First Weighing

This year's comparison study began on April 22 with the arrival of 65 East Friesian x Lacaune male lambs:  22 rams, 26 wethers, and 18 short-scrotum rams. The lambs ranged in weight from 28.0 to 71.0 lbs. and averaged 44.4 ± 10.6 pounds. The median weight was 42.0 lbs. The intact and short-scrotum ram lambs had slightly heavier starting weights than the wether lambs.

The lambs were weighed for the first time on May 22. They ranged in weight from 40.8 to 97.4 lbs. and averaged 64.1 ± 13.9 lbs.  The median weight was 62.6 lbs. For the first 28 days of the project, the lambs gained from 6.8 to 29.4 lbs. and averaged 19.4 ± 4.6 lbs. of gain. The median gain was 19.6 lbs. The intact and short-scrotum rams gained more weight than the wethers.

Average daily gain (ADG) ranged from 0.243 to 1.050 lbs. per day and averaged 0.703 ± 0.164 lbs. per day. The median gain was 0.703 lbs. per day. The intact and short scrotum rams had higher ADG than the wether lambs.

Sex	No.	Start wt.	28-day wt.	28-d ADG
Ram	22	45.0 ± 10.3	65.0 ± 14.0	0.717 ± 0.917
Short scrotum	18	45.1 ± 10.9	65.4 ± 14.6	0.726 ± 0.162
Wether	25	43.5 ± 10.9	62.4 ± 13.7	0.675 ± 0.133
ALL	65	44.4 ± 10.6	64.1 ± 13.9	0.703 ± 0.164

For the first 28 days of the project, the lambs have grazed mostly cool season perennial grasses. They have free choice access to grass hay and are being supplemented twice daily with a grain mixture of whole barley, soybean meal, and minerals. The grain has slowly been increased. The current feeding rate is ~5 percent of body weight.

So far, no lambs have required deworming. FAMACHA© scores have been all 1s and 2s. No other treatments have been administered. The lambs were vaccinated twice for CDT.

Arrival of Lambs

Sixty-eight East Friesan x Lacaune lambs were delivered to the University of Maryland's Western Maryland Research & Education Center on Wednesday, April 24. The lambs ranged in weight from 28 to 71 lbs and averaged 44.3 ± 10.4 lbs. The median weight was 42 lbs.

This year's lambs are considerably younger and lighter than last year's lambs.

Youth Involvement

Two youth programs will be held in conjunction with this year's research project:  4-H Small Ruminant Research Academy and 4-H Entrepreneurship Program.

Interested youth should contact Ashley Travis for more information and to apply. Ashley can be reached at ashley90@umd.edu or (301) 791-1304.

Final Results: Growth & Carcass

Data from the 2018 comparison study of ram, wether, and short-scrotum lambs were statistically analyzed by Dr. Dahlia O'Brien at Virginia State University.

The short-scrotum rams had heavier final weights than the wether lambs: 117.7  ± 2.0 vs. 110.4 ± 1.7 lbs. Ram lambs were intermediate:  113.4 ± 2.0 lbs. Short scrotum lambs had greater average daily gain (ADG) than wether lambs: 0.549 ± 0.02 lb/d vs. 0.482 ± 0.02 lb/d. Ram lambs were intermediate: 0.510 ± 0.02 lb/d.

There was a tendency for sex to influence rib eye area (REA), as determined by ultrasound. Wether lambs tended to have smaller REA compared to ram and short-scrotum lambs. However, when REA was adjusted to a common weight (100 lbs.), there was no difference between the sexes. Sex did not influence other ultrasonic measurements: backfat (BF) and loin depth.

Actual carcass measurements showed wethers to be fatter, having greater BF (0.15 ± 0.01 in.), thus yield grade (1.9 ± 0.1). Ram lambs produced the leanest carcasses (0.11 ± 0.01 in. and 1.5 ± 0.1, respectively). The short-scrotum lambs were intermediate (0.12 ± 0.01 in. and 1.6 ± 0.1, respectively). There was a tendency for sex to influence hot carcass weight (HCW), with short-scrotum lambs tending to have the heaviest HCW.

Sex did not affect dressing percentage (49.2 ± 0.3 percent), body wall thickness (0.60 ± 0.2 in.) REA (3.0 ± 0.1 sq. in.), REA adjusted to 100 lbs. (2.7 ± 0.04 sq.in.), percent kidney and heart fat (KH; 1.9 ± 0.1 percent), leg conformation score (12.2 ± 0.1), or percent boneless closely trimmed retail cuts (BCTRC; 49.9 ± 0.1 percent).

Conclusion
Compared to wether lambs, short-scrotum lambs showed superior growth and produced leaner carcasses. The short-scrotum procedure may offer a viable alternative to traditional castration.

Ultrasound vs. actual carcass measurements
Actual BF measurements were highly correlated with ultrasound BF measurements (r=0.7). REA measurements were also highly correlated (r=0.7) in wether and ram lambs. However, there was not a high correlation in REA measurements in the short scrotum lambs (r=0.4). Correlation coefficients (r values) vary from -1 to 1. The closer r is to -1 or 1, the more closely the variables are related.Closer to 0, the opposite is true.

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.

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.

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