Use of multitrait evaluation procedures to improve reliability of early prediction of survival

Multitrait, across-country evaluation procedures were adapted to improve reliability of survival breeding values by combining direct information with yield and functional traits: milk persistency, somatic cell count, fertility (male and female), and calving ease (direct and maternal). A set of bulls was selected from the Austrian Simmental population based on mean original reliabilities of at least 0.50 for yield traits or of at least 0.20 for functional traits. Only breeding values above these limits were retained. The breeding values were deregressed, assuming that they were obtained by single-trait, sire-maternal grandsire models. An expectation maximization restricted maximum likelihood algorithm based on the multitrait, across-country evaluation equations was used to compute genetic correlations among all of these traits. These equations were solved, and the reliabilities of the solutions were also estimated. Mean rank correlation between direct and combined breeding values was 0.85 with values as low as 0.67 for the group of youngest bulls, Direct (original), indirect, and combined reliabilities were compared to appreciate the impact of our procedures on improvement of reliability of survival breeding values; This improvement, dependent on the level of reliability of direct and indirect information, could be up to 0.24 for animals with low direct reliability and high indirect reliability. For young bulls born in 1992 without reliable direct survival information but with already reliable information on yield and functional traits, mean reliability improvement was 0.13. For all bulls this value was still 0.06

Cylindrical, periodic surface lattice — theory, dispersion analysis, and experiment

A two-dimensional surface lattice of cylindrical topology obtained via perturbing the inner surface of a cylinder is considered. Periodic perturbations of the surface lead to observation of high-impedance, dielectric-like media and resonant coupling of surface and non-propagating volume fields. This allows synthesis of tailored-for-purpose "coating" material with dispersion suitable, for instance, to mediate a Cherenkov type interaction. An analytical model of the lattice is discussed and coupled-wave equations are derived. Variations of the lattice dispersive properties with variation of parameters are shown, illustrating the tailoring of the structure's electromagnetic properties. Experimental results are presented showing agreement with the theoretical model

On the value of incorporating dominance effects in genetic evaluation of dairy cattle.

peer reviewedCurrent genetic evaluations ignore dominance effects. However, their incorporation might result in gain of accuracy of breeding values depending on dominance variance and on the number of animals with dominance relationships (Misztal et al., 1995). Furthermore, dominance effets can be used to implement mating systems (DeStefano and Hoeschele, 1992; Varona and Misztal, 1999). With the development of algorithms for large datasets using models with nonadditive genetic components, rapid inversion of dominance relationship matrices, and Method ℜ for computation of variance components with large data sets, there has been an interest in dominance effects over the last years. This interest is also due to datasets that include more relationships (e.g. fullsibs) necessary for estimating nonadditive genetic effects. The objectives of this papers were to 1) discuss previously estimated variance components for dominance effects in dairy cattle and to 2) use these components to draw conclusions on the value of incorporating dominance effects in genetic evaluation of dairy cattle

Improved genetic evaluation of survival using MACE to combine direct and correlated information from yield and functional traits

peer reviewedObjective of this study was to improve the estimation of survival breeding values using multiple-trait across country evaluation procedures to combine direct information with milk, fat and protein yields and functional traits: milk persistency, somatic cell count, fertility (male and female) and calving ease (direct and maternal). A set of bulls was selected from the Austrian Simmental population and their breeding values were deregressed. An Expectation-Maximization REML procedure based on the multiple-trait across country evaluation equations was used to compute genetic (co)variance components among all traits and to predict breeding values

Cross-breeding cattle for milk production in the tropics: achievements, challenges and opportunities

This paper reviews experiences with cross-breeding for milk production in the tropics. Data were compiled from 23 different studies evaluating the performance of different grades of cross-bred animals as well as local breeds. Relative performance of indigenous breeds compared with different grades of cross-breeds was calculated for three climatic zones. Traits considered were milk yield per lactation, age at first calving, services per conception, lifetime milk yield and total number of lactations completed. At 50 percent 'Bos taurus' blood, lactation milk yields were 2.6, 2.4 and 2.2 times higher than those of local cattle in the highland, tropical wet and dry, and semi-arid climatic zones, respectively; lactation lengths increased by 1.2, 1.2 and 1.9 months in the above-mentioned climatic zones, respectively; there was a reduction in calving interval by 0.8 times and in age at first calving by 0.9 times. Similarly, cross-breds with 50 percent 'B. taurus' genes had 1.8 times higher lifetime milk yields and a 1.2 times higher number of total lactations. Although cross-breeding faces a number of challenges such as better infrastructure, higher demand for health care, there are many advantages of using it. These are higher production per animal, higher income for the families and provision of high-value food. It is therefore likely to continue to be an important livestock improvement tool in the tropics in the future, where farmers can provide sufficient management for maintaining animals with higher input requirements and access to the milk market can be secured