Distinct habitat use strategies of sympatric rorqual whales within a fjord system.

We used ecosystem sampling during systematic surveys and opportunistic focal follows, comparison tests, and random forest models to evaluate fin whale (Balaenoptera physalus) and humpback whale (Megaptera novaeangliae) habitat associations within an inland feeding ground (Kitimat Fjord System, British Columbia, Canada). Though these species are sympatric and share a common prey source, they were attuned to different aspects of the local habitat. The fin whales were associated with habitat properties reminiscent of the open ocean. Humpback whales, in contrast, were associated with features more commonly associated with the inland waters of fjords. Fixed habitat features, such as seafloor depth and distance from the fjord mouth, were the most important predictors of fin whale presence, but fixed and dynamic variables, such as surface properties, predicted humpback whale presence with equal (moderate) success. With the exception of strong salinity gradients for humpback whales, habitat conditions were poor predictors of feeding state. Fin whales practiced a spatially confined, seasonally stable, and thus more predictable use of certain channels within the fjord system. These findings are compatible with site loyal behavior, which is interesting in light of the species' historical, unique use of this fjord system. The relatively lackluster performance of humpback-habitat models, coupled with the importance of oceanographic properties, makes the humpback's habitat use strategy more uncertain. The fact that two sympatric species sharing a common prey source exhibited different habitat use strategies suggests that at least one species was informed by something in addition to prey. Given that the two species are attuned to different aspects of the fjord habitat, their responses to habitat changes, including anthropogenic impacts, would likely be different in both nature and degree. Our findings highlight the value of comparative studies and the complexity of rorqual habitat use, which must be understood in order for critical habitat to be identified and protected.

ABC Triblock Copolymer Worms: Synthesis, Characterization, and Evaluation as Pickering Emulsifiers for Millimeter-Sized Droplets.

Polymerization-induced self-assembly (PISA) is used to prepare linear poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) [PGMA-PHPMA-PBzMA] triblock copolymer nano-objects in the form of a concentrated aqueous dispersion via a three-step synthesis based on reversible addition-fragmentation chain transfer (RAFT) polymerization. First, GMA is polymerized via RAFT solution polymerization in ethanol, then HPMA is polymerized via RAFT aqueous solution polymerization, and finally BzMA is polymerized via "seeded" RAFT aqueous emulsion polymerization. For certain block compositions, highly anisotropic worm-like particles are obtained, which are characterized by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The design rules for accessing higher order morphologies (i.e., worms or vesicles) are briefly explored. Surprisingly, vesicular morphologies cannot be accessed by targeting longer PBzMA blocks-instead, only spherical nanoparticles are formed. SAXS is used to rationalize these counterintuitive observations, which are best explained by considering subtle changes in the relative enthalpic incompatibilities between the three blocks during the growth of the PBzMA block. Finally, the PGMA-PHPMA-PBzMA worms are evaluated as Pickering emulsifiers for the stabilization of oil-in-water emulsions. Millimeter-sized oil droplets can be obtained using low-shear homogenization (hand-shaking) in the presence of 20 vol % n-dodecane. In contrast, control experiments performed using PGMA-PHPMA diblock copolymer worms indicate that these more delicate nanostructures do not survive even these mild conditions.

Complementary sex determination, inbreeding depression and inbreeding avoidance in a gregarious sawfly.

Although most Hymenoptera reproduce via arrhenotokous haplodiploidy, the underlying genetic mechanisms vary. Of these, the most widespread mechanism appears to be single-locus complementary sex determination (sl-CSD), in which individuals that are diploid and heterozygous at a sex-determining locus are female, and individuals that are homozygous or hemizygous are male. Because inbreeding increases the probability of producing diploid males, which are often sterile or inviable, sl-CSD can generate substantial inbreeding depression. To counteract this, Hymenoptera with traits that promote inbreeding, such as gregariousness, may evolve one or more of the following: inbreeding avoidance, functional diploid males or alternative sex determination mechanisms. Here, we investigate sex determination, inbreeding depression and inbreeding avoidance in Neodiprion lecontei, a gregarious, pine-feeding sawfly in the family Diprionidae. First, via inbreeding experiments and flow cytometry, we demonstrate that this species has CSD. By modeling expected sex ratios under different conditions, we also show that our data are consistent with sl-CSD. Second, via tracking survival in inbred and outbred families, we demonstrate that inbred families have reduced larval survival and that this mortality is partly attributable to the death of diploid males. Third, using a no-choice mating assay, we demonstrate that females are less willing to mate with siblings than nonsiblings. Together, these results suggest that inbreeding depression stemming from CSD has shaped mating behavior in N. lecontei. These results also set the stage for future comparative work that will investigate the interplay between sex determination, ecology and behavior in additional diprionid species that vary in larval gregariousness.

Improved Constraints on Cosmology and Foregrounds from BICEP2 and Keck Array Cosmic Microwave Background Data with Inclusion of 95 GHz Band.

We present results from an analysis of all data taken by the BICEP2 and Keck Array cosmic microwave background (CMB) polarization experiments up to and including the 2014 observing season. This includes the first Keck Array observations at 95 GHz. The maps reach a depth of 50 nK deg in Stokes Q and U in the 150 GHz band and 127 nK deg in the 95 GHz band. We take auto- and cross-spectra between these maps and publicly available maps from WMAP and Planck at frequencies from 23 to 353 GHz. An excess over lensed ΛCDM is detected at modest significance in the 95×150 BB spectrum, and is consistent with the dust contribution expected from our previous work. No significant evidence for synchrotron emission is found in spectra such as 23×95, or for correlation between the dust and synchrotron sky patterns in spectra such as 23×353. We take the likelihood of all the spectra for a multicomponent model including lensed ΛCDM, dust, synchrotron, and a possible contribution from inflationary gravitational waves (as parametrized by the tensor-to-scalar ratio r) using priors on the frequency spectral behaviors of dust and synchrotron emission from previous analyses of WMAP and Planck data in other regions of the sky. This analysis yields an upper limit r_{0.05}<0.09 at 95% confidence, which is robust to variations explored in analysis and priors. Combining these B-mode results with the (more model-dependent) constraints from Planck analysis of CMB temperature plus baryon acoustic oscillations and other data yields a combined limit r_{0.05}<0.07 at 95% confidence. These are the strongest constraints to date on inflationary gravitational waves.

Vermicious thermo-responsive Pickering emulsifiers.

Thermo-responsive vermicious (or worm-like) diblock copolymer nanoparticles prepared directly in n-dodecane via polymerisation-induced self-assembly (PISA) were used to stabilise water-in-oil Pickering emulsions. Mean droplet diameters could be tuned from 8 to 117 µm by varying the worm copolymer concentration and the water volume fraction and very high worm adsorption efficiencies (∼100%) could be obtained below a certain critical copolymer concentration (∼0.50%). Heating a worm dispersion up to 150 °C led to a worm-to-sphere transition, which proved to be irreversible if conducted at sufficiently low copolymer concentration. This affords a rare opportunity to directly compare the Pickering emulsifier performance of chemically identical worms and spheres. It is found that the former nanoparticles are markedly more efficient, since worm-stabilised water droplets are always smaller than the equivalent sphere-stabilised droplets prepared under identical conditions. Moreover, the latter emulsions are appreciably flocculated, whereas the former emulsions proved to be stable. SAXS studies indicate that the mean thickness of the adsorbed worm layer surrounding the water droplets is comparable to that of the worm cross-section diameter determined for non-adsorbed worms dispersed in the continuous phase. Thus the adsorbed worms form a monolayer shell around the water droplets, rather than ill-defined multilayers. Under certain conditions, demulsification occurs on heating as a result of a partial worm-to-sphere morphological transition.

Framboidal ABC triblock copolymer vesicles: a new class of efficient Pickering emulsifier.

Pickering emulsions offer important advantages over conventional surfactant-stabilized emulsions, including enhanced long-term stability, more reproducible formulations and reduced foaming problems. The recent development of polymerization-induced self-assembly (PISA) offers considerable scope for the design of a wide range of block copolymer nanoparticles with tunable surface wettability that may serve as bespoke Pickering emulsifiers. In the present study, we exploit PISA to design a series of model framboidal ABC triblock copolymer vesicles with exquisite control over surface roughness. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) were utilized to characterize these nanoparticles, which were subsequently used to stabilize n-dodecane emulsion droplets in water. The adsorption efficiency, Aeff, of the nanoparticles at the n-dodecane/water interface was determined as a function of increasing vesicle surface roughness using a turbidimetry assay. A strong correlation between surface roughness and Aeff was observed, with Aeff increasing from 36% up to 94%. This is a significant improvement in Pickering emulsifier efficiency compared to that reported previously for similar vesicles with smooth surfaces. In summary, nanoparticles with appreciable surface roughness are much more effective Pickering emulsifiers and this parameter can be readily fine-tuned using a highly efficient PISA formulation.

Are block copolymer worms more effective Pickering emulsifiers than block copolymer spheres?

RAFT-mediated polymerisation-induced self-assembly (PISA) is used to prepare six types of amphiphilic block copolymer nanoparticles which were subsequently evaluated as putative Pickering emulsifiers for the stabilisation of n-dodecane-in-water emulsions. It was found that linear poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) diblock copolymer spheres and worms do not survive the high shear homogenisation conditions used for emulsification. Stable emulsions are obtained, but the copolymer acts as a polymeric surfactant; individual chains rather than particles are adsorbed at the oil-water interface. Particle dissociation during emulsification is attributed to the weakly hydrophobic character of the PHPMA block. Covalent stabilisation of these copolymer spheres or worms can be readily achieved by addition of ethylene glycol dimethacrylate (EGDMA) during the PISA synthesis. TEM studies confirm that the resulting cross-linked spherical or worm-like nanoparticles survive emulsification and produce genuine Pickering emulsions. Alternatively, stabilisation can be achieved by either replacing or supplementing the PHPMA block with the more hydrophobic poly(benzyl methacrylate) (PBzMA). The resulting linear spheres or worms also survive emulsification and produce stable n-dodecane-in-water Pickering emulsions. The intrinsic advantages of anisotropic worms over isotropic spheres for the preparation of Pickering emulsions are highlighted. The former particles are more strongly adsorbed at similar efficiencies compared to spheres and also enable smaller oil droplets to be produced for a given copolymer concentration. The scalable nature of PISA formulations augurs well for potential applications of anisotropic block copolymer nanoparticles as Pickering emulsifiers.

Novel Pickering emulsifiers based on pH-responsive poly(2-(diethylamino)ethyl methacrylate) latexes.

The emulsion copolymerization of 2-(diethylamino)ethyl methacrylate (DEA) with a divinylbenzene cross-linker in the presence of monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA) at 70 °C afforded near-monodisperse, sterically stabilized PEGMA-PDEA latexes at 10% solids. Dynamic light scattering studies indicated intensity-average diameters of 190 to 240 nm for these latexes at pH 9. A latex-to-microgel transition occurred on lowering the solution pH to below the latex pKa of 6.9. When dilute HCl/KOH was used to adjust the aqueous pH, a systematic reduction in the cationic microgel hydrodynamic diameter of 80 nm was observed over ten pH cycles as a result of the gradual buildup of background salt. However, no such size reduction was observed when using CO2/N2 gases to regulate the aqueous pH because this protocol does not generate background salt. Thus, the latter approach offers better reversibility, albeit at the cost of slower response times. PEGMA-PDEA microgel does not stabilize Pickering emulsions when homogenized at pH 3 with n-dodecane, sunflower oil, isononyl isononanoate, or isopropyl myristate. In contrast, PEGMA-PDEA latex proved to be a ubiquitous Pickering emulsifier at pH 10, forming stable oil-in-water emulsions with each of these four model oils. Lowering the solution pH from 10 to 3 resulted in demulsification within seconds. This is because these pH-responsive particles undergo a latex-to-microgel transition, which leads to their interfacial desorption. Six successive demulsification/emulsification cycles were performed on these Pickering emulsions using HCl/KOH to adjust the solution pH. Demulsification could also be achieved by purging the emulsion solution with CO2 gas to lower the aqueous pH to 4.8. However, complete phase separation required CO2 purging for 4 h at 20 °C. A subsequent N2 purge raised the aqueous pH sufficiently to induce a microgel-to-latex transition, but rehomogenization did not produce a stable Pickering emulsion. Presumably, a higher pH is required, which cannot be achieved by a N2 purge alone.

Novel Pickering emulsifiers based on pH-responsive poly(tert-butylaminoethyl methacrylate) latexes.

Emulsion copolymerization of 2-(tert-butylamino)ethyl methacrylate in the presence of divinylbenzene (DVB) cross-linker and monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA) macromonomer at 70 °C afforded sterically-stabilized latexes at approximately 10% solids at pH 9. Dynamic light scattering and scanning electron microscopy (SEM) confirmed that relatively narrow size distributions were obtained. SEM confirmed the formation of spherical particles in the absence of any DVB cross-linker using a simple batch protocol, but in the presence of DVB it was necessary to use seeded emulsion polymerization under monomer-starved conditions to prevent the formation of latexes with ill-defined non-spherical morphologies. Lightly cross-linked latexes acquired cationic microgel character upon lowering the solution pH due to protonation of the secondary amine groups. Increasing the degree of cross-linking led to a progressively lower effective pK(a) of the copolymer chains from 8.0 to 7.3, which implies a gradual reduction in their basicity. Poly(tert-butylamino)ethyl methacrylate latex proved to be an effective Pickering emulsifier at pH 10, forming stable oil-in-water emulsions when homogenized with either n-dodecane or sunflower oil at 12,000 rpm for 2 min. These Pickering emulsions exhibited pH-responsive behavior: lowering the solution pH to 3 resulted in immediate demulsification due to the spontaneous desorption of the cationic microgels from the oil/water interface. Following rehomogenization at high pH, four successive demulsification/emulsification pH cycles could be achieved without a discernible loss in performance. However, no demulsification occurred on acidification of the fifth cycle, due to the progressive build-up of background salt.

Adsorption of sterically stabilized latex particles at liquid surfaces: effects of steric stabilizer surface coverage, particle size, and chain length on particle wettability.

A series of five near-monodisperse sterically stabilized polystyrene (PS) latexes were synthesized using three well-defined poly(glycerol monomethacrylate) (PGMA) macromonomers with mean degrees of polymerization (DP) of 30, 50, or 70. The surface coverage and grafting density of the PGMA chains on the particle surface were determined using XPS and (1)H NMR spectroscopy, respectively. The wettability of individual latex particles adsorbed at the air-water and n-dodecane-water interfaces was studied using both the gel trapping technique and the film calliper method. The particle equilibrium contact angle at both interfaces is relatively insensitive to the mean DP of the PGMA stabilizer chains. For a fixed stabilizer DP of 30, particle contact angles were only weakly dependent on the particle size. The results are consistent with a model of compact hydrated layers of PGMA stabilizer chains at the particle surface over a wide range of grafting densities. Our approach could be utilized for studying the adsorption behavior of a broader range of sterically stabilized inorganic and polymeric particles of practical importance.

Color and fatty acid profile of abdominal fat pads from broiler chickens fed lobster meal.

Consumer demands for food products enriched with healthful n-3 fatty acids are steadily increasing. Feeding marine byproducts may provide an economical means of increasing the long-chain n-3 content of broiler tissues. A study was conducted to evaluate the effect of dietary lobster meal (LM) on the color and fatty acid profile of broiler chicken fatty tissue. Broilers were fed increasing levels (0, 2, 4, 6, 8, and 10%) of LM for 35 d. Fat pad samples were collected at slaughter and color and fatty acid concentrations were determined. A linear effect was found of LM on red coloration (P < 0.05) as dietary LM increased. Fat pad eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels also increased (P < 0.0001) in a linear fashion. The essential long-chain fatty acids were lower for the 10% LM diet (0.37 mg of EPA/g; 0.16 mg of DHA/g) compared with the 8% LM diet (0.51 mg of EPA/g; 0.27 mg of DHA/g). Using lobster meal as a feed ingredient resulted in broiler abdominal fat pads with a favorable increase in n-3 fatty acids.

Preparation of Pickering emulsions and colloidosomes with relatively narrow size distributions by stirred cell membrane emulsification.

Stirred cell membrane emulsification has been used to prepare Pickering emulsions and covalently cross-linked colloidosomes using poly(glycerol monomethacrylate) stabilized polystyrene particles as the sole emulsifier. Pickering emulsions of 44-269 µm in size can be prepared with coefficients of variation as low as 25%, by varying the emulsification parameters. The cell membranes consisted of 5 µm pores with a pore-to-pore spacing of 200 µm. Significantly more uniform emulsions are produced when these open pores are restricted to a narrow ring around the membrane surface. Increasing the oil flux rate through this annular ring membrane increases both the size and polydispersity of the resulting emulsion droplets. There was no evidence for a "push off" force contributing to droplet detachment over the oil flux range investigated. Increasing the paddle stirrer speed from 500 to 1500 rpm reduces the average droplet diameter from 269 to 51 µm while simultaneously decreasing the coefficient of variation from 47% to 25%. Any further increase in surface shear led to droplet breakup within the dispersion cell and resulted in a significantly more polydisperse emulsion. The Pickering emulsions reported here have much narrower droplet size distributions than those prepared in control experiments by conventional homogenization (25% vs 74% coefficients of variation). Finally, low polydispersity colloidosomes can be conveniently prepared by the addition of an oil soluble polymeric cross-linker to the dispersed phase to react with the stabilizer chains.

Polyamine-functional sterically stabilized latexes for covalently cross-linkable colloidosomes.

Sterically stabilized polystyrene latexes were prepared by aqueous emulsion polymerization using a poly(ethylene imine) (PEI) stabilizer in the presence of 4-vinylbenzyl chloride (4-VBC; 1.0 wt % based on styrene). Partial quaternization of the amine groups on the PEI chains by 4-VBC occurs in situ, hence producing a chemically grafted steric stabilizer. Such 4-VBC-modified PEI chains were grafted more efficiently onto the polystyrene particles than unmodified PEI, as judged by aqueous electrophoresis, XPS, and nitrogen microanalysis. Moreover, partially quaternized PEI gave significantly smaller polystyrene particles than those synthesized in the absence of any PEI stabilizer or those synthesized using unmodified PEI. The partially quaternized PEI-stabilized polystyrene latex proved to be an effective emulsifier at pH 9, forming stable oil-in-water Pickering emulsions when homogenized (12,000 rpm, 2 min, 20 °C) with four model oils, namely, n-dodecane, methyl myristate, isononyl isononanoate, and sunflower oil. The primary and/or secondary amine groups on the PEI stabilizer chains were successfully cross-linked using three commercially available polymeric reagents, namely, tolylene 2,4-diisocyanate-terminated poly(propylene glycol) (PPG-TDI), poly(propylene glycol) diglycidyl ether (PPG-DGE), or poly(ethylene glycol) diglycidyl ether (PEG-DGE). Cross-linking with the former reagent led to robust colloidosomes that survived the removal of the internal oil phase on washing with excess alcohol, as judged by optical microscopy and SEM. PPG-TDI reacted very rapidly with the PEI stabilizer chains, with cross-linking being achieved during homogenization. Well-defined colloidosomes could be formed only by using sunflower oil and isononyl isononanoate with this cross-linker at 20 °C. However, cooling to 0 °C allowed colloidosomes to be formed using n-dodecane, presumably because of the slower rate of cross-linking at this reduced temperature. PPG-DGE proved to be a more generic cross-linker because it formed robust colloidosomes with all four model oils. However, cross-linking was much slower than that achieved using PPG-TDI, with intact colloidosomes being formed only after ∼12 h at 20 °C. The PEG-DGE cross-linker allowed cross-linking to be conducted at 20 °C from the aqueous phase (rather from within the oil droplets for the oil-soluble PPG-TDI or PPG-DGE cross-linkers). In this case, well-defined colloidosomes were obtained at 50 vol % with surprisingly little intercolloidosome aggregation, as judged by laser diffraction studies.

Parity violation constraints using cosmic microwave background polarization spectra from 2006 and 2007 observations by the QUaD polarimeter.

We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment's second and third seasons of observations by searching for a possible systematic rotation of the polarization directions of cosmic microwave background photons. We measure the rotation angle due to such a possible "cosmological birefringence" to be 0.55 degrees +/-0.82 degrees (random) +/-0.5 degrees (systematic) using QUaD's 100 and 150 GHz temperature-curl and gradient-curl spectra over the spectra over the multipole range 200

Use of diagnostic accuracy as a metric for evaluating laboratory proficiency with microarray assays using mixed-tissue RNA reference samples.

Effective use of microarray technology in clinical and regulatory settings is contingent on the adoption of standard methods for assessing performance. The MicroArray Quality Control project evaluated the repeatability and comparability of microarray data on the major commercial platforms and laid the groundwork for the application of microarray technology to regulatory assessments. However, methods for assessing performance that are commonly applied to diagnostic assays used in laboratory medicine remain to be developed for microarray assays. A reference system for microarray performance evaluation and process improvement was developed that includes reference samples, metrics and reference datasets. The reference material is composed of two mixes of four different rat tissue RNAs that allow defined target ratios to be assayed using a set of tissue-selective analytes that are distributed along the dynamic range of measurement. The diagnostic accuracy of detected changes in expression ratios, measured as the area under the curve from receiver operating characteristic plots, provides a single commutable value for comparing assay specificity and sensitivity. The utility of this system for assessing overall performance was evaluated for relevant applications like multi-laboratory proficiency testing programs and single-laboratory process drift monitoring. The diagnostic accuracy of detection of a 1.5-fold change in signal level was found to be a sensitive metric for comparing overall performance. This test approaches the technical limit for reliable discrimination of differences between two samples using this technology. We describe a reference system that provides a mechanism for internal and external assessment of laboratory proficiency with microarray technology and is translatable to performance assessments on other whole-genome expression arrays used for basic and clinical research.

Influence of stressors on normal intestinal microbiota, intestinal morphology, and susceptibility to Salmonella enteritidis colonization in broilers.

In modern poultry production systems, environmental stressors may influence bird performance and susceptibility to pathogens such as Salmonella Enteritidis. Experiments were conducted to determine the influence of 24-h feed withdrawal and 24-h exposure to high temperature (30 degrees C) on intestinal characteristics of broilers. Attachment of Salmonella Enteritidis to ileal tissue was determined using an in vitro ileal loop assay. Changes in commensal intestinal microbial populations were determined using denaturing gradient gel electrophoresis, and alterations in ileal morphology were determined histologically. Ex vivo attachment of Salmonella Enteritidis to ileal tissues increased by 1.5 logs (9.05 log10 vs. 7.59 log (10) Salmonella Enteritidis/g of ileal tissue; P = 0.0006) in broilers fasted for 24 h. Similarly, ileal tissues from birds subjected to 30 degrees C for 24 h had increased ex vivo attachment of Salmonella Enteritidis (8.77 log(10) vs. 8.50 log(10) Salmonella Enteritidis/g of ileum; P = 0.01) compared with birds held at 23 degrees C. Exposure to 30 degrees C for 24 h also altered microbial community structure in the ileum and cecum. Subjecting birds to 30 degrees C for 24 h reduced crypt depth (6.0 vs. 7.8 microm, respectively; P = 0.002), but had no effect on villus height or villus:crypt ratio. This research shows that acute stressors in poultry production systems can cause changes in the normal intestinal microbiota and epithelial structure, which may lead to increased attachment of Salmonella Enteritidis.

Feed withdrawal alters small-intestinal morphology and mucus of broilers.

In an effort to reduce carcass contamination and consequent reprocessing, market-age broilers are often subjected to feed withdrawal (FW) before processing to reduce intestinal content and intestinal ruptures during processing. However, little is known regarding the effects of FW on mucus content and intestinal morphology. Therefore, 2 experiments were conducted to determine the effects of FW on intestinal characteristics. Male broilers were raised in floor pens on standard industry diets to 42 and 39 d of age for Experiments (Exp.) 1 and 2, respectively. In Exp. 1, feed was removed 24, 12, 8, and 0 h before sampling, respectively (n = 5 birds/time). Birds remained on litter with access to water for the first 4-h of the FW period and were then placed in crates. Body weights, left pectoralis major weights, and distal ileal and jejunal segments were collected for determination of morphological characteristics. For Exp. 2, birds (n = 8 birds/time) were subjected to 0, 12, and 24 h of FW. Birds were injected with 5-bromo-2'-deoxyuridine and thymidine at 24 and 21 h, respectively, before sampling to determine epithelial cell migration rates. One-centimeter distal ileal segments were collected for mucus quantification at 0, 12, and 24 h. In Exp. 1, ileal villi heights were unaffected by FW, but villus width and crypt depth decreased with increasing FW time (P < or = 0.05). Jejunal villus height increased as FW progressed. Jejunal crypt depths increased until 12 h of FW and then declined at 24 h. Mucus content decreased linearly and was reduced by 46% from 0 to 24 h FW (P < 0.05). The intestinal morphology alterations and the depletion of intestinal mucus that occur during a short-term FW may reduce the integrity of the intestine.

Effect of dietary calcium and vitamin D3 on calcium and phosphorus retention in white Pekin ducklings.

Higher concentrations of Ca in the diet may decrease phytate-phosphorus hydrolysis because of chelation of Ca with the phytin molecule. In experiment 1, drakes were fed 0.74, 0.85, 0.95, or 1.11% Ca (analyzed) from 7 to 18 d of age (6 birds/cage, 8 cages/diet). Intestinal mucosa was collected at 18 d of age from birds fed 0.74 and 1.11% Ca for determination of intestinal phytase activity. In experiment 1, 17 d BW gain and feed consumption exhibited a quadratic response to increasing concentrations of Ca and were found to be maximal for ducks fed the 0.95% Ca diet. Toe ash percentage (18 d) had a quadratic response to increasing concentrations of Ca with a maximal response for birds fed the 0.85% Ca diet. Increasing dietary Ca did not affect P retention from 15 to 17 d of age or intestinal phytase activity and brush border vesicle Ca concentration. A positive correlation was found between the Vmax and the Ca concentration within the vesicles (r = 0.59, P < 0.02), suggesting that the vesicle Ca concentration did not negatively affect the kinetics of the phytase assay. In experiment 2, drakes were fed 0.6, 0.8, 1.0, or 1.2% Ca (formulated) with 826 or 8,260 ICU/kg of vitamin D3 from 0 to 13 d of age. There was no response to increasing concentrations of Ca for performance characteristics or bone ash measurements.

Performance and nutrient retention responses of broilers to dietary oxyhalogenic and ionic salts.

Two experiments were conducted to determine the effects of 2 ionic and antimicrobial mixtures on broiler performance and nutrient retention. In experiment 1, male broilers were fed 6 diets in a 2 x 3 factorial experiment (5 cages/diet, 9 chicks/cage) from 0 to 21d of age. Diets with 2 nutrient densities [normal industry diet (ND) and a low nutrient density diet (82% of ND)] and 3 ionic and antimicrobial mixtures [none (control) or 1 of 2 formulations containing different mixtures of ionic salts and oxyhalogenic compounds (sodium salts of chlorite, chlorate, chloride, borate, sulfate, bromide, salicylate, and hydrogen peroxide) at 4.4 mL/kg of feed (mix A and B)]. Birds fed mix B (568.6 g) were heavier (P < 0.05) at 21d of age than birds fed the control diet (501.7 g) and BW of birds fed mix A (536.1 g) did not differ from mix B or controls. Phosphorus and nitrogen retention from 18 to 20 d in birds fed mix B (78.05% and 82.23%, respectively) was greater (P < 0.05) than birds fed mix A (60.21 and 71.22%, respectively) and birds fed mix A had greater (P < 0.05) retention than birds fed the control diet (45.94 and 69.06%, respectively). In experiment 2, chicks were fed either 4.4 mL of mix B/kg feed, a diet with salinomycin and bacitracin, or a control diet. Birds fed the control or mix B diet had greater (P < 0.05) BW at 18 d than birds on the antibiotic treatment, whereas diet or nutrient retention differences were not present at 42 d of age. In conclusion, the ionic and antimicrobial mixtures improved performance and nutrient retention in young broilers but these did not last until market age.

The effects of copper on the efficacy of phytase, growth, and phosphorus retention in broiler chicks.

Copper is often added to broiler diets at prophylactic concentrations as an antimicrobial despite purported chelation with and reduced utilization of phytin phosphorus. Therefore, male chicks were fed 0, 62.5, 125, 250, or 375 ppm Cu from Cu sulfate in combination with 600 phytase units (FTU)/kg phytase from 9 to 22 d of age (6 cages/diet, 8 birds/cage). Nonphytate phosphorus (NPP) and Ca were formulated to 0.2 and 0.7% of the diet, respectively. Three additional control diets were formulated to contain 0.27, 0.34, and 0.40% NPP, each with 0.7% Ca. Birds fed increasing concentrations of Cu with 600 FTU phytase/kg had linear reductions in performance characteristics (P < or = 0.05). Birds fed increasing concentrations of Cu with 600 FTU phytase/kg had linear increases in toe ash percentage (P < or = 0.027), but tibia ash percentage was not affected (P > 0.05). Birds fed increasing Cu concentrations with 600 FTU phytase/kg had linear reductions in apparent P retention as a percentage of total P (P < or = 0.0005). Supplementation with increasing concentrations of Cu to a diet containing 600 FTU phytase/kg resulted in decreases in 21 d BW, BW gain, feed consumption, feed conversion, tibia and toe ash weights, and apparent P retention as a percentage of total P. In this experiment, Cu supplementation did not reduce the efficacy of phytase (i.e., improvement in apparent P retention with phytase supplementation) but did decrease apparent P retention, BW gain, feed consumption, feed conversion, and tibia ash and toe ash weights.