http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Gardinal, R.,Calomeni, G.D.,Consolo, N.R.B.,Takiya, C.S.,Freitas, J.E. Jr,Gandra, J.R.,Vendramini, T.H.A.,Souza, H.N.,Renno, F.P. Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.1
Objective: Two experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers. Methods: Exp 1: Eight ruminally fistulated steers [$503{\pm}28.5kg$ body weight (BW)] were distributed into a d $4{\times}4$ Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers ($350.5{\pm}26.5kg$ initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively). Results: Exp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+-SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of $NH_3-N$ (-10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM. Conclusion: Feeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM.
Ecological risk by potentially toxic elements in surface sediments of the Lake Maracaibo (Venezuela)
Julio Marin,Marinela Colina,Hilda Ledo,P.H.E. Gardiner 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.4
The evaluation of potential ecological risk of aquatic sediments associated with the presence of potentially toxic elements (PTE) determines its degree of danger on native biota. In this work, the potential ecological risk of V, Ti, Cr, Ni, Cu, Zn, As, Se, Cd, Sn, Hg and Pb in superficial sediments is explained in three different areas of Lake Maracaibo: El Tablazo Bay, Strait of Maracaibo and the lake itself, through a multi-guideline approach (elemental enrichment (enrichment factor, contamination degree, pollutant load index and geo-accumulation index), sediment quality guidelines and risk assessment code). The PTE levels ranged from 〈 0.025 to 176.722 mg·kg<SUP>−1</SUP> DW, with an overall proportion of V 〉Ti 〉 Pb 〉 Zn 〉 Cr 〉 Cu 〉 Ni 〉As 〉 Cd 〉 Se 〉 Hg 〉 Sn. The PTE concurrent effect on biota was El Tablazo Bay 〉 lake 〉 Strait of Maracaibo. The superficial sediments of Lake Maracaibo constitute a medium with a high potential ecological risk on estuarine biota. This is mainly due to the levels of As in El Tablazo Bay, Cd in the Strait of Maracaibo and Pb in the lake area. This represents a latent toxicity hazard for native biological communities and other associated organisms.