If you are interested in any of the following topics or if you have questions, please contact Peter von Rohr (Qualitas AG) Chamerstrasse 56, 6300 Zug; peter.vonrohr@qualitasag.ch, Tel 041 768 92 21.
Interbull provided a set of recommendations for harmonising calving traits in the framework of MACE (multiple across country evaluation) evaluations. The central task of the project will be to understand the current evaluation for calving traits (dairy population) in Switzerland and to implement the Interbull recommendations in the current system. To do this, adaption of data preparation and estimation of new variance components are required.
In populations with a low rate of artificial insemination, it is often a problem that effects of herds cannot be compared or estimated. There are different measures that indicate such problems. These measures are all contained in the general concept of connectedness.
An analysis comparable to https://doi.org/10.3168/jds.2018-15858 is to be developed.
Based on the results of a previous master thesis, different comparison studies should be undertaken where conventional linear mixed models are compared with the generalized linear mixed model based on the same data set.
Some beef cattle breeds (Charolais, Limousin, …) are looking into the genetic basis of the myostatin-gene (double-muscle). Recent developments in genomic selection of beef cattle in Switzerland give the possibility to analyse the status of the myostatin-gene in the Swiss beef cattle breeds. A specific emphasis is to be put to the relationship with other important characteristics of the animals such as calving traits.
This trait is associated with efficiency and with environmental footprint of animals. A number of publications already exist on this topic. Tasks would consist of
The Swiss Federal government has decided on measures to reduce the amount of phosphoros (P) and nitrogen (N) that is released to the environment due to livestock production. The possible impact of such measures is to be investigated.
In the more recent past huge efforts are undertaken to improve feed efficiency of dairy cows. Thies is due to the fact that the economic pressure for dairy farms have dramatically increased during the past few years and also because of the higher awareness of the impact of livestock production on the environment. In this project the possibilities to improve feed efficiency at the genetic level are to be researched, discussed and if possible evaluated.
Examples:
An important aspect of a change from a two-step marker-effect model to a single-step GBLUP-procedure is that the latter often assume that all SNP contribute a very small amount to the genetic variance. This violates the generic model of quantitative genetics which states that only a few QTL are responsible for the expression of a quantitative trait. The advantage of the single-step GBLUP-procedure is that it is stable across evaluations which is most likely due to its shrinkage feature.
Genetic variance of a trait of interest can usually not be explained completely by markers linked to QTL (cf. “missing heritability”). In single step genomic evaluations, where genomic and phenotypic information are combined in a single evaluation, this issue is commonly addressed by including a residual polygenic (RPG) term in the used models. This term is derived from pedigree information and included in the H-Matrix, the relationship matrix for single step evaluations. A weight is assigned to the RPG in comparison to the genetic part of the matrix. Commonly this term is set to a value between 0.1 and 0.3. A possible reference for this problem is Liu, Z., Goddard, M. E., Hayes, B. J., Reinhardt, F., & Reents, R. (2016). Technical note: Equivalent genomic models with a residual polygenic effect. Journal of Dairy Science, 99(3), 2016–2025. Technical note: Equivalent genomic models with a residual polygenic effect (available in Mendeley). In order to implement single step genomic evaluation a definition of RPG is required. During the project the problem of RPG will be adressed. The central task of the project will be to investigate and understand the effect of different RPG on single step breeding values and their reliabilities. Different criteria such as validation reliabilities will be used in order to investigate this question.
If you are interested in any of the following topics or if you have questions, please contact Peter von Rohr (Qualitas AG) Chamerstrasse 56, 6300 Zug; peter.vonrohr@qualitasag.ch, Tel 041 768 92 21.
Latest Changes: 2023-12-15 08:52:18 CET (pvr)