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Title: BREED OF SIRE DIFFERENCES FOR MALE AND FEMALE CALVES FOR CALCULATION OF ACROSS-BREED ADJUSTMENT FACTORS FOR GROWTH TRAITS

Author
item Van Vleck, Lloyd
item Cundiff, Larry

Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Weights of males and females can be considered to be correlated traits with different means and variances. This study attempted to determine if defin- ing traits as sex-specific would change estimates of breed of sire differ- ences needed to calculate across-breed factors for adjustment of within- breed EPD to across-breed EPD. Records from USMARC of progeny of Hereford and Angus dams mated to 12 sire breeds that were used to calculate breed o sire adjustments in 1996 were used. Breeds of sire were Hereford, Angus, Shorthorn, Brahman, Simmental, Limousin, Charolais, Maine-Anjou, Gelbvieh, Pinzgauer, Tarentaise, and Salers. Female and male records for birth, weaning and yearling weights were considered to be separate although corre- lated traits. Heritability estimates for females and males were: .44 and .47 for BWT, .25 and .19 for WWT, and .55 and .49 for YWT. Genetic corre- lations between sexes were .85, 1.00 and .92. Phenotypic standard devi- ations were slightly larger and coefficients of variation slightly smaller for males than for females with the largest differences for YWT. Breeds ranked similarly for female and male weights with major exceptions being Brahman for BWT and WWT; Simmental for WWT and YWT; Tarentaise for BWT; Hereford for WWT, and Limousin, Maine-Anjou and Gelbvieh for YWT. Averages of breed of sire contrasts for females and males were almost identical to contrasts from analyses of combined male and female records. Largest differences between averaged and combined breed of sire contrasts were less than 1 kg for BWT and WWT and slightly greater than 2 kg for YWT. The conclusion is that considering male and female weights as separate traits is not needed in calculation of across-breed adjustment factors from MARC records.