[The protein retention capacity of piglets of different breeds and genotypes]

The genetically caused intensity of growth from piglets (barrows) of four breeds and two crossbreeds was evaluated by estimation of maximum daily capacity per LW 0.67 kg of N-balance plus N-maintenance-requirement (A) on the basis of a total of 130 N balance measurings on 66 piglets in the live weight range between 10 and 20 kg. The estimation was realized by using the N utilization model by Gebhardt (1963) and of its further development. In comparison with Landrace (A = 2575 mg) the breeds Edelschwein (A = 3,242 mg) and Leicoma (A = 3,038 mg) had a higher A in the midst of the piglet period (9th and 10th week of life), but not so the breed Schwerfurter (A = 2,350 mg). The capacity of the following N balances during growing and fattening stages is not derivable from these values. The experimentally evaluated A of crossbreeds is in good agreement with the calculated A on the basis of the used races for breeding. The product A.b = 1.15 is characterizing the quality of the feed protein (a mixture of wheat and casein in the relation 2.2:1), independently of the live weight and also of the breed or the genotype of the pig.