INFLUENCE OF DIETHYL MALEATE AND CYSTEINE ON TISSUE GLUTATHIONE AND GROWTH IN BROILER-CHICKENS

The objectives of this study were to determine the effects of diethyl maleate (DEM) and l-cysteine (L-Cys) on tissue glutathione (GSH) and g rowth in male broiler chickens. In Experiment 1, broilers were treated with DEM (0, 1.5, 3, 6, or 12.0 mmol/kg BW, i.p.). After 1 h, maximum GSH depletions were to 9, 24, 20, 19, and 35% of control (0 mmol DEM/ kg) for liver, lung, kidney, heart, and brain, respectively. In Experi ment 2, time-course changes following 1.5 mmol DEM/kg (i.p.) were dete rmined; time-controls received an equal amount of corn oil (CO, .25 mL /kg BW). Levels of GSH in all tissues were low at 1 and 2 h after DEM in comparison to time-control values. Tissue GSH concentrations return ed to values that were not different from controls by 5 h in liver and kidney, by 12 h in heart, and by 24 h in brain and lung. In Experimen t 3, the effects of feeding a control diet (0% L-Cys) or one supplemen ted with 1% L-Cys from 3 to 7 wk of age with weekly i.p. injections (a t 3, 4, 5, and 6 wk of age) of DEM (1.5 mmol/kg BW) or CO (.25 mL/kg B W) on growth rate and tissue GSH were determined. There were no differ ences in BW among treatment groups between 3 and 6 wk of age. Although there were no differences in 7-wk BW between controls (0% L-Cys/CO) a nd birds treated with DEM fed either diet, the 1% L-Cys/CO group was h eavier (P < .05) than either the 0% or 1% L-Cys/DEM groups, and heavie r (P = .066) than controls at 7 wk of age. At 5 wk of age, 1% L-Cys ra ised GSH concentrations in liver, kidney, lung, and duodenum, but had no effect on heart GSH in birds treated with either CO or DEM. Control hepatic GSH concentrations were higher at. 7 than at 5 wk of age. Wit h the exception of duodenal GSH in CO birds, 1% L-Cys had no effect on tissue GSH concentrations in 7-wk-old birds. The result's of this stu dy provide an initial characterization of GSH metabolism in commercial male broilers and indicate that DEM produced dose- and time-dependent changes in GSH similar to reported changes in mammals. Results of thi s study also indicate that increased tissue GSH may be beneficial for growth.