Estimation of (Co)Variance Components for Jersey Type Traits Using a Repeatability Model

Abstract

ABSTRACT(Co)variance components for final score and 15 linear type traits of Jersey cows were estimated by multitrait REML using multiple diagonalization and a repeatability model with 34,999 records of 22,354 cows. Multiple diagonalization gave relative offdiagonals (ratio of squared off-diagonals to the product of diagonals) of <0.1%. Heritabilities and repeatabilities, respectively, were estimated as 0. Estimates of heritability generally were higher, and estimates of repeatability were lower, than values used previously for USDA genetic evaluations, which were based on data from the 1970s and early 1980s. Final score was highly correlated both genetically and phenotypically with dairy form and rear udder traits. These estimates of heritabilities and (co)variance components are necessary for multitrait genetic evaluation of linear type traits of US Jerseys. (

Genetic Parameters and Evaluation of Rear Legs (Rear View) for Brown Swiss and Guernseys

“…Variance components were estimated with MTC (multitrait REML estimation of variance components program by canonical transformation with support for multiple random effects; I. Misztal, University of Georgia, Athens, personal communication); calculations were as described by Gengler et al (1997aGengler et al ( , 1997bGengler et al ( , 1999 using expectation-maximization REML and canonical transformation as described in Misztal (1994) and Wiggans et al (2004). The model included fixed effects for the interaction of herd, appraisal date, and parity (first or later); appraisal age (2-mo group; more months included for youngest and oldest ages) within parity (29 levels for each breed); and lactation stage (1 through 8 as assigned by the breed association) within parity (1, 2, and ≥3) and random effects for animal, permanent environment, and residual.…”

“…A multitrait animal model (Gengler et al, 1997a(Gengler et al, , 1997b(Gengler et al, , 1999 has been used to calculate type evaluations for Brown Swiss and Guernseys since February 1998. The purpose of this study was to estimate genetic parameters for RLRV and to develop a genetic evaluation system for this trait.…”

Type Trait (Co)Variance Components for Five Dairy Breeds

“…The variance component estimation program was provided by I. Misztal (University of Georgia, Athens), and calculations were as described by Gengler et al (1997), using expectation-maximization REML and canonical transformation. Final score was not included in the multitrait analysis because the Ayrshire and Jersey breeds compute this trait from linear scores.…”

“…The highest heritability was 0.54 for stature in Ayrshires, and the lowest was 0.07 for rear legs (side view) in Jerseys. Changes in heritability between this analysis and those of Gengler et al (1997) are given in Table 11. The largest increase was 0.10 for rump angle in Milking Shorthorns.…”

“…The multitrait analysis used in the USDA evaluations was implemented using a canonical transformation with missing data (Ducrocq and Besbes, 1993). The required (co)variance matrices, which include all linear traits for each breed, were estimated as described by Gengler et al (1997Gengler et al ( ) in 1997 Changes in the appraisal system for linear type traits have been implemented since 1997. Scoring of body depth was discontinued during 2002 for the Jersey Additional edit of 10% sample based on herd code imposed.…”