SciELO - Scientific Electronic Library Online

 
vol.15 número1Caracterización de materiales orgánicos aplicados en sistemas agrícolas intensivos de UruguayEspecies indicadoras y estructura de praderas naturales de basalto con cargas contrastantes de ovinos índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Journal

Artigo

Links relacionados

Compartilhar


Agrociencia (Uruguay)

versão impressa ISSN 1510-0839versão On-line ISSN 2301-1548

Resumo

SARAVIA, Celmira; ASTIGARRAGA, Laura; VAN LIER, Elize  e  BENTANCUR, Oscar. Impact of Heat Waves on Dairy Cows in Salto (Uruguay). Agrociencia Uruguay [online]. 2011, vol.15, n.1, pp.93-102. ISSN 1510-0839.

The aim of this study was to characterise summer meteorological determining factors (MDF) of different severity in Salto (Uruguay) and their impact on the physiological and productive responses of dairy cows. The MDF were characterised according to the mean temperature-humidity index (THI), average hours per day with THI ³72 and minimum and maximum daily temperatures. Rectal temperature (RT) and respiratory frequency (RF) of the cows were taken at 6:00 and 15:00 h, and the time spent grazing (GT) during daytime. One severe heat wave (SHW), three light heat waves (LHW) and days of no heat wave (NHW) were identified. The MDF affected RT and RF of the cows (P<0,0001). The RF and RT (6:00 and 15:00) were higher in SHW compared to LHW and NHW (P<0,0001). Grazing time was less during SHW compared to LHW and NHW (P<0,0001). The production of milk, fat and protein were lower during SHW (P<0,0001) than during LHW and NHW. Somatic cell count was lower during SHW than LHW but not NHW (P=0,0618). During SHW cows did not maintain normothermia and spent less time grazing, reducing productivity. During LHW cows recovered normothermia during the night, with no reduction in productivity compared to NHW.

Palavras-chave : heat stress; rectal temperature; respiratory frequency; grazing time; milk production and composition.

        · resumo em Espanhol     · texto em Espanhol     · Espanhol ( pdf )

 

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons