Evaluation of ultrasound and other sources of information to predict beef carcass traits and final carcass value

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Title: Evaluation of ultrasound and other sources of information to predict beef carcass traits and final carcass value
Author: Dean, Dustin Tyler
Abstract: Purebred Beefmaster steers (n = 160 ) from five owners were fed at a commercial feedlot in South Texas beginning in November of 2004 ; 68 steers possessed pedigree information . Beginning in mid -November , steers were individually weighed and evaluated for ultrasound body composition at 56 -d intervals by a certified technician . Feeder calf frame (FRM ) and muscle (MUS ) scores were assigned at initial ultrasound evaluation . Steers were fed and marketed through a lean -based , branded beef program and were harvested in two groups in May and June of 2005 at a commercial beef plant . Analyses were conducted to investigate the ability to predict carcass traits from the different sources of information available on these cattle . Evaluation of carcass traits were investigated using four sets of independent variables referred to as sources A , B , C , or D and ultrasound scan session (1 ? ? 4 ) . An analysis included initial weight at first scan session (IWT ) , FRM and MUS as independent variables through GLM procedures . B analyses utilized ultrasound measures of the longissimus area , intramuscular fat , fat thickness , rump fat , and gluteus medius depth along with IWT as independent variables . Multiple regression was performed on each carcass trait using IWT and ultrasound traits at each scan session . Mallow ? ?s CP was used to select a model that best described each carcass trait . C analyses (GLM ) utilized variables from A and B analyses combined plus ranch . D analyses (GLM ) included variables from C analyses plus sire nested within ranch . Respective R -square values (scan 1 ? ? 4 ) for marbling score were .02 , .04 , .05 , and .10 using A information , .14 , .17 , .42 , and .54 , using B information , .35 , .35 , .47 , and .55 using C information , and .56 , .59 , .65 , and .76 using D information . R -square values ranged from .34 to .86 for carcass weight , .11 to .77 for fat thickness , .06 to .82 for ribeye area , and .10 to .81 for yield grade . Ultrasound data obtained closer to harvest and increasing amount of data related to genetic and management background showed increased R -square values , but may be best utilized in conjunction with one another to predict carcass traits and final carcass value .
URI: http : / /hdl .handle .net /1969 .1 /3919
Date: 2006-08-16

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Evaluation of ultrasound and other sources of information to predict beef carcass traits and final carcass value. Available electronically from http : / /hdl .handle .net /1969 .1 /3919 .

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