Comparison of ram, wether, and short-scrotum lambs for growth and carcass characteristics
1. Comparison of ram, wether, and
short-scrotum lambs for growth
and carcass characteristics
*Schoenian, S.1, Semler, J.1, Gordon, D.1,
Bennett, M.2, Anderson, C.1, and D. O’Brien3
1University of Maryland, 2West Virginia University, 3Virginia State University
3. Why castrate?
• Prevent indiscriminate breeding
• Eliminate undesirable behavior
and/or odor of intact male
• Ease of management
• For show
• Ease of shearing, crutching
• Better hygiene
• Improve meat quality
• Market preference
• Ease of processing
• Traditional management practice
4. Why not castrate?
• Males grow faster and produce heavier,
leaner carcasses.
• Castration is a painful procedure that has
risks associated with it.
• Some producers want to see how males
grow out before making selection
decisions.
• Some ethnic markets prefer an intact
male.
5. Is there an alternative?
INTACT MALE
NO CASTRATION
WETHER
CASTRATION
SHORT SCROTUM
CASTRATION
6. Short-scrotum “castration”
• Removal of scrotum with band, while leaving both
testicles close to or in the inguinal canal (as in a
cryporchid).
• Removal of scrotum prevents thermoregulation of
the testicles less than body temperature, thus
rendering spermatogenesis ineffective (sterility).
• Testosterone secretion from testicles allows
superior growth and carcass composition of male.
• Short scrotum “castration” is a less painful
procedure; therefore, animal welfare is improved.
8. Objectives
• Evaluate the growth, carcass
traits, and reproductive traits
of ram and wether lambs and
short-scrotum lambs.
• Determine if the short-scrotum
procedure is a viable
alternative for sheep producers
who put ewes and lambs to
pasture and/or want to manage
animals as a single group.
9. Materials and methods
• Lambs (n=60) male lambs (East Friesian x Lacaune)
form a commercial sheep dairy were utilized.
• By d 10, every third single, twin, and triplet lamb
was left entire (ram, n=19), castrated (wether, n-
24), or made a short scrotum (n=17).
• Management of lambs was typical of a sheep dairy.
• After weaning and being started on feed, lambs
were transported to the University of Maryland’s
Western Maryland Research & Education Center in
Keedysville for grazing/feeding.
10. Materials and methods
• Lambs were maintained as a single group on
pasture from April 26 until August 13 (for 110
days).
• They were reared on a moderate plane of nutrition
to support a moderate rate of gain, with a target
slaughter weight of approximately 54.5 kg.
• They were rotationally grazed among three
paddocks: 1) MaxQ™ fall fescue; 2) spring oats; and
3) dwarf pearl millet.
• They were supplemented with a complete feed
(16% CP) twice daily at approximately 2-3% of body
weight.
11. Materials and methods
• Lambs were handled bi-weekly to
determine body weights and the need
for deworming [no lamb required
deworming during of study].
• Lambs were scanned on d 102 by an
independent scanner.
• Lambs were evaluated for reproductive
traits on d 106 by Drs. Wildeus and
O’Brien from Virginia State University.
• Lambs were slaughtered on d 110 to
measure carcasses.
12. Statistical
analysis
• Growth and carcass data
were analyzed using PROC
GLM.
• Carcass correlations were
analyzed using PROC CORR.
• Start weight (d 0) was used
as a covariate in all an
analyses.
East Friesian x Lacaune
13. Results
No influence of sex on age, birth type, or birth weight
Sex No. Age, d
Birth
type
Birth weight,
kg
Start
weight, kg
Ram 19 81.3a 1.86a 5.6a 27.8
Short scrotum 17 75.7a 1.88a 5.5a 25.5
Wether 23 76.7a 1.90a 5.6a 25.3
ALL 60 77.9 1.90 5.6 26.1
14. Results
ADG (kg/d) was influenced by sex (p<0.03).
0.200
0.210
0.220
0.230
0.240
0.250
Ram Short scrotum Wether
ab
a
ac
+14%
15. Results
Final body weight (kg) was influenced by sex (p<0.03).
45.0
47.0
49.0
51.0
53.0
55.0
Ram Short scrotum Wether
a
ab
ac
+$15.97 advantage for
short scrotum lambs
(3.3 kg x $4.84/kg)
compared to wethers
16. Results
There was tendency for sex to influence HCW, kg (p=0.10).
23.5
24.0
24.5
25.0
25.5
26.0
26.5
Ram Short scrotum Wether
a
a a
17. Results
Sex had an effect on carcass back fat (mm)
(p<0.02) and yield grade (p<0.02).
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Carcass Ultrasound
Ram Short scrotum Wether
a a
a
a
ab
1.53a 1.56a 1.90b
18. Results
Sex had no influence on REA (cm2) or loin depth (cm).
CARCASS REA ULTRASOUND REA
15.0
16.0
17.0
18.0
19.0
20.0
21.0
Measured Adjusted
Ram Short scrotum Wether
9.0
9.5
10.0
10.5
11.0
11.5
12.0
12.5
13.0
Measured Adjusted
Ram Short scrotum Wether
AVG
19.3 ± 0.6 AVG
12.3 ± 0.6
AVG
11.6 ± 0.2
AVG
10.3 ± 0.1
19. Results
Sex had no influence on other carcass traits.
Sex DP BWT % KH fat Leg % BCTRC
Ram 48.6 ± 0.5 0.59 ± 0.3 1.74 ± 0.13 12.2 ± 0.2 50.1 ± 0.2
Short scrotum 49.1 ± 0.5 0.66 ± 0.3 1.82 ± 0.13 12.1 ± 0.2 50.1 ± 0.2
Wether 49.8 ± 0.4 0.66 ± 0.3 1.96 ± 0.12 12.2 ± 0.2 49.6 ± 0.2
All 49.2 ± 0.3 0.64 ± 0.02 1.85 ± 0.08 12.2 ± 0.1 49.9 ± 0.1
20. Results
There were strong correlations (r=0.7; p<0.001) between carcass and ultrasound
data, except for REA in short scrotum lambs (r=0.4; p=0.1).
REA, cm2 BF, mm
0.0
5.0
10.0
15.0
20.0
25.0
Ram Short scrotum Wether
Carcass Ultrasound
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Ram Short scrotum Wether
Carcass Ultrasound
21. Conclusions
• Results were similar to other studies in which
short-scrotum rams grew faster and produced
leaner carcasses than wether lambs.
• Short scrotum ram lambs had an average daily
gain that was 14.5 percent higher than wether
lambs.
• The short scrotum procedure increased the
value of the lambs by an average of $15.97 per
head (as compared to the wether lambs).
22. Discussion
• The short-scrotum procedure may be a
viable option for sheep producers.
• The short-scrotum procedure will preserve
the superior growth and carcass
composition of the male, while minimizing
some of the negative aspects of the male.
• The short scrotum procedure is easier to
perform and is less painful than full
castration.
• The study will be repeated in 2019 to see if
similar results are obtained.