%0 Journal Article
%T A Proposed Selection Index for Jersey Cattle in Zimbabwe
%A Edward Missanjo
%A Venancio Imbayarwo-Chikosi
%A Tinyiko Halimani
%J ISRN Veterinary Science
%D 2013
%R 10.1155/2013/148030
%X A multitrait selection index for Zimbabwean Jersey cattle was constructed. The breeding objective was defined in terms of production and functionality traits. The production component of the index included milk yield , butterfat yield , protein yield , butterfat percent , and protein percent , while the functional component included the somatic cell count (SCC). The index was termed as . The accuracy of the index was 91.1%, and the correlation between this index and the aggregate breeding objective was 0.954. A selection index is more important in the selection of sires and cows. This leads to the greatest genetic progress and hence productivity in the dairy sector. Therefore, the application of the selection index developed is necessary if the dairy cattle industry is to maximise the exploitation of genetics and to improve its relative competitive position. 1. Introduction K£¿nig and Swalve [1] presented a multiple correlation method of constructing optimum selection indexes. However, to solve the simultaneous equations, the genetic parameters (heritability and genetic correlations) and phenotypic parameters (standard deviation and correlations) among traits must be known. When these traits differ in variability, heritability, and in the correlation among their phenotypes and genotypes, index selection is more effective than independent culling levels or sequential selection [2], and the construction of an index is not easy without the use of matrix methods, particularly, if there are more than two sources of information, and improves as the number of traits in the selection index increases [3]. Dekkers [4] reported that the selection of both production traits (protein yield, protein %) and functional traits (longevity, milkability, and somatic cell score) increased the selection index efficiency to 58%. S£¿rensen et al. [5] found that the selection of milk yield, somatic cell score, udder depth, teat placement, and foot angle improved efficiency of response in the aggregate genotype by 1% to 4% over selection for milk yield alone. Sun et al. [6] reported that for improving milk yield, selection indices comprising milk, fat, or protein yields were 98%¨C100% as efficient as an index comprising all three traits. Selection on milk yield alone was 5% less efficient in improving milk yield compared with the selection using an index of all three traits. According to [7], every country should develop its selection index because the success of selection index from different countries cannot be compared, even though breeding goals are very similar. For some time
%U http://www.hindawi.com/journals/isrn.veterinary.science/2013/148030/