Metabolic Fate of S35 in the Lactating Cow When Fed S35O2 Preserved Silage

The making of grass silage is becoming increasingly important as a method for preserving forage for the feeding of livestock.For this reason, a continuous search is being made for more efficient silage preservatives.One promising result of this search is the use of sulfur dioxide for this purpose.Studies on the use of this material as a silage preservative by Knodt (10), Knodt et al. (11), Skaggs (13), and Skaggs and Knodt (14) indicate that the nutrients of silage treated with this chemical are exceptionally well preserved and that the silage is well accepted by cattle.These conclusions are supported by unpublished data from this station, as well as by the experience of scores of farmers who have used sulfur dioxide as a silage preservative the past 2 years.Although no one has reported any deleterious effects from feeding sulfur dioxide preserved silage to livestock, little work has been carried out to determine if such effects are possible.If large amounts of silage preserved with sulfur dioxide are to be fed to dairy cattle over long periods of time, it is important that a study on this subject be carried out.The first phase of such a study was an experiment to determine the metabolic fate of sulfur from sulfur dioxide used as a silage preservative.The results of this experiment are reported here. EXPERIMENTALPreparation of radioactive SOo.The radioactive SO_o used in this experiment was prepared from elemental S ~5 obtained from the Oak Ridge National Laboratories of the U. S. Atomic Energy Commission, Oak Ridge, Tenn.S 35 has a half life of 87.1 days and emits a beta particle of 0.167 m.e.v.A total of 30 me. was used.The sulfur was oxidized quantitatively to SO_~, which was stored in three standard 550-ml.SO o gas tanks in amounts of 45.4, 90.8, and 136 g. Preservation of silage.The silage was preserved in three 55-gal.steel drums.A large hole cut in the head of each drum was fitted with a gas-tight lid which Received for publication June 8, 1953.1 Scientific contribution No. 157 of the New Hampshire Agricultural Experiment Station.The radioactive SO~ was made and the activity measurements were carried out at Central Laboratories of General Foods Corporation.The silage making and animal phases of the experiment including processing silage and excreta for counting were conducted at the New Hampshire Agricultural Experiment Station.