Data/hora: 06/06/2024 14:15:29

Biblioteca(s): | Embrapa Pecuária Sudeste.
Data corrente: | 14/09/2018
Data da última atualização: | 15/12/2023
Autoria: | ROMANELLO, N.; LOURENÇO JUNIOR, J. de B.; BARIONI JUNIOR, W.; BRANDÃO, F. Z.; MARCONDES, C. R.; PEZZOPANE, J. R. M.; PANTOJA, M. H. de A.; BOTTA, D.; GIRO, A.; MOURA, A. B. B.; BARRETO, A. do N.; GARCIA, A. R.
Afiliação: | Narian Romanello, UFPA; José de Brito Lourenço Junior, UFPA; WALDOMIRO BARIONI JUNIOR, CPPSE; Felipe Zandonadi Brandão, UFF; CINTIA RIGHETTI MARCONDES, CPPSE; JOSE RICARDO MACEDO PEZZOPANE, CPPSE; Messy Hannear de Andrade Pantoja, UFPA; Daniela Botta, UFPA; Alessandro Giro, UFPA; Ana Beatriz Bossois Moura, UFF; Andréa do Nascimento Barreto, UFPA; ALEXANDRE ROSSETTO GARCIA, CPPSE.
Título: | Thermoregulatory responses and reproductive traits in composite beef bulls raised in a tropical climate.
Ano de publicação: | 2018
Fonte/Imprenta: | International Journal of Biometeorology, v.62, p.1575-1586, 2018.
DOI: | https://doi.org/10.1007/s00484-018-1557-8
Idioma: | Português
Conteúdo: | It is believed that increased livestock production is limited by tropical climate. Thermal imbalance in bulls can lead to hyperthermia and alter testicularmetabolism, causing subfertility or infertility. Therefore, the thermoregulation of composite Canchim bulls (5/8 Charolais × 3/8 Zebu) raised in tropical climate as well as their consequences in the physiological, hematological, hormonal, and andrological parameters were evaluated monthly. The bulls (n = 18; 30.0 ± 1.5 months; 503.8 ± 23.0 kg) were kept on pasture, in a single group, from August 2015 to March 2016, comprising the winter, spring, and summer seasons. Biometeorological variables were continuously monitored, and the Temperature and Humidity Index (THI) was calculated. A greater thermal challenge occurred in spring and summer (THI ? 72.0). Nevertheless, the bulls exhibited normothermia (38.6 to 38.9 °C) in these seasons. The cortisol did not vary between seasons (7.0 vs. 8.7 vs. 6.8 ng/ mL; P > 0.05) and remained within the physiological patterns. Independent of the seasons, stress leukogram was also not observed, refuting the incidence of acute or chronic thermal stress. It is noteworthy that T3 and testosterone increased (P < 0.0001, P < 0.05) in spring and summer, the time that coincides with the breeding season, when there is increased metabolic requirement from the bulls. The progressive thermal challenge increase did not affect the scrotal thermoregulatory capacity, and in general, scrotal temperature remained at 5.2 °C below the internal body temperature. In summer, there was a 5% reduction in the minor sperm defects (P < 0.05) and DNA fragmentation in 2.4% of spermatozoa, a compatible value for high fertility bulls. The results show that the studied composite bulls can be considered as climatically adapted and constitute a viable alternative to be used in production systems in a tropical climate, even if the breeding seasons occur during the most critical thermal condition periods of the year.
Palavras-Chave: | Homeothermy; Infrared thermography; Semen quality; Tropical livestock.
Thesagro: | Sêmen.
Thesaurus Nal: | Animal welfare; Thermoregulation.
Categoria do assunto: | G Melhoramento Genético
Registro original: | Embrapa Pecuária Sudeste (CPPSE)
Exemplares: | CPPSE - (24483-1) - UPC - AP - DD - PROCI-2018.00082 - ROM - 2018.00090 - DIS