Short-term testicular warming under anesthesia causes similar increases in testicular blood flow in Bos taurus versus Bos indicus bulls, but no apparent hypoxia

Autor(es)

Rizzoto, G. ^[1] ; Ferreira, J. C. P. ^[2] ; Mogollon Garcia, H. D. ^[2] ; Teixeira-Neto, F. J. ^[3] ; Bardella, L. C. ^[4] ; Martins, C. L. ^[5] ; Silva, J. R. B. ^[3] ; Thundathil, J. C. ^[1] ; Kastelic, J. P. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Calgary, Fac Vet Med, Dept Prod Anim Hlth, Calgary, AB - Canada

^[2] Sao Paulo State Univ UNESP, Sch Vet Med & Anim Sci, Dept Anim Reprod & Vet Radiol, Rua Prof Dr Walter Mauricio Correa S-N, BR-18618681 Botucatu, SP - Brazil

^[3] Sao Paulo State Univ UNESP, Sch Vet Med & Anim Sci, Dept Vet Surg & Anesthesiol, Botucatu, SP - Brazil

^[4] Sch Med, Expt Res Unit, Botucatu, SP - Brazil

^[5] Sao Paulo State Univ UNESP, Sch Vet Med & Anim Sci, Dept Anim Breeding & Nutr, Botucatu, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Theriogenology; v. 145, p. 94-99, MAR 15 2020.
• Citações Web of Science: 1

Resumo

Bull testes must be 4-5 degrees C below body temperature, with testicular warming more likely to cause poor-quality sperm in Bos taurus (European/British) versus Bos indicus (Indian/zebu) bulls. Despite a long-standing dogma that testicular hyperthermia causes hypoxia, we reported that increasing testicular temperature in bulls and rams enhanced testicular blood flow and O-2 delivery/uptake, without hypoxia. Our objective was to determine effects of short-term testicular hyperthermia on testicular blood flow, O-2 delivery and uptake and evidence of testicular hypoxia in pubertal Angus (B. taurus) and Nelore (B. indicus) bulls (nine per breed) under isoflurane anesthesia. As testes were warmed from 34 to 40 degrees C, there were increases (P < 0.0001, but no breed effects) in testicular blood flow (mean +/- SEM, 9.59 +/- 0.10 vs 17.67 +/- 0.29 mL/min/100 g, respectively), O-2 delivery (1.79 +/- 0.06 vs 3.44 +/- 0.11 mL O-2/min/100 g) and O-2 consumption (0.69 +/- 0.07 vs 1.25 +/- 0.54 mL O-2/min/100 g), but no indications of testicular hypoxia. Hypotheses that: 1) both breeds increase testicular blood flow in response to testicular warming; and 2) neither breed has testicular hypoxia, were supported; however, the hypothesis that the relative increase in blood flow is greater in Angus versus Nelore was not supported. Although these were short-term increases in testicular temperature in anesthetized bulls, results did not support the long-standing dogma that increased testicular temperature does not increase testicular blood flow and an ensuing hypoxia is responsible for decreases in motile, morphologically normal and fertile sperm. (C) 2020 Elsevier Inc. All rights reserved. (AU)

• Processo FAPESP: 18/02007-6 - Efeito do estresse térmico no fluxo sanguíneo e metabolismo testicular de bovinos: existe uma differença entre raças européias e zebuínos?
• Beneficiário: João Carlos Pinheiro Ferreira
• Modalidade de apoio: Auxílio à Pesquisa - Regular