Effect of season, lactation period and number of lactation on mastitis incidence and milk yields in dairy cows

T. Penev1*, Zh. Gergovska2, I. Marinov2, V. Kirov3, K. Stankov4, Y. Mitev1, Ch. Miteva1
1Department of Applied Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Animal Science, Faculty of Agriculture, Trakia University, 6000, Stara Zagora, Bulgaria
3Department of Animal Sciences, Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria
4Department of Management, Faculty of Economics, Trakia University, 6000, Stara Zagora, Bulgaria
Abstract. The aim of the present study was to study the effect of the season, period and number of lactation on mastitis incidence and milk yields in dairy cows. The climate in Bulgaria implies the presence of seasonal variations in mastitis prevalence in dairy cows, reared in free-stall barns all the year round: spring – 5.33%, summer – 4.9%, autumn – 4.2% and winter – 4.5%. The mastitis incidence during the lactation periods increased gradually from calving to the 120th lactation day. For the first 120 days of lactation, the mastitis incidence attained 26%. The reduction in milk yields after the lactation peak was associated with gradual decliine in cows affected by mastitis to 1.7% during the last month of lactation. With increasing the number of lactations, mastitis incidence also increased: 23.3% in 1st lactation cows, 26.7% in 2nd lactation cows, 48.9% in 3rd lactation cows and 43.3% in cows in fourth or subsequent lactation. The highest daily milk yield at the peak of lactation (34.05 kg) was established in cows affected by mastitis after the 180th lactation day, followed by cows with mastitis between the 60th and 180th lactation days (32.54 kg), and third came healthy cows (31.98 kg). The lowest daily milk yield at the peak of lactation was demonstrated in cows affected by mastitis in the first 60 days of the lactation (29.39 kg). It was proved that cows with exceptionally high milk yields in the beginning of lactation were more prone to mastitis at a later stage due to weakened systemic resistance and consequent disease. Cows with relatively lower milk yield during the lactation period (7580.3 kg) were more resistant to environmental factors, therefore were not affected by mastitis and produced highquality milk with lower costs vs those with highest milk yields affected by mastitis after the 180th day. These cows produced more milk (7607.9 kg) within a 305- day lactation, but the treatment costs could be hardly compensated. Cows in which mastitis occurred until the 60th and between the 60th and 180th lactation day, produced 7215.5 and 7484.1 kg milk, respectively. The average milk yield per lactation of healthy cows was by 137.83 kg higher than that of cows with mastitis. A statistically significant reduction in milk fat (Р < 0.05) and milk protein (Р < 0.001) between healthy and diseased cows was observed.

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Influence of the kinetics of salting for Bulgarian white brined cheese, produced by mechanized and traditional technology on the starter and adjunct microflora during ripening

P. Panayotov1, V. Mihailov2*, D. Rakov3
1Department of Milk and Milk Products, Technological Faculty, University of Food Technologies, 26 Maritza, 4002 Plovdiv, Bulgaria
2Department of Animal Husbandry – Ruminants and Dairy Farming, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
3Company “Dimitar Madjarov”, 180 Vasil Aprilov, 4027 Plovdiv, Bulgaria
Abstract. The salting of Bulgarian white brined cheese produced by the traditional method was performed in brine with a concentration of NaCl 20 % and a temperature of 13°C, for 14 h. The Bulgarian white brined cheese produced by the mechanized method with processing line “Alpma”, used dry salting (40 g NaCl per 1 kg of cheese). А mathematical model was established for the kinetics of salting for Bulgarian white brined cheese, produced by mechanized and traditional technology. The obtained results showed difference in the growth of starter and adjunct lactobacilli and lactococci for the two methods of production. The number of starter and adjunct lactobacilli and lactococci during ripening was higher in the cheese produced by the mechanical technology and dry salting.

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Productivity and grass density of the main types of pastures in Sakar and Strandja region

V. Vateva*
Department of Engineering and Technologies, Faculty of Technics and Technologies, Trakia University, 6000 Stara Zagora, Bulgaria
Abstract. Grassland associations are natural resource, which in their proper use might affect the welfare and economic development of the region in which they are located. In Sakar and Strandja regions such herbaceous plant associations occupy about 107.3 thousand hectares. Only in those regions of the country there is a favorable combination of environmental and climatic conditions allowing almost all year round utilization of pasture grass associations. They are the main potential to supply feed for the animals. In this experiment, the goal is to tracce and identify the productivity of natural pasture grass associations in Sakar and Strandja mountain. Observations were performed on the most typical, the most common and most used pastures located in these regions. The density of the pasture types was established. A comparative analysis of productivity of fresh mass and dry pasture grass of Sakar and Strandja region was performed. The results show that the pasture types in Strandja region possess higher density and greater productivity than those in Sakar region. With the highest density in Sakar region are the grassland type Agrostis capillaris – Festuca fallax, with a density of up to 1972 pieces/m2 at least. In Strandja region pasture type Agrostis capillaris – Cynosurus cristatus – Lolium perenne reaches density 3716 pieces/m2. These types of pastures are distinguished with the highest productivity of fresh and dry biomass. In Sakar region from pastures of type Agrostis capillaris – Festuca fallax 16680 kg/ha green mass and 4920 kg /ha dry matter can be obtained, and in Strandja region from grassland of type Agrostis capillaris – Cynosurus cristatus – Lolium perenne, 31700 kg/ha fresh mass and 7380 kg/ha dry matter can be obtained.

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Non-fish marine resources and their exploitation along the Bulgarian Black Sea coast

E. Petrova-Pavlova*
Institute of Fishing Resources Varna, 4 Primorski, 9000 Varna, Bulgaria
Abstract. Overfishing in the World Ocean including the Black Sea, as well as the global pollution led to a reduction in the quantity of industrial fish species. The occurring changes have led to the focus of fishing organizations and companies to catch some non-fish resources of economic importance. The catches help meet both the domestic market needs and increase the export list of some other marine resources. The main subject of the study are the mollusk populations of species such as black mussels (Mytilus galloprovincialis) and Rapana venosa used economically, the species form aggregations and could be subject to potential catch. The paper summarizes the results from the studies of these species in order to track the changes of their biological characteristics and to take measures for catch methods and control by the competent authorities.

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Changes of the humus status of Pellic Vertisol (FAO) soil type under long-term growing of field crops in a stationary trial without fertilization

V. Koteva1*, S. Kostadinova2
1Institute of Agriculture, 1 Indusrtialna, 8400 Karnobat, Bulgaria
2Department of Agrochemistry and Soil Science, Faculty of Agronomy, Agricultural University, 12 Mendeleev, 4000 Plovdiv, Bulgaria

Abstract. This investigation was aimed at determining the changes in the humus content of leached Pellic Vertisol under long-term growing of intensive field crops in crop rotation in a stationary field trial without fertilization. For this purpose agrochemical investigations were carried out in the 48-year-old stationary fertilizer trial maintained at the Institute of Agriculture, Karnobat, Bulgaria on Pellic Vertisol (FAO). The analyzed soil samples were taken from the 0-100 cm horizon of the stationary trial and from soil not subjected to anthropogenic influence (under forest vegetation and from virgin land). The total humus content was determined and the humus reserves and humus energy were calculated. It was found that the leached Pellic Vertisol subjected to long-term land use without introduction of fertilizers had humus content two times lower than the content in soil where natural soil formation processes occurred without anthropogenic influence (under forest vegetation and on virgin land). At 48-year growing of field crops without fertilization, humus content in the 40 cm soil horizon decreased with 5-7 relative percent. In the 40-100 cm horizon significant changes did not occur. High correlation was determined between the total humus reserves and the yield from the field crops (R from + 0.668 to + 0.724)

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New data about Agaricus (Section Minores, Agaricaceae) in Bulgaria

M. Lacheva*, Tz. Radoukova
Department of Botany and Agrometeorology, Faculty of Agronomy, Agricultural University, 12 Mendeleev, 4000 Plovdiv, Bulgaria
Abstract. Fungal specimens were collected in different floristic regions of Bulgaria during 2007 and 2012. According to the results, new data about Agaricus section Minores in Bulgaria are presented. The seven Agaricus species were registered in different floristic regions of the country. As a result of field and laboratory studies, 7 taxa belonging to Agaricus section Minores were identified. Of the species identified, Agaricus luteomaculatus (Møller) Møller, A. niveolutescens Huijsman, Agaricus porphyrizon P.D. Orton, and A. purpurellus (Møller) Møller are rare for European fungus biota. All taxa are presented with brief chorological data and notes on their distribution. Macroscopic images of some of the typical and rare species are presented. A dichotomous key for the determination of members is also included.

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Theoretical model of biogas production from cattle slurry with different additive of maize silage

K. Peychev*, R. Georgiev
Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
Abstract. A theoretical analysis of the impact of maize silage (in milky wax maturity) added as a co-ferment in slurry biomass for biogas production was conducted. Several alternative cattle slurry to maize silage ratios were studied. Regression equations were derived to determine how biogas production and potential energy rating (for cogeneration modules) vary in biomass with different relative content of maize silage. The addition of maize silage in the form of coferments in the slurry biomass has a positive impact on the biogas production and its relevant energy parameters (total structural heat and electric power). The methodology can be used in the practice to estimate the energy potential of slurry biomass in combination with a certain amount of maize silage The findings of the analysis are of purely practical nature for good practices in biogas production in Bulgaria.

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Growth and fruiting of the apple variety Braeburn 7926 grafted on M9 Pajam2 and MM106

G. Dobrevska*
Department of Fruit-Growing, Faculty of Viticulture and Horticulture, Agricultural University Plovdiv, 12 Mendeleev, 4000 Plovdiv, Bulgaria
Abstract. The growth and reproductive characteristics of the apple variety Braeburn 7926 grafted on two rootstocks with different growth potential – M9 Pajam2 and MM106 is studied. Both rootstocks induce growth manifestations on the variety which are in compliance with their commonly accepted characteristics in fruit growing – proven higher values of the cross – section area of the stem, as well as, in respect to the volume of the crown of the grafted variety are recorded in a combination with the semi – weakly growing rootstock MM106 in comparison to the weakly – growing M9 Pajam2. The combination Braeburn 7926/M9 Pajam2 is more productive during the first year of the observed period and this is due to the earlier fruitgrowing stage of the variety which is affected by the weakergrowing rootstock. The yields are slowly declining in the following years in comparison to the combination Braeburn 7926/MM106 because of the reflected smaller crowns volume affected by the weaker rootstock. The productivity coefficient shows higher values when rootstock M9 Pajam2 is used only during a part of the observed period. A higher planting density can be recommended when the weaker growing sort-rootstock combination is applied for a more rational usage of the vegetative area.

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Correlations between morphological and productive parameters in Burley tobacco

Y. Dyulgerski1, T. Radoukova2*

Abstract. The dependencies are investigated between important morphological and productive signs of Burley tobacco. Five important Burley tobacco varieties – Burley 1000, Burley 1317, Burley 21, Burley 420 and Pliskaare tested. Strong positive correlation between plant height and number of leaves is established. The number of leaves is positively correlated with yield but negatively with the size of the leaves. The size of the leaves is positively correlated with yield and percentage of classes. The length of the vegetative period is positively correlated with all studied morphological parameters and yield, but negatively with the percentage of first class. The increase in yield is related to the percentage of first class. The results obtained can be used successfully to optimize the selection process in Burley tobacco.

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