and the fat and protein contents were significantly negative for all lactations, likewise between protein content and the protein quantity. The correlation between fat content and fat quantity has been slightly positive (rg=0.08). The analysis of genetic trends revealed a substantial increase in quantity traits, whereas a negative trend has been observed for the milk content merits.

Gewichtsentwicklung beim Kaninchen (Oryctolagus cuniculus) nach Transfer reziproker Kernkombinationen in eine neutrale Ammenlinie

Abstract. Title of the paper: Development of body weight in rabbits (Oryctolagus cuniculus) after embryo transfer of reciprocal nuclear combinations to a neutral line of recipients. Ihe article describes differences in the development of body weight ofthe Fl-generations in the rabbit, which oecured after embryo transfer from reciprocal nuclear combinations to a neutral line of reeipients. These differences can be explained as expression of maternal cyto-plasmatical and / or imprinting-effects. The two races – Deutsche Riesen and Farbzwerge –, which are extremly different in body weight were used for the reciprocal crosses. The neutral reeipients were a commercial breed „Zika". Results show a significant higher litter weight of the offspring which descended from the heavier mother race. On the 84th day of life exists no differences in weight between the crosses. Differences were within the crosses between the females and males and between the crosses reciprocal different. Causes for the reciprocal sexdimorphism can be A: extrachromosomal respectively cytoplasmatic factors or B: a sex-linked and a sex-influenced heredity, which coinside and are regulated by imprinting

Monthly model for genetic evaluation of laying hens 1. Fixed regression

1. This paper addresses the possibility of using a monthly model for the genetic evaluation of laying hens, based on the definition of a test day model with fixed regression as used in dairy cattle, in which monthly records were treated as repeated measurements of the same trait. 2. Production records of 6450 hens, daughters of 180 sires and 1335 dams were analysed using an animal model with restricted maximum likelihood (REML). The traits considered were individual monthly egg production and cumulative egg production in 11 months. Four different models were fitted to various combinations of monthly and cumulative records. The covariates were derived from the regression of Ali and Schaeffer (1987). 3. Spearman rank correlations were computed to compare breeding values from different models. Two types of correlations were computed: between individual breeding values and between sire breeding values based on subsets of full-sib records. 4. The results indicated that a monthly model with nested covariates produced higher heritability and permanent environmental variance than the models with non-nested or without covariates. The estimates of heritability obtained from monthly model were lower than the estimates from the cumulative model. The monthly model resulted in higher correlations of sire breeding values between two subsets of full-sib records than those from cumulative models. 5. In conclusion, the monthly model with nested covariates appears to be better than the model with non-nested covariates or without covariate. Although the heritability estimates obtained from the monthly model were lower, the monthly model with nested covariates could be better than the cumulative model for genetic evaluation of laying hens in the 1st cycle of laying period when using either full or part records. The use of information from odd months of production could be of interest for the evaluation of full records.

Langzeitselektion bei asymmetrischer Merkmalsverteilung

Abstract. Title of the paper: Long-term selection by asymmetric trait distribution A quantitative trait is assumed to be genetically affected by a polygenic effect and a major effect of a Single dialellic locus. Such a model is called mixed model of inheritance and the identified gene is denoted as quantitative trait locus (QTL). By choosing the part of the QTL-variance, the degree of dominance and the frequency of the favourable allele it is possible to generate distributions with given level of asymmetry characterised by skewness and kurtosis. If the ratio of QTL- and phenotypic variance is small (less than 8%), then genotype-environment interaction can be used in the mixed inheritance model to explain values of skewness and kurtosis estimated with poultry data. The Situation is considered where the environmental variances given for the three QTL-genotypes show a wide ränge. In most of these cases the short- and long-term selection does not effects the high values for skewness and kurtosis over multiple generations. Further the ratio of response to selection and the difference of selection depends on the selection intensity.

Effektivität der Zuchtwertschätzung mit transformierten Daten, überprüft mit Mutter-Töchter-Paaren eines Wachtelexperimentes

Abstract. Title of the paper: Effectiveness of genetic evaluation with transformed data by using dam-daughter pairs of Japanese quails In estimation of variance components with REML it has been assumed that the data were normally distributed. Egg production traits of poultry have been shown to exhibit markedly non-normal distributions. In this study, six traits from an unselected quail line were analysed. The original data were transformed using the well-established power transformation to approach normality. The genetic evaluation was carried out with a multipletrait animal model, based on transformed and untransformed data, respectively. Two traits of laying performance, of egg weight and body weight were analysed simultaneously. To compare the efficiency of breeding values the method of simulated selection with biological data (dam-daughter pairs) was used. To select the dams with intensities between 10% and 90% we used individual records and BLUP-breeding values, estimated with transformed and untransformed data. The response of such a selection was estimated using the corresponding daughter records. Only for the trait laying Performance up to 200 days of life we could indicate an advantage of the transformation. It was shown, that by changing from one trait to multiple-trait genetic evaluation non-normality could be compensate. For 10% intensity the selection for individual laying performance provided an unexpected high response in comparing with the BLUP-method.

Simultane Zuchtwertschätzung mit Reinzucht- und Kreuzungsleistungen unter Dominanz

Abstract. Title of the paper: Joint genetic evaluation of purebred and crossbred data under dominance Currently available Software packages are not able to handle the Joint genetic evaluation of pure and crossbred data correctly. Instead, the same traits originating in the two purebreds and the crossbred are treated as three separate traits and analysed in a three trait animal model. Using selection index theory it can be demonstrated that this procedure contains model violations even if only additive genetic effects are considered. The effectiveness of the correct model which allows different contributions of the parental lines to the genetic variance of the cross including animal specific dominance effects is assessed on the basis of different selection indices. The sources of information chosen reflect those available in typical chicken breeding programs. The genetic parameters required for index construction – in particular the dominance variance and the genetic correlation between the pure and cross breds – were derived using a two locus model. If the purebred contribute extremely differently to the crossbred variance large losses in efficiency can be observed. With contributions of the sire line of 11, 19, 37 and 40% to the additive genetic variance of the cross corresponding losses in efficiency of selection where 13.1, 6.5, 0.6 and 0.2% respectively. Not considering the dominance variance – depending on its proportion relative to the total genetic variance – lead to a moderate loss of efficiency from 0.1 to 2.6%.

The occurrence of Poland and Poland-Moebius syndromes in the same family: further evidence of their genetic component

The combination of Moebius and Poland anomalies is rarely described in the literature. Some authors believe that this association is an independent syndrome, while others propose that Poland, Moebius and Poland-Moebius are a spectrum of the same condition. Here we report a family where a child has Poland-Moebius syndrome and an aunt is affected with Poland anomaly. This probably represents the second report of possible autosomal dominant transmission of Poland-Moebius syndrome. The presence of contralateral triphalangeal thumb in the proband and in other members of the family can be explained by chance alone or, alternatively, by a pleiotropic expression of this gene.

Pregnancy outcome after exposure to misoprostol in Brazil: a prospective, controlled study

BACKGROUND

Misoprostol, a synthetic prostaglandin E1 analog is labeled for the treatment of gastric and duodenal ulcers. In Brazil, where abortion is not a legal procedure, there is a widespread popular misuse of this drug in abortion attempts. This misuse and the fact that, in many cases the desired pregnancy termination does not occur, raise concerns about fetal safety. Case reports of congenital anomalies after maternal use of misoprostol have been published. The objective of this work was to compare pregnancy outcome following misoprostol exposure with a matched control group. This is the first prospective controlled study on fetal safety after misoprostol use.

METHODS

A prospective, observational cohort study with 86 exposed and 86 pair-matched, non-exposed controls.

RESULTS

There was no significant difference in the rates of major or minor birth between exposed compared to non-exposed infants (2/67 vs 2/81, major defects; 7/67 vs. 3/81, minor anomalies) There were significantly more miscarriages in the exposed group (17.1% vs. 5.8%; relative risk, 2.97; 95% confidence interval, 1.12 to 7.88). There was no statistical difference in gestational age at delivery, birth weight, sex ratio, rate of prematurity, low birth weight, or rates of cesarean section between groups.

CONCLUSIONS

Our study, despite its limited statistical power, does not suggest a potent teratogenic action of misoprostol exposure during pregnancy.

Use of misoprostol during pregnancy and Möbius' syndrome in infants

BACKGROUND

Patients with upper gastrointestinal ulceration may be treated with misoprostol, but it is not recommended for pregnant women because it may stimulate uterine contractions and cause vaginal bleeding and miscarriage. Recent data from Brazil, where misoprostol is used orally and vaginally as an abortifacient, have suggested a relation between the use of misoprostol by women in an unsuccessful attempt to terminate pregnancy and Möbius' syndrome (congenital facial paralysis) in their infants.

METHODS

We compared the frequency of misoprostol use during the first trimester by mothers of infants in whom Möbius' syndrome was diagnosed and mothers of infants with neural-tube defects in Brazil. All diagnoses in infants were made between January 16, 1990, and May 31, 1996, by clinical geneticists at seven hospitals who also interviewed the mothers and recorded information about the administration of misoprostol, among other data.

RESULTS

We identified 96 infants with Möbius' syndrome and matched them with 96 infants with neural-tube defects. The mean age at the time of the diagnosis of Möbius' syndrome was 16 months (range, 0.5 to 78), and the diagnosis of neural-tube defects was made within 1 week of birth in most cases. Among the mothers of the 96 infants with Möbius' syndrome, 47 (49 percent) had used misoprostol in the first trimester of pregnancy, as compared with 3 (3 percent) of the mothers of the 96 infants with neural-tube defects (odds ratio, 29.7; 95 percent confidence interval, 11.6 to 76.0). Twenty of the mothers of the infants with Möbius' syndrome had taken misoprostol only orally (odds ratio, 38.8; 95 percent confidence interval, 9.5 to 159.4), 20 had taken misoprostol both orally and vaginally, 3 had taken the drug vaginally, and 4 did not report how they took the drug.

CONCLUSIONS

Attempted abortion with misoprostol is associated with an increased risk of Möbius' syndrome in infants.

Thalidomide, a current teratogen in South America

Thalidomide, mainly used for the treatment of leprosy, is a current teratogen in South America, and it is reasonable to assume that at present this situation is affecting many births in underdeveloped countries. Moreover, the potential re-marketing of thalidomide for the treatment of a large variety of diseases may extend the problem to the developed world. When the drug is available, the control of its intake during early pregnancy is very difficult since most pregnancies are unintended. The ongoing occurrence of thalidomide embryopathy cases went undetected by the ECLAMC, due to several factors: (1) low populational coverage through this monitoring system; (2) pre-existence of the teratogen with its effects present in both baseline (expected) and monitored (observed) materials; and (3) lack of a defined phenotype to be monitored. Thus, if thalidomide re-enters the market throughout the world, due to the wide range of new applications, occurrence of phocomelia alone might not be sufficient to detect its effects. By a case-reference approach, the ECLAMC registered 34 thalidomide embryopathy cases born in South America after 1965 whose birthplaces correspond to endemic areas for leprosy. Phocomelia was found in five of eleven fully described cases. Thus, phocomelia alone is neither specific nor sufficient to serve as a suitable phenotype to survey the teratogenic effects of thalidomide. Therefore, a thalidomide-like phenotype, defined as any bilateral upper and/or lower limb reduction defect of the preaxial and/or phocomelia types, should be included in the routine surveillance of birth defects in all programmes.

The Wai Wai Indians of South America: history and genetics

Demographic medical and genetic information was obtained in a population of Carib-speaking Wai Wai Indians living in northern Brazil. At present mortality is low and fertility moderate, with a low variance in offspring number in completed families. Mobility is high, but about two-thirds of the unions are endogamic. Malaria is the main health problem. Phenotype and allele frequencies were obtained for 27 protein genetic systems. Comparison with six other Carib groups indicates closet affinities with another Amazonian tribe, the Arara. Quantification of the intra- and interpopulation genetic diversity in these seven populations indicate that the variation within groups is only slightly lower than the variation between groups. The level of Carib interpopulation diversity, on the other hand, does not differ significantly from that found in 11 Tupi-speaking populations. In accordance with their history of intermarriage with groups which speak slightly different languages, and consider themselves as distinct, the Wai Wai are clearly more diversified at the intrapopulation level than at least three of the six Carib populations with which they were compared.

Patterns in multimalformed babies and the question of the relationship between sirenomelia and VACTERL

Starting from a data base of over one million births investigated in 11 countries as a part of the Latin American Study of Congenital Malformations, 1,428 babies with three or more malformations without known pathogenesis or cause were studied. The objective was to search for statistically significant associations between defects and the delineation of new syndromes. One hundred and twenty-one patients presented an association between malformations of the digestive and urogenital systems involving mainly anal, renal, and genital anomalies, while 21 of them had 3 or more VACTERL defects. The frequencies of these defects were intermediate between those observed for VACTERL or sirenomelia, supporting the idea that these conditions have a similar pathogenesis. Statistical approaches like this one may be helpful in identifying processes and biological entities that may be missed using simple clinical observations.

Reconstructing history: the Amazonian Mura Indians

We studied demographic characteristics of two Mura Indian villages. Two-hundred six inhabitants of these villages and another population were tested in relation to 30 blood and 4 saliva genetic systems. These groups exhibit high mobility and exogamy rates and high fertility but relatively low mortality and variance in number of children per woman. Hb J Oxford and albumin Maku were observed, and they show high prevalences of GPT*1 and RH*R1 but low of HP*1 compared to other South American Indians. Four electrophoretic saliva systems are reported here for the first time in a predominantly Amerindian group. The amount of polymorphism was more limited than that found in Caucasian, black, and Oriental populations. The Mura are still predominantly Indian (82%) but have African (11%) and Caucasoid (7%) admixture. Using these values, the putative ancestral Mura gene frequencies were assessed. Problems related to quantitative estimations of admixture and the factors that influence the process are discussed.

Selection for fertility in mice - the selection plateau and how to overcome it

A long-term experiment for increasing the traits first day litter size (LS1) and litter weight (LW1) was conducted with two populations for 33 generations. The selection plateau was reached in population DU-C (selection and estrus synchronization (h(2) = 0.02±0.01); in population DU-K (selection) the plateau (h(2) = 0.05±0.2) was nearly reached. Selection progress per generation was in LS1 b = 0.11±0.02; b = 0.12±0.04 (1st to 18th generation DU-K, DU-C) and b = 0.10±0.03; b = 0.07±0.05 (19th to 33rd generation, DU-K, DU-C) in LW1 b = 0.16±0.04 g; 0.19±0.07 g (DU-K, DU-C) b = 0.20±0.09 g; 0.001±0.09 g (DU-K, DU-C). Reverse and relaxe selection as well as systematic inbreeding was applied for 10 generations. Reverse selection yielded h(2) = 0.28±0.11 (R-DU-K) and h(2) = 0.17±0.05 (R-DU-C) and showed that there was still additive genetic variance. Relaxe selection did not cause alterations in the selection parameters, whereas inbreeding lead to inbred depressions (b = LS1 = -0.42±0.15; -0.45±0.12; b = LW1 = -1.13±0.20; -0.82±0.18 I-DU-K, I-DU-C). The plateau was based upon the heterozygote advantage. Several methods for overcoming the plateau were applied. A new selective useful variance could be created by crossing the plateau populations (h(2) = 0.14±0.04). A short-term progress in overcoming the plateau (1st to 3rd generation) could be obtained by litter size standardization (LS = 388). Tandem selection (selection for body weight - BW42) as well as crossing of inbred strains were not suitable for overcoming the selection plateau. Altering the environmental conditions as a possibility for overcoming the plateau has been discussed.

Gd (+) Laguna, a new rare glucose-6-phosphate dehydrogenase variant from Brazil

A new G6PD variant, designated Gd (+) Laguna, was found in a 9-year-old Brazilian boy of Portuguese ancestry suffering from an iron-refractory anemia. The red cell enzyme activity of the subject was 64%. The mutant enzyme showed slower electrophoretic mobility, increased affinity for glucose-6-phosphate, decreased affinity for NADP+, elevated utilization of substrate analogues, decreased inhibition of NADPH, normal heat stability and a biphasic pH curve. The occurrence of the variant in two non-anemic relatives of the propositus indicates that the association between this G6PD type and anemia may be coincidental.