Changes in eucalypt litter quality during the first three months of field decomposition in a Congolese plantation

In fast-growing tree plantations, decomposition of leaf litter is considered as a key process of soil fertility. A three-month field experiment, spanning both rainy and dry seasons, was conducted to determine how changes in litter decomposition affect the main parameters of litter quality—namely, the concentrations of phenolic and non-phenolic carbon (C) compounds, nitrogen (N), and fibres, and the litter C mineralization rate. This study was conducted to test (1) if these changes vary according to the compound and to the season, and if they are greater for soluble compounds, and (2) if after a three-month period of field decomposition, the chemical composition of the remaining litter drives C mineralization, as measured in laboratory conditions, through a greater influence on the concentration of N and lignin. We found that the concentrations of water- and methanol-soluble phenolic compounds and the concentrations of non-phenolic compounds decreased during decomposition in all plots and in each season, while the fibre and N concentrations increased. The relationships among litter decomposition, C mineralization, and litter quality depended on the season, which strongly suggests that different processes are involved in dry and rainy seasons. The C mineralization rates were driven by soluble organic compounds in the initial litter and by soluble phenolic compounds in the decomposed litter.     

Radiographic assessment of pulmonary fluid clearance and lung aeration in newborn calves delivered by elective Caesarean section

The aim of this study was to develop a radiographic standard for the assessment of pulmonary fluid clearance and lung aeration in newborn calves. Caesarean‐delivered mature calves (n = 9) underwent lung assessment by thoracic radiography as well as arterial and venous blood gas analysis within the first 30 min, 1, 2, 3, 6, 12 and 24 hr after birth. The results indicated that newborn calves delivered by elective Caesarean section suffered from a physiological combined respiratory and metabolic acidosis with the dominance of respiratory acidosis, and an improvement in these conditions was recorded within 24 hr after birth. Concerning the radiographic results, clear lung fields, improvement in lung expansion, air content of the lung and absence of lung opacification occurred within 24 hr of birth. Furthermore, the ventral lung quadrant showed an improvement in radiographic opacification and lung expansion earlier than the dorsal lung regions. The findings of this study support the potential role of thoracic radiography in the assessment of pulmonary fluid clearance and lung aeration in newborn calves.     

Broiler responses to digestible threonine at different ages: a neural networks approach

Three experiments were conducted with broiler chickens to evaluate the effects of digestible threonine (DThr) and crude protein (CP) on their performance at three different phases of age: 1–14, 15–28 and 29–42 days. The measured traits included the following: average daily gain (ADG), feed intake (FI), feed conversion ratio (FCR), carcass crude protein (CCP), body lipid (BL), feather weight gain (FWG), protein deposited in feather (FCP), carcass plus feather protein (CFCP), carcass Thr deposition (CDThr) and nitrogen excretion (NE). A dilution technique was used to create seven diets (with eight replicates) increasing the DThr content from 1.5 to 10 g/kg of diet for phase 1, 1.3–8.9 g/kg of diet for phase 2, and 1.2–8.2 g/kg of diet for phase 3. Data measured were imported into neural networks (NNs) to: (i) predict the measured traits in response to DThr and CP, (ii) rank the importance of DThr and CP on these traits through sensitivity analysis and (iii) find the optimal levels of DThr and CP that lead to the desired (maximum or minimum) responses. For each trait investigated, 50 different random groups of data were generated using a bootstrapping method. These 50 data groups were then used to develop 50 separate NNs which were subsequently combined to construct the final ensemble NN model. In general, accuracy of the models constructed was acceptable, although models of high (ADG, FCR, CFCP, BL, DThr and NE; 0.64 ≤ R² ≤ 0.99) and low (CCP, FWG and FCP; 0.26 ≤ R² ≤ 0.79) accuracy were obtained. All models developed showed the greatest sensitivity to DThr. This may be explained by the dilution technique diet preparation used in these experiments. Optimization results showed decreases in optimal values of DThr and CP with increasing age for all traits. The highest level of DThr was suggested for minimum BL, followed by minimum FCR, maximum ADG, maximum CFCP, minimum NE and maximum CCP respectively. Results showed that the optimal values of DThr for minimum FCR in phases 1–3 were 8.5, 7.4 and 6.4 g/kg of diet, while these values for maximum ADG were 8.2, 7.2 and 6.4 g/kg of diet respectively.     

Classification of soils supporting mangrove plantation in Kuwait

The State of Kuwait has initiated an ambitious national program to establish greenery in 20000 ha of open spaces in inland and coastal areas. Afforestation of intertidal zones with mangrove plants is being considered as a viable option for greening coastal areas. In view of this fact, experimental plantations were established using two ecotypes of Avicennia marina (Bahrain and UAE) and one ecotype of Avicennia germinans (Florida). The study consisted of two 10-year old plantations and two 2-year old plantations. Seedlings established successfully and grew vigorously on some of the locations within the site. Therefore, studies were conducted during 2002-2003 to describe and classify soils that supported maximum mangrove establishment and growth under the harsh arid coastal conditions of Kuwait. For this purpose, eight soil profiles (four each representing areas where seedlings established successfully and grew vigorously and where all seedlings died in the initial stages of establishment) were investigated and classified according to the soil taxonomy. The main soil types observed in the study site were: Typic Aquisalids, Typic/sodic Aquicambids and Calcic Aquisalids. Mangrove growth performance in relation to the landform, soil type and properties of the soil at various depths is discussed in the paper. The plant growth appeared to be the better on the typic Aquisalid soil than that on the Typic/sodic Aquicambid soils. The relative proportions of the coarse sand fraction, occurrence of the anaerobic layer in the profile and the surface layer salinity influenced both the establishment and growth of mangrove plants.     

Effect of Artificial Insemination Protocol and Dose of Frozen/Thawed Stallion Semen on Pregnancy Results in Mares

Deep intra‐uterine insemination is commonly accepted as a routine procedure for artificial insemination in horses. The motives and principles of deep insemination are well described, but the equipment used may differ. In this trial, the efficiency of two different insemination pipettes for deep intra‐uterine insemination in the mare was compared with insemination into the uterine body using commercially available frozen–thawed semen of two stallions of proven fertility. These inseminations were performed using two different doses. The semi‐flexible Minitube pipette was compared with a newly designed insemination device with a more flexible telescopic insemination catheter (Ghent device). The semi‐flexible Minitube pipette performed better than the newly designed insemination device with respect to pregnancy outcome (p = 0.008). The superiority of deep horn insemination over uterine body insemination was reflected by the better pregnancy rates obtained after deep insemination using the same low doses (30.6% better pregnancy rates) (p = 0.0123).     

Caudal vena cava obstruction caused by redundant pacemaker lead in a dog

Inferior vena cava obstruction, a rare but serious complication of transvenous pacemaker lead placement in humans, has not been reported in dogs. We describe this complication in a dog that developed ascites 8 months after pacemaker implantation. Radiography disclosed a loop of redundant lead within the caudal vena cava (CVC), and angiography demonstrated obstruction to blood flow. Withdrawal of the loop from the CVC did not restore blood flow. Persistent obstruction was suspected secondary to fibrosis resulting from vascular damage caused by the loop of lead. Angioplasty of the CVC obstruction restored blood flow and resolved the dog's clinical signs.     

Temperature and surface-ocean water balance of the mid-holocene tropical western pacific

Skeletal Sr/Ca and 18O/16O ratios in corals from the Great Barrier Reef, Australia, indicate that the tropical ocean surface approximately 5350 years ago was 1 degrees C warmer and enriched in 18O by 0.5 per mil relative to modern seawater. The results suggest that the temperature increase enhanced the evaporative enrichment of 18O in seawater. Transport of part of the additional atmospheric water vapor to extratropical latitudes may have sustained the 18O/16O anomaly. The reduced glacial-Holocene shift in seawater 18O/16O ratio produced by the mid-Holocene 18O enrichment may help to reconcile the different temperature histories for the last deglaciation given by coral Sr/Ca thermometry and foraminiferal oxygen-isotope records.     

Growth trajectory analysis of Pacific whiteleg shrimp (Litopenaeus vannamei): Comparison of the specific growth rate,the thermal‐unit growth coefficient and its adaptations

Empirical growth models have widespread application in the field of aquaculture. These models allow estimates of harvest size and waste outputs in addition to nutrient and feed requirements. In an effort to increase the ability to predict shrimp growth, the specific growth rate (SGR) and thermal‐unit growth coefficient (TGC) models were fitted to 15 datasets encompassing growth of Pacific whiteleg shrimp (Litopenaeus vannamei). Shrimp were reared under commercial conditions in Southeast Asia with weights ranging from 0.01 g to 34 g. Growth rates were regressed against body weights to identify changes in growth pattern across life stages. Analysis identified two distinct patterns of growth, with a break point between stanzas at 7.5 g. The body weight exponent of the TGC model, traditionally assumed to be (1 ? b) = 1/3, was solved for iteratively in each identified growth stanza in an effort to improve the goodness of fit of the TGC model. Average body weight exponents in the first and second stanzas were 0.416 and 0.952 respectively. Projected growth trajectories using these exponents resulted in significantly better fits in comparison to the traditional TGC and the SGR on the basis of statistical measures of goodness of fit.     

Frost heaving of forest tree seedlings: a review

Soil frost heaving is the result of the formation of ice lenses in the soil caused by a segregation of the soil water. Ice lenses are growing from below and pushed upward. Seedlings heave when they are pushed out of the ground by the ice sheet formed at the surface of the soil. Frost heaving may greatly reduce growth and survival of forest tree seedlings particularly in regions where freezing and thawing are accompanied by high soil moisture. Resistance to frost heaving increases with size of seedling as the ability of a seedling to anchor itself increases. A few methods, such as fertilizing, choice of planting spots, sowing or planting at the proper time, shading, and use of mulches, appear to be effective in controlling frost heaving. Shade from natural plant cover can greatly reduce frost heaving.