Abstract: The effect of the diet containing mulberry leaves at the addition amounts of 2.5%, 5.0%, 7.5% and 10.0% on the quality of egg yolk was investigated. The results showed that egg yolk color became darker with the increased amount of mulberry leaves, and the content of egg yolk cholesterol was not significantly influenced by mulberry leaves. The egg yolk phosphorus content in diet groups with mulberry leaves at the amounts of 5.0% and 7.5% were significantly higher than those in the control group (P ＜ 0.05). The saturated fatty acid content in mulberry-leaf groups was significantly reduced when compared with the control group (P ＜ 0.05) and the content of monounsaturated fatty acid and polyunsaturated fatty acid revealed faster increase than that in the control group (P ＜ 0.01). The total content of seven essential amino acids in diet with mulberry leaves at the amounts of 5.0% and 7.5% groups were obviously higher than that in the control group (P ＜ 0.05). The content of yolk vitamin E was significantly increased with the addition amount of mulberry leaves (P ＜ 0.01), especially in the diet group with 10% mulberry leaves. The egg yolk in the diet groups with mulberry leaves had much better smell and taste than in the control group; similarly, the smell and taste of egg yolk in the diet groups with 5.0% and 7.5% mulberry leaves better than those in the other groups (P ＜ 0.05). In a word, the quality of egg yolk can be improved by adding mulberry leaves in diet, and the optimal addition amount of mulberry leaves was 5.0%—7.5%.

Key words: mulberry leaf, feed, egg, egg yolk, quality