[Content of essential amino acids in prematurely weaned piglets after a qualitatively and quantitatively variable...

A total of 60 piglets of German Landrace weaned at the age of 2 weeks were fed ad libitum with isoenergetic diets of different proteins (casein + dried skim milk, soybean protein + dried skim milk, only soybean protein) and different protein levels in the diet (20, 27, 34, 40% in D.M.). After 4 weeks the piglets were homogenized and examined for their content of essential amino acids in the whole body mass by ion exchange chromatography. On the fresh and dried material the contents of Thr, Val, Ile, Leu, Lys and Ser increased both with higher supply of protein and milk instead of soybean protein in the diet. The contents of Phe and Arg were only insignificantly changed by protein quality. Referred to the concentration of Met and Cys there were found higher standard deviations and interactions between protein supply and quality. The content of essential amino acids also was influenced by the protein quality of the diet, when related to the whole body protein. On the other hand a significant effect of increasing protein supply only took place if soybean protein was the single protein ingredient of the diet. Related to Lys the contents of Thr and Cys nearly were constant, whereas the amino acid/lysine proportion in the case of Met, Ile and Arg changed considerably.