Effect of subcutaneous selenium injection and supplementary selenium source on blood selenium and glutathione peroxidase in feedlot heifers

This study measured the effect on glutathione peroxidase (GSH-Px) and selenium (Se) in whole blood and plasma associated with subcutaneous Se injections in beef heifers fed organic or inorganic Se. Heifers (n = 120) were randomly divided into 2 groups, 1 of which received subcutaneous Se injections. Both groups were given the same total mixed ration with 3 mg of organic or inorganic Se daily. Until week 2, heifers that had received Se injections showed higher concentrations of plasma Se and GSH-Px and whole blood Se (P < 0.001) than those having had no injections. Concentrations of plasma Se and GSH-Px were higher in the group receiving organic Se than the group receiving inorganic Se. Whole blood GSH-Px concentrations increased significantly (P < 0.001) throughout a 12-week period but were not affected by Se source. Combination of Se injections and supplementation could help maintain normal Se and GSH-Px blood status in beef heifers during the first few weeks in the feedlot.     

Colour and decay resistance and its relationships in Eperua grandiflora

? Eperua grandiflora, which is widely distributed in the French Guiana forest region, shows high variability in decay resistance. Further information concerning this wood quality parameter is necessary, but standard testing methods are complex and time-consuming. We assessed the use of colorimetry to determine durability in heartwood samples from a range of trees.

? Eperua grandiflora colour parameters were measured using a CIELAB system, revealing that the tree effect was greater than the radial position and height effects.

? The wood samples were exposed to Coriolus versicolor and Antrodia sp. according to two European standards (En 350-1 and XP CEN TS 15083-1). Eperua grandiflora is more susceptible to brown rot. These two standards did not give the same durability classes. The high variation in natural durability was due to the tree effect.

? These two properties were found to be correlated and the assessment also distinguished the extreme durability classes but they are not sufficient to classify the class of durability of this species.

     

Isolation and characterization of efficient isoxaben-transforming Microbacterium sp strains from four European soils

Nutrient-agar plates containing isoxaben (500 mg litre(-1)) were used to isolate isoxaben-metabolising bacteria from four European soils incubated with the herbicide under laboratory conditions. In flask experiments, inoculation of a basal salts medium containing nitrogen and [phenyl-U-14C]isoxaben with an isolate (B2b) resulted in 33% recovery of the initial radioactivity as [14C]carbon dioxide after 2 weeks. A major metabolite identified by GC-MS and NMR analysis as 3-(1-ethyl-1-methylpropyl)isoxazol-5-ylamine accumulated both in basal salts and nutrient broth media. 2,6-Dimethoxybenzoic acid, a suspected metabolite of isoxaben, was not detected in either liquid media. However, the capability of the B2b isolate to use 2,6-dimethoxybenzoic acid as a source of carbon was demonstrated. Soil inoculation with the B2b strain resulted in an increase in the recovery of [14C] carbon dioxide from both [phenyl-U-14C] and [isoxazole-5-14C]isoxaben. The metabolite identified as 3-(1-ethyl-1-methylpropyl)isoxazole-5-ylamine only accumulated if the soil was autoclaved before inoculation. This metabolite was rapidly mineralized by the microflora of a natural soil without history of isoxaben treatment. Homology patterns of sequenced 16S rDNA between isoxaben-transforming isolates and reference strains showed that the four isolates identified belonged to the genus Microbacterium.     

Evaluation of shrimp or tilapia protein hydrolysate at graded dosages in low fish meal diet for olive flounder (Paralichthys olivaceus)

A study was carried out to examine and optimize the inclusion levels of shrimp hydrolysate (SH) or tilapia hydrolysate (TH) in low fishmeal diets for olive flounder (Paralichthys olivaceus). A fishmeal (FM)‐based diet was considered as a high FM (HFM) diet, and a diet containing soy protein concentrate (SPC) as a FM replacer at 50% substitution level was regarded as a low FM (LFM) diet. Six other experimental diets were prepared by dietary supplementation of SH or TH to LFM diet at different inclusion levels of 15 g/kg, 30 or 45 g/kg in the expense of FM (designated as SH‐1.5, SH‐3.0, SH‐4.5, TH‐1.5, TH‐3.0 and TH‐4.5, respectively). After 10 weeks of a feeding trial, growth performance and feed utilization efficiency of fish were significantly higher in fish fed HFM, SH‐3.0, SH‐4.5, TH‐1.5 and TH‐3.0 diets compared to those of fish fed LFM diet. Intestine diameter, villus height and goblet cell counts of fish were significantly increased by dietary inclusion of SH or TH into LFM diet. Dry matter and protein digestibility of diets were significantly improved by SH or TH incorporation. Innate immunity of fish was significantly enhanced by dietary SH or TH supplementation into LFM diet. Disease resistance of fish was significantly increased against Edwardsiella tarda by dietary inclusion of SH and TH at the highest inclusion level (45 g/kg). The optimum inclusion level of SH or TH in a SPC‐based LFM diet could be ~30 g/kg and 15–30 g/kg, for olive flounder.     

Seasonal variations of physiological parameters in the blue mussel mytilus spp. from farm sites of eastern Quebec

A seasonal monitoring of indigenous (Gaspé Bay, Carleton, Havre-St-Pierre, Magdalen Islands and Blanc-Sablon) and transplanted (Gaspé Bay, Carleton, Havre-St-Pierre) mussels from different farm sites of Eastern Quebec allowed us to study mussel physiology as a function of environmental factors. A positive influence of phytoplankton cell concentration and temperature on the reproductive cycle was discovered even if no significant relationship has been showed because of the fragmented pattern of gametogenesis. A decrease of digestive gland index (DGI) was observed during gametogenesis. Development of gametes needs much energy and its great influence on digestive gland weight prevented us to correlate mussel growth with environmental factors. A decrease of phagocytic activity was observed in each site in midsummer, concomitantly to the most active spawning period. A significant positive correlation was remarked between maturity index in males and phagocytosis. A decrease of phagocytic activity could then have a direct impact on mussel population since it occurred during high temperature period when mussels had to face spawning, bacterial developments and diseases. It appeared in our study that reproductive cycle is a key event in mussel physiology and important for mussel farmers to follow-up. In the near future, we intend to develop and validate reliable indicators of the reproductive cycle in cultured mussels.     

The form of nicotine in tobacco. Thermal transfer of nicotine and nicotine acid salts to nicotine in the gas phase

Thermal transfer to nicotine in the gas phase from neat nicotine, from various nicotine carboxylic acid salts, and from endogenous nicotine in Burley, Bright, and Oriental tobacco samples has been examined by thermogravimetric/differential thermal analysis/mass spectroscopy and evolved gas analysis. Under the conditions used in these studies, the peak transfer temperatures of these substances to nicotine in the gas phase are nicotine and nicotine acetate, both ca. 110-125 degrees C; nicotine malates, ca. 110-210 degrees C for nicotine to malic acid ratios of 1:0.56 and 1:1 and ca. 160-210 degrees C for a nicotine to malic acid ratio of 1:2; (S)-nicotine bis[(2R,3R)-hydrogen tartrate] dihydrate, ca. 195-210 degrees C; and tobacco samples, a range of ca. 160-220 degrees C. These results suggest that nicotine is mostly protonated in tobacco leaf. In all cases, the temperature of the transfer of nicotine to the gas phase was found to be many hundreds of degrees below the temperatures observed around the coal of a burning cigarette (smolder, ca. 500-775 degrees C; dynamic smoking, 600 to over 950 degrees C). Within the narrow zone of a puffing cigarette that encompasses an intermediate temperature range (125-250 degrees C), kinetic data suggest that these temperatures are not sufficient to volatilize significant amounts of nonprotonated nicotine, assuming any exists at all, during the short puff duration (2 s). It is concluded that nonprotonated nicotine and protonated nicotine (salts of nicotine with natural tobacco carboxylic acids) will transfer nicotine to smoke with comparable yields and efficiencies during the smoking process.     

Respective roles of recent hedges and forest patch remnants in the maintenance of ground-beetle (Coleoptera: Carabidae) diversity in an agricultural landscape

We compared three kinds of habitats: small remnants of native forests, recent hedges and barley crops, in order to investigate their respective roles in the maintenance of carabid-beetle diversity in a 950-ha area of an intensive agricultural landscape. Carabid faunas in remnants differed weakly from these found in hedges and crops. In particular, small remnants had few typical forest carabid species and a large number of open-area or ubiquitous species. Different approaches in the measurement of and -diversity (classical indices, and additive partitioning of Simpson's index) showed similar results: hedges supported a high -diversity but habitat types were quite similar overall, with weak differences between open and closed or disturbed and undisturbed habitats.A comparison of species dispersal powers in the various habitat types showed that species with a low dispersal power were rare in all habitats. However, wing development measured on two dimorphic species revealed, surprisingly, that brachypterous individuals were mainly present in hedges, which were expected a priori to be more disturbed, than remnants hence less suitable for the establishment of populations with a low dispersal power.These results suggest that small remnants do not behave as 'climax' habitats in this intensive agricultural landscape, probably because of their small size and strong isolation. We discuss the interest of new undisturbed habitats, such as recent hedges, for the maintenance of carabid diversity at both the local and landscape scale.     

Sexual Precocity of Nellore Bulls that are Offspring of Super Precocious,Precocious and Normal Cows in Extensive Farming Conditions

The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi‐square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls.     

Kinetics of leaf extension in maize: Parameterization for two tropically adapted cultivars planted on two dates at Gatton

The kinetics of extension of individual leaves and component laminae and sheaths in maize were studied in two field experiments at Gatton (Australia) using two cultivars, Pioneer 3527 and Pioneer C87, in one experiment and Pioneer C87 only in the second. Destructive sampling based on non-destructive observations to ensure accurate representation of the population was used to establish timing of leaf initiation, leaf tip appearance, ligule being able to be discerned and full extension of organs. The appearance and extension of leaves were related to thermal time, calculated from temperature measured in the region of cell division and extension. Extension of leaves and sheaths was analysed using the first three phases of a four phase framework consisting of two exponential phases, rapid (linear) extension and transition to final organ length. The last phase was not examined as there were insufficient data. Final organ length was related to leaf position, and linear extension rates of leaves and laminae were linearly related to final organ length, with differing equations for upper and lower leaves. The study has proposed extensions to an existing analytical approach, and argues that regular patterns of extension of leaves and sheaths can be explained in relation to the position of the ear using a physiological approach.