Phenotypic correlation between fiber density and pile ducts in alpacas (Vicugna pacos)

Abstract

Animal genetic improvement frequently deals with models that involve several characters, aiming for their simultaneous improvement. In multivariate relational scientific research, there are parameters that measure the relationship of association between variables, correlation coefficients form a group of these; It is necessary to define the most appropriate one, absolving the fulfillment of assumptions that give validity to its results. The objective was to determine the magnitude and significance of the linear association relationship between fiber density and number of hair ducts, for genetic selection purposes in alpacas, defining a selection criterion that increases productivity. In multivariate relational scientific research, there are parameters that measure the association relationship between variables, the correlation coefficients form a group of these; it is necessary to define the most appropriate one, acquitting the fulfillment of assumptions that give validity to its results. The objective of the study was to determine the magnitude and significance of the linear association between fiber density and number of hair ducts in alpacas.  The research is defined as Quantitative, non-experimental, cross-sectional and correlational; it was carried out at the Centro de Desarrollo Alpaquero Toccra de Arequipa, using 344 alpacas of the Huacaya and Suri breeds, of both sexes, categorized by age and of different colors.  The quantification of the variables was determined using the Fiber-Den equipment and accessories, in a work area prepared in the region of the middle rib of the animal, five readings of an area of one mm² each were recorded in the work area.  Pearson's moment product coefficient between the two traits was determined and the significance of which was determined by Student's t distribution approximation. Prior to its determination, compliance with the assumptions of bivariate normality, homoscedasticity and linearity was demonstrated; in addition, the power of the test, effect size and optimal sample size were determined.  The Pearson Correlation Coefficient (r) determined was r = 0.778 whose significance was p-value = 0.00000. It is concluded that r is positive, high and highly significant. The statistical power found was 0.99058 or 99.05 %.  The effect size was 0.5954 and the optimal sample size required was 25 individuals, defined for an α = 0.05 and a β = 0.99.