K. O. Ibiwoye, G. T. Iyeghe-Erakpotobor, F. O. Oke, J. J. Omage


A study was carried out to evaluate the effect of feed grade ascorbic acid dietary supplementation on thermoregulatory response of Hyla rabbit does under sub-humid tropical environment. A total of 81, matured rabbit of eighteen to thirty-six old does of average weight 2.75 kg comprising 35 multiparous pure New Zealand White (Parents), 31 primiparous pure New Zealand White (pure F1) and 15 cross Californian (cross F1) were used for the study. Heart rate, rectal temperature and respiratory rate were determined weekly for 14 weeks with a 2-week feeding adjustment period. Temperature-humidity index (THI) was calculated using temperature and humidity records taken inside and outside the Rabbitry in the morning and afternoon. Results indicated that ambient temperature ranged from 22.01 to 39.48°C while THI ranged from 20.87 to 33.86 from January to April. Heart and respiratory rates significantly (P<0.05) increased while rectal temperature significantly (P<0.05) decreased as the levels of ascorbic acid supplementation increased in the diet. Heart rate increased by 10.12 bpm in does fed 400 mg AA/kg diet while rectal temperature decreased by 0.80°C in does fed 300 and by 0.81°C in does 400 mg AA/kg diets compared to rabbit does fed the control diet. Doe group had significant (P<0.05) effect on heart rate, rectal temperature and respiratory rate while month of the year had significant (P<0.05) effect on heart and respiratory rates of the does. Interaction between ascorbic acid levels and doe group had significant (P<0.05) effect on heart rate and rectal temperature of the does. However, only respiratory rate was significantly (P<0.05) affected by interaction between ascorbic acid and month of the year. It could be concluded that the rabbit does were exposed to a high ambient temperature of 39.48°C and a THI of 33.86 which led to their higher respiratory but lower heart rates. Ascorbic acid supplementation might start at 200 mg/kg level in order to reduce the adverse effect of high ambient temperature on rabbits in the tropics.


Ascorbic acid, Thermoregulatory response, Ambient temperature, Rabbits.

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