Utjecaj vrijednosti temperaturno-humidnog indeksa na dnevnu proizvodnju mliječnih goveda

The objectives of this study were to determine the microclimatic conditions in stables in three climactic regions (East, Mediterranean, and Central) of Croatia as well as to evaluate the effect of temperature-humidity index (THI) values on the daily production of dairy cattle. With that purpose, 1675686 test-day records collected from January 2005 until April 2010 were extracted from HPA (Croatian Agricultural Agency) database. For estimation of the effect of THI on daily production of dairy cows fixed-effect model that took into account the effects of lactation stage, breed, calving season, measuring season, and THI group (T1 - THI≤72; T2 - THI>72) was used. Model was applied to each class of parity (P1, P2, P3, P4 and P5) and region. During the analysed period, the highest monthly averages of ambient temperature were determined in Mediterranean region, the highest monthly averages of relative humidity were observed in Central region, while the highest monthly mean values of temperature-humidity index (THI) were determined in Mediterranean region. Heat stress conditions indicated with mean daily values of THI>72 were determined during spring and summer season in all analysed regions. Absence of heat stress conditions during autumn and winter season also characterised all three regions. Highly significant (P72). Model je apliciran zasebno po razredima redoslijeda laktacije (P1, P2, P3, P4 i P5) te regije. Tijekom analiziranog razdoblja, najviše prosječne mjesečne vrijednosti ambijentalne temperature utvrđene su u mediteranskoj, najviše prosječne mjesečne vrijednosti relativne vlage utvrđene su u centralnoj, dok su najviše prosječne mjesečne vrijednosti temperaturno-humidnog indeksa (THI) utvrđene u mediteranskoj regiji. Toplinsko stresni uvjeti indicirani prosječnom dnevnom vrijednošću THI>72 utvrđeni su tijekom proljetne i ljetne sezone u svim analiziranim regijama. Odsustvo toplinsko stresnih uvjeta tijekom jesenske i zimske sezone karakteriziralo je sve tri regije. Visoko signifikantan (P