Ljubojević D., Ćirković M., Đorđević V., Puvača N., Trbović D., Vukadinov J., Plavša N. (2013): Fat quality of marketable fresh water fish species in the Republic of Serbia. Czech J. Food Sci., 31: 445-450.The chemical and fatty acid composition were evaluated of commercially important fish species (common carp, silver carp, bighead carp, grass carp, Wels catfish, and zander) which were collected from retail stores in the area of Novi Sad, Republic of Serbia. The amount of protein was the highest in zander (19.27%) and the lowest in grass carp fillets (14.73%). The percentage of fat ranged from 1.8 in zander to 10.07 in common carp. The total cholesterol content was the highest in Chinese carps fillets (approximately 65.38 mg/100 g), and the lowest in Wels catfish (33.14 mg/100 g). SFA were lowest in zander (28.6%). Bighead carp meat contained the highest percentage of PUFA (33.73%) while the lowest percentage was detected in common carp (20.1%). The chemical and fatty acid compositions of fish vary greatly between different species and within the same species. The quality of fish meat in Serbian retail stores is quite good but it should be improved by using feed mixtures on fish ponds.

The recent decline in managed honey bee populations, Apis mellifera L. (Hymenoptera: Apidae), has caused scientific, ecological, and economic concern. Research into the formation of reactive oxygen species (ROS), antioxidative defense mechanisms, and oxidative stress can contribute to our understanding of bee survival and conservation of this species. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S‐transferase (GST) enzymes together with levels of malondialdehyde (MDA) were measured in summer and winter honey bees sampled from three colonies. One colony was stationary (C1), entering the winter period having accumulated Robinia pseudoacacia L. (Fabaceae) honey, and two were migratory (C2 and C3), entering the winter period with mainly Tilia (Malvaceae) and Brassica (Brassicaceae) honey, respectively. Compared to summer workers, winter worker bees had decreased SOD and GST activity, and MDA level, whereas CAT activity increased in all three colonies. We also demonstrated that seasonality is the main factor responsible for changes in antioxidant enzymes and MDA levels in worker honey bees. Overall, our results indicate a difference between summer and winter worker bees, pointing at a reduced level of antioxidant enzyme defenses during overwintering which may be due to a decrease in production of ROS. The decreased levels of MDA measured in winter honey bees confirm this. As ROS are actively used by insects as a defense mechanism to fight pathogens, we suggest that reduced production of ROS contributes to higher susceptibility of winter honey bees to infections and reduced overwinter survival.

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Abstract: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 Received 12 October 2017 Accepted 19 October 2017Acta Agriculturae Serbica, Vol. XXII, 44(2017); 123-131 124 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.

Background: Fungal infections can cause serious problems infecting fish eggs, especially unfertilized or dead eggs. In the past, this problem was solved by using very effective chemicals such as malachite green and formalin. But, due to its toxicity and carcinogenicity, malachite green was banned for use in fish intended for human consumption. Formalin also has been banned in most countries. Chemicals and drugs recommended for use to treat fungal infections are hydrogen peroxide, salt, potassium permanganate etc. The goal of the present study was to determine and compare the efficacy of antifungal effects of hydrogen peroxide and sodium chloride on brown trout eggs. Materials, Methods & Results:The experiment was conducted in the brown trout hatchery, Šipovo, Bosnia and Herzegovina. The experimental groups contained 500 and 1,000 mg/L of hydrogen peroxide with 15 and 30 min of exposition; 1 and 2.5% of sodium chloride with 15 and 30 min of exposition and a negative control group (no chemical treatment). The treatment concentrations were calculated and prepared from hydrogen peroxide of 35% active ingredient, and sodium chloride (sterilized) of 100% active ingredient. Eggs for the study were spawned from 11 females and 4 males. The first treatment was performed on the fourth day, and each next treatment was performed at 3-day intervals. Six treatments were administered until the 19th day after the fertilization. The treatment of the eggs was provided until the eggs reached the eyed stage. The effectiveness of the chemical treatments was measured by a hatch rate. There was a significant difference between all treated groups and the negative control group (P < 0.05). Hydrogen peroxide with a concentration of 500 mg/L for 30 min was the most effective and demonstrated a higher hatching rate (75.7%). Sodium chloride treatments resulted in statistically significantly lower hatching rates than hydrogen peroxide treatments. The hatching rate in salt treatment with a concentration of 2.5% for 30 min was 27.3% lower than in hydrogen peroxide treatment with a concentration of 500 mg/L for 30 min. Discussion: Hydrogen peroxide is an effective antifungal, antibacterial and antiviral compound, and according to the Food and Drug Administration (FDA), hydrogen peroxide and salt are approved and classified as a low regulatory priority for the control of oomycetes on all species and life stages of fish. It is considered to be a very environmentally compatible chemical because it does not produce any toxic bioproducts when it decomposes. Hydrogen peroxide stood out as the best candidate substance for fungal control. The fact that the treatment with hydrogen peroxide at a concentration of 500 mg/L for 30 min was more effective than treatments at a concentration of 1,000 mg/L can be explained by temperature dependency and treatment frequency of this chemical. Salt was not such an effective fungicide as hydrogen peroxide. When using salt, toxicity to the eggs should also be considered. Salt solutions may cause egg deaths at levels of ...