Kerby, Joel L.

Nimr, Gary H.

Rouquette, F. M., Jr.

English

Texas A&amp;M Repository

    PUBLICATIONS 2000 CARCASS CHARACTERISTICS OF STEERS AND HEIFERS PREVIOUSLYGRAZED AT THREE STOCKING RATES AND FEEDLOT FINISHEDF. M. Rouquette, Jr., J. L. Kerby, and G. H. NimrBackground. A total of 272 Simmental-sired steers and heifers and Angus x Brahmansteers was grazed on rye-ryegrass pastures from December-May in each of 1997-98 and 1998-99.Three stocking rates (1.6, 2.2, and 2.8 600-lb stockers/ac) resulted in a range of ADG from about·I to 3 Ibslday and final, off-pasture weights of 750 to 1050 Ibslhd. Cattle were fed in a commercialfeedlot in Hereford, TX to an estimated visual backfat ofabout 0.4 inch. At feedlot finishing, cattlewere harvested at a commercial packing plant near Hereford. All carcass data were collected byCattlemen's Carcass Data Service at West Texas A&M University. Two companion reports providedetails on the grazing and feedlot phases. The objective of this research was to evaluate effects ofpre-feedlot, stocker gain and feedlot entry weight on carcass traits.Research Findings. In year I, 1997-98, two pens of cattle were fed for each pasturestocking rate (SR). The division of"heavy" and "lighter" cattle allowed for closer weight groupingand potential finish date for each pen. Three pens (both low SR and the heavy weight medium SR)were fed for 114 days and three pens (light weight medium SR and both high SR) for 148 days(Table 1). Hot carcass weight (HCW) averaged about 800 to 930 Ibs across the six pens. Withaverage HCW of932 lbs for Pen I-Low SR, this pen could npt have been fed much longer withoutsignificant price discounts attributable to carcass weight. Except for the heavy weight high SR cattle(Pen 1), dressing percent averaged 63 to 64%. The average USDA Quality Grade ranged fromSelect- to Select+ for all 6 pens. Cattle fed for 148 days had higher quality grades than those cattlefrom low SR pastures and fed for 114 days. This is in agreement with most feedlot studies in thatdays on feed has profound influence on intramuscular (marbling) fat content.The objective of finishing all pens to a uniform backfat of.4 inch was successfully met bythe trained feedlot personnel. Backfat ranged from 0.38 to 0.42-inch average for all 6 pens. Ribeyeareas ranged from 14 to 15 square inches and were deemed to be of appropriate size to meet mostretail demands. The USDA Yield Grades were acceptable at 2.4 to 2.8. Thus, theSe genotypes ofcattle continued to increase in lean, muscle growth for these feeding periods.Steers and heifers entering the feedlot in year 2, 1998-99, were approximately 100 lbs lighterthan cattle in year 1. Thus, feeding periods were longer for all stocking rates and final live andHCW were slightly less in year 2, but HCW was similar across all three pens. Dressing percentranged from 62 to 65%. Cattle which were fed for 175 days (high-stocked cattle) were fatter, had23higher USDA Quality Grade, and a higher USDA Yield Grade.Application. The genetic makeup of steers and heifers used in this experiment gradedUSDA Select- to Select+ after 114 to 175 days on feed. Given the feedlot entrance weights andprevious pasture performance, the target grade for finishing these types of cattle should likely beSelect rather than higher grades due to possible discounts related to heavy weight carcasses. Inorder to economically optimize life-time or component stages ofcattle, it becomes mandatory to addweight as cost-effectively as possible. Using grazing systems and animal genotypes which allowfor unusually high rates of gain (2.5 to 3 lbs/da) or unusually low rates ofgain «1 lb/da), retainedownership through the feedlot phase often becomes a reality. Knowledge or expectations offeedlotperformance and carcass characteristics become of paramount importance in decision-making forreducing potential marketing discounts associated with ~CW, Quality Grade, and/or Yield Grade.Table 1. Carcass traits of steers and heifers grazed at three stocking rates during 1997-98.LOWSR MEDIUMSR illGHSRITEMPen 1 Pen 2 Pen 1 Pen 2 Pen 1 Pen 2Number 22 21 22 23 24 26Days on feed 114 114 114 148 148 148Final live pay wt (lbs) 1451 1275 1368 1305 1403 1239Hot carcass wt (lbs) 932 807 872 827 883 792Dressing percent 64.13 63.25 63.74 63.42 60.32 63.96Marbling score SLlO SL40 SL30 SL80 SL90 SL50USDA Quality Grade Select- Select- Select- Select+ Select+ SelectFat thickness (in) 0.38 0.42 0.41 0.39 0.39 0.40Ribeye area (in2) 14.45 13.96 13.87 14.54 15.02 14.18Internal fat 2.23 2.14 2.05 2.07 2.04 ' 2.12USDA Yield Grade 2.80 2.58 2.80 2.39 2.44 2.40Table 2. Carcass traits of steers and heifers grazed at three stocking rates during 1998-99.ITEM LOWSR MEDIUM SR illGHSRNumber 36 48 50Days on feed 131 131 175Final live pay wt'(lbs) 1263 1213 1272Hot carcass wt (lbs) 806 788 799Dressing percent 61.9 64.9 62.8Marbling score SL 50 SL20 SL90USDA Quality Grade Select Select- Select+Fat thickness (in) 0.35 0.31 0.42Ribeye area (in2) 14.02 13.40 12.86Internal fat 1.64 1.54 1.88USDA Yield Grade 2.87 2.77 3.0424

Carcass Characteristics of Steers and Heifers Previously Grazed at Three Stocking Rates and Feedlot Finished

Texas A&M University

https://oaktrust.library.tamu.edu/bitstream/1969.1/189659/1/article191.pdf

Carcass Characteristics of Steers and Heifers Previously Grazed at Three Stocking Rates and Feedlot Finished

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Texas A&M University

Carcass Characteristics of Steers and Heifers Previously Grazed at Three Stocking Rates and Feedlot Finished

Abstract

Similar works

Full text

Available Versions

Texas A&amp;M Repository

Texas A&M University

Texas A&M Repository