Synthesis and characterization of Cu-ZrB2 alloy produced by PM techniques

The copper alloy with 7vol.% ZrB2 examined in this study was consolidated via powder metallurgy processing (PM) by combining mechanical alloying and hot pressing process. Structural changes, morphological properties and elemental analysis of the hotpressed samples were studied as a function of milling time with the use of X-ray diffraction, scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometry (EDS). Also, mechanical properties of the Cu-7vol.%ZrB2 alloy was investigated. Distribution of ZrB2 particles and presence of agglomerates in the Cu matrix directly depend on the milling time and show strong influence on hardness, compressive and electrical properties of Cu-ZrB2 alloys. [Projekat Ministarstva nauke Republike Srbije, br. 172005

Theoretical and Experimental Aspects of Electrode Reactions with Coupled Homogeneous Redox Reactions: D. C. and A. C. Polarography

We present here a survey of theoretical and experimental studies performed in our: laboratories, which deal with influences of homogeneous redox reactions in d. c. and a. c. polarography, with primary emphasis on the latter. These jnvestigations date back to the early 1960\u27s when effects of the catalytic mechanism on a. c. polarography were examined. However, the main thrust in this direction occurred in the past four years when theoretical strategies for handling second order homogeneous reactions coupled to heterogeneous electron transfer were perfected. This development permHted a focused theo,retical effort on this topic which encompassed a variety of mechani:srtic schemes, such as those involving disproportLonatiOl! l, and »nuances« of the consecutive and parallel ECE mechanisms. Experimental results obtained to date satisfactorily support predictiOIIls of the theoretical rate Jaws. One concludes from our studies and parallel efforts in other laboratories that kinetic characteristics of homogeneous redox reactions can substantially influence rthe polarographic observables under many circumstances. The COl!lclusicm follows that kinetic characteristics of homogeneous redox reactions are more broadly access1ble via polarographic, and other electrochemical relaxation techniques than previously thought. Also, proper care must be taken to account for, or show negligibility of, homogeneous redox reaction effects in studies whose attention is centered on the heterogeneous processes or on multi-component analysis

Features of the new breed of sheep in serbia called mis sheep 2. fattening and meat characteristics of lambs

In this paper, the results of fattening and meat characteristics of lambs of the new breed of sheep in Serbia, called Mis sheep, are presented. Mis breed as a meaty type of sheep, has been developed for the past 20 years at the Institute of Animal Husbandry, Belgrade-Zemun. The total and daily gains in 1-30 days were of 7.5 kg and 250 g, and in 61-90 days the growth dynamics was even higher by 60% with the total gain of over 12 kg; the daily value exceeded 400 g. Food consumption, calculated in units of energy, was about 13.5 MJ with a slightly larger share of concentrate in the mass of gain of lambs. The dressing percentage of lambs at the age of three months was about 59%. In addition, the highest percentage of carcass meat was of the first category, followed by the meat of the second category and the lowest representation of the third category of meat. Muscle tissue had an absolute advantage over the other tissues and accounted for over 57%, followed by fat, bone and connective tissue, which accounted for the remaining 43% of the weight of three rib pattern. Mis sheep population, similar to the known foreign meat breeds, has a little more fat, which influences the better technological and sensory properties

Važniji faktori koji utiču na plodnost kod ovaca

Efficiency of sheep production is conditioned by fertility. According to some authors number of offspring obtained per lambing is more important than gain of weight. Genetic relationships involving reproductive traits were seldom studied. Reproductive traits have low heritabilities, a discrete phenotypic expression, and are expressed only in sexually mature ewes leading to low selection intensities and long generation intervals. Documentation of realized selection response is also often complicated by the low heritabilities of fertility traits. Existence of a major gene affecting prolificacy had been suggested and at that time there were many sceptics who strongly doubted that a trait as complex as reproduction could be profoundly influenced by a single gene. Major genes affecting prolificacy in sheep was founded. A mutation in the bone morphogenetic protein 15 gene (BMP15, also known as GDF9B) responsible for high prolificacy in Inverdale sheep had been discovered and evidence of segregating major genes was being reported from flocks around the world. Development of gene mapping techniques, and locating alleles that are responsible for the fertility of sheep began a new chapter in predicting and controlling the fertility of sheep. The beneficial effects of nutrition on reproduction in sheep are well known. This procedure is known as flushing. The effect of Body Condition Score (BCS), before mating, during mating and after mating period, on reproductive efficiency of different breeds of sheep in the different rearing systems were studied. The farm manager has the ability to control or at least to manipulate the factors that have an impact on fertility.Efikasnost proizvodnje ovaca je uslovljena plodnošću. Prema nekim autorima broja potomaka dobijenih po jagnjenju je važnije od prirasta i mase tela. Genetski uticaji koji uključuju reproduktivne osobine se retko izučavaju. Plodnost ovaca ima nizak heritabilitiet, diskretnu fenotipsku ekspresiju, a izražena je samo u seksualno zrelih ovaca, što dovodi do niskog intenziteta selekcije i dugih generacijskih intervala. Otkriće major gena koji utiču na plodnost je u to vreme otkrilo mnogo skeptika koji su snažno sumnjali da takav kompleks reprodukcije može biti duboko pod uticajem jednog gena. Glavne geni utiču na plodnost kod ovaca i ovnova. Mutacija u koštanoj morfogenetsko proteina 15 gena (BMP15, takođe poznatom kao GDF9B) otkrivena je kod mnogih ovaca širom sveta, kao dokaz segregacije major gena. Razvojem tehnika mapiranja gena i lociranja alela koji su odgovorni za plodnost ovaca, počelo je novo poglavlje u predviđanju i kontrolisanju plodnosti ovaca. Povoljni efekti ishrane na reprodukciju u ovaca su dobro poznati. Ovaj postupak je poznat kao flushing, pred oplodnju. Uticaj kondicije tela (BCS), pred parenje, tokom parenja i posle parenja na reproduktivnu efikasnost različitih rasa ovaca u različitim podizanju sistema su takođe proučavali mnogi ovde pomenuti autori. Farmer putem menadžmenta ima mogućnost da kontroliše, ili bar da manipuliše faktorima koji imaju uticaj na plodnostovaca, a što je takođe predstavljeno u ovom preglednom radu

Genetički i fenotipski aspekti osobina telesnih mera Merinolandschaf rase ovaca

Merinolandschaf sheep breed was used to estimate relationship between the next traits: Body weight of adult ewes (BW), Height to withers (HW), Body length (BL), Girth of Chest (GC), Rump Width (RW), Body weight of lambs at birth (BWB), Body weight of lambs at weaning (BWW). The collected data were from 750 sheep and their lambs during the period of three year. Estimates of means and standard errors for linear body measures and body weight of adult ewes and lambs, were obtained using the software program SPSS (2006). To estimate genetic and phenotypic correlations of observed traits, the ASREML program was used. Research has shown that genetic correlations between BW and all body measures of dams, ranging from 0.728 (BW-GC) to 0.976 (BW-HW). Genetic correlation between body measures of dams have also been positive and ranged in the interval from 0.873 (HW-GC) to 0.999 (BL-GC). Values for phenotypic correlations were lower compared with the genetic and the range varied from 0.183 (RW-BWB) to 0.421 (GC-BWW). The weaker phenotype correlations can be interpreted as play of more complex genetic and residual factors.Merinolandschaf ovce su korišćene za procenu odnosa između sledećih osobina: Telesna masa odraslih ovaca (BW), visina grebena (HW), dužina tela (BL), obim grudi (GC), širina karlice (RW), telesna masa jagnjadi na rođenju (BWB) Telesna masa jagnjadi pri odlucivanju (BWW). Prikupljeni podaci potiču od 750 ovaca i njihove jagnjadi tokom perioda od tri godine. Procene sredina i standardnih grešaka za linearne telesne mere i telesne mase odraslih ovaca i jagnjadi, genetske i fenotipske korelacije, dobijeni su korišćenjem softvera SPSS (2006). Istraživanja su pokazala da genetske korelacije između BW i svim ostalim telesnim merama variraju, u rasponu od 0.728 (BW-GC) do 0.976 (BW-HW). Genetski korelacija između telesnih mera varirale su u pozitivnom opsegu od 0.873 (HW-GC) do 0.999 (BL-GC). Vrednosti fenotipskih korelacija bile su niže u poređenju sa genetskim u intervalu variranja od 0.183 (RW-BWB) do 0.421 (GC- BWW). Slabije fenotipske korelacije možemo tumačiti kao igru složenijih genetskih faktora i nedeterminisanih efekata

Uticaj genetskih i faktora životne sredine na fenotipske karakteristike jagnjadi

The aim of this study was to determine the influence of environmental factors affecting body weight variability of lambs in two crossbreed groups: Pirot x Württemberg and Sjenica x Württemberg. Both populations were managed under the same farm conditions. The data were analyzed to determine the effect of age of the dam, weight of dam, birth type, sex, year and season, on the birth weight and weaning weight of crossbreed lambs. Statistical analysis was performed by GLM procedure using the SPSS statistical package program. The average birth weight of Pirot x Württemberg lambs was 3.56 kg while Sjenica x Württemberg lambs was slightly higher at 3.69 kg. The difference on birth weight between the two crosses was not statistically significant (P>0.05). The average weaning weight of Pirot x Württemberg lambs was 23.54 kg while Sjenica x Württemberg lambs had higher weight at 24.37 kg. The difference of 0.83 kg on weaning weight was statistically significant (P (lt) 0.05). Body weight, depending on the environmental factors, ranged from 3.17 to 3.96 kg at birth and from 22.12 to 24.18 kg at weaning in Pirot x Württemberg lambs. Body weight of Sjenica x Württemberg lambs ranged from 3.39 to 3.99 kg at birth and from 22.69 to 25.44 kg at weaning. Statistical analysis showed that the differences were statistically significant (P (lt) 0.05) and highly significant (P (lt) 0.01).Cilj ovog istraživanja je bio da se utvrdi uticaj faktora životne sredine na varijabilnost telesne težine jagnjadi u dve grupe meleza: pirotska x virtemberg I sjenička x virtemberg. Obe populacije su držane pod istim uslovima na farmi. Podaci su analizirani da se utvrdi uticaj starosti majke, njene težine, tipa rođenja, pola, godine i sezone, na težinu na rođenju i odbijanju jagnjadi meleza. Statistička analiza je izvedena pomoću GLM procedure, koristeći SPSS statistički program paket. Prosečna telesna masa meleza pirotska x virtemberg je 3,56 kg, dok sjenička x virtemberg jagnjad bila nešto veća - 3,69 kg. Razlika u težini na rođenju između dve grupe meleza nije bila statistički značajna (P>0,05). Prosečna težina na odbijanju jagnjadi meleza pirotska x virtemberg je bila 23,54 kg, dok su jagnjad melezi sjenička x virtemberg imala veću težinu - 24,37 kg. Razlika težine na zalučenju od 0,83 kg je statistički značajna (P (lt) 0,05). Telesna masa, u zavisnosti od faktora sredine, kretala se u rasponu od 3,17 do 3,96 kg na rođenju i od 22,12 do 24,18 kg na odbijanju u jagnjadi pirotska x virtemberg. Telesna masa jagnjadi sjenička x virtemberg kretala se u rasponu od 3,39 do 3,99 kg na rođenju i od 22,69 do 25,44 kg na odbijanju. Statistička analiza pokazala je da su razlike statistički značajne (P (lt) 0,05) i visoko značajne (P (lt) 0,01)

Efekti dodavanja različitih oblika selena u obroke za tovnu jagnjad

The study included lambs of Mis population, divided into two groups (experimental and control) .All the animals fed with identical portions of meals consisted of alfalfa hay and fully concentrate mixtures. Meals are only different in the fact that the experimental group received organic selenium and contained 2000 mg of selenium / kg preparations, while the control group received inorganic selenium in the form of sodium selenite (Na2SeO3). Each animal consumed the same amount of selenium than 0.3 mg / kg of dry matter in the organic or inorganic form, which added in the mineral-vitamin premix. Diet of lambs has been ad libitum. The body weight of lambs in both (control and experimental groups), were balanced at 60 days (19.60 kg : 19.65 kg) and 100 days (31.06 kg : 32.88 kg). The result on average daily gain of the control and experimental groups were almost similar and there were no statistically significant differences (P> 0.05) in the measured values from 28 to 60 days (259.0 : 255.0 g), from the 60-100 days (286.0 : 330.0g), and on average from 28 to 100 days (274.0 : 297.0. g). Both treatment have no significant effect on lambs' performance (body weight and growth). The study results showed that the diet of lambs experimental group, based meal supplement organic selenium resulted in significantly higher concentration of Se in MLD, kidneys, liver and spleen, compared with the control group, which are consumed inorganic form of selenium. The differences between the Se content in MLD the experimental and control groups were on significance level P (lt) 0.05, while the differences in the content of Se in kidney, liver and spleen, the aforementioned treatments were statistically highly significant (P (lt) 0.01). So fattening lambs are better utilizing organic source of selenium, which is associated with better absorption of this element.Selen (Se) je esencijalni mikroelement za ljude i životinje i predstavlja centralnu strukturnu komponentu niza specifičnih enzima a pre svega glutation peroksidaze. Uglavnom potiče iz biljaka, koje iz zemljišta usvajaju selen u neorganskom obliku. Sadržaj Se u biljkama na našem području je nizak. Da bi se ublažile posledice nutritivnog deficita, neophodna je dopuna ovog elementa u obrocima za ishranu životinja. U tu svrhu se koriste organska i neorganska forma selena. Cilj ovog istraživanja je upoređivanje efekata različitih formi selena na proizvodne performanse i retenciju selena u tkivima tovne jagnjadi. Istraživanjem je bilo obuhvaćeno 30 jagnjadi Mis populacije, prosečnog uzrasta oko 28 dana, podeljenih u dve grupe. Grla su hranjena identičnim obrocima koji su se sastojali od sena lucerke i potpune smeše koncentrata. Obroci su se razlikovali u tome što je ogledna grupa dobijala organski selen koji je bio proizvod američke firme Alltech i sadržao je 2000 mg selena/kg preparata, dok je kontrolna grupa dobijala neorganski selen u obliku natrijumselenita (Na2SeO3). Svako grlo je konzumiralo identičnu količinu selena od 0.3mg/kg suve materije u organskom odnosno neorganskom obliku koji su dodavani u mineralnovitaminsku predsmešu. Rezultati ogleda su pokazali da su telesne mase jagnjadi kontrolne i ogledne grupe bile ujednačene, kako 60. dana (19.60 kg; 19.65 kg), tako i 100. dana (31.06 kg; 32.88 kg). Dnevni prirasti jagnjadi kontrolne i ogledne grupe su takođe bili slični i nije bilo statistički značajnih razlika (P>0.05) u vrednostima izmerenim od 28. do 60. dana (259.0 : 255.0g), od 60.-100. dana (286.0 : 330.0g), i prosečno od 28. do 100. dana (274.0 :297.0. g). Izvori selena nisu značajnije uticali na prosečno konzumiranje suve materije (0.695 : 0.680 kg), ukupnih proteina (134.0:130.0 g), OHJ (0.844:0.818), kao ni na konverziju hranljivih materija: suva materija (2.345: 2.481 kg); ukupan protein (452 :476 g), OHJ (2.847: 2.987 kg), u periodu od 28-100. dana ogleda. Ishrana jagnjadi ogledne grupe, obrokom na bazi suplementa organskog selena je rezultirala znatno većim koncentracijama Se u MLD, bubrezima, jetri i slezini, u poređenju sa grlima kontrolne grupe, koja su konzumirala neorgansku formu selena.Ustanovljene razlike između sadržaja Se u MLD jagnjadi ogledne i kontrolne grupe su na nivou značajnosti P (lt) 0.05, dok su razlike u sadržaju Se u bubrezima, jetri i slezini, na navedenim tretmanima, bile statistički veoma značajne (P (lt) 0.01). Dakle, tovna janjad su bolje iskoristila organski izvor selena, što se dovodi u vezu sa boljom apsorpcijom ovog element

Povezanost između mase tela pri rođenju i karakteristika porasta jagnjadi

Research was carried out in population of R2 generation Pirot pramenka x Pirot improved sheep during period of three years. Lambs were divided into three groups: I from 2.5 kg to 3.5 kg; II from 3.6 kg to 4.5 kg; III from 4.6 kg to 5.5 kg. Weight of lambs was controlled at birth, with 30, 60 and 90 days of age. Average body weight at birth of the tested lambs was 3.35 kg in the first group, 4.30 kg in the second group and 5.06 kg in the third group. At 30 days of age, the body weight of the lambs was 10.19 kg in the first group, 11.39 kg in the second and 12.49 kg in the third group. All these differences in body weight of lambs at birth were statistically highly significant (P¬ 0.01). With 60 days of age, average body weight was 16.48 kg in the first group, 19.01 kg in the second and 20.49 kg in the third group. Differences between groups of lambs at this age were statistically very significant (P¬0.01).On the end of experiment at 90 days of lambs age, we have found the following values of the body weight of lambs: 26.35 kg in the first group, when the second 30.49 kg and 28.93 kg in the third group. Differences between groups of lambs at this age were statistically very significant (P¬0.01). At the age of 90 days maximum weight of the body was in the second group of lambs, or a group which body weight at birth occupied the mean of the population. Correlations between body weights of lambs vary from weak to midsized values. The highest values of correlation coefficients were found between body weight at birth and weight of lambs at 30 days of age.Istraživanja su sprovedena u populaciji R2 generacije Pirotska pramenka x Pirotska oplemenjena ovca tokom perioda od tri godine. Jagnjad su bila podeljeni u tri grupe: I od 2,5 kg do 3,5 kg; II od 3,6 kg do 4,5 kg; III od 4,6 kg do 5,5 kg. Masa jagnjadi je kontrolisana na rođenju, sa 30, 60 i 90 dana starosti. Prosečna telesna težina na rođenju testiranih jagnjadi bila je 3,35 kg u prvoj grupi, 4,30 kg u drugoj grupi i 5,06 kg u trećoj grupi . Sa 30 dana starosti ,telesna masa jagnjadi bila je 10,19 kg u prvoj grupi, 11,39 kg udrugoj i 12,49 kg u trećoj grupi. Sve ove razlike u telesnoj masi jagnjadi na rođenju su visoko statistički značajne (P¬0,01). Sa 60 dana starosti, prosečna telesna masa je bila 16,48 kg u prvoj grupi, 19,01 kg udrugoj i 20,49 kg u trećoj grupi. Razlike između grupa jagnjadi u ovom uzrastu su statistički vrlo značajne (P¬0,01). Na kraju eksperimenta sa 90 dana starosti, pronašli smo sledeće vrednosti telesne mase jagnjadi: 26.35 kg u prvoj grupi, 30,49 kg u drugoj grupi i 28,93 kg u trećoj grupi. Razlike između grupa jagnjadi u ovom uzrastu su statistički vrlo značajne (P¬0,01). U uzrastu od 90 dana maksimalna masa tela je registrovana u drugoj grupi jagnjadi, ili grupi čija telesna masa na rođenju zauzima srednju vrednost populacije. Korelacija između telesne mase jagnjadi variraju od slabe do srednje vrednosti. Najveće vrednosti koeficijenata korelacije su pronađene između telesne mase na rođenju i mase jagnjadi sa 30 dana starosti

Uticaj bioaktivnog dodatka Biorila na rezultate jagnjadi u tovu

Investigations were carried out in order to determine whether the addition of bioactive substances 'Bioril' on different percentages in concentrate (0.3% and 0.6%), has an impact on weight gain and feed conversion in lambs. For the experiment were used lambs of Mis sheep breed, which at the beginning of the experiment were 50 days of age. The experiment lasted 42 days, so it is over when all lambs had 92 days of age. The experiment included 60 lambs (30 male and 30 female) were divided into three groups-20 lambs per group (control group I and II and III experimental groups ).The results shows that the greatest gains made lambs of group III. The difference between body weight of group I and II was 1.62 kg and was statistically significant (P (lt) 0.01). The difference between body weight of I and III group was 1.87 kg and was also statistically significant (P (lt) 0.01). The difference between the body weight of II and III groups was 0.25 kg and was not statistically significant (P>0.05). We find that lambs of all groups consumed per kg of gain more concentrated than hay. The difference in feed conversion between groups is not significant (P>0.05), but lambs of groups III and II consumed per unit of gain approximately 5g/kg and 10g/kg less concentrate than lambs of group I. Most hay consumed by lambs of group I. The difference in hay consumption between groups I and II is 20 g/kg. Lambs in group III consumed 30 g/kg which was less hay than group I and less 10 g/kg than lambs of group II. The most energy per kg of gain was consumed by lambs of group III, whereas lambs in II group consumed the least energy.Istraživanja su sprovedena kako bi se utvrdilo da li dodavanje bioaktivne supstance 'Bioril' u različitim procentima u koncentratu (0,3% i 0,6%), ima uticaj na prirast i konverziju hrane u jagnjadi. Za eksperiment su korišćena jagnjad od ovaca rase Mis, koja su na početku eksperimenta bila 50 dana starosti. Eksperiment je trajao 42 dana, tako da je završen kada su jagnjad imala 92 dana starosti. U eksperiment je uključeno 60 jagnjadi (30 muškog i 30 ženskog pola). Jagnjad su podeljena u tri grupe-20 jagnjadi po grupi (kontrolna grupa I i II i III eksperimentalne grupe). Rezultati pokazuju da su ostvareni najveći dnevni prirasti kod jagnjadi II eksperimentalne grupe. Razlika između telesne mase grupe I i II je 1.62 kg i bila je statistički značajna (P (lt) 0,01). Razlika između telesne mase I i III grupe je bila 1,87 kg i takođe je bila statistički značajna (P (lt) 0,01). Razlika između telesne mase II i III grupe je bila 0,25 kg i nije bila statistički značajna (P>0,05). Smatramo da je jagnjad svih grupa konzumirala po kg prirasta više koncentrata nego sena. Razlika u konverziji hrane između grupa nije značajna (P>0,05), ali jagnjad grupe III i II troši po jedinici prirasta oko 5g/kg i 10g/kg manje koncentrata nego jagnjad grupe I. Više sena troše jagnjad iz I grupe. Razlika u potrošnji sena između grupa I i II je 20g /kg. Najviše energije po kg prirasta troši jagnjad iz III grupe, dok jagnjad iz II grupe troši najmanje energije