The aim of this paper is to estimate breeding values for micro-environmental sensitivity (vEBV) in milk yield and somatic cell score, and their associated variance components, on a large dairy cattle data set having more than 1.6 million records. These differences appear to be heritable, and the need exists, therefore, to fit models to predict breeding values explaining differences in residual variance. Trait uniformity, or micro-environmental sensitivity, may be studied through individual differences in residual variance. Rönnegård, L Felleki, M Fikse, W F Mulder, H A Strandberg, E Variance component and breeding value estimation for genetic heterogeneity of residual variance in Swedish Holstein dairy cattle. Considering the differences in heritability between musculoskeletal robustness (mesomorphy) and subcutaneous adipose tissue (endomorphy) it may be questioned whether studying the genetics of BMI will eventually lead to a better understanding of the genetics of fatness, obesity and overweight. The heritability is also lower than values reported for, for example, body mass index (BMI), which next to the weight of organs and adipose tissue also includes muscle and bone tissue. For endomorphy, which represents a relative measure of subcutaneous adipose tissue, however, the results suggest heritability may be considerably lower than most values reported in earlier studies on adolescent twins. The findings suggest that the high heritabilities for mesomorphy and ectomorphy reported in earlier twin studies in adolescence are maintained in adulthood. For all components in men and women, more than 70% of the total variation was explained by sources of variance shared between the three components, emphasising the importance of analysing the ST in a multivariate way. After age-regression, variation of the population in ST components and their covariation is explained by additive genetic sources of variance (A), shared (familial) environment (C) and unique environment (E). The results indicate the significance of sex differences and the significance of the covariation between the three ST components. Eight hundred and three members of 424 adult Flemish twin pairs (18-34 years of age). To study the genetic and environmental determination of variation in Heath-Carter somatotype (ST) components (endomorphy, mesomorphy and ectomorphy). Peeters, M W Thomis, M A Loos, R J F Derom, C A Fagard, R Claessens, A L Vlietinck, R F Beunen, G P Heritability of somatotype components: a multivariate analysis.
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