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Red deer, roe deer, and wild boar belong to a group of large game and are the most common species of game in the hunting area in Eastern Croatia. The research was conducted by the company hunting staff in the Osijek-Baranja County, area of Kućanci in the interval from 2008 to 2018. Knowing the number of wildlife in the hunting area is the base for establishing growth and planning shootings. It is important to keep the balance in the hunting ground to avoid transmission and spreading of diseases and reduce traffic accidents as well as vehicle and wildlife damages. Given the fact that populations of large game have great importance in Croatia, the main objective of the study was to determine population trends of red deer, roe deer, and wild boar in the hunting ground in Eastern Croatia in 2008 – 2018.

Climate change drives population growth of wild boar directly by relaxing the negative effect of cold winters on survival and reproduction, and indirectly by increasing food availability. Air temperature is one of the main climatic elements when observing the climate of an area. Furthermore, humidity is an important factor for normal life of wild animals. Considering the great importance of the wild boar population in Croatia, the aim of this study was to determine the relationship between weather conditions and population size (regarding the categories: offspring, young, middle-aged, and mature) of wild boar population in hunting ground in Eastern Croatia during the analysed period from year 2008 to year 2018. Based on the conducted research following could be pointed out: during the analysed period from year 2008 till year 2018 the mean yearly air temperature varied in interval from 11–13 °C, during the analysed period from year 2008 till year 2018 the mean yearly humidity varied in interval from 76–84%, the lowest total number of offspring was determined in year 2017. Since the offspring are extremely susceptible to inadequate environmental conditions especially low temperature the decrease of boar population could be expected during the period characterised by extreme environmental conditions.

Variance components for daily milk production as well as breeding value of dairy Simmentals for daily milk production in terms of heat stress defined as different values of THI threshold values (72, 74, and 76) were estimated using 1,636,192 test-day records provided by the Croatian Agricultural Agency. Temperature-humidity index (THI) calculated from ambient temperature and relative humidity recorded in the barns on the milk recording day was used as the measure of heat stress. Bivariate estimation model accounted variances due to lactation stage, calving season, age at calving, breeding region, parity, permanent environment, interaction between hear and year, and individual animal. Obtained high genetic correlations between the daily milk production in normal and condition characterized by heat stress, as well as very high correlations between the EBVs in normal and heat stress conditions indicate animals’ high level of acclimatization to the environment on dairy cattle farms. Since microclimate measurements were carried out only once at a milk recording day, these results should be taken with caution. Generally, further research with multiple daily measurements of the microclimate parameters in the facilities is necessary to provide a fully unambiguous conclusion.

The objective of this research was to determine the effect of addition of n-3 unsaturated fatty acids (α-linoleic, eicosapentaenoic and docosahexaenoic) in dairy goats’ ration on milk composition (fat and protein content). Also, the persistence of the effect after supplementation was analysed. The research was conducted on dairy goats (Alpine and Saanen) bred at an indoor farm. Regarding the experimental period, the milk sampling at milking (morning and evening) was performed in the period before supplementation (BS), during supplementation (S), and after supplementation (AS). According to the added supplement, animals were randomly allocated into a group (G-4) with no added supplement and three test groups (G-1; G-2; G-3) where a supplement containing n-3 unsaturated fatty acid was added over a period of five days. The results of this research indicate that the addition of PUFA in goats’ ration changes the milk composition. The supplementation of α-linoleic resulted in increase of both milk fat and protein content. Furthermore, the addition of eicosapentaenoic and docosahexaenoic resulted in decrease of fat but increase of protein content in milk. The observed trends also persisted after the supplementation period.

With the aim of determining the effect of response to heat stress, parity, breed and breeding region on somatic cell count (SCC) in dairy cattle, the individual test-day records of dairy cows collected from 2005 to 2012 in regular milk recording (AT4 / BT4 method) in Croatia were used. The proportional differences in log somatic cell count, and logSCC (in %) in subsequent milk recordings (1st, and 2nd) were determined in cows with a significant decrease in daily milk yield at a set temperature-humidity index, THI threshold (68, 72, and 76). The results indicate high variability in somatic cell count due to the animal’s response to heat stress (heat stressed at THI in 68, 72, and 76), parity (1, 2, and 3+), breed (Holstein, and Simmental) and breeding region (Central, and Eastern Croatia). Also, it could be pointed out that Holsteins, especially cows in higher parities (2, 3+) reared in Eastern Croatia were shown to be more sensitive to environmental stress, even in the period after heat stress (1st, and 2nd subsequent milk recording). Since SCC is not only an indicator for mastitis, but also reflects a cow’s immune response to general stress situations, the high variability determined may be explained by the individual adaptation capabilities of these two breeds to breeding conditions in the analysed regions., U cilju utvrđivanja utjecaja odgovora na toplinski stres, redoslijeda laktacije, pasmine te regije uzgoja na broj somatskih stanica u mliječnih krava analizirani su zapisi na kontrolni dan prikupljeni u periodu od 2005. do 2012. tijekom provedbe redovite kontrole mliječnosti (AT4 / BT4 metoda) u Hrvatskoj. Proporcionalna razlika u logSCC (%) u slijedećim kontrolama mliječnosti (1. i 2.), utvrđena je u krava sa znakovitim padom dnevne količine mlijeka pri određenim graničnim vrijednostima THI (68, 72 i 76). Utvrđeni rezultati ukazuju na visoku varijabilnost u broju somatskih stanica uslijed odgovora grla na toplinski stres (u toplinskom stresu pri THI 68, 72 i 76), redoslijeda laktacije (1, 2 i 3+), pasmine (Holstein i Simmental) te regije uzgoja (središnja i istočna Hrvatska). Nadalje, može se istaknuti da su se grla Holstein pasmine, osobito krave u višim laktacijama (2., 3+) uzgajane u istočnoj Hrvatskoj, pokazale kao osjetljivije na stresne okolišne uvjete, čak i u razdoblju nakon toplinskog stresa (1., i 2. kontrola mliječnosti). Budući da broj somatskih stanica ne predstavlja samo indikator mastitisa, već odražava i imunološki odgovor krave na opće stresne situacije, utvrđena visoka varijabilnost može biti objašnjena individualnim adaptacijskim mogućnostima obiju pasmina na uvjete uzgoja u analiziranim regijama.

In order to estimate the variance components as well as the breeding value for daily milk production of Holstein cows in terms of heat stress defined as different THI threshold values (68, 70, and 72) 1,275,713 test-day records from 90,159 cows were used. Temperature-humidity index (THI) calculated from ambient temperature and relative humidity recorded in the barns on the milk recording day was used as the measure of heat stress. Daily milk production was analysed as a bivariate variable, in the normal conditions (under the set THIthreshold value), and in terms of heat stress (above the set THIthreshold value) using a model that accounted variances due to lactation stage, calving season, age at calving, breeding region, parity, permanent environment, interaction between hear and year, and individual animal. The estimated high genetic correlations between the daily milk production in normal and heat stress conditions, as well as high correlations among the EBVs in normal and heat stress conditions, point out that Holstein cows with high productivity in normal condition will sustain an alike level of production even in terms of heat stress. These results indicate that the Holstein cows are very well acclimatized to the environmental conditions at dairy farms in Croatia. However, these findings should be taken with caution, given that measurements of microclimate parameters were conducted only once at a milk recording day, so the reliability of such measurements could be questionable. In conclusion, in order to realize a completely unambiguous conclusion, further studies that include multiple daily measurements of microclimatic parameters in the farms facilities are necessary.

Aiming to determine the persistency of effect of heat stress in Simmental cows reared in Eastern Croatia regarding the parity and susceptibility to heat stress, 539, 993 test- day records from 59, 821 cows collected in the period from January 2005 to December 2012 were analysed. The cows with determined statistically significant decrease in daily milk production at set temperature-humidity index (THI) threshold value (68 and 72) were included in the further analyses. The persistency of heat stress effect was defined as the drop in daily milk traits in the subsequent milk recordings (1st and 2nd) after the heat stress. The obtained results indicate that cows heat stressed at lower THI threshold value had higher drop in daily milk yield in subsequent milk recordings. Furthermore, cows in first parity experience higher drop comparing to older cows. The negative effect of heat stress on daily milk contents that existed in all cows was more pronounced in the 2nd milk recording. Finally, the lower was THI threshold value (cows more susceptible to heat stress), the stronger and more persistent was heat stress effect. Given the very likely increase in the frequency of days with heat stress in the future, it is necessary to develop a proper mitigation strategy for dairy cattle production.

Aiming determination of the variability of production traits (daily milk yield and composition) and microclimate parameters (ambient temperature and humidity) in the barns; as well as the correlation between the analyzed groups of traits, 1,636,192 test-day records from Simmentals and 1,275,713 test-day records from Holsteins were analysed. Performed analysis indicate high variability of production traits due to cow's breed, parity as well as breeding region. Also, high variability of microclimate parameters in the barns due to season and breeding region was found. Furthermore, statistically highly significant (p lt 0.001) correlations between the production traits and microclimate parameters were determined. Finally, the negative effect of inadequate microclimate on daily milk production was determined in both breeds in all breeding regions. Since genetic evaluation and selection of dairy cattle for heat resistance is only long-term method for heat stress managing, determined effect will be taken into account in the statistical model for estimation of genetic parameters and breeding values. Cilj istraživanja je bio određivanje varijabilnosti proizvodnih osobina (dnevni prinos i sastav mleka) i mikroklimatskih parametara (temperatura i vlažnost okoline) u objektima za držanje krava za proizvodnju mleka; kao i korelacija između analiziranih grupa osobina; 1.636.192 zapisa za grla simentalske rase i 1.275.713 zapisa test dana grla holštajn rase. Izvršene analize pokazuju veliku varijabilnost proizvodnih osobina zbog rase krava, pariteta kao i odgajivaĉkog regiona. Takođe je utvrđena velika varijabilnost mikroklimatskih parametara u objektima zbog sezone i odgajivačkog regiona. Pored toga, utvrđene su statistički vrlo značajne (p lt 0,001) korelacije između proizvodnih svojstava i parametara mikroklime. Konačno, negativan uticaj neadekvatne mikroklime na svakodnevnu proizvodnju mleka utvrđen je kod obe rase u svim odgajivačkim regionima. Pošto je genetska procena i selekcija mlečnih goveda na otpornost na visoke temperature sredine samo dugoročna metoda za upravljanje toplotnim stresom, utvrđeni efekat biće uzet u obzir u statističkom modelu za procenu genetskih parametara i odgajivačkih vrednosti.

In order to determine the effect of breeding region on differences in persistency of heat stress effect in first parity Simmentals test-day records provided by the Croatian Agricultural Agency were analysed. Only cows with detected statistically significant decrease in daily milk yield at set temperature-humidity index (THI) threshold value (65, 70 and 75) were included in the further analyses. The persistency of heat stress effect regarding the daily milk traits was determined as a drop in the subsequent milk recordings (1st and 2nd). The research results indicate significant difference in animals’ response to heat stress effect due to breeding region and individual’s susceptibility to heat stress. The most pronounced and persistent negative effect of heat stress was determined in cows reared in Eastern region. Also, the negative effect of heat stress was more pronounced and more persistent in Simmentals that were heat stressed at the lower THI threshold values (cows that are more susceptible to heat stress).

Considering the great importance of the wild boar population in Croatia, the objective of this study was to determine the fluctuations of all categories (offspring, young, middle-aged, and mature) of wild boar population in the hunting area in Eastern Croatia during the analyzed period from 2008 to 2018. Based on the conducted analysis, the following can be emphasized: the last recorded maximum of offspring (male, and female) was in 2013, the highest number of young (male, and female) was determined in 2018, the last recorded maximum of middle-aged (male, and female) was in 2014, and the last recorded maximum of mature (male, and female) was in 2013. Considering the situation in the hunting area in 1955, the number of wild boars redoubled in the last 10 years. Compared to 1995 and given the fact that the hunting area today has much more resources available and there is significant human activity that can recreate the wildlife population by releasing heads, there is a possibility that the number of wild boars could increase slowly in the coming years.