Resumo do trabalho apresentado oralmente no Congresso Internacional de Etologia Aplicada - Indianapolis - IN - USA. ISAE
Physiological and behavioral response of crossbred zebu dairy cows submitted to different
shade availability on tropical pasture
Ferreira, Luiz C. B.1, Machado Filho, L. Carlos P. 1, Hötzel, Maria J.1, Alves, Andréa A. 2,
Barcellos, Alexandre O.2 AND Labarrère, Juliana G.3, 1Lab. de Etologia Aplicada, Depto. de
Zootecnia e Des. Rural, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga 1346 –
Itacorubi., 88034-001, Florianópolis, SC, Brazil, 2Embrapa, Parque Estação Biológica - PqEB
s/n°, 70770-901, Brasilia, DF, Brazil, 3Universidade de Brasilia, Campus Universitário Darcy
Ribeiro, 70910-900, Brasília, DF, Brazil; pinheiro@cca.ufsc.br
Shade and water are major welfare constrains for grazing cattle. However, many believe that, because zebu cattle and their crosses are well adapted to the heat, they may dispense shade. This study was designed to evaluate the effect of different shade availability and shape on the physiological and behavioral response of crossbred zebu dairy cows on tropical pasture. Four groups of three lactating cows were tested in a 4x4 latin-square design, with periods of three days, in the following treatments: without shade (WS), single artificial shade (AS), bush (B) and scattered trees (ST). The behavioral variables were recorded in scans every 10min, from 8:30h to 15:40h by visual direct observation. Milk production, water consumption, rectal temperature and respiratory rate were recorded daily for all cows during the experimental period. Data were statistically analyzed by ANOVA. No differences were found for the studied variables when cows were in treatments B and ST. However, compared to the treatments WS and AS, cows presented higher frequencies of grazing (p≤0.03), and of shade use (p≤0.001), as well as lower rectal temperatures and respiratory rates (p≤0.005). Water intake (p≤0.002), ruminating (p≤0.003) and lying (p≤0.03) time were higher in B and ST than in WS, whereas cows showed intermediate values for these variables when in AS treatment. When in WS, cows showed greater time on other behaviors, presented the highest frequency of idling, lowest water consumption and greatest respiratory rate of all other treatments. It is concluded that the presence of abundant shade in pasture may prevent heat stress, indicating better welfare for crossbred zebu dairy cows raised on pasture in tropical areas.
