Fibre Diameter Distribution Characteristics of Midside (Fleece) Samples and Their Use in Sheep BreedingThe relationship between fibre diameter mean and distribution was studied in a large dataset of midside samples from hundreds of flocks. The implications of the relationships are discussed in relation to using these measurements in sheep breeding programs. Some modifications to current phenotypic parameter estimates are suggested.
The Relative Importance of Information on Unrelated Individuals on the Prediction of Genomic Breeding ValuesThe theory of genomic selection is based on the prediction of the effects of genetic markers in linkage disequilibrium (LD) with quantitative trait loci (QTL). However, there is increasing evidence that genomic selection also relies on relationships between individuals or the patterns of LD associated with these relationships to accurately predict genetic value. This study aimed to examine the relative importance of information on essentially unrelated individuals on the estimation of breeding value when using gBLUP and BLUP. Analysis was undertaken using a simulated population of 2000 animals. Two reference populations were formed from 1750 animals and the accuracy of prediction was assessed for the remaining 250 animals that formed the test population. Two test populations were constructed such that one included 10 families that had no family members in the reference population and the other included 5 half siblings from 50 families. The gBLUP method more accurately predicted breeding value than BLUP in both test populations. The highest accuracy was achieved when gBLUP was used to predict the breeding value of closely related animals. However, gBLUP was still able to predict breeding value accurately even when animals were distantly related.
Preference-Based Approaches to Deriving Breeding Objectives: Application to Sheep and Plant BreedingA preference-based approach, using the internet-based software 1000Minds, was used to derive part-worth utilities of farmers’ assessments with respect to traits in the definition of a breeding objective for sheep in Ireland and pasture plants in Australia. The most critical issue in developing such approaches is the clear definition of traits and the use of realistic ranges of variation in trait performance in order to define alternatives. Conversion of part-worth utilities (percentages) into economic values requires that the economic value is generated within the survey by providing respondents with options that relate to traits which can be defined in economic terms. In presenting alternatives, application of discounted gene-flow principles to breeding objectives in survey-based methods depends on the way questions are asked. It was apparent that respondents’ understanding of traits (attributes, levels), experience with the traits, and how alternatives are presented are very important in using preference-based approaches to define breeding objectives. Issues related to separation of true differences in preferences,confounding and double counting (in animal breeding objectives) are challenges in development of breeding objectives from such preference approaches.
- Without ignoring breed standards and common sense, breeders can apply their own interpretations and tastes, creating the healthy diversity necessary for the ultimate survival of the species. I realize that I’ve made this point before – but it’s an important one and bears repeating. No matter what your own personal vision or dream is, before you decide to embrace a trend, ask yourself: “Is it fad or function?”
- Strategies for breeders and breed associations.