The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

ABSTRACT

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance.

2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days.

3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age).

4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction).

5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present.

6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.     

Bovine arsenic toxicosis.

A ranch in central South Dakota had a number of dead calves because of arsenic poisoning. The clinical picture included diarrhea, central nervous system signs, and death. Gross necropsy findings included adequate body fat, stomachs full of normal-appearing ingesta, and large amounts of greenish brown watery fluid in the intestine and colon. Microscopically there was severe lymphoid tissue necrosis in the mesenteric lymph nodes and gut-associated lymphoid tissue. Chemical analysis of kidneys showed no significant amounts of lead; however, kidney arsenic concentrations were 25 to 44 ppm. The source was a small pile of Paris Green (common name for cupric acetoarsenite) found in an old dump site in the pasture.     

Wildfire Effects on Understory Vegetation,Natural Regeneration,and Forest Floor Fuels in a Sierran Mixed Conifer Stand

Wildfire effects on understory shrubs and herbs, regeneration of the seedling and sapling size classes, and downed and dead fuels were assessed in a mixed conifer stand located in the Lake Tahoe Basin in which California white fir (Abies concolor var. lowiana [Gord.] Lemm.) was most abundant but with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) also prevalent. In burned and unburned stand portions, prefire measurements served as a basis of comparison for the postfire measurements pertinent to each study component. Fire severely suppressed the understory vegetation, which was dominated by shrubs such as bush chinquapin (Chrysolepis sempervirens [Kellogg] Hjelmqvist) and antelope bitterbrush (Purshia tridentata [Pursh] DC.), while a tepid postfire recovery of most of the preexisting species in the burned stand portion was augmented by new ones, including shrubs such as snowbrush (Ceanothus velutinus Douglas ex Hook.) and whitethorn (Ceanothus cordulatus Kellogg) ceanothus and herbs such as Holboell's rockcress (Arabis holboellii Hornem.). Tree seedling abundance was also substantially reduced in the burned portion, but the postfire population was dominated by Jeffrey pine whereas white fir had been most prevalent originally. Sapling regeneration was eliminated from the burned stand portion regardless of species. Downed and dead fuel loading was severely diminished by the fire, especially regarding fine fuels, permitting subsequent sheet erosion to imperil new seedling regeneration. These results contribute to an understanding of the direction and pace of postwildfire succession on sites occupied by Sierra Nevada mixed conifer and similar forest cover types, which is critical in decisions concerning the need for, and extent of, postfire site rehabilitation measures.     

Light quality treatments enhance somatic seedling production in three southern pine species

Embryogenic cultures of loblolly pine (Pinus taeda L.), slash pine (Pinus elliottii Engelm.), longleaf pine (Pinus palustris Mill.) and slash pine x longleaf pine hybrids were initiated from immature seeds on an initiation medium containing 13.57 microM 2,4-dichlorophenoxyacetic acid and 2.22 microM benzylaminopurine. Embryogenic cultures proliferated and somatic embryos developed, matured and germinated following a modified protocol and media originally developed for radiata pine (Pinus radiata D. Don.) somatic seedling production. A discrete, light-sensitive pre-germination stage and a later germination (radicle emergence) stage were identified by the differential response of somatic embryos to light of different wavelengths. Different light quality treatments were applied during the pre-germination and germination steps, using cool white fluorescent bulbs or light-emitting diodes (LEDs), or both. In general, red wavelengths provided by LEDs during these steps resulted in higher frequencies of somatic embryo germination (up to 64%) and conversion (up to 50%), longer tap roots and more first-order lateral roots than the standard cool white fluorescent treatments or treatment with blue wavelengths from LEDs. In addition, exposure to red light allowed germination of somatic embryos of some clones that failed to produce germinants under fluorescent light. Germination and conversion were further enhanced by sequential application of cool white fluorescent light and red light, resulting in up to 100% germination and conversion in one experiment. Longleaf pine somatic embryos were especially responsive to the light quality treatments, resulting in the first report of somatic seedling production for this species.     

Spatial patterns of shrub cover after different fire disturbances in the Pyrenees

? Woody encroachment into grasslands is a worldwide phenomenon. In the Pyrenees, fire has been used as a management tool to transform part of the encroached land to grassland.

? This study aims to compare the spatial patterns of shrub cover 4 y after 4 different fire disturbances (prescribed burning, repeated prescribed burning, wildfire in 20 year-old shrubs and wildfire in 5 year-old shrubs); and also to compare shrub cover after different fire disturbances, accounting for spatial autocorrelation. The study focuses on the shrub Cytisus balansae. Two-dimensional transects (20 × 0.5 m) were established to monitor shrub cover for 4 y after each disturbance type. Autoregressive models and Markov models were used with a Monte Carlo procedure to account for the presence of spatial autocorrelation.

? Shrub cover was greater after prescribed burning than after repeated prescribed burning, and it increased with shrub age before disturbance. Differences in spatial patterns were detected in shrub patch size, with repeated prescribed fires and wildfires reducing shrub patch size by half in comparison with prescribed burning.

? From the management point of view, the effects of repeated prescribed burning were similar to those of a wildfire on reducing shrub cover and shrub patch size.

     

Effect of Ampicillin on E. Coli of Swine Origin

The in vitro susceptibility of 103 cultures of E. coli isolated from scouring and nonscouring pigs, and four cultures of Salmonella isolated from a case of necrotic enteritis was tested against Ampicillin contained in nutrient broth at concentrations of 0, 0.1, 1.0 and 5.0 uG per ml. of the medium. All but three cultures of E. coli were found to be susceptible to 5.0 uG/ml., all Salmonella isolates were also susceptible to this concentration of the antibiotic. Susceptibility of E. coli was also tested by plating dilutions of fecal samples obtained from either a scouring or a nonscouring pig, with E.M.B. agar containing 0, 0.1, 1.0, 2.5, 5.0 and 10.0 uG Ampicillin per ml. of the medium. No difference in the growth of E. coli was observed at 0, 0.1 and 1.0 uG concentrations. The three higher concentrations of the antibiotic inhibited the growth of E. coli proportional to the amount of Ampicillin in each concentration.

Ampicillin proved very effective in alleviating the symptoms of hemorrhagic enteritis in a 11-week old pig. The disappearance of scours was associated with the replacement of the previously existing sero-biotypes of fecal E. coliwith another aberrant type of E.coli which produced H₂S. No Ampicillin resistant strains of E. coli emerged following treatment of the animal with this antibiotic.

     

Impact of sampling and storage technique,and duration of storage,on the composition of fresh grass when analysed using near‐infrared reflectance spectroscopy

The objective of this study was to examine the effect of sampling technique (pluck or cut), storage duration (immediate analysis, 24‐h or 48‐h), storage temperature (ambient or chilled) and storage conditions (air present, air excluded or breathable) on the composition of fresh grass sampled from a sward managed to simulate grazing. Treatments were repeated across four sampling dates, with grass samples stored in grip seal bags prior to analysis using near‐infrared reflectance spectroscopy. Grass sampled by ‘pluck’ had a higher crude protein and ME content, and a lower acid detergent fibre (ADF) content, compared to that sampled by ‘cut’. Grass stored for 48 h had a lower water soluble carbohydrate (WSC) and ME content and a higher ADF content than for immediate analysis. Samples stored for 24 h did not differ from immediate analysis. Grass stored at ambient temperature had a lower WSC and ME content compared to immediate analysis. Grass stored under ‘breathable’ conditions had a lower ME content and higher ADF content than immediate analysis or samples stored with air present or air excluded. It is recommended that grass for analysis should be sampled by cutting, stored chilled (4°C) in a sealed bag to minimize exposure to oxygen and analysed within 24 h of harvest.     

Islands in the forest: effects of patch size and isolation on farmland bird species richness and community composition of farmland patches in forest landscapes

Landscape Ecology - Theory predicts that species diversity of isolated habitat patches depends on patch size and isolation. However, there are few previous studies of how patch size and isolation...     

EFFECT OF DAY-NIGHT TEMPERATURE REGIMES ON GROWTH AND MORPHOLOGICAL DEVELOPMENT OF TIMOTHY PLANTS DERIVED FROM WINTER AND SUMMER TILLERS

Winter (vernalized) and summer (non-vernalized) timothy tillers were grown to anthesis in day/night temperature regimes of 32/26°, 27/21°, 21/15°, and 15/10°C. Herbage and total plant yields, total leaf-blade number and area, and total plant growth-rate were highest, or very nearly so, in the 21/15°C regime for both the winter and summer plants. However, summer plants reached anthesis 13 to 14 days later than winter plants in each temperature regime. Even though virtually all primary shoots produced an infiorescence, summer plants had significantiy more leaves and leaf-blade area, produced significantiy higher yields of leaf blade, stem plus sheath, stubble, and root tissues and had a significantly higher total plant growth rate than winter plants in each temperature regime.