40 research outputs found
Rezultati primene tehnologije genetskog unapreÄenja populacije simentalskih goveda u Srbiji
Results of production traits obtained from first calving cows and evaluation of the breeding value of bull sires of Simmental breed in Serbia. Data was analyzed using the method of least squares and for evaluation of bulls' breeding value mixed model of random sire effect (BLUP method). Based on obtained results it was established in statistical analysis that breeding region had highly significantly affected (P lt 0.01) the deviation of production traits from the general average. Considerable deviation from the general average was caused by the year and season of calving (P lt 0.05), and interaction of breeding region and calving season contributed to high variation in yield of milk and milk fat (P lt 0.01).U radu su prikazani rezultati koji se odnose na proizvodne osobine krava-prvotelki i ocena priplodne vrednosti bikova - oÄeva simentalske rase goveda u Srbiji. Podaci su analizirani metodom najmanjih kvadrata, a za ocenu priplodne vrednosti bikova koriÅ”Äen je meÅ”oviti model sluÄajnog uticaja oca (BLUP metod). Na osnovu rezultata dobijenih u statistiÄkoj analizi ustanovljeno je da je odgajivaÄko podruÄje visoko znaÄajno (P lt 0.01) prouzrokovalo odstupanja proizvodnih osobina od opÅ”teg proseka. Sistematski faktori okoline, odgajivaÄko podruÄja, godina i sezona telenja su prouzrokovali visoko znaÄajno (P lt 0,01) i znaÄajno (P lt 0,05) odstupanje prinosa mleka i mleÄne masti krava - prvotelki, a tako dobijeni rezultati ukazuju na opravdanost koriÅ”Äenja linearnih metoda odnosno korekcije sistematskih faktora okoline. KoriÅ”Äenjem meÅ”ovitog modela, sluÄajnog uticaja bika - oca na prinos mleka kÄeri, kao i formiranjem ranga bikova na osnovu priplodne vrednosti, dobijeni su rezultati koji pokazuju da je bik pod rednim brojem 9 superioran u odnosu na ostale. Bik - otac broj 23 ima najnižu priplodnu vrednost za osobine prinosa mleka i mleÄne masti. Na osnovu dobijenih rezultata može se ustanoviti da BLUP metod daje objektivnu ocenu priplodne vrednosti. Ovaj metod uvažava veliki broj sistematskih faktora okoline, uticaj razliÄitog genetskog nivoa bikova i genetski trend te stoga doprinosi objektivnoj oceni priplodne vrednosti bikova
Application of controlled experiments for studies of radial tree growth
V Älanku je predstavljen pregled objav o nadzorovanih poskusih ogrevanja in hlajenja dreves ter njihov pomen za raziskave debelinske rasti dreves. Poskusi, ki so jih opravili razliÄni raziskovalci na Å”tevilnih vrstah, so pokazali, da je mogoÄe vplivati na delovanje kambija in procese nastanka lesa in floema ter s tem na njuno anatomsko zgradbo, vendar pa se je kambij pri razliÄnih vednozelenih in listopadnih drevesnih vrstah razliÄno odzival na lokalno poviÅ”ane oz. znižane temperature. NaÅ”i najnovejÅ”i rezultati pa kažejo, da utegne tudi starost dreves oziroma debelina skorje (lubja) vplivati na uÄinek tovrstnih eksperimentov na kambijevo delovanje in razvoj celic.In the paper, a review of publications on controlled experiments of heating and cooling of trees and their significance for the studies of radial tree growth is presented. The experiments carried out by different researchers in anumber of tree species have demonstrated that it is possible to affect cambial activity and processes of wood and phloem formation and by that their anatomical structurehowever, the response of cambium to locally elevated or decreased temperatures differed in various evergreen and deciduous tree species. Our most recent findings indicate that tree age and thickness off bark (i.e. outer dead bark) appear to influence the extent of such experimentson cambial activity and cell development