The paper gives the analysis on the state in population of Simmental cattle reared in Europe with a special review on the state in Simmental cattle in our country which makes about 80 % total cattle fund in Serbia, and is characterized by a negative trend in the number of cattle, as well as by a low average milk production per cow. The most important results obtained by both domestic and foreign authors by means of various methods of improving Simmental breed and its raising in different systems have been shown. The directions for improving Simmental cattle according to the productive directions have been analyzed. Possible methods of improving the Simmental cattle in our country have been pointed out, which should be in accordance with already existing genetic potential of each actual population, its purpose (registered breeding stock, production breeding stock), as well as with the market needs for cow milk, milk products and meat (primarily beef meat, for export). A special emphasis has been given to the importance of organizing the production of meat in the cow-calf system in which Simmental breed, following the model of many European countries, should have good performance also in our country, if the same production should be organized in deserted hilly and mountainous regions. In this way we could contribute to more significant increase in overall beef production, and to reactivate unused natural resources as well.

nema

**Originalni nau ni rad-Original scientific paper Rad je finansiran od strane Ministarstva za nauku i zaštitu životne sredine, R. Srbije u okviru projekta TR-6858B Apstrakt: Ekonomi nost i uspeh u sto arskoj proizvodnji naj eš e zavise od više osobina. Iz tih razloga neophodno je vršiti takozvanu simultanu selekciju na nekoliko osobina. Fenotipska povezanost osobina u govedarstvu odnosi se na postojanje zajedni ke pozitivne ili negativne kovarijanse, koja nastaje kao rezultat delovanja genetskih i faktora spoljne sredine. Ovim istraživanjem je obuhva ena 3.461 kontrolisana prvotelka simentalske rase, sa laktacijama zaklju enim u toku jedne godine. Sve prvotelke su se nalazile na imanjima individualnih poljoprivrednih proizvo a a na podru ju Republike Srbije.U radu su ispitane fenotipske korelacije izme u slede ih osobina mle nosti i plodnosti: trajanje laktacije, prinos mleka, sadržaj mle ne masti, prinos mle ne masti, prinos 4% MKM, uzrast pri prvom telenju, trajanje servis perioda. Rezultati istraživanja fenotipskih korelacija dobijeni su koriš enjem mešovitih modela LSMLMW (Harvey, 1990). Ovaj metod omogu ava optimalno sagledavanje brojnih uticaja na ispitivane osobine (bikova-o eva, odgajiva kog podru ja, sezone telenja, godina telenja).

nema

The effect of systematic factors on production traits over complete lactations was investigated in 2,805 Simmental cows born in 1982 and onwards. The cows were housed at three farms in different areas: at the Zlatiborski Suvati dairy farm, Zlatibor, at the Dobricevo Agricultural Farm, Cuprija and at private farms in the region of Kotraze. The systematic factors (farm, calving season, lactation groups, group (year x season of birth), farm x calving season and farm x lactation group interactions) and age at first conception had statistically highly significant (P<0.001) effects on all complete lactation traits, with the exception of the effect of calving season on complete lactation duration (P<0.05) and milk-fat content (P>0.05). No statistically significant effect was produced by age at first conception on complete lactation duration and milk-fat content (P>0.05). Determination coefficients ranged from 0.100 in complete lactation duration to 0.361 in milk-fat content.