Prinos suve materije i produkcija proteina lucerke, ježevice, livadskog vijuka, engleskog ljulja i njihovih smeša sa različitim dozama azotnog đubriva

Grass-leguminous mixtures and pure crops are important for ensuring of sufficient quantities of high quality roughage, especially in conditions of low land livestock production, in conditions of farm housing system as well as in the system of free grazing of animals. Studies were carried out on pure crops of three grass species and their mixtures with different component ratios. Fertilization using different doses of nitrogen led to considerable increase of yield of pure crops and their mixtures. The highest yields were recorded in treatment with 100 kgN ha- 1, and the lowest yield in treatment without fertilization. Fertilization led to decrease of share of alfalfa, meadow fescue and perennial ryegrass in dry matter, and increased the content of cocksfoot. The highest protein yield of pure crops was recorded for perennial ryegrass - 495.5, and in mixtures, the highest protein yield was recorded for four component mixture of alfalfa, cocksfoot, meadow fescue and perennial ryegrass of 568.0 kg ha-1. Fertilization with N increased protein yield considerably in pure crops as well as in their mixtures.Travno-leguminozne smeše kao i usevi čistih kultura su od značaja za obezbeđenje kvalitetne kabaste stočne hrane, naročito u uslovima nizijskog stočarstva, u uslovima farmskog držanja kao i pri slobodnom sistemu ispaše životinja. Istraživanja su obavljena na čistim usevima tri vrste trava i lucerke, najzastupljenije leguminoze kod nas, kao i njihovih smeša u različitom odnosu učešća pojedinih komponenti. Đubrenje različitim količinama azota dovelo je do značajnog povećanja prinosa kako čistih useva tako i njihovih smeša. Najvećim prinosima odlikuju se tretmani sa 100 kgN ha-1, a najmanjim tretmani bez đubrenja. Đubrenje je smanjilo sadržaj lucerke, livadskog vijuka i engleskog ljulja u suvoj materiji travnjaka, a povećalo sadržaj ježevice. Najvećim prinosom proteina od čistih useva odlikuje se engleski ljulj (495,5 kg ha-1), a od smeša četvorokomponentna smeša lucerke, ježevice, livadskog vijuka i engleskog ljulja (568,0 kg ha-1). Đubrenje N je značajno povećalo prinos proteina kako kod čistih useva tako i kod njihovih smeša

Uticaj telesne mase koza i laktacije po redu na porast jaradi u dojnom periodu

The paper presents results of investigation of milk yield by lactation, by order, and mother's body weight on growth rate of kids of the domestic Balkan goat. Daily weight gains of 376 single kids (168 male and 208 female), in three monthly intervals, and their final body weight at 90 days of age were established. Variability of analyzed traits was presented using descriptive statistics parameters, and differences of growth traits for weight gain of kids resulting from the effect of milk yield of female goats by order of lactation were investigated by single analysis of variance. The effect of independent variables, mothers' milk yield and body weight, on body weight of kids was tested using multiple regression analysis. During the entire suckling period, established average values for kids body weight differed significantly (P lt 0.001), increasing from the 1st toward later lactations. At 90 days of age the lowest values were established in kids from the youngest mothers (11.86 kg), while for kids of mothers in the fourth or later lactations these values were higher (13.93 kg). Coefficients of determination indicate that the variability percentage for individual growth traits of kids was in the 0.08 - 0.17 interval, indicating its significance. Both 'b' coefficients (b1 and b2) are positive and statistically highly significant, except for coefficient b2 in the analysis of body weight of kids at birth. The positive sign and high statistical significance indicate a pronounced effect of mother's milk yield and body weight on the body weight of kids up to 90 days of age.U ovom radu prikazani su rezultati ispitivanja uticaja količine mleka u laktaciji po redu, i telesne mase majke na porast jaradi domaće balkanske koze do 90 dana. U cilju ispitivanja razvoja telesne mase jaradi u zavisnosti od količine mleka u laktaciji po redu u toku dojnog perioda ukupno je izmereno 376 jaradi jedinaca (168 muških i 208 ženskih). Varijabilnost analiziranih osobina je prikazana parametrima deskriptivne statistike, dok su razlike u osobinama porasta jaradi koje su nastale pod uticajem mlečosti koza u laktaciji po redu, ispitivane jednostrukom analizom varijanse. Višestruko regresionom analizom ispitivan je uticaj nezavisno promenljivih veličina, mlečnost majke i telesna masa majke, na porast jaradi. Utvrđene vrednosti telesnih masa u toku čitavog dojnog perioda značajno su se razlikovale (P lt 0,001) i povećavale od prve ka kasnijim laktacijama, pri čemu su u uzrastu od 90 dana najmanje vrednosti utvrđene kod jaradi od najmlađih koza (11,86 kg), dok su kod jaradi čije su majke bile u četvrtoj i kasnijim laktacijama te vrednosti iznosile 13,93 kg. Koeficijenti determinacije ukazuju na to da se procenat varijabilnosti pojedinih osobina porasta jaradi nalazio u intervalu od 0,08 do 0,17, što ukazuje na njihovu značajnost. Oba 'b' koeficijenta (b1 i b2) su pozitivna i statistički visoko značajna, osim koeficijenta b2 u analizi telesne mase jaradi pri rođenju. Pozitivni predznak i visoka statistička značajnost ukazuju na izražen uticaj mlečnosti i telesne mase majki na porast jaradi do 90 dana

Electrotactile Communication via Matrix Electrode Placed on the Torso Using Fast Calibration, and Static vs. Dynamic Encoding

Electrotactile stimulation is a technology that reproducibly elicits tactile sensations and can be used as an alternative channel to communicate information to the user. The presented work is a part of an effort to develop this technology into an unobtrusive communication tool for first responders. In this study, the aim was to compare the success rate (SR) between discriminating stimulation at six spatial locations (static encoding) and recognizing six spatio-temporal patterns where pads are activated sequentially in a predetermined order (dynamic encoding). Additionally, a procedure for a fast amplitude calibration, that includes a semi-automated initialization and an optional manual adjustment, was employed and evaluated. Twenty subjects, including twelve first responders, participated in the study. The electrode comprising the 3 × 2 matrix of pads was placed on the lateral torso. The results showed that high SRs could be achieved for both types of message encoding after a short learning phase; however, the dynamic approach led to a statistically significant improvement in messages recognition (SR of 93.3%), compared to static stimulation (SR of 83.3%). The proposed calibration procedure was also effective since in 83.8% of the cases the subjects did not need to adjust the stimulation amplitude manually

High-valent [MnFe] and [FeFe] cofactors in ribonucleotide reductases

Ribonucleotide reductases (RNRs) are essential for DNA synthesis in most organisms. In class-Ic RNR from Chlamydia trachomatis (Ct), a MnFe cofactor in subunit R2 forms the site required for enzyme activity, instead of an FeFe cofactor plus a redox-active tyrosine in class-Ia RNRs, for example in mouse (Mus musculus, Mm). For R2 proteins from Ct and Mm, either grown in the presence of, or reconstituted with Mn and Fe ions, structural and electronic properties of higher valence MnFe and FeFe sites were determined by X-ray absorption spectroscopy and complementary techniques, in combination with bond-valence-sum and density functional theory calculations. At least ten different cofactor species could be tentatively distinguished. In Ct R2, two different Mn(IV)Fe(III) site configurations were assigned either L4MnIV(μO)2FeIIIL4 (metal–metal distance of ~ 2.75 Å, L = ligand) prevailing in metal-grown R2, or L4MnIV(μO)(μOH)FeIIIL4 (~ 2.90 Å) dominating in metal- reconstituted R2. Specific spectroscopic features were attributed to an Fe(IV)Fe(III) site (~ 2.55 Å) with a L4FeIV(μO)2FeIIIL3 core structure. Several Mn,Fe(III)Fe(III) (~ 2.9–3.1 Å) and Mn,Fe(III)Fe(II) species (~ 3.3–3.4 Å) likely showed 5-coordinated Mn(III) or Fe(III). Rapid X-ray photoreduction of iron and shorter metal–metal distances in the high-valent states suggested radiation-induced modifications in most crystal structures of R2. The actual configuration of the MnFe and FeFe cofactors seems to depend on assembly sequences, bound metal type, valence state, and previous catalytic activity involving subunit R1. In Ct R2, the protonation of a bridging oxide in the MnIV(μO)(μOH)FeIII core may be important for preventing premature site reduction and initiation of the radical chemistry in R1

Nitrogen dynamics in grass-legume associations; how can fixed nitrogen use be optimised?

The composition of grass-legume associations both modifies and is modified by the N cycle. The identity of the plants in the association has an effect on crop-level fixed-N inputs, N transfer while the association is in place, and the N remaining during the rest of the crop rotation cycle. The N used by the grass that is generated by the legume varies: it can reach 60% in white-clover-based associations, 50% in red-clover-based associations and 40% in lucerne-based associations. The percentage of legumes that optimises N transfer to grasses in grazed pastures (30%) is less than the percentage that maximises N fixation in hay meadows (70%). Making improvements to plants so that they can be used in associations, selecting certain plant varieties, and managing plant cover (e.g., via fertilisation, defoliation) are major tools that can be used to fine-tune the balance between the plants composing grass-legume associations. To some degree, these tools can also be used to influence relative contributions to the N balance of crop rotation systems.Free full text: [http://www.afpf-asso.fr/download.php?type=1&id=2085&statut=0