Determining chlorophyll and carrotenoid content in Bombyx mori L. excreta by Near Infrared Spectroscopy

S. Atanasova, M. Panayotov, D. Pavlov, M. Duleva
Abstract. For the needs of the experiment excreta age five of silkworms (populations of the monovoltine crossbreds of Bombyx mori L. Super1хХеса2, 19х1014 and 1013х1014) raised in spring have been used. Spectral measurement (NIR spectroscopy) of excreta has been made non-destructively by measuring diffuse reflection of samples within the range 900–1700 nm with the spectrometer NIRQuest 512. Afterwards chlorophyll a, chlorophyll b and carotenoids content in these samples has been determined through acetone extraction and determining the absorption of the resulting solution at 440.5, 644 and 662 nm by spectrophotometer Spekol 11. Partial Least Square Regression (PLS) has been used to obtain equations for determining the amount of chlorophyll and carotenoids in excreta based on near-infrared spectral data. The results obtained show that chlorophyll a, chlorophyll b and carotenoids content in silkworm excreta can be successfully determined by non-destructive spectral analysis within the range 900-1700 nm. The obtained correlation coefficients, revealing the relationship between the parameters tested are higher than 0.96. Extremely high accuracy has been reached in determining the content of chlorophyll a and carotenoids. Lower is the accuracy in determining chlorophyll b, which can be accounted for by the fact that chlorophyll b is more unstable and quickly dissociates after extraction.

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Influence of the amount of milk clotting enzyme with microbial and camel origin on the coagulation time of cow’s milk

P. Panayotov, K. Yoanidu, P. Boyanova, B. Milenkov
Abstract. A study of rennet coagulation of cow’s milk was conducted using chymosin of microbial and camel origin in the range 10 to 60 cm3.10-2 dm-3 with an equivalent activity to 1:50000. As a control calf chymosin was used. The monitoring includes heuristic, optical and viscosimetric methods. Significant differences in both initial coagulation time, as well as in time of full coagulation of milk were determinated. The data obtained in a research study can be used in laboratory and manufacturing practices using chymosin of camel origin, which can mainly be used in cheese making, using stream dosing of the coagulant and low impact of the enzyme on the cheese ripening process.

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Effect of supplementary honey and artificial sugar feeding of bees on the composition of royal jelly

R. Balkanska, I. Zhelyazkova, M. Ignatova, B. Kashamov
Abstract. The purpose of this study was to assess the effect of supplementary honey and artificial sugar feeding of bees on the composition of royal jelly. A total of 29 royal jelly samples were harvested and analyzed from May to August 2012. The results obtained show the following values for royal jelly samples harvested from bee colonies fed with sugar solution: water content (58.30–63.50%), proteins (15.04–18.79%), fructose (4.30–6.91%), glucose (2.87–4.43%), sucrose (1.39–4.19%), pH (3.65–4.18), total acidity (3.69–4.46 ml 0.1 N NaOH/g), electrical conductivity (166.00–214.00 μS/cm). The respective physicochemical parameters in royal jelly samples produced by feeding with honey were: water content (59.70–63.70%), proteins (15.28–18.53%), fructose (3.96–6.74%), glucose (2.64–4.49%), sucrose (1.40–3.87%), pH (3.76–4.19), total acidity (3.69–4.66 ml 0.1 N NaOH/g), electrical conductivity (174.00–191.00 μS/cm). Statistical analysis showed no significant differences between the physico-chemical parameters (water content, proteins, fructose, glucose, sucrose, pH, total acidity, electrical conductivity) in the feeding experiment. These data show that the studied types of feeding do not influence the royal jelly composition. These results, however, are not only essential from scientific point of view. They have also practical purposes and are important for beekeepers who produce royal jelly.

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Fatty acids and lipid indices of buffalo milk yogurt

N. Naydenova, T. Iliev, G. Mihaylova
Abstract. The present investigation had the objective to study the changes in the atherogenic index and the lipid preventive score as nutrition indicators for assessment of the risk of cardio-vascular diseases. The study was performed with buffalo milk, obtained from purebred Bulgarian Murrah buffaloes from II lactation, reared in the herd of the private farm in Dimitrievo village. The content of saturated fatty acids in buffalo yogurt is higher than in raw milk at the expense of unsaturated fatty acids. Omega-6/omega-3 ratio varies from 3.58 for yogurt to 4.30 for raw milk, which is within the range of the optimal values for healthy nutrition. The atherogenic index was calculated on the obtained values for the lauric (C12:0), myristic (C14:0) and palmitic (C16:0) acids and the unsaturated fatty acids. The obtained data for the raw milk and yoghurt are 2.68 and 3.24, respectively. The values of lipid preventive score calculated on the basis of fat content and fatty acid groups – saturated, monounsaturated and polyunsaturated, showing the degree of preventive effect regarding the risk of cardiovascular disease, are 12.42 for raw milk and 14.52 for the produced yogurt, respectively.
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Carcass composition and meat quality in lambs reared indoors and on pasture

T. Popova, P. Marinova
Abstract. An experiment was carried out with 28 male lambs of Northeastern Bulgarian Fine Wool Breed (NBFWB) and lamb crosses of this breed with Ile de France (NBFWB x IDF) reared indoors and on pasture in the Institute of Animal Science – Kostinbrod. Carcass composition and quality parameters of m. Longissimus dorsi and m. Semimembranosus were studied in the lambs according to their rearing and breed. Most of the lambs reared indoors and on pasture belonged to O and R conformation classes. According to the breed the highest percentage of lambs of NBWFB were in the O class while the carcasses of the crossbred lambs were equally distributed between O and R classes. Lambs reared indoors or on pasture were in classes 2 and 3 according to their degree of fatness. The distribution in both breeds showed that the carcasses of the NBFWB were fatter than those of the cross. Rearing did not affect significantly the thickness of fat in different carcass locations as well as the content of muscle, bone and total fat in the half carcasses. Breed influenced the pelvic fat content which was higher in the lambs of the cross (P<0.05). No significant effect of rearing on the content of meat, bone and fat in the separate parts of the carcass was observed while breed affected significantly the percentage of pelvic fat (P<0.05) and intermuscular fat (P<0.01) in the loin, as both were higher in the lambs of NBFWB x IDF. Rearing influenced the meat colour of m. Longissimus dorsi. It was brighter (P<0.05) in the lambs reared on pasture, compared to the indoors reared lambs. Breed affected significantly the colour of both m. Longissimus dorsi and m. Semimembranosus (P<0.05) and in the lambs of the NBFWB x IDF it was darker. The way of rearing the lambs led to significant differences in the content of myoglobin in m. Longissimus dorsi (P<0.05).

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Changes of some agro-chemical parameters of Pellic Vertisol (FAO) soil type in growing cereal crops under organic system of agriculture

V. Koteva
Abstract. The investigation was carried out in a field certified for organic agriculture, on soil type Pellic vertisol (FAO) during 2004 – 2012. The changes in soil acidity, total humus content and reserves of mineral nitrogen, mobile phosphorus and available potassium in soil after growing of cereals without soil organic fertilization were followed. The obtained results were compared to the values of these indices from the same soil type subjected to intensive cultivation (conventional system of agriculture) and the amounts obtained from soil covered with perennial grasses (virgin soil). The realization of the production potential of common wheat and winter barley grown on Pellic Vertisol without soil organic fertilization is pointed out.

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Biological activity of plant protection products against Tuta absoluta (Meyrick) in tomato grown in greenhouses

N. Valchev, V. Yankova, D. Markova
Abstract. Tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera:Gelechiidae) is a dangerous pest in tomato grown in greenhouses. The control of this pest is difficult because of the latent way of life of the larvae in the mines, high reproductive potential, polyvoltine development and manifestation of resistance to great part of applied insecticides. Integrated Plant Protection programmes including a complex of measures are developed for successful control of the pest. The most frequently used practice for control on T. absoluta is still the application of chemical insecticides. During the period 2011-2012 experiments were performed for determination of the effectiveness of some insecticides in tomato variety Velocity grown in heated greenhouses. A very good biological activity towards the larvae (L1-L4) of tomato leaf miner (Tuta absoluta Meyrick) was established in the products Avant 150 ЕC 250 ml/ha (E=79.38% 14th day after treatment) and Coragen 20 SC 0.018% (E=79.18% 14th day after treatment).

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Stability evaluation of mixtures among preparations with different biological effect on the basis of grain yield in spring vetch

G. Delchev, N. Georgieva, I. Nikolova
Abstract. With the purpose to study the stability of mixtures among preparations with different biological effect on the basis the grain yield in spring vetch a three-factor field trial was carried out during the period 2007-2009 in Institute of Forage Crops, Pleven using the split plot method. Factor A includes the three years of the research. Factor B (preparations) includes 8 levels: untreated control, Atonic (growth stimulator) – 600 ml/ha, Masterblend (combined leaf fertilizers) – 1.6 kg/ha, Atonic + Masterblend, Confidor (insecticide) – 150 g/ha, Confidor + Atonic, Confidor + Atonic + Masterblend, Confidor + Masterblend. Factor C (stages of treatment) includes three levels: budding, budding + flowering, flowering. The most stable mixtures with regard to the grain yield are Atonic + Masterblend and Confodor + Masterblend, and with single use of preparations – the insecticide Confidor. Technologically valuable mixtures which match high stability and high productivity in the different years are all combinations with twofold application at budding and flowering and with the best parameters are distinguished the combinations Confidor + Atonic and Confidor + Masterblend. The single treatment at flowering stage should be avoided because of reduced productivity independently that it is characterized with high stability during the different years.

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Productivity of irrigation cotton cultivated under different inter-row spaces

I. Saldzhiev, A. Muhova
Abstract. Field trial on cotton (Vega cultivar) was carried out during 2007–2011 on leached vertisols under irrigation regime of sprinkling – 75 % of the field moisture capacity (FMC) for the soil layer of 0 – 40 cm. The trial included the following variants: factor A) Irrigation with lower rates:1). Single irrigation of 600 mm/ha at the interphase period blooming-boll formations; 2). Two irrigations of 450 mm/ha – the first one at the blooming stage and the second – in the boll formations period; 3).Two irrigations of 600 mm/ha – the first one at the blooming and the second – in the boll formations period; 4). Non-irrigated variant – for standard. Factor B) Width of inter-row space: 1). 60 cm. 2).80 cm. It was established that the best results were obtained for the variant where cotton cultivated at 80 cm of inter-row space and with second irrigation with 600 mm – 939 kg/ha more than the non-irrigated control and 11.9 % more than the variant with irrigated norm 600 mm/ha. In reference of net profit of 1000 m3 irrigated water the best results were achieved after single irrigation norm of 600 mm/ha. In respect to width of inter-row space the yield from a unit of area with inter-row space 0.80 cm we receive 4.6 % more than sowing at 0.60 cm inter-row space.
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Investigations on friction coefficients of cow hooves with different dairy farm floor types

T. Penev, Z. Manolov, I. Borissov, V. Dimova, Tch. Miteva, Y. Mitev, V. Kirov
Abstract. The investigation was performed in three Bulgarian free-stall cattle farms with different flooring types. The floor of farm A was covered with two rubber mat types, with and without abrasion lining. At the other two farms, floors were made of grooved concrete which was used for 6 years (farm B) and for 4 years (farm C). The purpose of the investigation was to determine the friction coefficients on the different floorings with tribometer described by Phillips and Morris (2000) and the influence of some factors as usage period, presence of manure and water on the floor. The coefficient of static friction of dry floors at the studied farms varied from 0.46 on the concrete floor at farm B to 0.59 on the rubber floor with abrasion lining. It indicated that dry floors at the surveyed farms provided good safety for standing animals. The dynamic friction of dry floors was the lowest at farm B – 0.44, and the highest on the rubber floor with abrasion lining at farm 1 – 0.56. When water was spilled on the floor, static friction coefficients of all studied floorings decreased except for the rubber floor with abrasion lining, where it increased up to 0.61. The dynamic friction coefficients were lower when all floors were wet. The lowest dynamic friction coefficient was determined on the floor at farm B – 0.39, which is under the critical minimum. This was attributed to its longer usage and thus, its wearing and smoothing. Static friction coefficients on manure-covered floors varied from 0.4 to 0.49. The lowest dynamic friction coefficient (0.36) was measured on the floor at farm B, and the highest (0.46) – on the rubber floor with abrasion lining, farm A.

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