Abstract:
Snake venom contains medically important toxic proteins. Proteroglyphous snakes of the
family Elapidae: Naja naja is the only recognized species of cobra in Sri Lanka and is
responsible for a considerable number of envenomation and deaths due to snake bites. The
dose of antivenin depends upon the amount of venom inflicted by the snake and the kinetics
of venom distribution in the whole body. Although several studies have been conducted
regarding this subject, the amount of venom ejecting per bite is still under investigation.
The current study investigated whether the body size, sex and other morphological
characteristics of N. naja have any influence on venom yield when milked manually. For
milking, small-sterilized beakers that are tightly covered with parafilms layers were used. The
head of each milking snake was held and venom was extracted to the prepared beakers by
applying a gentle pressure to the venom glands. After that, the volume of wet venom of each
snake was measured using graduated pipets and these volumes were used for statistical
analysis. N. naja
The average wet venom volume in 40 adult cobra (mean total length 1698 ± 161mm; mean
body weight 1466 ± 287g) ranges from 200-1500μl (mean 485.15 ± 178.9μl) and 10 juvenile
snakes (mean total length 632 ± 95mm and body weight 420 ± 93g) were 15-70μl.
The venom yield positive correlated with the length and body weight of the snakes. Even
though males hold slightly high volume of venom than females, this volume difference is not
significant. In summary, we found that the venom yield is more correlated to the body size
and total length than the sex and other morphological characters of snakes. Further studies are
necessary to find out whether venom yield differs due to geographic variations or other
related ecological factors.
