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Doctoral thesis, 2002

Biomonitoring of cadmium in pig production

Lindén, Anna

Abstract

Cadmium is a nephrotoxic metal with increasing levels in arable soils. The non-smoking population is exposed to cadmium mainly from vegetable food, especially cereal products. The major part of pig feed is cereals, and accumulated cadmium in pig kidney could reflect cadmium in the local agricultural environment. In this thesis, the possibility to use pig kidney as a bioindicator of the availability of cadmium in the agricultural environment was evaluated. There were significant correlations between cadmium levels in soil and wheat, between feed and kidney and between feed and faeces. Cadmium level in feed explained 12% of the variance of cadmium level in kidney. Cadmium levels in barley, the main ingredient in the feeds, were not correlated to feed or kidney. The non-locally produced feed components rapeseed and soybean meal, vitamin-mineral mixtures and beet fibre contributed to a large extent to the cadmium in feed. The nonlocally produced feed components constitute an external source of cadmium to the arable soils when farmyard manure is applied, as most cadmium in feed is excreted in faeces. Pigs given feeds with less rapeseed and soybean meal and more cereals than controls, had lower cadmium intake, but higher cadmium levels in kidney than control pigs. This can partly be explained by different bioavailability of cadmium in different feed components. Cadmium level in kidney was positively related to age at slaughter and negatively related to kidney weight. No difference in kidney levels of cadmium due to sex was seen. Cadmium levels in kidney differed between breeds given the same feed. Organically outdoor raised pigs had higher levels in kidneys and faeces than conventional pigs raised indoors, despite a lower cadmium level in the organic feed. The organic pigs were exposed to cadmium from soil via rooting. Differences in feed compositions and bioavailability of cadmium from the feed components may also explain the different kidney levels of cadmium. However, no significant difference in solubility of cadmium from the feeds after in vitro digestion was detected. When soil was added to the feed and digested in vitro, the fractional solubility of cadmium was decreased. Animals from the same farm and raised under similar conditions had cadmium levels in kidney that could differ several times. This great variation together with the high cadmium contribution from non-locally produced feed components limit the possibilities to use cadmium in pig kidney as an indicator of available cadmium in the agricultural environment.

Keywords

animal feed; bioindicator; ecological; environment; food chain; monitoring; porcine; renal; sustainable; swine

Published in

Acta Universitatis Agriculturae Sueciae. Veterinaria
2002, number: 126
ISBN: 91-576-6372-6
Publisher: Swedish University of Agricultural Sciences

Authors' information

Lindén, Anna
Swedish University of Agricultural Sciences, Department of Pharmacology and Toxicology

UKÄ Subject classification

Animal and Dairy Science

URI (permanent link to this page)

https://res.slu.se/id/publ/107624