Effect of tryptophan supplementation on aflatoxicosis in laying hens

Two experiments were conducted to determine the relationship of supplemental Trp on liver fat accumulation and egg production during aflatoxicosis in laying hens. In Experiment 1, two levels of Trp (0 and 2,000 ppm; basal = .16% Trp) and two levels of aflatoxin (AFLA) (0 and 10 ppm) were supplemented to a complete layer ration. In Experiment 2, a third level of AFLA (5 ppm) was added to the design. Single Comb White Leghorn hens (58 and 68 wk old) were fed the diets for 3 wk for Experiments 1 and 2, respectively. Henday production and egg weights were measured daily. Feed intake was measured weekly. Liver weights, liver moisture, and liver total lipids were determined at the end of each trial. In Experiment 1, supplemental Trp by itself caused a significant (P less than .01) reduction in total liver lipids compared to the controls (no Trp or AFLA). Adding trp and AFLA increased total liver lipids and caused a significant (P less than .05) decrease in egg production compared with adding AFLA alone. Total liver lipids were 41.1, 32.8, 54.8, and 62.4% (dry weight basis) for 0 Trp:0 AFLA, 2,000 Trp:0 AFLA, 0 Trp:10 AFLA, and 2,000 Trp:10 AFLA, respectively. Similar results were observed in Experiment 2. It was concluded that supplemental Trp by itself caused a reduction in total liver lipids, but when supplemented to a diet containing AFLA, Trp caused an increased severity of lesions associated with aflatoxicosis in layers.