Y. NACHEVA, N. PETKOV and P. TZENOV
Sericultural Experimental Station, BG-3000 Vratza, Bulgaria
NACHEVA, Y., N. PETKOV and P. TZENOV, 2001. Mathematical forecast of breeding effect based on cocoon shell weight index of silkworm (Bombyx mori L.). Bulg. J. Agric. Sci., 7: 345-347
An individual selection for the index of cocoon shell weight was carried out among the primary races of silkworm hybrid Vratza 35 x Merefa 2, developed for rearing in certain areas of the country. The progeny of the highest parents and primary populations of zero selection intensity was reared.
Breeding effect was determined as the difference between the phenotypic index value of the progeny of selected parents and the average index value for the population of preceding generation, based on the realized index of inheritance and breeding differential. The forecast value of cocoon shell weight index was calculated by adding breeding effect to the average phenotypic index value of the primary population.
It was established that the method of genetics and breeding used for the purpose of forecast enabled the establishment of breeding effect of selection for cocoon shell weight index. The relative forecast error is within 0.34-0.37%, i.e. the coincidence between actual and forecast value is high enough.
The genetic and breeding parameters established, such as realized heritability coefficient, breeding differential, mean quadrate deviation and breeding effect allow for the development of a scientific breeding program for selection based on cocoon shell weight index, aiming at increased efficiency of new and improvement of existing silkworm races.