Tests of Reciprocal recurrent selection (RRS) type actualize the need of continuous shifts of cocks in breeding pens without losing the pedigree accuracy for female chicks (RRS is not concerned with male chicks) hatched from eggs laid the first time (about 3 weeks) after a shift. Silverudd's multiple cock shift system (SMCSS) is based on definite colour genotypes of the strains. The variations of colour of chicks after different cocks will indicate the male progenitor of all female chicks (in many cases also of male chicks). When shifting cocks in the pens, SMCSS will safeguard full pedigree for all female chicks, even when several cocks are kept in one pen, provided the shifting is done in accordance with the rules governing SMCSS. Starting with only 4 groups, 144 sexable combinations can be made for as many RRS‐tests in less than a one year. SMCSS may very well be utilized in such a way that, at the same time, complete sexing automation is achieved. Through the medium of SMCSS entirely new possibilities have been created for a time‐saving and more comprehensive RRS and for obtaining a combination of strain breeding and RRS.

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