Effects of Moderate Lysine Deficiency on Digestibility and Metabolisable Energy of Diets and on Nitrogen Retention and Uric Acid Excretion in Chicks

[Nitrogen metabolism in the broiler chicken determined by means of 15N labeled wheat]

Studies were made on the N and 15N excretion of 4-weeks-old male broilers fed 15N labelled wheat. The broilers excreted an average of 1143 mg N per bird per day. This would correspond to a level of N retention of 1105 mg N per day (49% of N intake) for birds consuming 2248 mg N daily. 53.9 mg of the 148 mg of 15N ingested on the first day of tracer administration (=36% of the amount administered) were excreted on the same day. Separation of the excreta by chemical means was not found to be a suitable method for the subsequent 15N isotope analysis of faecal and urinary N. Only colostomated birds can be used if the degree of labelling of faecal and urinary N has to be determined.

[Studies on the use of wheat rich in crude protein in the feeding of broilers. 1. Experimental procedure, weight gains, food consumption and food efficiency]

A fattening trial was carried out with 8 groups of broilers each comprising 1225 birds. Within this trial tests were made to replace the protein feeds of newly hatched chicks over a period of up to 56 days of age, by wheat rich in crude protein. If wheat with a high crude protein content is fed supplementation with lysine and methionine will be necessary depending on the kind of protein feed used. No supplementation with amino acids is required if rations of fish meal + extracted soya bean meal are used despite their reduced content of these amino acids. The broilers consumed larger quantities of the wheat + extracted soya bean meal+fish meal ration than of the mixtures containing no fish meal. Food requirements per unit of weight gain were the same for the mixtures containing high-protein wheat and for the standard maize ration. The lowest food consumption per unit of weight gain was computed for the wheat + extracted soya bean meal diet supplemented with amino acids. The same quantities of lysine, thioamino acids and threonine were necessary for broilers receiving the wheat rations as for birds of the standard group. Protein feed may be saved by using high-protein wheat in the fattening of broilers. The rates of weight gain obtained with these rations are the same or even better than those achieved with rations of maize + fish meal+soya bean meal.