Dietary methionine requirement of the Chinese egg-laying duck

Abstract

1. The dietary methionine requirement of egg-laying ducks was assessed by feeding diets supplemented with graded levels of DL-methionine (0, 4, 8, 12, 16 g/kg dietary protein) for 8 weeks. The basal diet contained 175 g protein and 2·6 g methionine per kg feed (or 14·9 g/kg protein) and an estimated ME of 11·5 MJ/kg.

2. A total of 800 Shaoxin laying ducks (420 d old) were randomly divided into 5 groups of 160 each and fed in 4 separate pens.

3. Dietary supplementation of methionine significantly increased egg production and feed conversion efficiency.

4. Dietary methionine requirement for optimum egg production was estimated to be 25·7 g/kg of dietary protein or 4·5 g/kg of the diet or 380 mg/bird-d.

5. Methionine supplementation increased the methionine level in plasma, and the free glutamic acid and aspartic acid concentrations in plasma were quadratically related to dietary methionine levels. Increasing dietary methionine had little effect on egg quality characteristics.

Acknowledgements

This research was funded by the Science and Technology Office of Hunan Province. Academic advice and English revision by Dr Mingan Choct of The University of New England in Australia and Dr Paul Rose of Harper Adams University College in the UK are gratefully appreciated.

Notes

¹The mineral mix provided the following (per kg of diet): CuSO₄·5H₂O 0·02 g, ZnCO₃ 0·1 g, MgSO₄·7H₂O 3·5 g, MnSO₄·H₂O 0·65 g, NaMoO₄·2H₂O 9 mg, KI 40 mg, CoSO₄·7H₂O 1 mg, Na₂SeO₃ 0·215 mg.

²The vitamin mix provided the following (per kg of diet): thiamin-HCl 20 mg, nicotinic acid 80 mg, riboflavin 10 mg, D-Ca-pantothenate 30 mg, vitamin B₁₂ 0·04 mg, pyridoxine-HCl 6 mg, D-biotin 0·6 mg, folic acid 4 mg, menadione dimethylpyrimidinol bisulphite 2 mg, ascorbic acid 250 mg, cholecalciferol 15 µg, retinyl acetate 1·789 µg, tocopheryl acetate 2010.