[Supplementation of the amino acid composition of protein-rich wheat with protein concentrates and L-lysine in rations for laying hens. 4. Effect of various rearing diets on crude protein, fat and ash contents of the utilizable and nonutilizable parts of carcasses of slaughter hens].

The present paper is concerned with the effects of four rations of varying composition (fed to pullets from the eighth to the twenty-second week of life) on the composition of the carcasses of laying hens at the end of a 52-week trial. Ration 1 served as a control; ration 2 contained 68% protein-rich wheat as a protein carrier, 2% extracted soybean meal. 4% fish meal; the two other rations contained only 94% protein-rich wheat with or without addition of 2% lysine. The mean live-weights of the animals for slaughter were: 1792 g +/- 71 g; 1760 g +/- 78 g; 1701 g +/- 92 g; and 1655 +/- 102 g, respectively. The mean portion of edible parts (heart, liver, stomach, fatty tissue, follicles, flesh) of the 104 carcasses was 61.6% +/- 3.0%. The edible parts contained (mean values): crude protein, 18.0% +/- 2.0%; raw fat, 22.8% +/- 5.7%; and crude ash, 1.02% +/- 0.16%. The values calculated for the bonefree, uneatable parts (to be used as feed) were: crude protein, 16.2% +/- 0.7%; raw fat, 8.7% +/- 1.5%; and crude ash, 3.45% +/- 0.32%. The ash content of the edible parts is increased by lysine-rich diets. The rearing as well as the feeding during the laying period exerted no targeted effect on the crude protein and raw fat contents of the carcasses. The fat content of the carcass is determined by the consumption of energy.