Some factors influencing the physiological parameters of greater grasscutter (Thryonomys swinderianus) in the rainforest ecological zone of Nigeria
The study was conducted to determine the effects of sex, body weight, time of the day and temperature-humidity index (THI) on the rectal temperature and respiratory rate of greater grasscutters. The study was carried out in the grasscutter unit of the Obafemi Awolowo University Teaching and Research Farm, for 6-weeks, using fourteen apparently healthy grasscutters. The rectal temperature and respiratory rate of each animal were measured daily using a digital clinical thermometer and a stopwatch respectively. These measurements were taken at different alternating times each day. The exact hours of measurement were 8.00 - 9.00 hrs for mornings, 12.00 - 13.00 hrs for afternoons and 17.00 - 18.00 hrs for evenings. The results showed that there was no significant difference (P>0.05) between the rectal temperature of male and female, 37.08±0.05 °C and 36.94±0.06 °C, as well as the respiratory rate, 143.98±1.06 counts/min and 142.62±1.50 counts/min, respectively. The results also indicated that the weight of the grasscutters had no effect on the rectal temperature but rather on the respiratory rate. The average rectal temperature was lower in the morning than afternoon and evening (P<0.05), while there was no significant difference in respiratory rates of the grasscutters between the morning, afternoon and evening periods. Also, rectal temperature increased as THI increased, while there was no effect of THI on respiratory rate. It was concluded that there is no difference in rectal temperature and respiratory rates of the male and the female grasscutters, the weight of the grasscutter did not influence the rectal temperature of the grasscutter, though influenced the respiratory rate. The time of the day and the THI did not influence the respiratory rate but had an effect on the rectal temperature.
Keywords: Grasscutter; rectal temperature; respiratory rate; body weight; Temperature-Humidity Index; diurnal variation