The Effects of Linear Models Assumed for the Analysis of Environmental Sources of Variation Upon Parameter Estimates : I. Models and Environmental Parameters

Authors: Yusuf VANLI, Hikmet ORHAN, Sinan BAŞ

Abstract: The production records of Merino lambs used in this study had been collected during a period of 16 years. The result obtained from the analysis of environmental factors can be summarised as (I) an important part of teh phenotypic variation observed on birth and weaning characteristics can be attributed to the effects of measurable environmental factors, (ii) the environmental factors investigated caused more variation on quantitative measurement, than that of the scored values, (iii) the constant estimates for the age of dam, sex of lamb and type of birth or rearing showed higher values by the analysis of Model 4 from which birth weight as a covariable was removed, (iv) the level of significance of some environmental factors was depended upon the mathematical models assumed. Consequently, statistical control and adjustment for cartain environmental causes of phenotypic variation was found significant for selecting the lambs at weaning with respect to the characteristics under consideration.

Keywords: Quantitative characters of lambs, sources of variation, models for statistical Analysis, phenotypic variation