Application of Canonical Transformation with Missing Values to Multitrait Evaluation of Jersey Type

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Genetic parameters were estimated for rear legs (rear view; RLRV) and 15 current linear type traits of Brown Swiss and Guernsey dairy cattle. The Brown Swiss Cattle Breeders' Association of the USA and the American Guernsey Association began scoring RLRV in 2004. For Brown Swiss, 8,502 records were available for 7,676 cows in 417 herds; Guernsey data included 5,437 records for 4,749 cows in 229 herds. Nine unknown-parent groups were defined for each breed, each with 2 birth years. The model included fixed effects for the interaction of herd, appraisal date, and parity; appraisal age within parity; and lactation stage within parity and random effects for animal, permanent environment, and residual error. The multitrait analysis for RLRV and the 15 linear type traits used canonical transformation, multiple diagonalization, and a decelerated expectation-maximization REML algorithm. For Brown Swiss, heritability was 0.102 for RLRV and ranged from 0.099 for rear legs (side view) to 0.453 for stature. For Guernseys, heritability ranged from 0.078 for RLRV to 0.428 for stature. For Brown Swiss, the highest genetic correlation with RLRV was 0.71 for rear udder width; the most negative correlation was −0.19 with rump angle. For Guernseys, the highest genetic correlations with RLRV were 0.43 for rear udder width and 0.42 for body depth; the most negative correlation was −0.46 with rear legs (side view). With heritability near 0.10, RLRV should be useful in selection for improved locomotion. Release of genetic evaluations for RLRV began in May 2006 for Brown Swiss and Guernseys.

Section: Calculation Of Evaluationsmentioning

confidence: 99%

Section: Estimation Of Variance Componentsmentioning

confidence: 99%

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

Wiggans

Thornton

Neitzel³

et al. 2006

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“…Required variance components for solving step 2 were those from the fourth analysis that included records with observations for all lactation stages. Solutions for step 2 were obtained using data from all lactation stages for cows with records in analysis 1 and the method of Gengler et al (6). Records then were adjusted for solutions from step 2, and the adjusted records were used to compute solutions for step 1.…”

Section: Iterative Solutionmentioning

confidence: 99%

Estimation of (Co)Variances of Test Day Yields for First Lactation Holsteins in the United States

Gengler¹,

Tijani²,

Wiggans³

et al. 1999

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ABSTRACT(Co)variance components for milk, fat, and protein yields during first lactation were estimated from data for test days from 23,029 Holstein cows from 37 herds in Pennsylvania and Wisconsin. Four lactation stages of 75 d were defined, and the test day nearest the center of each interval was used. In four analyses, a lactation stage was added, and observations with missing values were deleted; 17,190 observations were available for the final analysis of lactations with test days in all lactation stages. Missing values were deleted because a canonical transformation was used for estimation of (co)variance matrices. Heritability estimates were similar across analyses, which indicated little effect from selection. Heritabilities usually increased with lactation stage and were highest for milk; mean heritability estimates were 0.19 for milk, 0.14 for fat, and 0.16 for protein. Phenotypic and genetic correlations were higher between milk and protein than between milk and fat. Within a yield trait, genetic correlation declined from 0.90 for adjacent stages to 0.75 for milk and protein and to 0.82 for fat between initial and final lactation stages. Within lactation stage, mean genetic correlations were 0.40 between milk and fat, 0.78 between milk and protein, and 0.56 between fat and protein; corresponding mean phenotypic correlations were 0.64, 0.91, and 0.66. The effect of solving the model iteratively was examined with records that had been adjusted using solutions from fitting the full model. Heritabilities for the beginning of lactation increased slightly with the iterative solution, which indicated a better model fit.

“…Solutions and reliabilities were computed using the method of Gengler et al (6) and the (co) variances estimated in this study. The procedures for evaluation were based on a canonical transformation extended to multiple random effects, which allowed for missing values (2,4,6).…”

Section: Genetic Evaluationmentioning

confidence: 99%

Animal Model Genetic Evaluation of Type Traits for Five Dairy Cattle Breeds

Gengler

Wiggans

Wright

1999

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A system to calculate genetic evaluations based on an animal model was developed for final score (single-trait model) and 15 linear type traits (multitrait model) of Ayrshires, Brown Swiss, Guernseys, Jerseys, and Milking Shorthorns. (Co)variance components were estimated from appraisals that were scored during 1988 and later and that included all linear traits. The model for (co)variance components included fixed effects for interactions of herd, appraisal date, and parity; parity and appraisal age; and parity and lactation stage. Random effects were included for permanent environment, animal, and residual. A canonical transformation was used with approximate diagonalization. Data for estimating breeding values included appraisals from 1980. Effects for appraisal age and lactation stage were defined within appraisal year group. The model for calculation of breeding values also included a random effect of interaction between herd and sire. Solutions for appraisal age from a preliminary analysis were smoothed with a quadratic curve to generate additive age adjustments by month for appraisal age, parity, and appraisal year group. Correlations of solutions from this model and from the former USDA sire model for bulls that were born during 1975 or later and that had 20 daughters were highest (generally 0.90) for Guernseys and were lowest (generally <0.80) for Milking Shorthorns. The evaluation system was implemented in February 1998 and was extended to Red and Whites.