Ultrasound Results: Unanalyzed Data

The lambs were scanned on August 6 to determine carcass characteristics.The short-scrotum lambs (n=17) scanned with slightly larger rib eye areas (1.88 in²) than the ram (n=19) or wether (n=23) lambs (1.85 and 1.70 in², respectively) but when rib eye area was adjusted to a common weight (100 lbs), they had slightly smaller rib eye areas (1.54 in²⁾, and there were no differences between the ram and wether lambs (1.58 in²⁾. The ram and short-scrotum lambs had deeper loins compared to the wether lambs (0.99 vs. 0.93 inches).

For the 59 lambs scanned, the average rib eye measurement was 1.8 in² or 1.59 in² per 100-lb. live weight. It is worth noting that the actual carcass measurements were considerably higher.  For the 51 carcasses measured, the average rib eye measurement was 3.04 in² or 2.70 in² 100-lb. live weight.

Group	No.	Live Wt., lbs.	REA, in2	REA per cwt	Loin depth, in.	Backfat, in.
Ram	19	117.5	1.85	1.58	0.99	0.086
Short-scrotum	17	116.5	1.88	1.54	0.99	0.088
Wether	23	104.4	1.70	1.58	0.93	0.102
ALL	59	113.3	1.80	1.59	1.00	0.090

It is not yet known if any of the differences are statistically significant.

According to scanning, the wether lambs had a little more backfat (0.102 inches) than the ram and short-scrotum lambs (0.086 and 0.088 inches, respectively). Average backfat for the 59 lambs scanned was 0.09 inches, compared to 0.128 for the actual carcass measurements (n=51). All carcass measurements (ultrasound and actual) were taken between the 12th and 13th ribs. Rib eye was measured on the carcass using a plastic grid (Iowa State University), where 20 dots are equal to 1 in².

The moderate level of nutrition (pasture, plus some grain) provided did not result in the majority of lambs reaching market readiness. Lambs with less than 0.8 inches of backfat fail to qualify for the USDA Choice grade. The yield grade of a lamb with 0.9 inches of backfat is only 1.3 Yield grade 1 lambs are considered too thin and generally do not receive the price premiums than yield grade 2 and 3 lambs receive.

Fertility: Preliminary Results

The fertility of ram (n=17), wether (n=24), and short-scrotum (n=17) lambs was evaluated. Blood samples were collected from each lamb to measure testosterone levels.

Libido was evaluated using a pen test. Each lamb (n=60) was placed in a 8 ft. x 8 ft. pen with two estrus ewes. The ewes had been treated with CIDR inserts so that they were in estrus (heat) on the day of testing (August 9). There were two pens of two ewes. Lambs were randomly assigned to a pen (A or B).

Each lamb was in the pen with ewes for five minutes. Breeding behaviors were observed and recorded. Behaviors observed included sniffing, butting, kicking, lip curling (flehman's response), mounting, servicing (ejaculating), and time to service.

Pen test to evaluate libido

The short-scrotum lambs displayed similar breeding behavior as the ram lambs, though the ram lambs had twice as many services and a shorter time to service (table 1). 

Table 1.  Libido

Sex	No.	Mounts, #	Services, #	Time, sec.
Ram	19	1.78a	1.11a	103a
Short scrotum	17	2.05a	0.53b	143a
Wether	24	0.22b	0c	NA

Numbers with different superscripts are statistically different.

Semen was collected from six rams and six short-scrotum lambs. An estrus ewe was used for collection. The semen was collected using an artificial vagina (AV). The semen samples were evaluated on site, then later in a lab by Dr. Dahlia O'Brien from Virginia State University.

Ejaculates of short scrotum lambs were essentially devoid of sperm and could not be tested with standard procedures.  Ejaculates of the intact rams had a concentration of 1.2 billion sperm/ml, 87% motility, and 82% viability. Ejaculate characteristics of short scrotum males would have rendered them sterile.

Click to view video of ejaculate from intact ram lamb
Click to view video of ejaculate from short-scrotum lamb

Testicles were collected at the time of slaughter, five pairs each from rams and short-scrotum lambs. The testes were dissected and weighed by Dr. Stephan Wildeus at Virginia State University. The short-scrotum lambs had significantly smaller testes than the ram lambs: 114.5 g vs. 393 g. The testicles from the short-scrotum rams also had a different consistency. The epididmymal weight was also smaller (21 vs. 50 g) in the short-scrotum lambs, as were the ratios of parenchyma: tunica and testis: epididmymis (table 2)

Table 2. Organ weights

Sex	No.	Total testes, g	Epididymal wt, g	Parenchyma: tunica	Testis: epididymis
Ram	5	393.4a	50.0a	14.9a	7.31a
Short scrotum	5	114.5b	21.0b	12.0b	5.39a

Numbers with different superscripts are statistically different.

Testicles from short-scrotum (L) and ram (R) lambs

Zero Problems With Worms

During the 110-day grazing period, the lambs had ZERO problems with worms. There are several reasons why. The lambs were rotated among three grazing areas, all clean pastures. Upon arrival on April 26, they were given access to a silvopasture, ~2.5 acres of mostly cool season grasses (tall fescue). This pasture had not been grazed for ~18 months.

The next pasture they grazed was a 5 acre paddock of spring oats, an annual forage. Later in the summer, they were switched to a 5 acre paddock of dwarf pearl millet, another annual forage. The lambs always had access to the grass (fescue) in the central laneway. Like the silvopasture, it had not been grazed for ~18 months.

Silvopastuure:  cool season perennials

Previously, the pasture system had been used to graze the bucks in the Western Maryland Pasture-Based Meat Goat Performance Test. After 11 years of performance testing, levels of pasture infectivity (with worm larvae) had reached very high levels, as evidenced by the very high fecal egg counts in many of the goats.

After the last buck test ended in 2016, the fields were rested, then planted in corn. By the time the corn was harvested, it was too late to establish perennial pasture, so annual forages were used for this year's project. Now that this year's project is over, the fields will be seeded to cool season perennial forages. Two acres will be set aside for warm season annuals.

Spring oats

"Worm-free"
Another reason why the lambs didn't have any problems with worm parasites is because they came to the site relatively "worm-free," as they had been born in the winter in a confinement (dairy) system. After (early) weaning, they remained in confinement, never pastured or exposed to worm larvae. Zero grazing is a common method of keeping lambs relatively free from parasite infection.

Mouthful of millet

Early-born
The lambs were born in the winter months (January-February). Upon arrival on April 26, their average age was 78 days. In July-August, when worm parasites are typically the worst (in Maryland), the lambs were 4-5 months old. This aged lamb can tolerate parasites better than a 2-3 month old lamb, born in the spring. One way to reduce parasite problems is to lamb/kid earlier in the year (or in the fall).

Supplemental feeding
The lambs were also supplemented with feed, a 16% CP mixture of whole barley, soybean meal, and minerals. The grain was gradually increased, until the lambs were consuming 2 lbs. per head per day. The feed was always hand-fed twice daily in 8 foot galvanized metal feed troughs. Despite being fed twice a day, the lambs proved to be active grazers.

Eventually, the feed was increased to 2.5 lbs and to 3 lbs. towards the very end of the project. Supplemental feeding is another way to mitigate the effects of parasitism. Animals in better body condition are better able to tolerate the negative effects of parasites. By-pass protein has proven to be especially beneficial.

Supplemental feed

Throughout the project, the lambs had FAMACHA© scores of mostly 1's, with some 2's, and an occasional 3. There was no point in collecting fecal samples, as parasites were a non-issue in the project. It was fun to raise small ruminant when parasites are a non-issue!

Ending Weights Determined

We ran into some problems with the scales, so the data from the last several weighings has been discarded, for concerns of accuracy. Final weights were determined by weighing the lambs on certified scales at the local county fairgrounds. The fairgrounds are located on an adjacent property, so the lambs weren't transported far. After weighing, they were transported to the slaughterhouse for immediate slaughter.

Final weights were determined using certified scales.

For the 60 lambs, ending weights ranged from 84 to 141 lbs. and averaged 113.4 ± 13.4 lbs. The median ending weight was 116.5 lbs. Starting weights ranged from 36.0 to 80.3 lbs. and averaged 57.3 ± 9.6 lbs. The median starting weight was 56.3 lbs. The feeding period lasted for 110 days (April 26-August 13). Gain ranged from 35.0 to 76.2 lbs. and averaged 56.1 ± 8.7 lbs. The median gain was 55.7 lbs. 

Average daily gain (ADG) ranged from 0.318 to 0.693 lbs. per day and averaged 0.510 ± 0.079 lbs. per day. The short-scrotum rams (n=17) had the highest ADG:  0.548 ± 0.063 lbs. per day. The wethers (n=24) had the lowest ADG: 0.482 ± 0.078 lbs. per day. The ram lambs were intermediate in ADG: 0.512 ± 0.083 lbs. per day. The data will be analyzed to determine if the differences are statistically significant.

The ram lambs were the heaviest upon arrival on April 26. They averaged 61.2 ± 11.5 lbs. Their median weight was 64.4 lbs. The short-scrotum rams and wethers were similar in starting weights:  56.2 ± 7.7 and 55.0 ± 8.5 lbs., respectively. At the conclusion of the feeding period, the ram lambs and short-scrotum rams were similar in weight: 117.5 ± 16.4 and 116.5 ± 8.2 lbs., respectively. The wether lambs were the lightest at 108.0 ± 12.3. lbs.
 

Sex	No.	Start Wt., lbs.	End Wt., lbs.	ADG, lb/d
Ram	19	61.2  ± 11.5	117.5 ± 16.4	0.512 ± 0.083
Wether	24	55.0 ± 8.5	108.0 ± 12.3	0.482 ± 0.078
Short scrotum	17	56.2 ± 7.7	116.5 ± 8.2	0.548 ± 0.063
ALL	60	57.3 ± 9.6	113.4 ± 13.4	0.510 ± 0.079

During the 110 day feeding period, the lambs were fed at a moderate nutrition level: pasture + some grain. Pastures were a mixture of annual forages (spring oats and dwarf pearl millet) and perennial grass (mostly fescue). Grain was a mixture of whole barley, soybean meal, and minerals (hand-fed twice daily). Hay was fed at the beginning of the period, as pastures were slow coming.