Scientists have conducted and continue to conduct extensive research involving St. Croix Hair Sheep. This is a non-exhaustive list of research studies published in peer-reviewed scientific journals. In summary, the research proves that these sheep demonstrate resistance to most internal parasites, breed year round, generally produce twins, tolerate stress, generate immunological responses better than most other breeds, and while they are smaller, they have a greater meat to bone ratio than other breeds.

Research About Parasite Resistance

• Amarante, A.F.T and Amarante,M.R.V. 2003. Breeding Sheep for Resistance to Nematode Infections. Journal of Animal and Veterinary Advances, 2: 147-161.
• Bowdridge, S., MacKinnon, K., McCann, J. C., Zajac, A. M., & Notter, D. R. (2013). Hair-type sheep generate an accelerated and longer-lived humoral immune response to Haemonchus contortus infection. Veterinary parasitology, 196(1-2), 172–178. https://doi.org/10.1016/j.vetpar.2013.01.008
• Bowdridge, S. A., Zajac, A. M., & Notter, D. R. (2015). St. Croix sheep produce a rapid and greater cellular immune response contributing to reduced establishment of Haemonchus contortus. Veterinary parasitology, 208(3-4), 204–210. https://doi.org/10.1016/j.vetpar.2015.01.019
• Burke, J.M. and J.E. Miller.  2004. Relative resistance to gastrointestinal nematode parasites in Dorper, Katahdin, and St. Croix lambs under conditions encountered in the southeastern region of the United States.  Small Ruminant Research 54:43-51.
• Burke, J.M. and J.E. Miller.  2002. Relative resistance of Dorper crossbred ewes to gastrointestinal nematode infection compared with St. Croix and Katahdin ewes in the southeastern United States.  Veterinary Parasitology 109:265-275.
• Courtney, C.H., C.F. Parker, K.E. McClure, and R.P. Herd. 1985. Resistance of exotic and domestic lambs to experimental infection with Haemonchus contortus. International Journal of Parasitology 15:101-109.
• Courtney, C.H., C.F. Parker, K.E. McClure, and R.P. Herd. 1985. Resistance of nonlambing exotic and domestic ewes to naturally acquired gastrointestinal nematodes. International Journal of Parasitology 15:239-244.
• Courtney, C.H., C.F. Parker, K.E. McClure, and R.P. Herd. 1984. A comparison of the periparturient rise in fecal egg counts of exotic and domestic ewes. International Journal of Parasitology 14:377-381.
• Gamble, H.R. and A.M. Zajac. 1992. Resistance of St. Croix lambs to Haemonchus contortus in experimentally and naturally acquired infections. Veterinary Parasitolology. 41:211-225.
• Garza, J. J., Greiner, S. P., & Bowdridge, S. A. (2017). Serum-mediated Haemonchus contortus larval aggregation differs by larval stage and is enhanced by complement. Parasite immunology, 39(3), 10.1111/pim.12409. https://doi.org/10.1111/pim.12409
• Garza, J. J., Greiner, S. P., & Bowdridge, S. A. (2018). Ovine vital neutrophil extracellular traps bind and impair Haemonchus contortus L3 in a breed-dependent manner. Parasite immunology, 40(9), e12572. https://doi.org/10.1111/pim.12572
• Holt RM, Shepherd EA, Ammer AG, Bowdridge SA. Effects of peripheral blood mononuclear cells on Haemonchus contortus larval motility in vitro. Parasite Immunol. 2015 Oct;37(10):553-556. doi: 10.1111/pim.12219. PMID: 26223339.
• Jacobs, J. R., Greiner, S. P., & Bowdridge, S. A. (2018). Impaired interleukin-4 signalling promotes establishment of Haemonchus contortus in sheep. Parasite immunology, 40(12), e12597. https://doi.org/10.1111/pim.12597
• Jacobs, J. R., Greiner, S. P., & Bowdridge, S. A. (2015). Serum interleukin-4 (IL-4) production is associated with lower fecal egg count in parasite-resistant sheep. Veterinary parasitology, 211(1-2), 102–105. https://doi.org/10.1016/j.vetpar.2015.04.024
• Jacobs, J. R., Middleton, D., Greiner, S. P., & Bowdridge, S. A. (2020). RNA-Sequencing of ovine PBMC after exposure to Haemonchus contortus larval antigen. Parasite immunology, 42(5), e12697. https://doi.org/10.1111/pim.12697
• Jacobs, J. R., Sommers, K. N., Zajac, A. M., Notter, D. R., & Bowdridge, S. A. (2016). Early IL-4 gene expression in abomasum is associated with resistance to Haemonchus contortus in hair and wool sheep breeds. Parasite immunology, 38(6), 333–339. https://doi.org/10.1111/pim.12321
• MacKinnon, K. M., Bowdridge, S. A., Kanevsky-Mullarky, I., Zajac, A. M., & Notter, D. R. (2015). Gene expression profiles of hair and wool sheep reveal importance of Th2 immune mechanisms for increased resistance to. Journal of animal science, 93(5), 2074–2082. https://doi.org/10.2527/jas.2014-8652
• Mansfield, L.S. and H. R. Gamble. 1995. Alveolar mastocytosis and eosinophilia in lambs with naturally acquired nematode infections of Protostrongylus rufescens and Haemonchus contortus. Veterinary Immunology and Immunopathology. 49(3) :251-262.
• Middleton, D., Garza, J. J., Greiner, S. P., & Bowdridge, S. A. (2020). Neutrophils rapidly produce Th2 cytokines in response to larval but not adult helminth antigen. Parasite immunology, 42(1), e12679. https://doi.org/10.1111/pim.12679
• Panitz, E., R.W. Godfrey and R.E. Dodson. 2002. Resistance to Ivermectin and the effect of topical Eprinomectin on faecal egg counts in St Croix White Hair sheep. Veterinary Res Communic. 26(6):443-446 [Resistance of worms to ivermectin on the Virgin Islands]
• Roberts, J.A., S. Widjayanti, E. Estuningsih, and D.J. Hetzel. 1997. Evidence for a major gene determining the resistance of Indonesian thin tail sheep against Fasciola gigantica. Veterinary Parasitology. 68:309-314.
• Roberts, J.A., E. Estuningsih, S. Widjayanti, E. Wiedosari, S. Partoutomo, and T.W. Spithill. 1997. Resistance of Indonesian thin tail sheep against Fasciola gigantica and F. hepatica. Veterinary Parasitology. 68:69-78.
• Romjali, E., V.S. Pandey, R.M. Gatenby, M. Doloksaribu, H. Sakul, A. Wilson, A. Verhulst. 1997. Genetic resistance of different genotypes of sheep to natural infections with gastro-intestinal nematodes. Animal Science 64:97-104.
• Romjali, E., P. Dorny, A. Batubara,V.S. Pandey, and R.M. Gatenby. 1997. Peri-parturient rise in faecal strongyle egg counts of different genotypes of sheep in North Sumatra, Indonesia. Veterinary Parasitology 68:191-196.
• Shepherd, E., Greiner, S. P., Russ, B., & Bowdridge, S. A. (2020). Interleukin-13 induces paralysis of Haemonchus contortus larvae in vitro. Parasite immunology, 42(10), e12758. https://doi.org/10.1111/pim.12758
• Shepherd, E., Greiner, S. P., & Bowdridge, S. A. (2020). Characterization of ovine monocyte activity when cultured with Haemonchus contortus larvae in vitro. Parasite immunology, 42(11), e12773. https://doi.org/10.1111/pim.12773
• Shepherd, E. A., Garza, J. J., Greiner, S. P., & Bowdridge, S. A. (2017). The effect of ovine peripheral blood mononuclear cells on Haemonchus contortus larval morbidity in vitro. Parasite immunology, 39(4), 10.1111/pim.12424. https://doi.org/10.1111/pim.12424
• Vanimisetti, H. B., Greiner, S. P., Zajac, A. M., and D.R. Notter. 2004. Performance of hair sheep composite breeds: Resistance of lambs to Haemonchus contortus. Journal of Animal Science 82:595-604.
• Weaver, A. R., Garza, J. J., Greiner, S. P., & Bowdridge, S. A. (2021). Immune mechanisms of Texel sheep to adult and egg stages of Haemonchus contortus. Parasite immunology, 43(10-11), e12876. https://doi.org/10.1111/pim.12876
• Zajac, A.M., S. Krakowka, R.P. Herd, K.E. McClure. 1990. Experimental Haemonchus-contortus infection in three breeds of sheep. Veterinary Parasitology 36:221-235.

Research About Reproduction

• Burke, J.M.  2005. Lamb production of Dorper, Katahdin, and St. Croix bred in summer, winter, or spring in the southeastern United States. Sheep Goat Res J. 20:51-59.
• Brown, M.A. and W. G. Jackson. 1995. Ewe productivity and subsequent preweaning lamb performance in St. Croix sheep bred at different times during the year. J Anim Sci 73:1258-1263.
• Bunge, R., D. L. Thomas, and T. G. Nash. 1995. Performance of hair breeds and prolific wool breeds of sheep in southern Illinois: lamb production of F1 adult ewes. J Anim Sci 73: 1602-1608.
• Bunge, R., D. L. Thomas, and T. G. Nash. 1993. Performance of hair breeds and prolific wool breeds of sheep in southern Illinois: lamb production of F1 ewe lambs. J Anim Sci 71: 2012-2017.
• Bunge, R., D. L. Thomas, T. G. Nash, and R. L. Fernando. 1993. Performance of hair breeds and prolific wool breeds of sheep in southern Illinois: effect of breed of service sire on lamb production of Suffolk and Targhee ewes. J Anim Sci 71: 321-325.
• Godfrey, R.W., A.J. Weis, and R.E. Dodson. 2003. Effect of flushing hair sheep ewes during the dry and wet seasons in the U.S. Virgin Islands. J. Anim. Vet. Adv. 2:184-185.
• Godfrey, R.W., J.R. Collins, and E.L. Hensley. 2001. Behavioral and endocrine responses of hair sheep ewes exposed to different mating stimuli around estrus. Theriogenology 55:877-884.
• Godfrey, R.W., J.R. Collins, and M.L. Gray. 1998. Evaluation of sexual behavior of hair sheep rams in a tropical environment. J Anim Sci 76:714-717.
• Godfrey, R.W., M.L. Gray, and J.R. Collins. 1998. The effect of ram exposure on uterine involution and luteal function during the postpartum period of hair sheep ewes in the tropics. J Anim Sci 76:3090-3094.

Growth, Meat, or Carcass Focused Research

1. Bunch,T. D., R. C. Evans, S. Wang, C. P. Brennand, D. R. Whittier, and B. J. Taylor. 2004. Feed efficiency, growth rates, carcass evaluation, cholesterol level and sensory evaluation of lambs of various hair and wool sheep and their crosses. Small Ruminant Research 52:239-245.
2. Bunge, R., D. L. Thomas, T. G. Nash, and C. J. Lupton. 1996. Performance of hair breeds and prolific wool breeds of sheep in southern Illinois: wool production and fleece quality. J Anim Sci 74: 25-30.
3. Burke, J.M. , J. K. Apple, W. J. Roberts, C. B. Boger and E. B. Kegley . 2003. Effect of breed-type on performance and carcass traits of intensively managed hair sheep.  Meat Science 63:309-315.
4. Cole, N.A. 1999. Nitrogen retention by lambs fed oscillating dietary protein concentrations. J. Anim Sci 77:215-222.
5. Dodson, R.E., A.J. Weis and R.W. Godfrey. 2005. Post-weaning growth and carcass traits of St. Croix White and Dorper X St. Croix White lambs grazing pasture during the dry and wet seasons in the U.S. Virgin Islands. Sheep Goat Res J 20:25-31.
6. Godfrey, R.W. and A.J. Weis . 2005. Post-weaning growth and carcass traits of St. Croix White and Dorper X St. Croix White lambs fed a concentrate diet in the U.S. Virgin Islands. Sheep Goat Res J 20:32-36.
7. Godfrey, R.W. and R.E. Dodson. 2003. Effect of supplemental nutrition around lambing on hair sheep ewes and lambs during the dry and wet seasons in thve U.S. Virgin Islands. J Anim Sci. 81:587-593.
8. Godfrey, R.W., M.L. Gray, and J.R. Collins. 1997. Lamb growth and milk production of hair and wool sheep in a semi-arid tropical environment. Small Ruminant Research 24:77-83.
9. Goetsh, A. L. (1998). A note on the effect of lamb growth potential, litter size, and concentrate supplements on performance of lambs and lactating ewes consuming low to moderate quality grass hay. Journal of Animal and Feed Sciences, 7(1), 37-44. https://doi.org/10.22358/jafs/69193/1998
10. Goetsch, A.L. 1999. Growing and finishing performance by lambs differing in growth potential consuming diets during growing varying in levels of corn and rumen undegradable protein. Small Ruminant Research 31:245-257.
11. Goetsch, A.L. and Z.B. Johnson. 1999. Feed intake and digestion in the summer and fall by different breeds of ewes consuming forages differing in quality. Small Ruminant Research 31:109-116.
12. Hammond, A. C. and S. Wildeus. 1993. Effects of coconut meal or fish meal supplementation on performance, carcass characteristics and diet digestibility in growing St. Croix lambs fed a tropical grass-based diet. Small Ruminant Research 12:13-25
13. Horton, G.M.J., and C.C. Burgher. 1992. Physiological and carcass characteristics of hair and wool breeds of sheep. Small Ruminant Research 7:51-60.
14. Ockerman, H.W., H. Emsen, C.F. Parker, and C.J. Pierson. 1982. Influence of type wooled or hair and breed on growth and carcass characteristics and sensory properties of lamb. J. Food Sci 47:1365-1368.
15. Phillips, W.A., M.A. Brown, H.G. Dolezal and G.Q. Fitch. 2005. Feedlot performance and carcass characteristics of lambs sired by Texel, Romanov, St. Croix or Dorset rams from Polypay and St. Croix ewes. Sheep Goat Res J 20:11-16.
16. Wildeus, S., K.E. Turner, and J.R. Collins. 2005. Growth Performance of Barbados Blackbelly, Katahdin and St. Croix Hair Sheep Lambs Fed Pasture- or Hay-Based Diets. Sheep Goat Res J. 20:37-41.

Research About Other Topics

• Hussein, A. H., Patra, A. K., Puchala, R., Wilson, B. K., & Goetsch, A. L. (2022). Effects of Restricted Availability of Drinking Water on Blood Characteristics and Constituents in Dorper, Katahdin, and St. Croix Sheep from Different Regions of the USA. Animals : an open access journal from MDPI, 12(22), 3167. https://doi.org/10.3390/ani12223167
• Seabury, C.M. and J.N. Derr. 2003. Identification of a novel ovine PrP polymorphism and scrapie-resistant genotypes for St. Croix White and a related composite breed. Cytogenet Genome Res 102:85-88.
• Spangler GL, Rosen BD, Ilori MB, Hanotte O, Kim ES, et al. (2017) Whole genome structural analysis of Caribbean hair sheep reveals quantitative link to West African ancestry. PLOS ONE 12(6): e0179021. https://doi.org/10.1371/journal.pone.0179021
• Wildeus, S. 1997. Hair sheep genetic resources and their contribution to diversified small ruminant production in the United States. J Anim Sci 75:630-640