@article{
author = "Hristov, Slavča and Stanković, Bojan and Joksimović-Todorović, Mirjana and Bojkovski, Jovan and Davidović, Vesna",
year = "2007",
abstract = "During the hottest summer months in our country, conditions for thermal stress development in cows are present, especially when values of temperature and air humidity increase simultaneously. When temperature rises, cow organism becomes less efficient, due to primary non-evaporative patterns of heat release (radiation, conduction, convection), relying mostly on evaporative cooling through sweating and gasping. High relative humidity impedes evaporative cooling, so cows do not use enough body heat to prevent body temperature increase during hot and humid conditions, which are very common during summers in Serbia. Increase of ambient temperature, temperature-humidity index and rectal temperature of the cows above critical values are accompanied by decrease of dry matter intake and milk production, making dairy production less remunerative. Modifications which include shade, increase of passive ventilation and additional usage of fans and sprinklers in stables increase body heat release, decrease body temperature and support dry matter intake. New technologies, which include tunnel system of ventilation, were studied in order to evaluate cooling efficiency. Selection of cows for heat tolerance is possible, and it must be emphasized that continual selection for productive traits improvement and neglect of heat tolerance leads to increased sensitivity to heat stress. Nutritive needs of dairy cows change during heat stress demanding modifications of meal composition in order to decrease dry matter content, increase of its nutritive value, to prevent nutritive oversteps and to maintain normal function of rumen. In the future, maintenance of dairy production during hot and humid climate conditions will demand improvement of possibility of cooling, continuous improvement of meal composition, as well as genetic advances which include selection for heat tolerance and identification of genetic traits responsible for heat tolerance. ., U našoj zemlji, u toku najtoplijih letnjih meseci, postoje uslovi za razvoj termalnog stresa kod krava, naročito kod istovremenog povećanja temperature i relativne vlažnosti. Zbog primarnih neevaporativnih načina odavanja toplote (radijacija, kondukcija, konvekcija), organizam krava postaje manje efikasan sa povećanjem ambijentne temperature i oslanja se u znatnoj meri na evaporativno rashlađivanje u obliku znojenja i dahtanja. Visoka relativna vlažnost ometa evaporativno rashlađivanje, tako da za vreme toplih i vlažnih uslova, čestih u Srbiji u letnjem periodu, mlečne krave ne troše telesnu toplotu u dovoljnoj meri, da bi se sprečilo podizanje telesne temperature. Povećanje temperature sredine, indeksa temperature i vlažnosti i rektalne temperature krava iznad kritičnih granica prati smanjenje unošenja suve materije i proizvodnje mleka, čime se smanjuje rentabilnost u proizvodnji mleka. Modifikacije koje uključuju hladovinu, povećanje intenziteta prirodne ventilacije i dopunsko korišćenje mehaničkih ventilatora i prskalica u stajama povećavaju odavanje telesne toplote, snižavaju telesnu temperaturu i pospešuju unošenje suve materije. Nove tehnologije koje uključuju tunelski sistem ventilaticije su proučavane radi procene efikasnosti rashlađivanja. Selekcija krava na toplotnu toleranciju je moguća, ali treba imati u vidu da kontinuirana selekcija na poboljšanje proizvodnih osobina, zbog zanemarivanja toplotne tolerancije, dovodi do porasta osetljivosti na toplotni stres. Nutritivne potrebe krava se menjaju tokom toplotnog stresa zbog čega su potrebne izmene u sastavu obroka u pravcu smanjenja unošenja suve materije, povećanja hranljive vrednosti obroka, sprečavanja nutritivnih prekoračenja i održavanja normalne funkcije rumena. Održanje proizvodnje krava u toku toplih i vlažnih klimatskih uslova zahtevaće u budućnosti unapređenje mogućnosti rashlađenja, kontinuirani napredak u sastavljanju obroka, kao i genetska poboljšanja koja uključuju selekciju na toplotnu toleranciju i identifikaciju genetskih osobina koje povećavaju toplotnu toleranciju. .",
publisher = "Institut PKB Agroekonomik, Padinska skela",
journal = "Zbornik naučnih radova Instituta PKB Agroekonomik",
title = "Influence of heat stress on dairy cows production, Uticaj toplotnog stresa na proizvodnju mlečnih krava",
pages = "54-47",
number = "3-4",
volume = "13",
url = "https://hdl.handle.net/21.15107/rcub_agrospace_1519"
}
