Per Madsen

Genotype by Environment Interaction in Nordic Dairy Cattle Studied Using Reaction Norms

Genotype by environment interaction for production and fertility was studied by use of a reaction norm model. Milk recording data, comprising 927 929 records, were analysed to predict reaction norms for young bulls of the Nordic Red dairy breeds. Random regressions were estimated for each bull, regressing phenotypic values of daughters on herd environment. The phenotypic measures were 305 days kg protein production and days open in first lactation. The herd environment was defined as the herd-year average of protein production and days open, respectively. Heritability of protein production and days open and genetic correlation between the two traits were estimated as functions of the herd environment. The results showed that the genetic parameters change over environments, which are measured on a continuous scale across countries. Grouping of observations is avoided and thereby the problem of genetic connectedness between groups or countries may be avoided. Although significant genetic variation for the slope of the reaction norm was found, there was little reranking of sires, except between extreme environments. More appropriate models and methods need to be developed for further studies of genetic variation in reaction norms.

Genetic improvement of livestock for organic farming systems

Abstract Organic farming which experienced a constant rise over the last two decades is a system based on sustainability and on a concept tending towards functional integrity. Legislation as well as the wish to produce separately from conventional farming raise the question whether organic farming should be conducted completely apart from conventional farming or not. This paper discusses the aspects that affect animal breeding under these circumstances, e.g., maintaining genetic diversity by using local breeds and possible G×E interactions which might occur when breeds adapted to conventional farming systems are used in organic farming. Ways of modelling G×E are presented, moreover examples of G×E in dairy cattle, swine, and poultry are given. Trends in selection index theory—designing multi-trait breeding goals including functional traits on one hand, and developing methods for using customised selection indices on the other hand—support breeding work for organic farming systems. It is concluded that before the technical issues can be addressed, all parties involved, farmers, consumers as well as legislators, have to agree on the socio-cultural conditions under which organic farming should be conducted.

An approximate multitrait model for genetic evaluation in dairy cattle with a robust estimation of genetic trends (Open Access publication)

In a stochastic simulation study of a dairy cattle population three multitrait models for estimation of genetic parameters and prediction of breeding values were compared. The first model was an approximate multitrait model using a two-step procedure. The first step was a single trait model for all traits. The solutions for fixed effects from these analyses were subtracted from the phenotypes. A multitrait model only containing an overall mean, an additive genetic and a residual term was applied on these preadjusted data. The second model was similar to the first model, but the multitrait model also contained a year effect. The third model was a full multitrait model. Genetic trends for total merit and for the individual traits in the breeding goal were compared for the three scenarios to rank the models. The full multitrait model gave the highest genetic response, but was not significantly better than the approximate multitrait model including a year effect. The inclusion of a year effect into the second step of the approximate multitrait model significantly improved the genetic trend for total merit. In this study, estimation of genetic parameters for breeding value estimation using models corresponding to the ones used for prediction of breeding values increased the accuracy on the breeding values and thereby the genetic progress.

Unit testing using design by contract and equivalence partitions

Extreme Programming [1] and in particular the idea of Unit Testing can improve the quality of the testing process. But still programmers need to do a lot of tiresome manual work writing test cases. If the programmers could get some automatic tool support enforcing the quality of test cases then the overall quality of the software would improve significantly.

Genetic Parameters of Foot and Leg Traits in Future AI Bulls: I. Influence of Age at Recording and Classifier

Information on foot and leg traits was collected on 8494 young potential future AI bulls of the three populations Danish Red, Danish Friesian and Danish Jersey by two classifiers between 1985 and 1996. Each animal was assessed at 5 and 10 months of age. The data set was used to examine the influence of age and classifier on genetic parameters of foot and leg traits by treating traits recorded at two different times or by two different people as a different characteristic in a bivariate analysis. The general incidence of foot and leg diseases was very low in young animals: only interdigital dermatitis, heel necrosis and solar bruising showed a frequency higher than 2% in 10-month-old bulls. The same traits measured on different claws yielded very high genetic correlations (rg 0.77-0.98), suggesting that the number of measurements could be reduced. Hooves increased in size with age, and the genetic correlation between the two age classes was high (rg 0.60-0.77). The agreement between classifiers was very high for objectively measured traits, especially for the younger age class, and interdigital dermatitis and heel necrosis, but inconclusive for the subjectively scored characteristics.

Genetic Parameters of Beef Production Traits and Disease Incidence of Growing Bulls

Wassmuth, R., Boelling, D., Madsen, P., Jensen, J. and Andersen B.B. (Institute of Animal Husbandry and Genetics, University of Göttingen, Albrecht-Thaer-Weg 3, D-37075 Göttingen, Germany and Department of Animal Breeding and Genetics, Danish Institute of Agricultural Sciences, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark). Genetic parameters of beef production traits and disease incidence of growing bulls.. Accepted August 17, 1999. Acta Agric. Scand., Sect. A, Animal Sci. 50: 103–110, 2000.

A Parallel Solver for Animal Genetics

The use of linear multivariate mixed models in animal genetics, leads to very large, sparse linear systems of equations. The sparse, symmetric coefficient matrix is too large to be constructed explicitly. We describe a parallel, iterative linear equation solver for large sparse systems, developed by DIAS and UNI-C. The solver takes advantage of the structure of the multivariate mixed model equations, and is based on Gauss-Seidel and second order Jacobi iteration. It is parallelized for distributed memory architectures.

Changes in body weight and frame and its genetic variation during the productive life of dairy cows

Abstract Data used were body weights and physical measures on hip height, body depth, chest girth, hip width, and body length taken at an experimental dairy herd of three breeds (Holstein, Jersey and Danish Red). Random regression mixed models were used to evaluate changes in variances through the productive life of dairy cows in body weight and in each of the physical measures. To indicate the frame size of a cows body, a frame index was established based on linear physical measures, which was a simple cross-product of body depth by hip width. Further analyses with a random regression mixed model indicated that the changes in the index values over age reflect well the process of growth, and were only marginally affected by stages of lactation. Frame index and body weight were highly correlated. However, if breeding for frame size was desired, the frame index would be a preferred selection criterion over the more conventional criterion of body weight, because body weight measures were affected equally by growth and body condition.

Clearancebestimmungen mit Radioisotopen — Experimentelle und klinische Anwendung

Zur Beurteilung einzelner Nierenfunktionen werden zunehmend Untersuchungen mit Hilfe radioaktiv markierter Substanzen herangezogen, obwohl mit konventionellen Methoden (Inulin-, Paraaminohippursaure-, Kreatininclearance-bestimmungen) anscheinend bereits zufriedenstellende Ergebnisse erzielt werden konnen.