Behavior of grazing purebred and crossbred dairy cows under tropical conditions

Recent dairy development thrusts in the Philippines focus on increasing existing stock through the importation of dairy animals, particularly Holstein x Sahiwal crossbreds. This study was conducted to determine and compare the behavior of purebred Holstein and crossbred (Holstein x Sahiwal) dairy cows under tropical conditions. A total of 10 dry cows (5 purebreds, 5 crossbreds) were used in the study following a 2x5 factorial experiment with the two breeds and three grazing periods (0700-1000 h, 1000-1400 h, 1400-1700 h) as factors. Observations were done in a mixed-grass pasture lot dominated by Panicum maximum, Pennisetum purpureum and Cynodon plectostachyus. Behavioral observations were made every half hour and the frequency of grazing, walking, standing, lying down, ruminating, drinking and urinating/defecating were noted. Furthermore, respiratory frequency was also monitored in each animal. Mean temperature and humidity values in the pasture area during the study were 33.2 degrees C and 68%, respectively. Wind velocity average of 3.5 kph and zero rainfall were also noted. Significant results were obtained in grazing, walking, standing and lying down behavioral activities among the three grazing periods but not between breeds. However, crossbreds were found to graze more in the open during the hottest time period, i.e., 1000-1400 h. Respiratory frequency in purebreds was significantly higher than crossbreds and varied significantly among the three grazing periods. (C) 1998 Elsevier Science B.V. All rights reserved.