the consequences of selection for shell quality in poultry在家禽中壳质量选择的后果.pdfVIP

THE CONSEQUENCES OF SELECTION FOR SHELL QUALITY IN POULTRY 1)( W. F. van TIJEN Institute for Poultry Research rc Het Spelderholt u, Beekbergen, The Netherlands SUMMARY In two strains, one of W)iite Leghorns, the other of Rhode-Island Red three generations of selec- tion for raising egg-shell quality traits gave a positive result for the selected trait, but a detri- mental correlated response for characters of laying intensity and egg weight, as compared to a control population in each case. The following is a report on a selection experiment with regard to shell quality which we carried out at our Institute. After we had found a heritability for defor- mation of and for out White and Rhode Island Red strain 320. o.o4 Leghorn respec- tively -as an average over 6 generations -we wanted to see what would happen when we actually were going to select for the strength of the shell. Basically the project was set up to find the answer to two questions : firstly : what are the possi- bilities of improving shell quality by means of selection ? Secondly : what happens with other traits -like production, egg weight and other egg quality factors -when a one-sided selection for shell quality is practised ? The following are some particulars about the animal material which was used. As already mentioned it consisted of a White Leghorn and a Rhode Island Red strain which in 1959 had been bought from private breeders and which were known as Babcock and Parmenter respectively. There were strong reasons to believe that they had been bred as closed groups before that time. After they had been obtained they were bred as closed groups with a mild selection press