The line graph associated to the total graph of a commutative ring

Let R be a commutative ring with identity and T(Gamma(R)) its total graph. The subject of this article is the investigation of the properties of the corresponding line graph L(T(Gamma(R))). The classification of all commutative rings whose line graphs are planar or toroidal is given. It is shown that for every integer g >= 0 there are only finitely many commutative rings such that gamma(L(T(Gamma(R)))) = g

On the radius and the relation between the total graph of a commutative ring and its extensions

We discuss the determination of the radius of the total graph of a commutative ring R in the case when this graph is connected. Typical extensions such as polynomial rings, formal power series, idealization of the R-module M and relations between the total graph of the ring R and its extensions are also dealt with

Principi razvoja stočarstva u Republici Srbiji

Livestock production is an important branch of agriculture in the Republic of Serbia because it provides necessary products (milk, meat, eggs). In addition, livestock production provides raw materials for food industry and leather industry. Livestock production is expected to provide quality products for export, primarily beef and lamb. There is an opportunity for export of cheese (especially sheep and goat milk cheese) with defined origin and standard of quality. However, based on available data, the situation in livestock production is assessed as negative. In the last years, number of heads of all species of domestic animals has decreased continuously. In several years, Serbia will become member of European Union (EU). This means that livestock production should prepare for competition in the single developed market, without any state trade barriers. Serbia's membership in international organizations, liberalization of trade in livestock products, a small possibility of protection from imports, the implementation of quality standards (HACCP, ISO, Global GAP), reduced levels of domestic support, elimination of export subsidies, increase profitability and ability to be competitive on the international market. Based on these circumstances, it is necessary to build efficient livestock production that can compete in the European market contributing to the growth of farmers and national income.Stočarska proizvodnja je važna grana poljoprivrede u Republici Srbiji i posmatrani istorijski, oduvek je igrala vodeću ulogu u održanju egzistencije stanovništva. Stočarstvo pruža neophodne proizvode (mleko, meso, jaja), a takođe obezbeđuje sirovine za prehrambenu industriju i industriju kože. Od stočarske proizvodnje se takođe očekuje da obezbedi kvalitetne proizvode za izvoz, pre svega govedine i jagnjetine. Priliku za izvoz imaju sir (posebno od ovčijeg i kozjeg mleka), sa definisanim poreklom i standardom kvaliteta. Međutim, na osnovu raspoloživih podataka, situacija u stočarstvu se ocenjuje kao negativna. U poslednjih nekoliko godina broj grla svih vrsta domaćih životinja kontinuirano se smanjuje. Srbija je dobila kandidaturu za članstvo u Evropskoj uniji (EU). To znači da bi stočarska proizvodnja trebala da se pripremi za konkurenciju na jedinstvenom razvijenom tržištu, bez ikakvih državnih trgovinskih barijera. Članstvo Srbije u međunarodnim organizacijama, liberalizacija trgovine stočarskih proizvoda, mala mogućnost zaštite od uvoza, implementacija standarda kvaliteta (HACCP, ISO, GLOBAL GAP), smanjeni nivo domaće podrške, eliminisanje izvoznih subvencija,rast profitabilnosti i sposobnost da budu konkurentna na međunarodnom tržištu, su još dodatni izazovi sa kojima se suočava ili će se suočiti stočarstvo Srbije. Na osnovu ovih okolnosti, neophodno je da se izgrade principi za efikasan razvoj stočarske proizvodnje, koja može da se takmiči na evropskom tržištu i doprinosi rastu poljoprivrede i nacionalnog dohotka

Uticaj metoda oplodnje genotipa, pola i tipa rođenja na porast jagnjadi

Estrus synchronization methods was use to control the reproductive traits of sheep, as well as bringing more females at the same stage of estrus and ovulation. According to the points mentioned above, the aim of the present study was to investigate and compare mating method and influence of fixed factors on birth and weaning weight of lambs. Statistical analysis showed that exist difference in the body weights between genotypes of lambs. In the first group, the difference in weight of lambs at birth, regardless of mating method was not significant (P> 0.05), while in the second group, the difference was slightly significant (P (lt) 0.05). As for the birth type, sex and within the same genotype, there was a statistical significance (P (lt) 0.05) between singles obtained naturally, between the triplets obtained naturally and between triplets received hormonal method. All the differences between body weight at 30 days (mating method, sex and birth type under the same genotype) were statistically significant (P (lt) 0.05).The determined differences in the body weights at 60 days (sex, mating method and type of birth under the same genotype) were statistically significant (P (lt) 0.05). The results showed that the differences (mating method, sex and type of birth under the same genotype) were statistically significant (P (lt) 0.05), except in between body weight at 90 days in twins among two genotypes obtained by natural method, which were not statistically significant (P> 0.05).Metod sinhronizacije estrusa se koristi da kontroliše reproduktivne osobine ovaca. Cilj ovog rada bio je da se ispita i uporedi način parenja i uticaj osnovnih fiksnih faktora na masu jagnjadi. Statistička analiza je pokazala da je razlika telesne mase između grupa jagnjadi na rođenju bila statistički značajna. U prvoj grupi, razlika u masi jagnjadi na rođenju, zavisno od načina oplodnje nije bila značajna (P> 0,05), dok je u drugoj grupi, razlika statistički značajna (P (lt) 0,05). Što se tiče tipa rođenja, a u okviru istog genotipa, postoji statistička značajnost (P (lt) 0,05) između jedinaca dobijenih prirodno, između prirodno dobijenih trojki i između trojke dobijenih hormonskim metodom. Sve razlike između masa tela muških grla sa 30 dana (načinu oplodnje, tipa rođenja i u okviru istog genotipa) su statistički značajne (P (lt) 0,05). Utvrđene razlike u telesnoj masi sa 60 dana su takođe statistički značajne (P (lt) 0,05). Rezultati su pokazali da su razlike između genotipova pod uticajem fiksnih faktora statistički značajne (P (lt) 0,05), osim između telesne mase sa 90 dana kod blizanaca (P> 0,05)

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)