Changes in carbon stocks in Eucalyptus globulus Labill. plantations induced by different water and nutrient availability

Changes in the carbon stocks under different soil water and nutrient conditions were studied in Eucalyptus globulus Labill. stands in a field experiment, at O ´ bidos (central Portugal). The treatments were irrigation plus a complete fertiliser solution to simulate ‘near optimal’ nutrition (IF), irrigation only (I), and fertilisers added to rain-fed plots (F). The control (C) received neither water nor fertilisers (except a small amount at planting). The production of biomass (aboveground), the litterfall and the soil chemical composition were evaluated regularly during the experiment. Root biomass was estimated at the end of the experiment. Carbon in biomass, litterfall and soil, increased significantly when water and/or nutrients were supplied, in comparison to the control. The amount of carbon accumulated in the system, 6 years after planting, was 8.22, 10.22, 11.23 and 13.76 kg C m 2 in the control, F, I and IF treatments, respectively. The increase of carbon in the system during the same period was 5.86, 7.86, 8.87 and 11.40 kg C m 2 in the control, F, I and IF treatments, respectively. This rise in carbon resulted from the accumulation of long-lived woody biomass, which represented between 77.7 (in IF) and 82.9% (in the control) of the total rise in carbon. Although water was the main limiting factor for biomass accumulation, the allocation of carbon to the soil was mainly related to nutrient supply, irrespective of water availability. The amount of carbon stored belowground, i.e. soil and forest floor, plus stumps and roots, reached 4.2, 4.7, 4.8 and 6.3 kg C m 2 in the control, F, I and IF treatments, respectively. The increase in C in the mineral soil regarding the initial state was, in the same order as above, 0.21, 0.75, 0.58 and 1.21 kg C m 2. These values were 3.6, 9.6, 6.6 and 10.6% of the C accumulated in the whole system, during the experimental period

Traveling length and minimal traveling time for flow through percolation networks with long-range spatial correlations

We study the distributions of traveling length l and minimal traveling time t through two-dimensional percolation porous media characterized by long-range spatial correlations. We model the dynamics of fluid displacement by the convective movement of tracer particles driven by a pressure difference between two fixed sites (''wells'') separated by Euclidean distance r. For strongly correlated pore networks at criticality, we find that the probability distribution functions P(l) and P(t) follow the same scaling Ansatz originally proposed for the uncorrelated case, but with quite different scaling exponents. We relate these changes in dynamical behavior to the main morphological difference between correlated and uncorrelated clusters, namely, the compactness of their backbones. Our simulations reveal that the dynamical scaling exponents for correlated geometries take values intermediate between the uncorrelated and homogeneous limiting cases

Effect of salt concentrations on in vitro rumen fermentation of cellulose, starch, and protein

The aim of this study was to evaluate the effects of various concentrations of three salts (sodium chloride (NaCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2)) on the in vitro rumen fermentation of cellulose, starch, and protein substrates. Six salt concentrations were tested, separately, namely 0, 100, 200, 400, 800, and 1600 mg/dL. The experiment was conducted using the completely randomized design in a 6 × 3 × 3 factorial arrangement with main effects of salt concentration and salt type (six levels of three salts (NaCl, MgCl2, or CaCl2) (0, 100, 200, 400, 800, and 1600 mg/dL) into three substrates [starch, cellulose, and glucose]) with three replicates. Cellulose- and glucose-fermenting bacteria were sensitive to NaCl concentrations greater than 400 mg/dL (17.48 decisiemens per metre (dS/m)) and 800 mg/dL (20.55 dS/m) in the media, respectively. In contrast, starch-fermenting bacteria continued to grow in NaCl concentrations up to 1600 mg/dL (29.09 dS/m). Thus, it was concluded that starch-fermenting microorganisms tolerated higher concentrations of NaCl compared with the other microbial groups. Cellulose-fermenting microorganisms are less tolerant to MgCl2 in relation to the other microbial groups. Starch, cellulose-, and glucose-fermenting bacteria from cattle tolerate CaCl2 concentrations of up to 1600 mg/dL (12.26 dS/m). These results suggest that brackish water may be used for ruminants. However, it is important perform an analysis of that water and then to adjust diets to minimize the effects of types of salt and concentrations of salt on rumen microorganisms. Keywords: brackish water, dissolved salts, rumen microbes, water qualit

Metabolic profile and histopathology of kidneys and liver of lambs fed silages of forages adapted to a semi-arid environment

Thirty-two mixed-breed ram lambs (average age, 5.6 ± 0.4 months, and average live weight, 17.61 ± 2.63 kg) were used to evaluate the effect of diets containing silages of forages adapted to a semi-arid environment on the metabolic profile in serum and the histopathological assessment of liver and kidney tissues of the lambs. Lambs were allocated, in a completely randomised design, to four treatments (silage of old man saltbush (Atriplex nummularia Lind), buffelgrass (Cenchrus ciliaris), gliricidia (Gliricidia sepium) and ‘pornunça’ (Manihot sp.). The feedlot period was 49 days, and animals were slaughtered at an average weight of 27 ± 4.6 kg. On the last day of the experiment, blood was collected from the jugular vein of all animals to measure the protein, metabolic and energy profiles of the lambs. At slaughter, kidney and liver samples were collected for histopathological examination. The consuming of the diet containing buffelgrass silage resulted in a significantly higher activity of alanine-aminotransferase (30.14 IU/L) and the concentrations of urea (44.25 mg/dL), creatinine (0.94 mg/dL) and albumin (4.48 g/dL) in serum. Diets containing gliricidia silage resulted in significantly higher gamma-glutamyl transferase activity (92.0 IU/L), while the diets with pornunça silage resulted in higher serum levels of triglycerides (37.85 mg/dL). The diets had no effect on aspartate-aminotransferase enzyme activity and total protein, cholesterol and globulin concentrations, or the albumin : globulin ratio in serum. Mild congestion, necrosis and foci of mineralisation were observed in the kidneys of animals fed diets containing old man saltbush (50%) and pornunça (25%) silages, and mild fatty degeneration and mild mononuclear inflammatory infiltrate in their livers. In conclusion, diets containing silages of forages that are adapted to semi-arid environments may be used for feeding lambs, given the absence of dysfunctioning plasmatic levels of liver enzymes and energy and protein profiles. Additionally, kidney failure was not observed in lambs fed these diets during the feedlot period.Keywords: blood parameters, buffelgrass, gliricidia, old man saltbush, pornunç

Characteristics of carcass and non-carcass components of lambs fed diets containing silages of forages adapted to the semi-arid environment

The aim of this study was to evaluate the effects of diets containing silages of forages that are adapted to the semi-arid environment on the characteristics of the carcass and of non-carcass components of 32 mixed-breed lambs at approximately six months old, with an average live weight of 17.61 ± 2.63 kg. Lambs were assigned to four treatments (diets containing silages of Atriplex nummularia Lind, Cenchrus ciliaris, Gliricidia sepium and Manihot sp.) in a completely randomized design with eight replicates. Animals fed the diet containing old man saltbush showed higher values for the intakes of dry matter (1.080 g/day), crude protein (190 g/day) and total digestible nutrients (740 g/day), body condition score (2.81 points), fatness (2.87 points), carcass conformation (3.19 points), live weight (29.1 kg), empty bodyweight (23.41 kg), weights of the commercial cuts neck, shoulder and ribs (0.46, 0.82 and 1.12 kg, respectively), and skin weight (1.972 kg). No differences were found between the diets for carcass dressing percentage, external and internal carcass lengths, leg length and circumference, rump circumference and width, chest width and depth, full bodyweight, empty bodyweight, cooling losses, pH before and after cooling, loin, and leg. Silages of old man saltbush, buffelgrass, gliricidia and pornunça are recommended for inclusion in lamb diets. Diets with old man saltbush silage provide the best results for characteristics of the carcass and of non-carcass components besides weight gain, which can reach up to 200 g/day depending on the formulation.Keywords: Carcass composition, feedlot, saltbush, shee

Carcass characteristics and meat quality of sheep fed buffelgrass silage to replace corn silage

The aim of the study was to evaluate the carcass characteristics, proximate composition, and sensorial attributes of meat from sheep fed diets in which buffelgrass silage replaced corn silage. Thirty-two intact male crossbred Santa Inês sheep with an average live weight of 20.09 ± 2.0 kg were housed in individual stalls and allotted at random to four treatments in which corn silage was replaced by buffelgrass silage at the levels of 0 (control), 33.3%, 66.6%, and 100%. After an adaption period of 10 days, the sheep were fed for an additional 61 days. Feed was offered ad libitum and corn silage comprised 60% of the diet for the control group. Carcass characteristics, non-carcass components and meat quality were evaluated. Hot carcass yield, cold carcass yield, true carcass yield, trimmings, fat weight, and mesenteric and omental fat weight were highest for the control group (P <0.05). Loin eye area had a quadratic response (P =0.02), with the largest areas being observed in animals fed the diet containing 66.6% buffelgrass silage. Liver weight (P <0.01), luminosity of the meat (P <0.05), and cooking loss (P <0.05) likewise had nonlinear responses to the concentration of buffelgrass silage in the diet. The treatments did not have significant negative influence on the nutritional and organoleptic characteristics of the meat

EFEITO DA MONENSINA SÓDICA NO CONSUMO DE ALIMENTOS E pH RUMINAL EM OVINOS

The main aim of the present research work was the study of the effects of the ionophore sodium monensin on feed voluntary intake and on the pH of the ruminal liquid in sheep. Four Santa Inês non pregnant, non lactating and rumen-cannulated lambs were used within a Latin square experimental design with four treatments: T1 - 0; T2 - 25; T3 - 50 and T4 - 75 mg monensin/animal/day. Feed, dry matter intake and ruminal fluid pH were evaluated. Sampling of ruminal fluid for pH determination was carried out at 0, 2, 4, 6 and 8 hours after feeding. According to the analysis of variance no significant values were found for intake of diet and dry matter, in regard to the levels of monensin. No siginificant effect in the average values of ruminal pH of each treatment and in the treatment x time interaction were found, the pH values being considered normal. There was a statistic difference in regard to the values found along the day. The voluntary feed intake and ruminal pH had not been influenced by the addition of sodium monensin in the diet of the sheep, the pH values remaining elevated, characterizing a good evironment of ruminal fermentation.Objetivou-se avaliar os efeitos da adição da monensina sódica no consumo de alimentos e no pH do líquido ruminal em ovinos. Foram utilizadas quatro ovelhas da raça Santa Inês, não prenhas, não lactantes e canuladas no rúmen. O delineamento experimental utilizado foi o quadrado latino, com quatro tratamentos (T1 - 0; T2 - 25; T3 - 50 e T4 - 75 mg de monensina/ animal/dia). Foram avaliados o consumo de ração, de matéria seca e o pH do fluido do rúmen. A colheita do líquido ruminal para determinação do pH foi realizada às 0; 2; 4; 6 e 8 horas após a alimentação. As análises de variância para consumo de ração e de matéria seca mostraram não haver efeito significativo dos níveis de monensina. Não foi observado efeito significativo nos valores médios do pH ruminal de cada tratamento e na interação tratamento x tempo; os valores de pH ruminal foram considerados normais. Houve diferença estatística no decorrer das horas. O consumo voluntário de alimentos e o pH do líquido ruminal não foram influenciados pela adição da monensina sódica na dieta dos ovinos, para a qual os valores de pH permaneceram elevados, caracterizando um bom ambiente de fermentação ruminal