Bovine Reproduction. Группа авторов

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Bovine Reproduction - Группа авторов


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blood flow is the main source of testicular heat in bulls and higher ambient temperatures significantly increase testicular blood flow. Theriogenology 116: 12–16.

      18 18 Waites, G. and Setchell, B. (1964). Effect of local heating on blood flow and metabolism in the testis of the conscious ram. Reproduction 8: 339–349.

      19 19 Kastelic, J., Wilde, R., Rizzoto, G., and Thundathil, J. (2017). Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia. Vet. Med. 62: 437–442.

      20 20 Kastelic, J., Wilde, R., Bielli, A. et al. (2019). Hyperthermia is more important than hypoxia as a cause of disrupted spermatogenesis and abnormal sperm. Theriogenology 131: 177–181.

      21 21 Rizzoto, G., Hall, C., Tyberg, J. et al. (2018). Increased testicular blood flow maintains oxygen delivery and avoids testicular hypoxia in response to reduced oxygen content in inspired air. Sci. Rep. 8: 10905.

      22 22 Rizzoto, G., Hall, C., Tyberg, J. et al. (2019). Testicular hyperthermia increases blood flow that maintains aerobic metabolism in rams. Reprod. Fertil. Dev. 31: 683–688.

      23 23 Rizzoto, G., Ferreira, J., Mogollón Garcia, H. et al. (2020). Short‐term testicular warming under anaesthesia causes similar increases in testicular blood flow in Bos taurus versus Bos indicus bulls, but no apparent hypoxia. Theriogenology 15: 94–99.

      24 24 Coulter G. (1988) Thermography of bull testes. In: Proceedings of the 12th Technical Conference on Artificial Insemination and Reproduction. Columbia, MO: National Association of Animal Breeders, pp. 58–63.

      25 25 Purohit, R., Hudson, R., Riddell, M. et al. (1985). Thermography of the bovine scrotum. Am. J. Vet. Res. 46: 2388–2392.

      26 26 Lunstra, D. and Coulter, G. (1997). Relationship between scrotal infrared temperature patterns and natural‐mating fertility in beef bulls. J. Anim. Sci. 75: 767–774.

      27 27 Skinner, J. and Louw, G. (1966). Heat stress and spermatogenesis in Bos indicus and Bos taurus cattle. J. Appl. Physiol. 21: 1784–1790.

      28 28 Johnston, J., Naelapaa, H., and Frye, J. (1963). Physiological responses of Holstein, Brown Swiss and Red Sindhi crossbred bulls exposed to high temperatures and humidities. J. Anim. Sci. 22: 432–436.

      29 29 Wildeus, S. and Entwistle, K. (1983). Spermiogram and sperm reserves in hybrid Bos indicus × Bos taurus bulls after scrotal insulation. J. Reprod. Fertil. 69: 711–716.

      30 30 Vogler, C., Saacke, R., Bame, J. et al. (1991). Effects of scrotal insulation on viability characteristics of cryopreserved bovine semen. J. Dairy Sci. 74: 3827–3835.

      31 31 Vogler, C., Bame, J., DeJarnette, J. et al. (1993). Effects of elevated testicular temperature on morphology characteristics of ejaculated spermatozoa in the bovine. Theriogenology 40: 1207–1219.

      32 32 Barth, A. and Bowman, P. (1994). The sequential appearance of sperm abnormalities after scrotal insulation or dexamethasone treatment in bulls. Can. Vet. J. 35: 93–102.

      33 33 Kastelic, J., Cook, R., Coulter, G., and Saacke, R. (1996). Insulating the scrotal neck affects semen quality and scrotal/testicular temperatures in the bull. Theriogenology 45: 935–942.

      34 34 Bedford, J. (1991). Effects of elevated temperature on the epididymis and testis: experimental studies. In: Temperature and Environmental Effects on the Testis (ed. A.W. Zorgniotti), 19–32. New York;: Plenum Press.

      35 35 Waites, G. and Setchell, B. (1990). Physiology of the mammalian testis. In: Marshall's Physiology of Reproduction, 4e, vol. 2 (ed. C.E. Lamming), 1–105. Edinburgh: Churchill Livingstone.

      36 36 Setchell, B., Voglmayr, J., and Hinks, N. (1971). The effect of local heating on the flow and composition of rete testis fluid in the conscious ram. J. Reprod. Fertil. 24: 81–89.

      37 37 Barth, A. and Oko, R. (1989). Abnormal Morphology of Bovine Spermatozoa, 139. Ames, IA: Iowa State University Press.

      38 38 Rahman, M., Vandaele, L., Rijsselaere, T. et al. (2011). Scrotal insulation and its relationship to abnormal morphology, chromatin protamination and nuclear shape of spermatozoa in Holstein‐Friesian and Belgian Blue bulls. Theriogenology 76: 1246–1257.

      39 39 Fernandes, C., Dode, M., Pereira, D., and Silva, A. (2008). Effects of scrotal insulation in Nellore bulls (Bos taurus indicus) on seminal quality and its relationship with in vitro; fertilizing ability. Theriogenology 70: 1560–1568.

      40 40 Burfening, P. and Ulberg, L. (1968). Embryonic survival subsequent to culture of rabbit spermatozoa at 38° and 40°. J. Reprod. Fertil. 15: 87–92.

       Leonardo F.C. Brito

       STgenetics, Middleton, WI, USA

Schematic illustration of mean serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone concentrations in bulls during the infantile (a), prepubertal (b), and pubertal/postpubertal (c) periods. Data from 2 to 6 weeks are adapted from Hereford times Charolais bulls [1]. Data from 10 to 70 weeks are from Angus and Angus times Charolais bulls receiving adequate nutrition [2–5]. Infancy is the period that extends from birth until approximately eight weeks of age.

      Sources: Data from [2,4–6].

      The infantile period is characterized by low gonadotropin and testosterone secretion and relatively few changes in testicular cellular composition. This period extends from birth until approximately two months of age in Bos taurus bulls.

      Gonadotropin secretion during the infantile period is low


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