Feed processing effects on digestibility,palatability, excreta fermentation products and blood parameters in blue‐fronted amazon parrots (Amazona aestiva)†

Captive parrots show a high incidence of obesity and other metabolic disorders due to the consumption of unbalanced diets. Therefore, this study evaluated the digestibility and metabolic effects of transitioning blue‐fronted amazons from a high fat diet (sunflower seeds) to processed diets with three degrees of starch gelatinization (SG). The same feed formulation was processed to obtain pelletized feed (PEL) at 27.1% SG; low‐cooked extruded feed (EXT_L) at 81.6% SG; and high‐cooked extruded feed (EXT_H) at 98.5% SG. Thirty adult parrots were fed sunflower seeds for 90 days, then were distributed in a completely randomized design with 10 repetitions per treatment, and fed one of the three prepared diets for 160 days. Feed palatability, apparent digestibility, excreta concentrations of volatile fatty acids, lactate and ammonia, initial and final radiographic examinations, blood cell counts and glucose, triglycerides, cholesterol, total protein, albumin, aspartate aminotransferase (AST) and uric acid levels were evaluated. The data were analysed by an analysis of variance and compared by Tukey's test (p < 0.05). Sunflower seed was more digestible than processed feeds (p < 0.05). Diet processing interfered with fat and starch digestibility (p < 0.001), being higher in the PEL than in the EXT_H and EXT_L respectively. Transitioning from sunflower seeds to balanced diets reduced serum glucose, triglycerides, cholesterol and AST (p < 0.05) and increased red blood cell, haemoglobin, lymphocyte, monocyte and leucocyte counts (p < 0.01). Radiographs indicated a decreased hourglass (p = 0.015) and a reduced heart‐liver ratio after ingesting the processed feeds (p < 0.05). Feed processing did not affect blood cell counts, serum biochemistry or radiographic examinations. In conclusion, parrots preferred the extruded diet and did not require an extensive SG to properly digest the feed. Consuming the processed diets improved the birds’ metabolism and health.     

Use of surgical hemoclips in radiation treatment planning

The goal of this prospective study was to determine the effect of hemoclip use on the size of radiation treatment fields based on a 3-cm margin around a surgical incision alone (field setup 1) vs. a 3-cm margin around the surgical incision plus hemoclips (field setup 2). Forty-seven dogs that underwent surgical resection of a total of 55 soft tissue masses had surgical hemoclips placed at the time of surgery and orthogonal radiographs made immediately postoperatively. Radiation treatment field simulation was done and field areas measured. Additional determinations included number of hemoclips outside of the radiation treatment field based on a margin around the incision alone, hemoclip distance from the incision, and association between incision length and greatest distance of hemoclips from the incision. There was a significant difference in radiation treatment field size using information regarding the location of hemoclips in conjunction with the surgical scar compared with the surgical scar alone for truncal (P = 0.0003) vs. extremity tumors (P = 0.087). In simulating radiation treatment fields hemoclips were located outside of field setup 1 for the majority of tumors (79%) resected from the trunk but only in a minority of tumors (10.7%) resected from extremity sites. The findings from this study suggest that surgical hemoclips have potential utility in simulation of radiation treatment fields in the postoperative setting.     

A Multi-Omics Characterization of the Natural Product Potential of Tropical Filamentous Marine Cyanobacteria

Microbial natural products are important for the understanding of microbial interactions, chemical defense and communication, and have also served as an inspirational source for numerous pharmaceutical drugs. Tropical marine cyanobacteria have been highlighted as a great source of new natural products, however, few reports have appeared wherein a multi-omics approach has been used to study their natural products potential (i.e., reports are often focused on an individual natural product and its biosynthesis). This study focuses on describing the natural product genetic potential as well as the expressed natural product molecules in benthic tropical cyanobacteria. We collected from several sites around the world and sequenced the genomes of 24 tropical filamentous marine cyanobacteria. The informatics program antiSMASH was used to annotate the major classes of gene clusters. BiG-SCAPE phylum-wide analysis revealed the most promising strains for natural product discovery among these cyanobacteria. LCMS/MS-based metabolomics highlighted the most abundant molecules and molecular classes among 10 of these marine cyanobacterial samples. We observed that despite many genes encoding for peptidic natural products, peptides were not as abundant as lipids and lipopeptides in the chemical extracts. Our results highlight a number of highly interesting biosynthetic gene clusters for genome mining among these cyanobacterial samples.     

Canopy and hydraulic conductance in young, mature and old Douglas-fir trees

We tested for reductions in water transport with increasing tree size, a key component in determining whether gas exchange and growth are hydraulically limited in tall trees. During the summers of 1998 and 1999, we measured water transport with Granier-type, constant-heat sap flow probes, vapor pressure deficit, and leaf and soil water potentials in overstory Pseudotsuga menziesii (Mirb.) Franco trees in three stands differing in size and age (15, 32 and 60 m in height and about 20, 40 and 450 years in age, respectively) in a P. menziesii-dominated forest in the Pacific Northwest, USA. A total of 24 trees were equipped with sap flow sensors--six 60-m trees, nine 32-m trees and nine 15-m trees. Based on the sap flow measurements and leaf area information estimated from leaf area-sapwood area relationships, we estimated crown-averaged stomatal conductance (GS) and leaf-specific hydraulic conductance (KL). We tested the hypothesis that GS and KL vary inversely with tree height (15 > 32 > 60 m). Analysis of variance of GS ranked as 15 = 60 > 32 m during the early summer and 15 > 60 > 32 m during late season drought. Over the growing season, mean daily GS (+/- SE) was 29.2 +/- 4.4, 24.0 +/- 6.8 and 17.7 +/- 7.2 mmol m-2 s-1 for the 15-, 60- and 32-m trees, respectively. The value of K(L) differed among tree heights only during late season drought and ranked 15 > 32 = 60 m. A hydraulic mass balance suggests that greater sapwood conductivity in 60-m trees compared with 32- and 15-m trees is a likely cause for the departure of the above rankings from those predicted by height and leaf-to-sapwood area ratio.     

An investigation of hydraulic limitation and compensation in large,old Douglas-fir trees

The hydraulic limitation hypothesis (Ryan and Yoder 1997) proposes that leaf-specific hydraulic conductance (kl) and stomatal conductance (gs) decline as trees grow taller, resulting in decreased carbon assimilation. We tested the hydraulic limitation hypothesis by comparison of canopy-dominant Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) trees in stands that were approximately 15 m (20 years old), 32 m (40 years old) and 60 m (> 450 years old) tall in Wind River, Washington, USA. Carbon isotope discrimination (Delta) declined with tree height (18.6, 17.6 and 15.9 per thousand for stands 15, 32 and 60 m tall, respectively) indicating that gs may have declined proportionally with tree height in the spring months, when carbon used in the construction of new foliage is assimilated. Hydraulic conductance decreased by 44% as tree height increased from 15 to > 32 m, and showed a further decline of 6% with increasing height. The general nonlinear pattern of kl versus height was predicted by a model based on Darcy's Law. Stemwood growth efficiency also declined nonlinearly with height (60, 35 and 28 g C m-2 leaf area for the 15-, 32- and 60-m stands, respectively). Unlike kl and growth efficiency, gs and photosynthesis (A) during summer drought did not decrease with height. The lack of decline in cuvette-based A indicates that reduced A, at least during summer months, is not responsible for the decline in growth efficiency. The difference between the trend in gs and A and that in kl and D may indicate temporal changes (spring versus summer) in the response of gas exchange to height-related changes in kl or it may be a result of measurement inadequacies. The formal hydraulic limitation hypothesis was not supported by our mid-summer gs and A data. Future tests of the hydraulic limitation hypothesis in this forest should be conducted in the spring months, when carbon uptake is greatest. We used a model based on Darcy's Law to quantify the extent to which compensating mechanisms buffer hydraulic limitations to gas exchange. Sensitivity analyses indicated that without the observed increases in the soil-to-leaf water potential differential (DeltaPsi) and decreases in the leaf area/sapwood area ratio, kl would have been reduced by more than 70% in the 60-m trees compared with the 15-m trees, instead of the observed decrease of 44%. However, compensation may have a cost; for example, the greater DeltaPsi of the largest trees was associated with smaller tracheid diameters and increased sapwood cavitation, which may have a negative feedback on kl and gs.     

Biophysical controls of carbon flows in three successional Douglas-fir stands based on eddy-covariance measurements

We measured net carbon flux (F(CO2)) and net H2O flux (F(H2O)) by the eddy-covariance method at three Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)-western hemlock (Tsuga heterophylla (Raf.) Sarg.) sites located in the Wind River Valley of southern Washington State, USA. Stands were approximately 20, 40 and 450 years old and measurements were made between June 15 and October 15 of 1998 in the 40- and 450-year-old stands, and of 1999 in the 20- and 450-year-old stands. Our objectives were to determine if there were differences among the stands in: (1) patterns of daytime F(CO2) during summer and early autumn; (2) empirically modeled relationships between local climatic factors (e.g., light, vapor pressure deficit (VPD), soil water content, temperature and net radiation) and daytime F(CO2); and (3) water-use efficiency (WUE). We used the Landsberg equation, a logarithmic power function and linear regression to model relationships between F(CO2) and physical variables. Overall, given the same irradiance, F(CO2) was 1.0-3.9 mol m-2 s-1 higher (P < 0.0001 for both seasons) at the two young stands than at the old-growth stand. During summer and early autumn, F(CO2) averaged 4.2 and 6.1 mol m-2 s-1 at the 20- and 40-year-old stand, respectively. In contrast, the 450-year-old forest averaged 2.2 and 3.2 mol m-2 s-1 in 1998 and 1999, respectively. Increases in VPD were associated with reduced F(CO2) at all three stands, with the greatest apparent constraints occurring at the old-growth stand. Correlations between F(CO2) and all other environmental variables differed among ecosystems, with soil temperature showing a negative correlation and net radiation showing a positive correlation. In the old-growth stand, WUE was significantly greater (P < 0.0001) in the drier summer of 1998 (2.7 mg g-1) than in 1999 (1.0 mg g-1). Although we did not use replicates in our study, the results indicate that there are large differences in F(CO2) among Douglas-fir stands of different ages growing in the same general area, and that variations in age structure and site conditions need to be considered when scaling flux measurements from individual points to the landscape level.