Genetic Analysis of Some Growth and Carcass Traits in Beef Cattle

Growth and carcass data were collected during 10 yr at the Fort Keogh Livestock and Range Research Laboratory in Miles City, MT from a Hereford herd selected at random. The objective was to compare genetic parameter estimates from this randomly selected herd with estimates from published selection studies. Only bulls were included in the data set. Bulls were slaughtered between 14 and 17 mo of age. Genetic parameters were estimated by the paternal half-sib procedure. Data were subdivided into three subgroups: 1) all bulls that had birth weights, 2) bulls with complete records for growth traits, and 3) bulls with complete carcass and growth records. The heritability estimate for birth weight on 736 progeny from 86 sires was .18. The second group included 616 progeny representing 85 sires and heritability estimates were weaning weight, .17; daily gain from birth to weaning, .20; final test weight, .42; and daily gain on test, .47. The third group included 401 progeny from 75 sires and heritability estimates were carcass weight, .38; longissimus muscle area, .51; marbling, .31; slaughter weight, .42; and dressing percentage, .25. Thus, these estimates of heritability were in quite good agreement with previously published values, with a tendency for these estimates to be lower for early growth weights. Phenotypic and environmental correlations were in good agreement and genetic correlations were in general agreement with the data reviewed. Estimates of heritabilities from this herd selected at random were not larger than previous estimates from selected herds.

Section: Resultssupporting

confidence: 93%

Section: Resultscontrasting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

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Paternal half-sib heritabilities and genetic, environmental, and phenotypic correlation estimates from randomly selected Hereford cattle

Veseth

Reynolds

Urick

et al. 1993

“…The rg of adjusted fat at 12th rib, marbling score, and longissimus muscle fat with carcass composition (e.g., percentage of retail product and carcass fat weight) were high. However, the rg of marbling score with other measures of fat were lower than those reported by Cundiff et al (1964) and by Koch et al (1982). The positive rg of marbling score with other measures of fat (e.g., .66 If: .l2 with percentage of fat trim) and negative rg between marbling score and measures of carcass composition (e.g., -.60 k .20 with percentage of retail product) reflect the difficulty of genetically increasing marbling score while maintaining a favorable 1ean:fat ratio in the carcass.…”

Section: Least Squares Means Genetic and Phenotypic Sfandard Deviatcontrasting

confidence: 49%

Genetic and phenotypic (co)variances for growth and carcass traits of purebred and composite populations of beef cattle

Gregory

Cundiff

Koch

1995

Self Cite

Least squares means, genetic ( ug), and phenotypic ( up) standard deviations, and phenotypic coefficients of variation ( C V ) were estimated on an age-constant basis for growth, carcass, and meat traits of castrate males from 12 breed groups combined, for 9 purebreds combined, and for the F 3 generation of three composite populations combined to which the nine purebreds contributed. Also, heritabilities ( h2) and genetic ( rg) and phenotypic ( rp) correlations were estimated among growth, carcass, and meat traits for all breed groups combined involving 1,594 individuals that were the progeny of 306 sires (214 purebred and 92 composites). Coefficients of variation and ug generally were similar for composites and contributing purebreds for growth and size-related traits. For traits relating to carcass composition and meat quality, means, up, or CV for composites and contributing purebreds generally were similar. Generally, estimates of ag and h2 were similar among all breed groups combined, contributing purebreds combined, and composites combined. Generally, rg were high among all measures of carcass fat, indicating major diffkulty in achieving a high percentage of retail product simultaneously with a high fat content of the longissimus muscle that is required for carcass quality grade. Generally, rp were of smaller magnitude than rg. All rp of marbling score or percentage of ether-extracted fat in the longissimus muscle with all end-use properties relating to palatability including shear force, and sensory evaluation of tenderness, juiciness, and flavor were below .30.

“…Woodward et al (1992) concluded that the lower additive genetic variance estimates for carcass traits, in comparison to growth traits, suggest that slow genetic progress in carcass traits would result if major emphasis were put on carcass traits in a selection program. Others (Cundiff et al, 1964;Dinkel and Busch, 1973;Wilson et al, 1976;Koch, 1978) also have determined that selection emphasis placed on growth traits is more effective than selection on carcass traits.…”

Section: Carcassmentioning

confidence: 99%

Use of expected progeny differences for marbling in beef: I. Production traits.

Vieselmeyer

Rasby

Gwartney

et al. 1996

Six Angus bulls with HIGH (>.4) and six bulls with LOW (<−.16) expected progeny differences (EPD) for marbling were used to evaluate the impact of marbling on progeny production and carcass traits. Bulls were randomly bred to MARC II ( Ô Hereford, Ô Simmental, Ô Angus, Ô Gelbvieh) composite cows in each of 2 yr to calve in the spring. At weaning, steers and heifers were separated and managed in different production systems. Steers ( n = 131) were fed a growing diet (1.1 Mcal of NE g /kg) for 48 d followed by adaptation to a 93% concentrate finishing diet. Heifers ( n = 125) were fed a growing diet (.79 Mcal of NE g /kg) for 191 d followed by adaptation to the same 93% concentrate diet. Steers and heifers from each treatment were slaughtered at two times spaced about 60 d apart within both years. Marbling EPD class had no effect on fat thickness, USDA yield grade, carcass weight, finishing daily gain, finishing DMI, or finishing efficiency ( P > .18). More ( P < .05) carcasses of calves from sires with HIGH EPD for marbling graded USDA Choice than from LOW EPD sires, 74% vs 47%, respectively. Angus sires can be selected to produce progeny that have increased ability to grade Choice without increasing yield grade or decreasing animal growth or feed efficiency.