Comparison of ram, wether, and short-scrotum lambs for growth and carcass characteristics
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Abstract presented at annual meeting of the Southern Section of the American Society of Animal Science. January 28, 2019.
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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
- 2. Castration Removal or destruction of the testicles in a male.
- 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.
- 7. COMPARISON INTACT MALE • Superior growth • Heavier carcass • Leaner carcass • Breeding risk • Undesirable behavior/odor • Processing issues WETHER • No (low) breeding risk • Ease of management • Meat quality (?) • Slower growth • Lighter carcass • Fatter carcass • Painful procedure (welfare) SHORT SCROTUM
- 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.