Beeswax is one of the most important products for the well-being of bee colonies. The wax glands of young worker bees produce beeswax, which serves as a building material for honeycomb construction. Beekeepers using hives with mobile frames mainly utilize local beeswax to make foundations. Any paraffin addition represents adulteration, resulting in a high degree of contamination. During the preparation of re-used beeswax, losses during the process may instigate producers to add cheaper, wax-like substances like paraffin and tallow. This article presents a systematic investigation of the quality of beeswax foundation from six major producers in Vojvodina, Serbia, by applying the classic analytical procedure for the determination of selected physicochemical parameters and instrumental gas chromatography coupled with mass spectrometry (GC–MS) and Fourier transform infrared attenuated total reflection (FTIR–ATR) spectroscopy techniques. FTIR–ATR detected possible paraffin and beef tallow in 72 foundation sheet samples. This technique was complemented with GC–MS. This analysis revealed that paraffin content ranged between 19.75 and 85.68%, while no tallow was detected over the two-year period. Two sheets from each manufacturer were placed into wired Langstroth–Ruth frames and placed in beehives. The construction, based on built cells, was monitored every 24 h. Evaluating newly inserted sheets proved that without quality nectar, there is no intensive building, regardless of adulteration.

The aim of this study is to determine correlation between change in milk production and metabolic adaptation of cows during heat-stress. Experiment included 30 Holstein-Frisian cows. Cows exposed to heat-stress, which is expressed in high THI index, have lower milk production, higher concentration of insulin and lover concentrations of glucose and NEFA. Indexes of insulin resistance-RQUICKI, insulin: glucose and insulin: NEFA relations are higher in cows under heat stress. Grouping cows in accordance to reduced milk yield have showed that trend of reduction of glucose and NEFA levels, followed by increased insulin level, higher RQUICKI, greater insulin: glucose and insulin: NEFA ratios, started and increased during the reduction in milk production. Among this, significant correlation was founded between these parameters and milk yield. Significant correlation was also noted between those parameters. Change in metabolic value is of great importance for prediction of cows that would have decreased milk yield (above 18%). With almost 90% certainty cows with great reduction in milk yield can be detected. These cows have had following relative changes in values of metabolic parameters during heat-stress compared to thermo-neutral period: insulin increased for ≥12.5%, reduction in NEFA values for ≤14.1%, reduction in glucose for 21.5%, RQUICKI index increased for ≥9.6%, insulin: NEFA ratio increased for ≥20.1% and insulin: glucose for ≥20.3%. Dynamical changes in metabolites and insulin resistance values have great influence on milk yield in cows under heat stress. Decreasing in glucoses followed by increased insulin level and increased insulin sensitivity indicate that glucose is transferred from udder to other tissues which can cause decreased milk production.

The aim of this study is to determine value of temperature-humidity index (THI) in period of 2005-2016. in Vojvodina and their correlations with milk production and temperature of body surface of animals. THI index is calculated according to the following formula THI=(1,8×Temperature)-(1-Relative Humidity) × (Temperature- 14,3)+32. Temperature and humidity data were collected directly from Hydrometeorological Institute of Serbia. Average THI values were calculated for every month for every year from 2005 to 2016. Measuring spots were cities Vršac, Zrenjanin, Kikinda, Palić, Sombor, Rimski Šančevi and Sremska Mitrovica. Temperature and humidity are noted at 14h, so they represented maximal average values of THI index. Trend of THI values was represented for each day in every month in years from 2005. to 2016. Average production of drinking milk for year of 2016 was calculated. This year was chosen because is the last year of research and represents cumulative effect of heat stress in cows. Data were collected from Statistic Institute of R. Serbia. Thermo-vision camera was used for determining skin temperature of udder and skin in eye region. Results were showed that temperature ranged from 40.3 in January to 77.5 in July. Average maximal THI value in period of 2005-2016 showed that heat stress was presented in May, June, July and August. Drinking milk production was the greatest in January. After that it started dropping. The lowest production of drinking milk was noted in August with an increase afterwards till December. Body surface temperature was ranged from 34.1 to 38.5ºC. The highest body temperature was measured at August and the lowest in winter time. Significant negative correlation between ten-year average THI value and milk production was noted. Positive correlation was noted between THI and body temperature. From 2005 to 2016 positive linear trend of THI values that were measured in hottest period of day was noted. In every month statistically significant linear trend of rising THI value was founded, except in January, October and November. Extremely hot summers in Serbia appear in every five years when cows are affected the most. Showed data indicated global warming and climate changes which affect biological adaptation of cows.

The study of invasive plant species occupies a lot of researchers all over the world, because this category of plants is one of the more important factors of endangering native flora of specific area. In the flora of Serbia, presence of invasive plants, disturbs, primarily, composition of vegetation and bipolar character of life forms. In this paper we are, especially, pointing out the species which are pollinated by bees, wanting to emphasize that besides already known ways of spreading invasive species, insufficient knowledge of their biology and ecology, can become a focus and a new way of spreading some species, such as Robina pseudacacia, Amorpha fruticosa, Syphyotrichum lanceolatum and Asclepias syriaca, since they are well-known melliferous plants.

In 1893. Jovan Zivanovic notes that based on the color of the abdomen of bees, two varieties of bees are present in Vojvodina, one dark and the other with two yellow rings on abdomen. Up to the present time there are mixed opinions about the presence of one or more populations of bees in Vojvodina, especially about the presence of the yellow variety in Banat. The aim of this paper is to establish the existence of one or more populations of bees, using genetic analysis of bees. Evaluation of genetic connections, diversity within the population and structure of the bee population in Vojvodina, were calculated on the basis of allele variation of 25 microsatellite loci. A genetic typification of the following microsatellites was performed: A8, A14, A24, A29, A43, A79, A88, A113, Ac11, Ac88, Ac139, Ac306, Ap15, Ap68, Ap85, Ap90, Ap223, Ap224, Ap226, Ap249, Ap273, Ap274, Ap288, At168, At188. 92% or 23 loci proved to be polymorphic in samples of bees from Srem and Backa, and 88% or 22 loci proved to be polymorphic in samples of bees from Banat. Heterozygosity calculated for the whole population is not significantly different from the expected heterozygosity. It was found that the obtained genetic differences between bees of Srem and Backa, and Banat region are not sufficient for these two populations to be considered separate.

Providing stable milk production is one of the priorities in dairy cattle. The aim of this study was to examine the relationship between milk production and endocrine and metabolic parameters and to determine whether homeoresis and unfavorable metabolic adaptation affecting milk production during early lactation. The experiment included 40 Holstein cows. The blood was taken during the first week of lactation, and is determined by the glucose concentration, Ca, and BHB bilirubin. Milk production was monitored in first 8 weeks of lactation. The results show that cows with lower values of insulin and higher values of cortisol and STH have higher milk production in the first weeks of lactation. However, these relationships are not easy and apparently are caused by other factors, and depend on the week in which we investigated the concentrations of the hormones themselves. When cows classified according to the metabolic status, so to compare milk production between cows with unfavorable and favorable metabolic status at the result showing that cows who have an unfavorable metabolic status (lower concentrations of glucose and calcium and higher BHB and bilirubin concentration) showed lower milk production. Impact of endocrine and metabolic status on milk production has been determined. A relationship between hormones, metabolites, and milk production is complex and must be interpreted within the concept of homeostasis and homeoresis or biological capacity of cows to adjust to lactation but also to maintain the continuity of the body.