Feeding day-old \Vhite Leghorn male chicks 9 different diets for 4 weeks with the orthogonal composite design, we studied the relationship among dietary protein, energy levels and chick's responses.The ellipsoid relationship has been found fitted to describe the relationship between dietary composition and weight gain or feed efficiency of chicks, whereas declined planes are fitted to show the relationship between dietary composition and carcass protein or fat levels of chicks. Dietary protein level has great influence on nitrogen retention. but dietary energy level has little effect.The linear relationship between total digestible nutrients and metabolizable energy in diets is presented.

Feeding day-old White Leghorn male chicks 9 different diets for 4 weeks with the orthogonal composite design, we studied the relationship among dietary protein, energy levels and chick's responses. The ellipsoid relationship has been found fitted to describe the relationship between dietary composition and weight gain or feed efficiency of chicks, whereas declined planes are fitted to show the relationship between dietary composition and carcass protein or fat levels of chicks. Dietary protein level has great influence on nitrogen retention, but dietary energy level has little effect. The linear relationship between total digestible nutrients and metabolizable energy in diets is presented.

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