Contributions to the Study of Sura de Stepa Cattle Breeds.

Sura de Stepa breed, which is on the verge of extinction, has been included in a preservation programme for animal genetic resources (H.G. nr. 822/2008), being raised in a reduced nucleus at S.C.D.C.B. - Dancu, Iasi. Researches were carried out on a number of 30 Sura de Stepa cows, focused on: milk production indicators by successive lactations, genetic determinism at the studied characters and at main lacto-proteins systems, the improvement value of breeding. The quantity of milk per normal lactation at Sura de Stepa population from S.C.D.C.B. - Dancu Iasi, has an upward evolution from 1589.64 kg in the first lactation to 2535.43 kg in the fifth lactation which is also the maximum one. First lactation represents 62.69% from maximum lactation, a value which highlighting the tardiness of Sura de Stepa breed in terms of milk production. Heritability analysis of the studied indicators show medium values for the quantity of milk and fat respectively a hereditary influence greater than h2 = 0.71% for percentage of milk fat and h2 = 0.57% for kappa-casein (K-cz) from milk. Lacto-proteins systems, beta-lacto globulin (β-lg), betacasein (β-cz), alpha-casein S1 (αS1-cz), have a low to intermediate heritability (0.19 to 0.29%) [ABSTRACT FROM AUTHOR]