Effect of body mass and clothing on decomposition of pig carcasses

Abstract

Carcass mass and carcass clothing are factors of potential high forensic importance. In casework, corpses differ in mass and kind or extent of clothing; hence, a question arises whether methods for post-mortem interval estimation should take these differences into account. Unfortunately, effects of carcass mass and clothing on specific processes in decomposition and related entomological phenomena are unclear. In this article, simultaneous effects of these factors are analysed. The experiment followed a complete factorial block design with four levels of carcass mass (small carcasses 5–15 kg, medium carcasses 15.1–30 kg, medium/large carcasses 35–50 kg, large carcasses 55–70 kg) and two levels of carcass clothing (clothed and unclothed). Pig carcasses (N = 24) were grouped into three blocks, which were separated in time. Generally, carcass mass revealed significant and frequently large effects in almost all analyses, whereas carcass clothing had only minor influence on some phenomena related to the advanced decay. Carcass mass differently affected particular gross processes in decomposition. Putrefaction was more efficient in larger carcasses, which manifested itself through earlier onset and longer duration of bloating. On the other hand, active decay was less efficient in these carcasses, with relatively low average rate, resulting in slower mass loss and later onset of advanced decay. The average rate of active decay showed a significant, logarithmic increase with an increase in carcass mass, but only in these carcasses on which active decay was driven solely by larval blowflies. If a blowfly-driven active decay was followed by active decay driven by larval Necrodes littoralis (Coleoptera: Silphidae), which was regularly found in medium/large and large carcasses, the average rate showed only a slight and insignificant increase with an increase in carcass mass. These results indicate that lower efficiency of active decay in larger carcasses is a consequence of a multi-guild and competition-related pattern of this process. Pattern of mass loss in large and medium/large carcasses was not sigmoidal, but rather exponential. The overall rate of decomposition was strongly, but not linearly, related to carcass mass. In a range of low mass decomposition rate increased with an increase in mass, then at about 30 kg, there was a distinct decrease in rate, and again at about 50 kg, the rate slightly increased. Until about 100 accumulated degree-days larger carcasses gained higher total body scores than smaller carcasses. Afterwards, the pattern was reversed; moreover, differences between classes of carcasses enlarged with the progress of decomposition. In conclusion, current results demonstrate that cadaver mass is a factor of key importance for decomposition, and as such, it should be taken into account by decomposition-related methods for post-mortem interval estimation.

Differential Decomposition Among Pig, Rabbit, and Human Remains

“…Numerous studies have also found that body weight and composition, within and among carrion species, can cause significant variation in decomposition rates and byproducts in the soil . For instance, Sutherland et al found that small pigs decompose nearly three times faster than larger pigs, while Matuszewski et al found that larger pig carcasses had higher TBS than smaller pigs for the first 100 ADD, after which the pattern reversed. Although Simmons et al note that body mass differences are only a factor when insects are present, the majority of these studies have shown that intraspecific body mass is a significant factor in decomposition.…”

Carcass mass has little influence on the structure of gravesoil microbial communities

“…One of the first studies, which was not replicated, reported that larger mass corpses decay faster than smaller mass corpses [18]. Most of the later studies concluded that smaller corpse masses decay faster [19][20][21][22][23]. The exact functional nature of the decay rate in these studies, however, is not fully agreed upon [20][21][22][23].…”

Analysis of volatile organic compounds released from the decay of surrogate human models simulating victims of collapsed buildings by thermal desorption–comprehensive two-dimensional gas chromatography–time of flight mass spectrometry

“…The animals were prepared in a local slaughterhouse in compliance with EU regulations. During euthanasia, efforts were made to reduce blood loss, as blood plasma is considered an additional fluid Table 1 An overview of the main factors affecting the decomposition rate [3,9,10,12,18,24,31,32,35]. The carcasses were placed amongst ruins for simulating the entrapment environment after the collapse of a building.…”

“…Each of these factors, independently or in combination, can highly affect the decomposition rate, changing the volatile profile. For example, the effect of body mass and/or clothing on decomposing pig carcasses was recently highlighted [31]. The combination of all these factors makes the study of decomposition VOCs an extremely complex and challenging process.…”