Friday, September 28, 2018

Research Project Provides Lamb for Campus

The University of Maryland dining halls featured local food at its September 26 Harvest Festival. One of the local foods featured was the lamb from our research project. Campus dining services purchased all sixty lambs from our research project.

One of the university's chefs

The lambs from the project were provided by Shepherds Manor Creamery in Westminster. Shepherds Manor Creamery is operated by Mike & Colleen Histon. It is Maryland's first and only licensed sheep dairy. The lambs used in the research project were a cross between the East Friesian and Lacaune breeds. They averaged 113 pounds at the time of harvest. They were finished on a combination of pasture and grain.

The Harvest Festival featured "Braised Leg of Lamb." It was delicious. Lamb will be featured again in the spring. Dining services has indicated a desire to purchase the lambs from next year's project.

Saturday, September 22, 2018

Getting Ready for Next Year

We're already making plans for next year's research project. The project will be similar. We will be comparing ram, wether, and short-scrotum lambs. It is important to replicate this year's project to see if we get similar results.

Fall planting of cool season pasture mix

The farm that provided this year's lambs has agreed to provide lambs for next year's project. This is great news. This year's lambs were very healthy, despite all the rain, and produced good quality carcasses. They were docile and easy to handle.

The lambs grazed mostly annuals this year:  spring oats and dwarf pearl millet. We are establishing perennial pastures, leaving two acres for annual forages. A cover crop was planted into these two acres. The perennial pasture mixes include a variety of cool season grasses (orchardgrass, fescue ryegrass, and bromegrass), clovers (red and white), and herbs (chicory).

The pasture system consists of 10 acres. It will be divided into five, 2-acre paddocks for rotational grazing. There is an additional ~2.5 acres of silvopasture that contains mostly cool season grasses (fescue). The lambs always have access to a central laneway that contains shelter (40 ft. x 40 ft. roofed structure), water troughs, feeders, and the handling system.

Tuesday, September 4, 2018

Carcass Measurements

After determining ending weights (LW) on August 13, the lambs (n=60) were transported to Hamzah Slaughterhouse (in Williamsport, Maryland) for immediate slaughter. The slaughterhouse was 9.5 miles away.

Carcass data was obtained from 51 lambs:  16 ram lambs, 15 short-scrotum lambs, and 20 wethers. Hot carcass weights (HCW) were determined immediately after slaughter. After overnight chilling, the carcasses were evaluated. The carcasses were split between the 12 and 13th ribs to expose the rib eye. A plastic grid was used to measure the area of the rib eye muscle (REA; 20 dots=1 in²). A metal ruler was used measure to backfat thickness (BF) and thickness of the body wall (BWT). Kidney and heart fat (KH) and leg conformation scores (LC) were subjectively evaluated.


Dressing percentage (DP) was determined using the following formula HCW ÷ LW. A few cold carcass weights were obtained. Shrinkage was less than 1 percent. REA was converted to an equivalent weight basis (100 pounds; CWT) using the following formula:  (REA ÷ LW) x 100. Yield grade (YG) was calculated using the following formula:  (back fat x 10) + 0.4. Percent boneless, close trimmed retail cuts (BCTRC) was calculated using the following formula:  49.936 - (0.0848 x HCW) - (4.376 x BF) - (3.530 x BW) + (2.456 x REA)*.

Group No. LW HCW DP BF BWT REA CWT KH LC YG BCTRC
Ram 16 117.5 56.3 48.7 0.122 0.619 3.06 2.66 1.84 12.4 1.62 50.0
Short-scrotum 15 116.5 57.3 49.1 0.113 0.647 3.19 2.74 1.79 12.1 1.53 50.1
Wether 20 104.4 53.4 49.6 0.145 0.640 2.91 2.71 1.85 12.1 1.85 49.7
ALL 51 113.3 55.4 49.2 0.128 0.636 3.04 2.70 1.85 12.2 1.68 49.9
It is not known if any of the differences are statistically significant.

HCW ranged from 37.0 to 72.0 pounds and averaged 55.4 ± 7.5 lbs. The short-scrotum lambs had the heaviest HCW:  57.3 ± 5.3 lbs. HCW of the ram lambs (56.3 ± 8.8 lbs) was more than the wether lambs (53.4 ± 7.6 lbs). DP ranged from 44.9 to 53.3 and averaged 49.2 ± 1.9 percent. The median DP was 49.2 percent. The wethers had slighter higher DP (49.6 ± 2%) than the short-scrotum (49.1 ± 1.7%) and ram lambs (48.7 ± 1.9%).

Jeff Semler
BF ranged from 0.5 to 0.25 inches and averaged 0.128 ± 0.05 inches. The median BF was 0.10 inches. The wether lambs had the most backfat (0.145 ± .056 in) . The short-scrotum lambs had the least (0.113 ± 0.035 in). The ram lambs were intermediate (0.122 ± 0.045 in). BWT ranged from 0.30 to 0.80 and averaged 0.635 ± 0.144 inches. The median BWT was 0.60 inches. The ram lambs had the lowest BWT:  0.619 ± 0.167 inches. Short-scrotum and wether lambs were similar.

REA ranged from 2.25 to 3.85 in² and averaged 3.04 ± 0.45 in². The median REA was 3.10 in². The short-scrotum lambs had the largest REA: 3.19 ± 0.45 in². The wethers had the smallest REA:  2.91 ± 0.48 in². The ram lambs were intermediate: 3.06 ± 0.44 in². REA per 100 lbs. (CWT) ranged from 2.00 to 3.41 in² and averaged 2.70 ± 0.29 in².  The median was 2.64 in². CWT was lowest for the ram lambs (2.66 ± 0.20 in²) and similar for the short-scrotum (2.74 ± 0.32 in²) and wether lambs (2.71 ± 0.32 in²).

KH ranged from 1 to 3 and averaged 1.85 ± 0.65 percent. The median KH was 2.0 The three groups of lambs had similar KH. LC ranged from 10 (low Choice) to 14 (average Prime) and averaged 12.2 ± 0.9. The median LC was 12 (Choice plus). YG ranged from 0.9 to 2.4 and averaged 1.68 ± 0.48. The median YG was 1.40, The short-scrotum lambs had the lowest YG: 1.53 ± 0.35. The wether lambs had the highest YG: 1.85 ± 0.56. The ram lambs were intermediate: 1.62 ± 0.45.


Group No. YG 1 YG 2 YG3 Choice < Choice
Ram 16 11 5 0 14 2
Short-scrotum 15 11 4 0 15 0
Wether 20 8 11 1 18 2
ALL 51 30 20 1 47 4

Thirty lambs (58.8%) were yield grade 1. Only 21 (41.1%) of the lambs were yield grade 2 or 3. Yield grade 1 lambs may be suitable for some ethnic markets, but they are generally considered to be too thin (not finished). They typically sell for lower prices than yield grade 2 or 3 lambs, unless they are sold as feeder lambs for further feeding/finishing.  Four lambs (two rams and two wethers) had less than 0.8 inches of back fat; thus, failing to qualify for the USDA Choice grade. All other lambs graded USDA Choice or higher.

Percent BCTRC ranged from 46.9 to 52.8 percent and averaged 49.9 ± 0.84 percent. There were numerical differences between the three groups, but they are not likely statistically significant. 

Compared to ultrasound data
 While the carcass measurements showed the lambs to have more BF and larger REA, the comparisons between the three groups of lambs were similar, regardless of data source.

Group No. BF-scan BF-carcass REA-scan REA-carcass
Ram 16 0.860 0.122 1.81 3.06
Short-scrotum 15 0.900 0.113 1.86 3.19
Wether 19 0.104 0.142 1.69 2.87
ALL 50 0.940 0.127 1.78 3.03

*Source: Scott Greiner, Lamb Carcass Evaluation, Virginia Tech

Lamb Served in Dining Halls

For the second year in a row, the lamb from our comparison study of ram, wether, and short-scrotum lambs was served in the dining halls at t...