MeTABOLISM OF “C-DDT
Metabolism of “C-DDT by Ovine Rumen Fluid in vitro John D. Sink,* Hugo Varela-Alvarez, and Christine Hess ~~~~~
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An in vitro study of I4C-DDTmetabolism by ovine (0r;is aries) rumen fluid was conducted t o determine the effect of nutritional regimen, concentrate, and roughage. Rumen samples were obtained using a stomach tube. Half of the samples were boiled and half were not. All were incubated at 39” C with I4C-DDTfor 0, 4, 8, and 12 hr. Following incubation the samples were extracted, concentrated, thin-layer chromatographed, and assayed by scintillation counting. Concentrate diets were more
t is well established that p,p’-DDT [l,l,l-trichloro-2,2bis(p-chloropheny1)ethanel metabolizes t o p,p’-DDE [1,1dichloro-2,2-bis(p-chlorophenyl)ethylene] in the body and is stored in the adipose tissues primarily in this form (Dale and Quinby, 1963). The subsequent metabolism of D D E appears to proceed rather slowly, if at all (Peterson and Robison, 1964). Several reports (Miskus et al., 1965; Fries et al., 1969; Kutches and Church, 1971) have noted the conversion of D D T to DDD [l ,l-dichloro-2,2-bis(p-chlorophenyl)ethane] by bovine rumen fluid. Mendel and Walton (1966) obtained evidence that this same reductive dechlorination process takes place in the gastrointestinal tract of monogastric animals (rats) and results from bacterial action. Bacterial populations, a t least in ruminants, are greatly influenced by the kind of nutritional regimen fed the animal (Hungate, 1966). Despite these and other studies on various aspects of DDT degradation, the Mrak report (1969) stressed the urgent need for expanded research on understanding the mechanism of metabolism with special emphasis on delineating specific influences (i.e., nutritional) on body responses. Previous work in our laboratory (Wilson et al., 1970) established genetic differences in body responses of ruminant animals fed similar diets. It was the purpose of this study to examine the response of genetically similar ruminants fed dissimilar nutritional regimens.
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MATERIALS AND METHODS
Sampling. Eight mature (approximately 11 months of age and 41 kg live weight) castrate male (wether) animals (Ocis aries) from similar genetic and nutritional backgrounds were used. Twenty-five days prior to sampling these animals were randomly divided into two lots of four animals each. One lot was fed a n all roughage (alfalfa hay) diet, and the other was fed an all concentrate (primarily corn with small amounts of oats and barley) regimen. The animals also received the necessary vitamin and mineral supplements as well as free access to water. Following this nutritional treatment, rumen fluid samples (100 ml) were obtained from each animal 2 hr after feeding. These were obtained by a stomach tube and the fluid was filtered through four layers of cheesecloth to remove the large particles. The 100-ml individual Department of Animal Science, The Pennsylvania State University, University Park, Pennsylvania 16802.
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