• Ibiwoye, K. O. Department of Animal Science, Faculty of Agriculture, Ahmadu Bello University, Samaru, Zaria, Nigeria
  • Dauda, V. M. Department of Animal Science, Faculty of Agriculture, Ahmadu Bello University, Samaru, Zaria, Nigeria
  • Iyeghe-Erakpotobor, G. T. National Animal Production Research Institute (NAPRI), Ahmadu Bello University, Shika, Zara, Nigeria


A study was carried out to evaluate the effect of dietary supplementation of ascorbic acid on
physiological response of Hyla rabbit does under sub-humid tropical environment. A total of 81
rabbit does comprising of 35 multiparous pure New Zealand White (Parents) and 46primiparous
F1 progenies of the parents (31 pure New Zealand White and 15 cross Californian x New
Zealand White F1) were used for the study.Ascorbic acid (AA) was included in the diets of the
rabbits at levels of 0 (control), 200, 300 and 400 mg AA/kg feed.Heart rate, rectal temperature
and respiratory ratewere determined weekly for 14 weeks with a 2-week adjustment period.
Temperature-humidity index was calculated using temperature and humidity records taken
inside the Rabbitry in the morning and afternoon. Results obtained indicated that temperaturehumidity index of the Rabbitry ranged from 20.17 to 31.15 from January to April. Rabbit does
on 0 and 300 mg AA levels had similar (P>0.05) but significantly lower respiratory rates than
those on 400 mg AA/kg feed level. Heart rate increased as level of ascorbic acid increased in
the diet by 10.95 bpm on 400 mg AA/kg feed, while rectal temperature decreased by 0.21-
0.14°C on 300 and 400 mg AA/kg feed than for rabbit does on the control. Doe group had no
effect on respiratory rate, heart rate and rectal temperature of does. There was no interaction
between ascorbic acid levels and doe group on physiological performance of the does. The
month of the year had a significant effect on heart and respiratory rates the does, being lower in
January and February than in March and April.There was significant interaction between
ascorbic acid and monthon respiratory rate. It could be concluded that the rabbit does were
exposed to a high ambient temperature as high as 37°C. This is evidenced in their higher
respiratory and higher heart rates. Ascorbic acid supplementation might start at 200 mg/kg level
in order to reduce the adverse effect of high ambient temperature and improve reproductive and
productive performance of rabbits in the tropics.