Ultrazvučna karakterizacija cementnih kompozita tijekom hidratacije

Ultrasonic measurements used to monitor the hydration of cement based materials are becoming an important tool in the quality assurance in production. Also, using these methods can be cost benefit for the construction companies because they can provide information about evolution of material properties in real time. In this paper ultrasonic testing is used to characterize a hydration process of cement paste. A technique is based on the system for measuring the ultrasonic pulse velocity (UPV). To obtain more information about wave propagation characteristics the technique of acoustic emission (AE) is also used. Entire waveform of the signal is recorded. AE parameters are extracted from the signal and used to characterize different processes in cement paste during hydration. An analysis is performed on cement pastes made with different water-cement ratios. Ultrasonic wave parameters are compared to the initial and final setting time using the Vicat needle test and compressive strength development.Korištenje ultrazvučnih mjerenja za praćenje hidratacije materijala na bazi cementa postaje važan alat osiguranja kvalitete u proizvodnji. Također, korištenje tih metoda može biti ekonomski isplativo za izvođačke tvrtke jer omogućavaju trenutno dobivanje informacija o razvoju svojstava materijala. U ovom radu ispitivanje ultrazvukom je primijenjeno za karakterizaciju procesa hidratacije cementne paste. Metoda mjerenja temeljena je na sustavu za mjerenje brzine ultrazvučnog impulsa (UPV). Kako bi se dobilo više informacija o svojstvima širenja valova korištena je i metoda akustične emisije (AE). Cijeli valni zapis je sniman te su iz signala izračunati parametri akustične emisije koji su korišteni za karakterizaciju različitih procesa u cementnoj pasti tijekom hidratacije. Analiza je provedena na cementnim pastama izrađenim s različitim vodo-cementnim omjerima. Parametri ultrazvučnih valova uspoređeni su s početkom i krajem vezanja dobivenim Vicatovom iglom i razvojem tlačne čvrstoće

Ultrazvučna karakterizacija cementnih kompozita tijekom hidratacije

Ultrasonic measurements used to monitor the hydration of cement based materials are becoming an important tool in the quality assurance in production. Also, using these methods can be cost benefit for the construction companies because they can provide information about evolution of material properties in real time. In this paper ultrasonic testing is used to characterize a hydration process of cement paste. A technique is based on the system for measuring the ultrasonic pulse velocity (UPV). To obtain more information about wave propagation characteristics the technique of acoustic emission (AE) is also used. Entire waveform of the signal is recorded. AE parameters are extracted from the signal and used to characterize different processes in cement paste during hydration. An analysis is performed on cement pastes made with different water-cement ratios. Ultrasonic wave parameters are compared to the initial and final setting time using the Vicat needle test and compressive strength development.Korištenje ultrazvučnih mjerenja za praćenje hidratacije materijala na bazi cementa postaje važan alat osiguranja kvalitete u proizvodnji. Također, korištenje tih metoda može biti ekonomski isplativo za izvođačke tvrtke jer omogućavaju trenutno dobivanje informacija o razvoju svojstava materijala. U ovom radu ispitivanje ultrazvukom je primijenjeno za karakterizaciju procesa hidratacije cementne paste. Metoda mjerenja temeljena je na sustavu za mjerenje brzine ultrazvučnog impulsa (UPV). Kako bi se dobilo više informacija o svojstvima širenja valova korištena je i metoda akustične emisije (AE). Cijeli valni zapis je sniman te su iz signala izračunati parametri akustične emisije koji su korišteni za karakterizaciju različitih procesa u cementnoj pasti tijekom hidratacije. Analiza je provedena na cementnim pastama izrađenim s različitim vodo-cementnim omjerima. Parametri ultrazvučnih valova uspoređeni su s početkom i krajem vezanja dobivenim Vicatovom iglom i razvojem tlačne čvrstoće

PROPERTIES OF STEEL-POLYPROPILENE HYBRID FIBERS REINFORCED CONCRETE

This paper present the results of mechanical properties of hybrid reinforced concrete made by adding polypropylene and steel fibers into concrete mixture. For the testing purposes were used steel fibers with hooked ends and monofilament polypropylene fibers. The total of 5 batches of concrete were made: concrete with addition of steel fibers, polypropylene fibers and their combination in amount of 0,5 % of the concrete volume. The test results show that concretes made by adding of 0.4% steel and 0.1% polypropylene fibers have better performance compared to other concretes

Opetovani lipomatozni tumor hipofarinksa: prikaz slučaja i pregled literature

Liposarcoma is one of the most common soft-tissue sarcomas in adults, but head and neck are rarely involved, especially regions of the larynx and hypopharynx. According to Enzinger and Weiss, liposarcoma can be divided into 5 subtypes: well-differentiated, myxoid, round cell, pleomorphic and dedifferentiated. We present an unusual case of well-differentiated liposarcoma of the hypopharynx in a patient with previous three procedures of endoscopic removal of hypopharyngeal tumor classified as benign lipoma. Well-differentiated liposarcoma is a tumor of low-grade malignancy, which frequently recurs locally, but does not metastasize. Wide tumor resection with free margins is mandatory. Immunohistochemistry is a useful diagnostic tool. We also discuss recently published literature on this unusual presentation of well-differentiated liposarcoma.Liposarkom je jedan od najčešćih mekotkivnih sarkoma u odrasloj dobi. Usprkos tome, zahvaćenost glave i vrata je rijetka, osobito u regijama larinksa i hipofarinksa. Prema Enzingeru i Weissu, liposarkom se može podijeliti u 5 podtipova: dobro diferenciran, miksoidni (miješani), tumor kružnih stanica, pleomorfni i nediferencirani. Mi predstavljamo neobičan slučaj bolesnika s dobro diferenciranim liposarkomom u hipofarinksu, koji je prije bio tri puta endoskopski operiran, a svaki je put odstranjeni tumor bio dijagnosticiran kao benigni lipom. Dobro diferencirani liposarkom je tumor niskog malignog potencijala, koji često nakon toga opetovano raste, ali ne daje metastaze. Široka resekcija tumora sa slobodnim rubovima je metoda prvoga izbora. Imunohistokemijska analiza je od osobitog dijagnostičkog značenja. Također, u radu se raspravlja o podacima iz novije literature glede neobičnih prikaza dobro diferenciranih liposarkoma hipofarinksa

Kontaminacija toksigenim vrstama gljiva i njihovim mikotoksinima uzoraka kukuruza iz različitih regiona u Srbiji

This study was carried out in order to investigate the natural occurrence of toxigenic fungi and levels of zearalenone (ZEA), deoxynivalenol (DON) and aflatoxin B1 (AFB1) in the maize stored immediately after harvesting in 2016 and used for animal feed in Serbia. A total of 22 maize samples were collected from four different districts across the country: City of Belgrade (nine samples), Šumadija (eight samples), Podunavlje (four samples) and Kolubara (one sample). Toxigenic fungi were identified according to the morphological characteristics whereas the mycotoxins contamination were detected using biochemistry enzyme-linked immuno-sorbent (ELISA) assay. The tested samples were mostly infected with Aspergillus, Fusarium and Penicillium spp., except that one sample originated from Kolubara was not contaminated with Aspergillus species. Fusarium graminearum was the most common species in the maize sample from Kolubara district (60%), F. verticillioides in the maize samples from Podunavlje (43.75%) and City of Belgrade (22.4%) districts, and Penicillium spp. in the maize samples from Šumadija district (26.38%). In the analysed maize samples the presence of Aspergillus species was low (0-1.78%). Mycotoxicological analysis revealed the presence of zearalenone (ZEA), deoxynivalenol (DON) and aflatoxin B1 (AFB1) in all the investigated samples, except that DON and AFB1 were not recorded in the samples from Podunavlje and Kolubara districts, respectively. The investigated samples were highly contaminated with ZEA, with incidence of 100% for the samples from Šumadija, Podunavlje and Kolubara districts and 88.89% for the samples from City of Belgrade district. In addition, the samples contamination with DON was 100% and 22.2% for the samples from Šumadija, Kolubara and City of Belgrade, districts, respectively. The highest number of AFB1 positive samples was found in Šumadija district (87.5%), while in the City of Belgrade and Podunavlje districts, 55.56% and 50% AFB1 positive samples were established, respectively. Generally, remarkable infection of all the tested samples with toxigenic fungal species from Aspergillus, Fusarium and Penicillium genera were recorded. In addition, high contamination with mycotoxins ZEA, DON and AFB1 were also recorded; nevertheless, only in one sample the level of DON exceeded the allowed legal limit (1750 μg kg-1 ) according to Regulation for unprocessed maize. Therefore, permanent mycological and mycotoxicological analyses of maize grain are necessary for risk assessment of fungal and mycotoxin contamination throughout the food chain.Ispitivanja u ovom radu izvedena su s ciljem da se odredi prirodna pojava potencijalno toksigenih gljiva iz rodova Aspergillus, Fusarium i Penicillium i sadržaj mikotoksina zearalenona (ZEA), deoksinivalenola (DON) i aflatoksina B1 (AFB1) u kukuruzu uskladištenom neposredno posle berbe u 2016. godini i korišćenom za ishranu životinja. Ukupno 22 uzoraka zrna kukuruza sakupljeni su iz četiri regiona u Srbiji: Beogradski (devet uzoraka), Šumadijski (osam uzoraka), Podunavski (četiri uzorka) i Kolubarski (jedan uzorak). Toksigene vrste gljiva su identifikovane na osnovu morfoloških osobina, a sadržaj mikotoksina određen je pomoću biohemijske, imunoadsorpcione enzimske metode (ELISA). Ispitivani uzorci kukuruza većinom su bili inficirani sa Aspergillus, Fusarium i Penicillium spp., izuzev što u uzorku iz Kolubarskog regiona nisu bile identifikovane Aspergillus vrste. Fusarium graminearum bila je najučestalija vrsta u uzorku kukuruza iz Kolubarskog regiona (60%), F. verticillioides u uzorcima iz Podunavskog (43,75%) i Beogradskog regiona (22,4%) i Penicillium spp. u uzorcima iz Šumadijskog regiona (26,38%). U ispitivanim uzorcima kukuruza zastupljenost Aspergillus vrsta bila je niska (0-1,78%). Mikotoksikološkim analizama ustanovljeno je prisustvo zearalenona (ZEA), deoksinivalenola (DON) i aflatoksina B1 (AFB1) u svim ispitivanim uzorcima kukuruza, izuzev što DON nije detektovan u uzorcima iz Podunavskog a AFB1 u uzorku iz Kolubarskog regiona. Ispitivani uzorci su visoko kontaminirani sa ZEA, 100% uzoraka iz Šumadijskog, Podunavskog i Kolubarskog regiona i 88,89% uzoraka iz Beogradskog regiona. Isto tako, sa DON bilo je kontaminirano 100% uzoraka iz Šumadijskog i Kolubarskog regiona i 22,2% iz Beogradskog regiona. Najveći broj AFB1 pozitivnih uzoraka ustanovljen je u Šumadijskom regionu (87,5%), dok je u Beogradskom i Podunavskom regionu ustanovljeno 55,56% i 50% AFB1 pozitivnih uzoraka, respektivno. Uopšteno razmatrajući, u ovim analizama ustanovljena je visoka zastupljenost toksigenih vrsta u svim ispitivanim uzorcima kukuruza. Isto tako, ustanovljena je visoka kontaminiranost uzoraka sa mikotoksinima ZEA, DON i AFB1, iako je samo u jednom uzorku sadržaj DON premašio dozvoljeni limit (1750 μg kg-1 ) prema zakonskoj regulativi za neprerađeni kukuruz. Zbog toga, stalne mikološke i mikotoksikološke analize zrna kukuruza neophodne su radi ocene rizika od gljivične i mikotoksin kontaminacije u lancu ishrane

Uticaj vremena žetve na prinos i kvalitet silokrme kukuruza

Maize is the very important silage source in the world. Timely harvesting ensure high maize forage yield and quality. Therefore, the study focused on the effects of four harvesting times (starting at the 12 August every 7 days) on yield and qualitative parameters of forage green mass of maize hybrid ZP 677. The experiment was set in Vojvodina Province, Serbia, during the 2013 and 2014 growing seasons. Plant height, stem diameter, number of leaves per plant, ear percentage, forage yield, dry matter content and crude protein content were higher, while stem percentage was lower in 2014 with favorable climatic condition. Forage yield, crude protein content, ADF and NDF decreased, while dry matter content significantly increased with delay in harvesting. The maize hybrid should be harvested when the milk line is three-quarter of the way down the grain that is in the third decade of August.Kukuruz je veoma važan izvor silaže u svetu. Pravovremenom žetvom kukuruza obezbeđuje se visok prinos i kvalitet krme za silažu. Stoga je istraživanje fokusirano na uticaj četiri datuma žetve (počev od 12. avgusta svakih sedam dana) na prinos i kvalitativne parametre silokrme hibrida kukuruza ZP 677. Eksperiment je postavljen u Vojvodini, u Srbiji, tokom 2013. i 2014. godine. Visina biljke, prečnik stabla, broj listova po biljci, udeo stabla, prinos krme, sadržaj suve materije i sadržaj sirovih proteina bili su veći, dok je udeo stabla bio manji u 2014. godini sa povoljnim klimatskim uslovima. Prinos krme, sadržaj sirovih proteina, ADF i NDF su se smanjivali, dok se sadržaj suve materije povećavao sa kašnjenjem u žetvi. Hibrid kukuruza za krmu treba sakupljati kada je mlečna linija tri četvrtine visine zrna što je u trećoj dekadi avgusta

Čimbenici rizika za infekciju kirurškog mjesta u operacijama karcinoma grkljana

Surgical site infection (SSI) is a significant factor of morbidity and mortality in patients surgically treated for laryngeal carcinoma. The aim of this prospective study in 277 patients was to determine the incidence of SSI in patients surgically treated for laryngeal squamous cell carcinoma and to identify risk factors for development of SSI. Patients with previous chemotherapy and/or radiotherapy were excluded. All patients had tracheostomy postoperatively and received antibiotic prophylaxis with cephalosporin, aminoglycoside and metronidazole. The overall incidence of SSIs in our cohort was 6.5% (18 patients): 4 (22.22%) patients with superficial infections, 11 (61.11%) with deep infections and 3 (16.66%) with organ-space infections. The remaining infections included pneumonia (1 case) and Clostridium difficile colitis (2 cases). The median hospital stay in patients having developed SSIs was longer than in those without SSIs (33.5 vs. 16 days, p<0.001). By using univariate analysis American Society of Anesthesiologists score ≥3, duration of surgery longer than 120 minutes and National Nosocomial Infections Surveillance risk index ≥1 were found to be significantly associated with the occurrence of SSI. Age, sex, body mass index, history of smoking, underlying diabetes and preoperative length of stay were found not to be associated with SSI. The most frequently isolated microorganism was Klebsiella spp.Infekcije kirurškog mjesta (IK M) predstavljaju značajan čimbenik za obolijevanje i smrtnost u bolesnika operiranih zbog karcinoma grkljana. Cilj ove prospektivne studije koja je obuhvatila 227 bolesnika bio je odrediti incidenciju IK M te utvrditi čimbenike rizika za njezin nastanak. Studija je isključila bolesnike s prethodnom radio- i/ili kemoterapijom. Svi su bolesnici imali poslijeoperacijsku traheostomu, a primali su antibiotičku profilaksu koja je sadržavala cefalosporin, aminoglikozid i metronidazol. Uočeno je da je srednja incidencija IK M 6,5% (18 bolesnika), uz 4 (22,22%) slučaja s površinskom incizijskom infekcijom, 11 (66,22%) s dubokom incizijskom infekcijom i 3 (16,66%) s infekcijom organa ili prostora. Ostale infekcije su bile upala pluća (1 bolesnik) i kolitis prouzročen bakterijom Clostridium difficile (2 bolesnika). Srednje trajanje bolničkog liječenja u bolesnika kod kojih se razvila IK M bilo je dulje od onih bez IK M (33,5 dana prema 16 dana; p<0,001). Koristeći univarijatnu analizu nađeno je da su ASA skor ≥3 Američke udruge anesteziologa, kirurška intervencija dulja od 120 minuta i NNI S (Nacionalno praćenje nozokomijalnih infekcija) indeks rizika ≥1 značajno udruženi s pojavom IK M. Godine, spol, tjelesna masa, pušenje, dijabetes, duljina prijeoperacijskog boravka u bolnici nisu povezani s IK M. Najčešće izolirani mikroorganizam je bila Klebsiella spp

Influence of tannins on protein quality in ruminant nutrition

Tanini predstavljaju heterogenu grupu polifenolnih jedinjenja koji se odlikuju sposobnošću taloženja proteina, polisaharida i minerala. To su fenolna sekundarna jedinjenja biljaka koja se većinom (preko 80%) nalaze u drvenastim višegodišnjim dikotiledonim biljkama i manjim delom (oko 15%) u jednogodišnjim i zeljastim višegodišnjim dikotiledonim biljkama, ali su prisutni i u hranivima, ljudskoj hrani i nekim pićima (vinu na primer) i predstavljaju četvrtu najbrojniju grupu jedinjenja u vezikularnom tkivu, posle celuloze, hemiceluloze i lignina. Tanini se sastoje od 12 do 16 fenolnih grupa i 5-7 aromatičnih prstenova. Nalaze se u gotovo svim delovima biljke: u semenu, plodu, listu, stablu, kori i korenu, i njihova primarna funkcija je zaštita biljke protiv patogena, insekata, štetočina i biljojeda. Iako postoji nekoliko klasifikacija, glavna podela tanina je na kondenzovane i tanine podložne hidrolizi. Tanini se odlikuju astrigentnošću, oporim ukusom i dugo su smatrani isključivo antinutritivnim materijama koje dovode do brojnih smetnji i zdravstvenih problema životinja. Od 80ih godina XX veka počinje da se ispituje njihov pozitivan uticaj na životinje. Biljke mogu da sadrže i do 20% tanina u suvoj materiji. Sadržaj tanina zavisi od biljne vrste, fenofaze, a menja se i u skladu sa uslovima okoline. Najčešće ispitivane krmne kulture koje sadrže tanine su: žuti zvezdan (Lotus corniculatus) sa sadržajem tanina 20-40 g/kg suve materije, zatim esparzeta (Onobrichis vicifolia) sa 5-22 mg/g zelenog lista, hmelj (Humulus sp.), cikorija (Chicorium intybus), ajčica (Coronilla varia), čič (Astragalus cicer), sula (Hedysarum coronarium), karob (Ceratonia siliqua) i druge. Zadnjih godina sve više se u ishrani preživara koriste ekstrakti tanina dobijeni od drvenastih vrsta, pre svega hrasta (Quercus sp) i kestena (Castanea sp) koji u zavisnosti od proizvođača sadrže oko 70% tanina. Proteini su najskuplja komponenta hrane za životinje i teži se njihovom boljem iskorišćavanju. U ishrani preživara, usled buražne fermentacije dolazi do određenih gubitaka proteina. Iz tog razloga se teži povećanju sadržaja proteina u hrani za preživare koji izbegavaju buražnu fermentaciju (tzv. „by-pass“ proteini). Tanini sa proteinima u uslovima neutralne sredine (kakva je u buragu) stvaraju nerastvorljive komplekse, dok u kiseloj sredini (kakva je u tankim crevima) dolazi do razgradnje ovih kompleksa. Zahvaljujući ovim osobinama tanina, može se uticati na povećanje sadržaja „by-pass“ proteina u ishrani preživara i time optimalnije normirati obroci. Reaktivnost tanina zavisi od njihovog izvora, oblika, koncentracije, pH vrednosti sredine, vrste proteina sa kojima reaguju i drugih faktora. Usled korišćenja tanina može doći do optimalnijeg iskorišćavanja proteina što dalje može da vodi ka poboljšanoj produktivnosti životinja (veći prirasti, povoljnija konverzija hrane, veći prinosi) kao i do promena masnokiselinskog sastava mesa i mleka usled izmenjene buražne fermentacije. Takođe, primećeno je da tanini povećavaju otpornost preživara na crevne parazite, poboljšavaju antioksidativna svojstva i doprinose boljem zdravstvenom stanju životinja. S druge strane, ukoliko su koncentracije tanina u hrani za životinje previsoke, mogu se ispoljiti negativni efekti, od kojih su neki: niska konzumacija hrane usled neprijatnog (oporog) ukusa, smanjena svarljivost vlakana i šećera, niži prirasti, različiti oblici intoksikacija životinja i drugo. Takođe, tanini pored proteina mogu reagovati i sa enzimima, kao i sa neproteinskim organskim azotnim jedinjenjima. Upotreba tanina u ishrani preživara je veoma aktuelna. Ipak, potrebno je obaviti još istraživanja kako bi se odredile optimalne koncentracije različitih vrsta tanina iz različitih izvora i u potpunosti razumela njihova uloga, svarljivost i reaktivnost u organizmu životinja.Tannins represent a heterogeneous group of polyphenolic compounds that are characterized by the ability to precipitate proteins, polysaccharides and minerals. These are phenolic secondary compounds of plants that are mostly (over 80%) found in woody perennial dichotyledonous plants and a smaller part (around 15%) in annual and perennial dicotyledon plants, but also present in nutrients, human food and some drinks (wine on example) and represent the fourth largest group of compounds in the vesicular tissue, after cellulose, hemicellulose and lignin. Tannins consist of 12 to 16 phenolic groups and 5-7 aromatic rings. They are found in almost all parts of the plant: in the seeds, fruits, leaves, trees, roots and roots, and their primary function is to protect the plant against pathogens, insects, pests and herbivores. Although there are several classifications, the main division of tannin is on condensed and hydrolisable tannins. Tannins are characterized by astringency, resistance to taste and have long been considered only antinutritive substances that lead to numerous disorders and animal health problems. From the 80s of the 20th century, their positive impact on animals is examined. Plants can contain up to 20% tannin in dry matter. The content of tannin depends on the plant species, phenophase, and changes in accordance with environmental conditions. The most commonly studied fodder cultures containing tannins are: Birdsfoot trefoil (Lotus corniculatus) with tannin content of 20-40 g / kg of dry matter, then Sainfoin (Onobrichis vicifolia) with 5-22 mg / g green leaf, hops (Humulus sp.), chicory (Chicorium intybus), Coronilla varia, Astragalus cicer, sulla (Hedysarum coronarium), Ceratonia siliqua and others. In recent years, tannin extracts of woody species, primarily oak (Quercus sp) and chestnuts (Castanea sp), are used in ruminant nutrition, which, depending on the producer, contain about 70% tannin. Proteins are the most expensive component of animal feed and are striving for better use. In the feed of ruminants, due to sterile fermentation, certain protein losses occur. For this reason, it seeks to increase the content of proteins in food for the ruminants that avoids fermentation (the so-called "by-pass" protein). Tannins with proteins in the conditions of a neutral environment (such as in the rumen) create insoluble complexes, while in the acidic environment (such as in the small intestine) there is a degradation of these complexes. Thanks to these tannin properties, it may be possible to increase the content of by-pass proteins in ruminant nutrition and thus to better normalize the meals. Reactivity of tannin depends on their source, shape, concentration, pH of the environment, the types of proteins with which they react and other factors. Due to the use of tannins, optimum protein utilization can be achieved, which can lead to improved animal productivity (higher growth, better food conversion, higher yields), and changes in the fatty acid composition of meat and milk due to modified fermentation. It has also been observed that tannins increase the resistance of ruminants to intestinal parasites, improve antioxidant properties and contribute to a better health condition of animals. On the other hand, if tannin concentrations in animal feed are too high, negative effects can be observed, some of which are: low consumption of food due to unpleasant taste, reduced digestibility of fibers and sugar, lower growth, different forms of animal intoxication and other . Also, tannins besides protein can also react with enzymes, as well as with non-protein organic nitrogen compounds. The use of tannin in ruminant nutrition is very actual. However, more research is needed to determine the optimum concentrations of various tannins from different sources and fully understand their role, digestibility and reactivity in the animal's organism

Determining elastic modulus of the material by measuring the deflection of the beam loaded in bending

U radu je dan teorijski model i projektno rješenje uređaja za određivanje modula elastičnosti na osnovi savijanja, a ne istezanja materijala (ispitnih uzoraka) kao što je uobičajeno. Uređaj je projektiran, realiziran i uspješno testiran u laboratoriju. Provedeno je eksperimentaln o određivanje modula elastičnosti mjerenjem vrijednosti progiba ispitivanih uzoraka materijala pri konstantnom opterećenju. Na bazi teorijskih ovisnosti, dolazi se do vrijednosti modula elastičnosti. Provedeno je mjerenje i analizirane su greške mjerenja, odnosno uređaja.The paper presents a theoretical model and design solution for the device which determines the modulus of elasticity by bending the material (test samples), instead of the usual stretching. The device was designed, assembled and successfully tested in the laboratory. Experimental determination of the elastic modulus was conducted by measuring the deflection of samples under a constant load. Values of the elastic modulus resulted from theoretical relations. Measurement was performed and measurement errors, i.e. device errors, were analysed

Harvest time effect on quantitative and qualitative parameters of forage maize

Maize silage is source of palatable and high-energy forage for ruminants. Therefore, production of high quality forage maize represents an essential strategy for stable production of milk and meat on livestock farms. This study examined the effect of harvest date (early dent, at half milk line, at three quarters milk line and black layer) on the quantitative and qualitative parameters of whole maize plant under contrasting climatic conditions in the Srem - Serbia. A 2 × 4 factorial (two years and the four cutting times) randomized blocks design was used, with three replications. The plant height, stem diameter, number of leaves per plant, forage yield, dry matter yield and dry matter content were higher in 2014 probably due to favorable weather conditions. With the delay of the harvest the forage yield, crude protein content, acid detergent fiber (ADF) and neutral detergent fiber (NDF) decreased, and dry matter yield, dry matter content and ear percentage increased. Sufficiently high dry matter content and ear percentage were achieved at the third harvest. However, the delay of harvested time reduces the quality parameters of the biomass, but this loss in the entire plant is moderated by grain filling