Current Edition

current edition

Terminal sire test takes the guess work out of ram buying

Written by Whit Stewart

Identifying, selecting and disseminating superior genetics for the lamb industry is the focus of the University of Wyoming (UW), Wyoming Wool Growers Association and Mountain States Lamb Cooperative Terminal Sire Ram Test. Sixty rams from 13 ranches were evaluated for growth performance, carcass ultrasound characteristics and feed efficiency data over a 62-day period. Ram lambs arrive to the University of Wyoming Laramie Research and Extension Center the end of May and conclude performance testing the end of July. The 2017 Terminal Sire Test was again successful in identifying superior performing Suffolk, Hampshire, Shropshire and Composite rams.

Central performance testing is not a new selection tool, yet the UW Terminal Sire Test is the only of its kind in the nation, due to the ability to collect individual animal intake and thereby measure feed efficiency and residual feed intake. Measuring these economically relevant traits and identifying superior performing rams allows producers to select rams that will sire lambs that excel in the feeding phase and on the rail.

Since these terminal sires will produce lambs destined for harvest, the traits measured on the test are combined into an overall index that combines average daily gain, loin eye area, back fat thickness, residual feed intake and cost per pound of gain. These traits are weighted in the index based upon their heritability estimates and economic importance to identify the superior performing individuals. By taking a proven selection tool in central performance testing and incorporating new technologies, including feed efficiency and carcass ultrasound data, we are ensuring a premier product at the ranch, feed yard and retail case. 

The top 25 percent, or 15, rams will be offered Sept. 12 at the 89th annual Wyoming State Ram Sale at Wyoming State Fairgrounds in Douglas. The following rams represent the top 25 percent.

1 – Tag 159 – Index: 0.249, ADG: 0.95, LEA: 3.04, BF: 0.18, RFI: -1.3781, Cost per Pound of Gain: 0.52, Visual: 4.0, Scrotal: 29.5, Consignor: Reed

2 – Tag 7319 – Index: 0.219, ADG: 1.00, LEA: 3.24, BF: 0.20, RFI: -0.6846, Cost per Pound of Gain: 0.79, Visual: 5.0, Scrotal: 34.5, Consignor: Laramie Research and Extension Center (LREC)

3 – Tag 751 – Index: 0.218, ADG: 1.03, LEA: 3.05, BF: 0.17, RFI: -0.7722, Cost Per Pound of Gain: 0.58, Visual: 3.3, Scrotal: 30.0, Consignor: Dona

4 – Tag 7209 – Index: 0.197, ADG: 1.00, LEA: 3.43, BF: 0.17, RFI: -0.0765, Cost per Pound of Gain: 0.71, Visual: 4.3, Scrotal: 36.0, Consignor: LREC

5 – Test Number 43 – Index: 0.194, ADG: 1.02, LEA: 3.36, BF: 0.23, RFI: -0.1803, Cost Per Pound of Gain: 0.66, Visual: 4.0, Scrotal: 34.0, Consignor: Maneotis

6 – Tag 713 – Index: 0.165, ADG: 0.79, LEA: 3.77, BF: 0.21, RFI: -0.1781, Cost Per Pound of Gain: 0.86, Visual: 4.3, Scrotal: 37.0, Consignor: Dona

7 – Tag 119 – Index: 0.165, ADG: 1.08, LEA: 3.28, BF: 0.29, RFI: 0.0268, Cost Per Pound of Gain: 0.71, Visual: 3.3, Scrotal: 40, Consignor: Regan Smith

8 – Tag W706 – Index: 0.161, ADG: 0.97, LEA: 3.40, BF: 0.18, RFI: 0.0773, Cost Per Pound of Gain: 0.72, Visual: 4.3, Scrotal: 34.5, Consignor: Fenster

9 – Tag 752 – Index: 0.155, ADG: 0.81, LEA: 3.20, BF: 0.17, RFI: -0.8260, Cost Per Pound of Gain: 0.65, Visual: 2.7, Scrotal: 32.0, Consignor: Dona

10 – Test Number 39 – Index: 0.148, ADG: 1.10, LEA: 2.64, BF: 0.25, RFI: -0.7899, Cost Per Pound of Gain: 0.77, Visual: 3.7, Scrotal: 31.5, Consignor: Maneotis

11 – Test Number 40 – Index: 0.136, ADG: 0.76, LEA: 3.20, BF: 0.23, RFI: -1.0161, Cost Per Pound of Gain: 0.71, Visual: 4.0, Scrotal: 31.0, Consignor: Maneotis

12 – Tag 710 – Index: 0.130, ADG: 1.06, LEA: 3.15, BF: 0.16, RFI: 0.3251, Cost Per Pound of Gain: 0.68, Visual: 3.7, Scrotal: 36, Consignor: Atkinson

13 – Tag S731 – Index: 0.125, ADG: 0.98, LEA: 3.06, BF: 0.19, RFI: -0.1487, Cost Per Pound of Gain: 0.65, Visual: 4.0, Scrotal: 32.0, Consignor: Stewart

14 – Tag 7330 – Index: 0.104, ADG: 0.82, LEA: 3.46, BF: 0.24, RFI: 3.46, Cost Per Pound of Gain: 0.80, Visual: 4.3, Scrotal: 37.0, Consignor: LREC

15 – Tag 7325 – Index: 0.100, ADG: 0.94, LEA: 3.25, BF: 0.25, RFI: 0.0866, Cost Per Pound of Gain: 0.75, Visual: 4.3, Scrotal: 33.0, Consignor: LREC

For more information on these and other high-quality rams offered at the state ram sale, visit wyowool.com for a catalog. Producers interested in participating in central performance testing – either Terminal Sire or White Face –  at the University of Wyoming should contact me at This email address is being protected from spambots. You need JavaScript enabled to view it. or 307-766-5374.