İneklerde Ovaryum Kistlerinin Tanısı, Tedavisi ve Korunma Yöntemleri
Yıl 2022,
Cilt: 11 Sayı: 2, 121 - 136, 16.12.2022
Gulseda Karsavuranoğlu
,
Mustafa Kemal Sarıbay
,
Ahmet Gözer
,
Onur Bahan
Öz
Süt ineği işletmelerinde fertilite açısından temel hedef, doğumdan sonra en uygun zamanda tohumlama yapılarak yılda bir buzağı alınmasıdır. Bu amaç doğrultusunda postpartum dönemde ineklerin genital organ muayenelerinin rutin kontrolleri en kısa zamanda yapılarak herhangi bir anormallik olup olmadığı tespit edilmelidir. Aksi takdirde infertilite problemlerinin zamanında tespit edilememesine bağlı olarak oluşan büyük ekonomik kayıplar işletmelerin sürdürülebilirliğini tehlikeye sokmaktadır. Ovaryum kistleri ineklerde postpartum dönemde yaygın olarak görülen, hem doğum-gebe kalma süresinin uzamasına hem de tedavi ve hekim masraflarının artmasına bağlı olarak önemli ekonomik kayıplara yol açabilen infertilite nedenlerindendir. Bu derlemede, ineklerde ovaryum kistlerinin etiyoloji, patogenez, tanı, tedavi ve korunma yöntemleri ile ilgili güncel bilgilere yer verilmeye çalışılmıştır.
Kaynakça
- Akar, Y., Gazioglu, A. (2006). Relationship between vitamin A and b-carotene levels during the postpartum period and fertility parameters in cows with and without retained placenta. Bulletin of the Veterınary Institute in Pulawy, 50, 93–96.
- Alaçam, E. (2002). İnekte infertilite sorunu. Alaçam, E. (Ed). Evcil Hayvanlarda Doğum ve İnfertilite (Üçüncü Baskı). 267-290, Medisan, Ankara.
- Allison, R. D., Laven, R. A. (2000). Effect of vitamin E supplementation on the health and fertility of dairy cows: a review. Veterinary Record, 147(25), 703-708.
- Ambrose, D. J., Schmitt, E. J. P., Lopes, F. L., Mattos R. C., Thatcher, W. W. (2004). Ovarian and endocrine responses associated with the treatment of cystic ovarian follicles in dairy cows with gonadotropin releasing hormone, and prostaglandin F2α, with or without exogenous progesterone. Canadian Veterinary Journal, 45, 931-937.
- Amiridis, G. (2009). Comparison of aspiration and hormonal therapy for the treatment of ovarian cysts in cows. Acta Veterinaria Hungarica, 57(4), 521-529.
- Annalisa, R., Debora, C., Maddalena, M., Giuseppe, M., Massimo, S., Luigi, S. R. (2011). Epidural vs intramuscular administration of lecirelin, a GnRH analogue, for the resolution of follicular cysts in dairy cows. Animal Reproduction Science, 126,19-22.
- Arbeiter, K., Aslan, S., Schwarzenberger, F. (1990). Untersuchungen über die Ovarzyste beim Rind oe Entstehung, Therapieerfolge, Fruchtbarkeit. Deutsche tierärztliche Wochenschrift, 97, 380-382.
- Arthur, G. H., Noakes, D. E., Pearson, H. (1989). Veterinary Reproduction and Obstetrics (Theriogenology) (6th Ed.). Bailliere Tindall, London.
- Bartlett, P. C., Ngategize, P. K., Kaneene, J. B., Kirk, J. H., Anderson, S. M. et al. (1986). Cystic follicular disease in Michigan Holstein–Friesian cattle: incidence, descriptive epidemiology and economic impact. Preventive Veterinary Medicine, 4, 15-34.
- Bartolome, J. A., Archbold, L. F., Morresey, P. (2000). Comparison of synchronization of ovulation and induction of estrus as therapeutic strategies for bovine ovarian cysts in the dairy cow. Theriogenology, 53, 815-825.
- Bartolome, J. A., Thatcher, W. W., Melendez, P., Risco, C. A., Archbald, L. F. (2005). Strategies for the diagnosis and treatment of ovarian cysts in dairy cattle. Journal of the American Veterinary Medical Association, 227(9), 1409-1414.
- Boos, A (1987). β- carotin und Follikle-Lutein-Zysten rind. Zuchthyg, 2, 223-228.
- Borş, S. I., Borş, A. (2020). Ovarian cysts, an anovulatory condition in dairy cattle. Journal of Veterinary Medical Science, 82, 1515–1522.
- Boyd, J. S., Omran, S. N. (1991). Diagnostic ultrasonography of the bovine female reproductive tract. In Practice, 13(3), 109-118.
Braw-Tal, R., Pen, S., Roth, Z. (2009). Ovarian cysts in high-yielding dairy cows. Theriogenology, 72, 690-698.
- Brito, L. F. C., Palmer, C. W. (2004). Cystic Ovarian Disease in Cattle. Large Animal Veterinary Rounds, 4, 1-6.
- Britt, J. H., Harrison, D. S., Morrow, D. A. (1977). Frequency of ovarian follicular cysts, reasons for culling, and fertility in Holstein-Friesian cows given gonadotropin-releasing hormone at two weeks after parturition. American Journal of Veterinary Research, 38, 749.
- Britt, J. H., Kittok, R. J., Harrison, D. S. (1974). Ovulation, estrus and endocrine response after GnRH in early postpartum cows. The Journal of Animal Science, 39, 915.
- Calder, M. D., Manikkam, M., Salfen, B. E., Youngquist, R. S., Lubahn, D. B., Lamberson R. L. et al. (2001). Dominant Bovine Ovarian Follicular Cysts Express Increased Levels of Messenger RNAs for Luteinizing Hormone Receptor and 3β-hydroxysteroid Dehydrogenase Δ4 , Δ5 Isomerase Compared to Normal Dominant Follicles. Biology of Reproduction, 65, 471-476.
- Calder, M. D., Salfen, B. E., Bao, B., Youngquist, R. S., Garverick, H. A. (1999). Administration of progesterone to cows with ovarian follicular cysts results in a reduction in mean LH and LH pulse frequency and initiates ovulatory follicullar growth. The Journal of Animal Science, 77, 3037-3042.
- Carroll, D. J., Pierson, R. A., Hauser, E. R., Grummer, R. R., Combs, D. K. (1990). Variability of ovarian structures and plasma progesterone profiles in dairy cows with ovarian cysts. Theriogenology, 34, 349-370.
- Cattaneo, L., Signorini M. L., Bertoli, J., Bartolome, J. A., Gareis, N. C., Diaz, P.U. et al. (2014). Epidemiological description of cystic ovarian disease in Argentine dairy herds: risk factors and effects on the reproductive performance of lactating cows. Reproduction in Domestic Animals, 49, 1028-1033.
- Coleman, D. A. Cystic Ovarian Disease. http://www.wvu.edu/~exten/infores/pubs/livepoul/dirm25.pdf. Erişim Tarihi: 19.03.2022.
- Cook, D. L., Parfet, J. R., Smith, C. A., Moss, G. E., Youngquist, R. S., Brown, E. M., Garverick, H. A. (1991). Secretory patterns of LH and FSH during development and hypothalamic and hypophysial characteristics following development of steroid-induced ovarian follicular cysts in dairy cattle. Journal of Reproduction and Infertility, 91, 19-28.
- Cook, D. L., Smith, C. A., Parfet, J. R., Youngquist, R. S., Brown, E. M., Garverick, H. A. (1990). Fate and turnover rate of ovarian follicular cysts in dairy cows. Journal of Reproduction and Fertility, 89, 155-166.
- Cruz, C. E., Corbellini, L. G., Driemeier, D. (2004). Simple procedure for emptying long-term ovarian cysts in cattle. Veterinary Record, 155(19), 599-601.
- Day, N. (1991). The diagnosis, differentiation, and pathogenesis of cystic ovarian disease. Veterinary Medicine,7, 753-760.
- Dobson, H., Smith, R. F. (2000). What is stress, and how does it affect reproduction?. Animal Reproduction Science, 60-61, 743-752.
Douthwaite, R., Dobson, H. (2000). Comparison of different methods of diagnosis of cystic ovarian disease in cattle and an assessment of its treatment with a progesterone‐releasing intravaginai device. Veterinary Record, 147(13), 355-359.
- Drost, M., Thatcher, W. W. (1992). Application of gonadotrophin releasing hormone as therapeutic agent in animal reproduction. Animal Reproduction Science, 28, 11-19.
- Duchens, M., Forsberg, M., Edqvist, L. E., Gustafsson, H., Rodriguez-Martinez, H. (1994). Effect of induced suprabasal progesterone levels around estrus on plasma concentrations of progesterone, estradiol-17β and LH in heifers. Theriogenology, 42, 1159-1169.
- Farin, P. W., Youngquist, R. S., Parfet, J. R., Garverick, H. A. (1992). Diagnosis of luteal and follicular ovarian cysts by palpation per rectum and linear-array ultrasonography in dairy cows. The Journal of the American Veterinary Medical Association, 200(8), 1085-1089.
- Garverick, H. A. (1997). Ovarian follicular cysts in dairy cows. Journal of Dairy Science, 80, 995-1004.
- Garverick, H. A. (2007). Ovarian follicular cysts. Youngquist, R. S., Threlfall, W. R. (Eds). Current Therapy in Large Animal Theriogenology. 379-382, St. Louis Saunders Elsevier.
- Gürkan, N. (2014). Kistik ovaryumlu ineklerde kan serumunda progesteron düzeyleri ile sütün biyokimyasal ve mikrobiyolojik profilinin araştırılması. (Doktora tezi). İstanbul Üniversitesi Sağlık Bilimleri Enstitüsü, İstanbul.
- Hamilton, S. A., Garverick, H. A., Keisler, D. H., Xu, Z. Z., Loos, K., Youngquist, R. S. et al. (1995). Characterization of ovarian follicular cysts and associated endocrine profiles in dairy cows. Biology of Reproduction, 53, 890-898.
- Hanzen, C. H., Pieterse, M., Scenzi, O., Drost, M. (2000). Relative accuracy of the identification of ovarian structures in the cow by ultrasonography and palpation per rectum. The Veterinary Journal, 159, 161-170.
- Harrison, J. H., Hancock, D. D., Conrad, H. R. (1984). Vitamin E and selenium requirements of the dairy cow. Journal of Dairy Science, 67, 123-132.
- Hartigan, A. A. (1995). Cattle breeding and infertility. Meredith, M. J. (Ed). Animal Breeding and Infertility. 82-162, Blackwell Science Ltd, Oxford.
- Hatler, T. B., Hayes, S. H., Laranja De Fonseca, L. F., Silvia, W. J. (2003). Relationship between endogenous progesterone and follicular dynamics in lactating dairy cows with ovarian follicular cysts. Biology of Reproduction, 69, 218-223.
- Henderson, E. A. (1982). A review of ıhe response of dairy cattle with cystic ovaries to gonadotropin releasing hormone. Canadian Veterinary Journal, 23, 145.
- Hooijer, G. A., Van Oijen, M. A. A. J., Frankena, K., Valks, M. M. H. (2001). Fertility Parameters for Dairy Cows with Cystic Ovarian Disease after Treatment with Gonadotropin-Releasing Hormone. Veterinary Record, 149, 383-386.
- Ijaz, A., Fahning, M. L., Zemjanis, R. (1987). Treatment and control of cystic ovarian disease in dairy cattle: A review. British Veterinary Journal, 143(3), 226-237.
- Isobe, N. (2007). Follicular Cysts in Dairy Cows. Animal Science Journal, 78, 1-6.
- Isobe, N., Kitabayashi, M., Yoshimura, Y. (2005). Microvascular distribution and vascular endothelial growth factor expression in bovine cystic follicles. Domestic Animal Endocrinology, 29, 634-645.
- Jaskowski, J. M. (1993). The effect of antepartum doses of selenium vitamin E combinations on the incidence of puerperal disorders in cattle. Tierarztliche Praxis, 21, 111-116.
- Jeengar, K., Chaudhary, V., Kumar, A., Raiya, S., Gaur, M., Purhoit, G. N. (2018). Ovarian cysts in dairy cows: old and new concepts for definition, diagnosis and therapy. Animal Reproduction, 11(2), 63-73.
- Jonsson, N. N., Mc Gowan, M. R., Mc Guigan, K., Davison, T. M., Hussain, A. M. (1997). Relationships among calving season, heat load, energy balance and postpartum ovulation of dairy cows in a subtropical environment. Animal Reproduction Science, 47, 315-326.
- Kahn, C. M. (2010). Cystic ovary disease. The Merck Veterinary Manual (10th ed.). 1243-1247, Whitehouse Station, N.J., Merck & Co Inc, USA.
- Kastelic, J. P., Pierson, R. A., Ginther, O. J. (1990). Ultrasonic morphology of corpora lutea and central luteal cavities during the estrous cycle and early pregnancy in heifers. Theriogenology, 34(3), 487-498.
- Kesler, D. J. (1977). Endocrine and ovarian responses and reproductive performance in dairy cows following GnRH tteaunent during the early postpartum period and following GnRH and/or PGF2a in cows with ovarian cysts. (PhD Thesis). Univ. of Missouri, Columbia.
- Kesler, D. J., Garverick, H. A. (1982). Ovarian cysts in dairy cattle: a review. The Journal of Animal Science, 55(5), 1147-1159.
- Kesler, D. J., Garverick, H. A., Youngquist, R. S., Elmore, R. G., Bierschwal, C. J. (1978b). Ovarian and endocrine responses and reproductive performance following GnRH treatment in early postpartum dairy cows. Theriogenology, 9(4), 363-369.
- Kim, K. D., Ki, K. S., Kang, H. G., Kim, I. H. (2005). Risk factors and the economic impact of ovarian cysts on reproductive performance of dairy cows in Korea. The Journal of Reproduction and Development, 51(4), 491-498.
- Lievaart, J. J., Parlevliet, J. M., Dieleman, S. J., Rientjes, S., Bosman, E., Vos, P. L. (2006). Transvaginal aspiration as first treatment of ovarian follicular cysts in dairy cattle under field circumstances. Tijdschr Diergeneeskd, 131, 438-442.
- Lopez-Diaz, M. C., Bosu, W. T. K. (1992). A review and update of cystic ovarian degeneration in ruminants. TheriogenoIogy, 37(6), 1163-1183.
- Lopez-Gatius, F., Lopez-Bejar, M. (2002). Reproductive performance of dairy cows with ovarian cysts after different GnRH and cloprostenol treatments. Theriogenology, 58(7), 1337-1348.
- Lopez-Gatius, F., Santolaria, P., Yaniz, J., Fenech, M., Lopez-Bejar, M. (2002). Risk factors for postpartum ovarian cysts and their spontaneous recovery or persistence in lactating dairy cows. Theriogenology, 58(8), 1623-1632.
- Lucy, M. C. (2001). Reproductive Loss in High Producing Dairy Cattle: Where Will It End? Journal of Dairy Science, 84(6), 1277-1293.
- Mehdi, Y., Dufrasne, I. (2016). Selenium in cattle: a review. Molecules, 21(4), 545.
- Mimoune, N., Azzouz, M. Y., Khelef, D., Kaidi, R. (2021). Ovarian cysts in cattle: a review. Veterinarska Stanica, 52(5), 587-603.
- Mimoune, N., Baazizi, R., Azzouz, M. Y., Benaissa, M. H., Kaidi, R. (2019). Basic and new concepts of ovarian cyst pathogenesis in cattle. Veterinaria, 68(2), 73-80.
- Mohammed, H. O., White, M. E., Guard, C. L., Smith, M. C., Mechor, G. D., Booker, C. W. et al. (1991). A Case- Control Study of the Association Between Blood Selenium and Cystic Ovaries in Lactating Dairy Cattle. Journal of Dairy Science, 74, 2180-2185.
- Mueller, K. (2008). Cystic ovarian disease in cows diagnosis and treatment decisions. UK Vet Livestock, 13(1), 44-50.
- Mwaanga, E. S., Janowski, T. (2000). Anoestrus dairy cows: Causes, prevalance and clinical forms: A Review. Reproduction in Domestic Animals, 35(5), 193-200.
- Nelson, S. T., Martin, A. D., Ostreas, O. (2010). Risk Factors Associated with Cystic Ovarian Disease in Norvegian Dairy Cattle. Acta Veterinaria Scandinavica, 52(1), 60.
- Opsomer, G., Leroy, J., Vanholder, T., Bossaert, P., de Kruif, A. (2006). High Milk Production and Good Fertility in Modern Dairy Cows: The Results of Some Recent Items. Slovenian Veterinary Research, 43(1), 31-39.
- Ortega, H. H., Marelli, B. E., Rey, F., Amweg, A. N., Diaz, P. U., Stangaferro, M. L. et al. (2015). Molecular aspects of bovine cystic ovarian disease pathogenesis. Reproduction, 149(6), 251-264.
- Özsoy, S., Altunatmaz, K., Horoz, H., Kaşıkçı, G., Alkan, S., Bilal, T. (2005). The Relationship Between Lameness, Fertility and Aflatoxin in a Dairy Cattle Herd. The Turkish Journal of Veterinary and Animal Sciences, 29(4), 981-986.
- Parkinson, T. (2001). Infertility in the cow: structural and functional abnormalities, management deficiences and non-spesific infectiones. In: Arthur’s Veterinary Reproduction and Obstetric (8th Ed). 383-472, W.B. Saunders, London.
- Peter, A. T. (2004). An update on cystic ovarian degeneration in cattle. Reproduction in Domestic Animals, 39(1), 1-7.
- Peter, A. T. (1997). Infertility due to abnormalities of the ovaries. Youngquist, R. S. (Ed). Current Therapy in Theriogenology. 349-354, WB Saunders Company, Philadelphia.
- Peter, A. T., Dhanasekaran, N. (2003). Apoptosis of granulosa cells: a review on the role of MAPK‐signalling modules. Reproduction in Domestic Animals, 38(3), 209-213.
- Probo, M., Comin, A., Mollo, A., Cairoli, F., Stradaioli, G., Veronesi, M. C. (2011b). Reproductive performance of dairy cows with luteal or follicular ovarian cysts after treatment with buserelin. Animal Reproduction Science, 127(3-4), 135-139.
- Purohit, G. N., Joshi, B. K., Bishnoi, B. L., Gupta, A. K., Joshi, R. K. et al. (2001). Cystic ovarian disease in Rathi Cattle. Annals of Arid Zone, 40(2), 199-202.
- Rauch, A., Krüger, L., Miyamoto, A., Bollwein, H. (2008). Colour Doppler sonography of cystic ovarian follicles in cows. The Journal of Reproduction and Development, 54, 447-453.
- Rizzo, A., Minoia, G., Trisolini, C., Mutinati, M., Spedicato, M. (2009). Renin and ovarian vascularization in cows with follicular cysts after epidural administration of a GnRH analogue. Animal Reproduction Science, 116(3-4), 226-232.
- Roberson, M. S., Wolfe, M. W., Stumpf, T. T., Kittok, R. J., Kinder, J. E. (1989). Luteinizing hormone secretion and corpus luteum function in cows receiving two levels of progesterone. Biology of Reproduction, 41(6), 997-1003.
- Robinson, R. S., Hunter, M. G., Mann, G. E. (2006). Suprabasal progesterone concentrations during the follicular phase are associated with development of cystic follicles in dairy cows. The Veterinary Journal, 172(2), 340-346.
- Salvetti, N. R., Acosta, J. C., Gimeno, E. J., Müller, L. A., Mazzini, R. A., Taboada, A. F. et al. (2007). Estrogen Receptors α and β and Progesterone Receptors Normal Bovine Ovarian Follicles and Cystic Ovarian Disease. Veterinary Pathology, 44(3), 373-378.
- Santos, J. E. P., Rutigliano, H. M., Sa Filho, M. F. (2009). Risk factors for resumption of postpartum estrous cycles and embryonic survival in lactating dairy cows. Animal Reproduction Science, 110(3-4), 207-221.
- Santos, J. E., Huber, J. T., Theurer, C. B., Nussio, C. B., Nussio, L. G., Tarazon, M. et al. (2000). Effects of grain processing and bovine somatotropin on metabolism and ovarian activity of dairy cows during early lactation. Journal of Dairy Science, 83(5), 1004-1015.
- Schjervin, L. (1971). A clinical study on cystic ovarian disease in dairy cattle with special reference to incidence, treatment and factors related to recovery and fertility. (PhD Thesis). Oslo Veterinary College, Norway.
- Scott, S. J., Dobson, H. (1997). Postmonem comparison of ultrasonography, endocrine measurements and histology of large abnonnal ovarian follicles in cows. Veterinary Record, 140(25), 654-656.
- Silva, A. M., Moreira, R. J. C., Fernandes, C. A. C., Palhão, M. P., Gioso, M. M., Neves, J. P. (2012). Treatment of ovarian cysts in cattle with lecirelin acetate. Animal Reproduction, 9(3), 591.
- Silvia, W. J., Hatler, T. B., Nugent, A. M., Da Fonseca, L. L. (2002). Ovarian follicular cysts in dairy cows: an abnormality in folliculogenesis. Domestic Animal Endocrinology, 23(1-2), 167-177.
- Smith, M. F., McIntush, E. W., Ricke, W. A., Kojima, F. N., Smith, G. W. (1999). Regulation of ovarian extracellular matrix remodelling by metalloproteinases and their tissue ınhibitors: effects on follicular development, ovulation and luteal function. Journal of Reproduction and Fertility, 54, 367-381.
- Souza, A. H., Cunha, A. P., Silva, E. P. B., Gümen, A., Ayres, H. (2009). Comparison of gonadorelin products in lactating dairy cows: Efficacy based on induction of ovulation of an accessory follicle and circulating luteinizing hormone profiles. Theriogenology, 72(2), 271-279.
- Stassi, A. F., Gasser, F., Velazquez, M. M. L., Belotti, E. M., Gareis, N. C., Rey, F. et al. (2019). Contribution of the VEGF system to the follicular persistence associated with bovine cystic ovaries. Theriogenology, 138, 52-65.
- Stock, A. E., Fortune, J. E. (1993). Ovarian follicular dominance in cattle: relationship between prolonged growth of ovulatory follicle and endocrine parameters. Endocrinology, 132(3), 1108-1114.
- Şenünver, A., Nak, Y. (2015). İnfertilite. Semacan, A., Kaymaz, M., Fındık, M., Rişvanlı, A., Köker, A. (Eds). Çiftlik Hayvanlarında Doğum ve Jinekoloji. 2nd ed., 365-419, Medipres Yayınları, Malatya.
- Tebble, J. E., O’Donnell, M. J., Dobson, H. (2001). Ultrasound diagnosis and treatment outcome of cystic ovaries in cattle. Veterinary Record, 148(13), 411-413.
- Todoroki, J., Yamakuchi, H., Mizoshita, K., Kubota, N., Tabara, N., Noguchi, J. et al. (2001). Restoring ovulation in beef donor cows with ovarian cysts by progesterone-releasing intravaginal silastic devices. Theriogenology, 55(9), 1919-1932.
- Vanholder, T., Opsomer, G., De Kruif, A. (2006). Aetiology and pathogenesis of cystic ovarian follicles in dairy cattle: a review. Reproduction Nutrition Development, 46(2), 105-119.
- Viana, J. H. M., Nascimento, A. A., Pinheiro, N. L., Ferreira, A. M., Camargo, L. S., Vanderlei, F. S. et al. (2003). Caracterizaçao de seqüelas subseqüentes a punçao folicular em bovinos. Pesquisa Veterinária Brasileira, 23, 119-124.
- Watson, C. L., Cliff, A. J. A. (1997). Survey of cystic ovarian disease in practice. The Bovine Practitioner, 31, 15-18.
- Wilde, D. (2006). Influence of macro and micro minerals in the peri-parturient period on fertility in dairy cattle. Animal Reproduction Science, 96(3-4), 240-249.
- Yousefdoost, S., Samadi, F., Moghaddam, G., Hassani, S., Jafari Ahangari, Y. (2012). A comparison of hormonal, metabolite and mineral profiles between Holstein cows with and without ovarian cysts. International Journal of Agriculture Sciences, 2(12), 1107-1115.
- Zaied, A. A., Garverick, H. A., Bierschwal, C. J., Eimore, R. G., Youngquist, R. S., Sharp, A. J. (1980). Effect of ovarian activity and endogenous reproductive hormones on GnRH-induced ovarian cycles in postpartum dairy cows. Journal of Animal Science, 50, 508.
- Zarczynska, K., Sobiech, P., Radwinska, J., Rekawek, W. (2013). Effects of selenium on animal health. Journal of Elementology, 18(2), 329-340.
- Zulu, V. C., Nakao, T., Yamada, K., Moriyoshi, M., Nakada, K., Yutaka, S. (2003). Clinical response of ovarian cysts in dairy cows after PRID treatment. Journal of Veterinary Medical Science, 65(1), 57-62.
- Zulu, V. C., Penny, C. (1998). Risk Factors of Cystic Ovarian Disease in Dairy Cattle. The Journal of Reproduction and Development, 44(2), 191-195.