The Effect of Cement and wrapping on the Decomposition rate of the Rabbit Carcasses

Abstract

Taphonomic study was first time conducted in Kuala Lumpur, capital city of Malaysia. In this research model, male Oryctolagus cunicullus weighed 1.8-2.6 kg each were killed by Dolethal intravenously at the ear region. In Phase 1 study, eight subjects were wrapped in a sack and cemented within a container to be compared with the other four controls at each location labelled A (ground) and B (manmade freshwater pond). Phase 2 involved duplicating set of 15 cemented samples comparable to 1 control made up to total of 32 subjects which were all put into a compact polytank containing freshwater to simulate a case study. Taphonomic changes were observed and scored using TBS system incorporating of fresh stage, early decomposition stage, advanced decomposition stage and skeletonisation stage. The ambient temperature of surroundings with 28.81C±4.21°C and 29.21°C±4.57°C (mean±S.D.) while relative humidity of air with 74.49 %±14.61% and 79.15%±16.32% (mean±S.D.) were recorded for Phase 1 and Phase 2 study respectively. Time taken for ground control exposed and wrapped carcasses to reach first sign of skeletonised stage were four days and five days respectively. Whilst freshwater controls reached initial skeletonised stage within one week for exposed carcass and two weeks for wrapped carcass. Within the control and cemented sample carcasses, TBS scores increased from initial stages of decomposition and become plateau after advanced decomposition. The cementing factor have superseded the wrapping factor due to its stronger physical barrier effect to slow down the decomposition more than half compared to controls based on Multiple way ANOVA test. Phase 2 study has demonstrated more accurately on the decomposition rate of the cemented samples. It showed that wrapping and cementing factors have delayed the decomposition process of the rabbit carcasses about 4 times to reach the initial stage of skeletonisation compared to the control carcasses. There was absence of insect activity within the cemented samples, hence the microorganism activity would be the only contributor to the decaying process within the cemented samples at slower rate comparing to the exposed or wrapped controls.