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1999 Beef & Bison Production Field Day

Observations on effects of breed of sire on

feedlot gain and carcass traits

V. L. Anderson

Carrington Research Extension Center

Three sire breeds have been used during the past few years on the crossbred cow herd at the Carrington Research Extension Center. The breeds represented are Red Angus, Limousin, and South Devon. Sires were procured from area breeders and natural matings allowed for 45-50 days. Two years are represented in this data. The steers represented were produced by crossbred cows of primarily Red Angus and Limousin influence and lesser amounts of Tarentaise and Hereford in their genetic makeup. Red Angus and Limousin sires were mated to the most unrelated dams. South Devon sires were mated to a cross section of the breed groups with sires used on groups of heifers two years and mature cows one year.

Spring born calves (March 10 - April 25) were used in creep feed trials and weaned in late September. Steers were placed on growing rations for approximately three months with high grain finishing diets offered until marketing in April. The steers were randomly allotted to diet treatments in other trials so feed intake and gain per unit feed are not available by sire breed. Carcass data was collected at slaughter.

Observations on feedlot gain during growing and finishing, and carcass traits are presented in Tables 1 and 2. This information should be considered as an observation only at this time as there are other factors that may have affected the data and no statistical tests were applied to the data. A more complete comparison will be made in the future when more data has been accumulated.

Table 1. Effects of sire on the performance of feedlot steers during growing and finishing

Item                              Limousin      South Devon        Red Angus        St Err  
Actual weaning wt, lb   600 561 584 13.6
Growing ADG, lb 2.85 2.79 2.83 .11
Finishing ADG, lb 3.44 3.27 3.57 .15
Final weight, lb 1152 1147 1176 18.2

Weaning weights were numerically lower for the South Devon steers, probably due in part to the large number of calves from first calf heifers in this sample. Milk production has a greater influence on weaning weight than sire breed so weaning weight should be considered as a start point for feedlot performance. Gains during growing and finishing appear to be very similar for all three groups.

Carcasses from South Devon steers appear to contain less fat, suggesting more time on feed may have improved the percent of carcasses grading choice. However, average marbling scores appear similar indicating a few carcasses graded average choice or higher.

Table 2. Effects of sire on carcass traits of finished steers

Item                                 Limousin   South Devon    Red Angus       St Err   
Shrunk slaughter wt, lb 1106 1095 1129 17.5
Hot carcass weight, lb 689 683 700 12.1
Dressing percent 62.3 62.4 62.0 .35
Fat thickness, in .37 .34 .48 .02
Rib eye area, sq in 12.97 12.74 12.01 .22
KPH, % 2.53 2.39 2.53 .03
Yield Gradea 2.39 1.68 2.66 .14
Marbling scoreb 376 371 396 8.1
Percent Choice 37.5 19 58 -

a Yield Grade is a calculation based on proportions of fat and lean muscle in the carcass with higher numbers indicating increased fat content.

b Marbling scores are used to determine carcass quality grade with 300-399= select, 400 to 499 = low choice, 500 to 599 = average choice.

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