Reference parameters of peripheral immune cell populations in broiler chickens using a large database

ABSTRACT

1. Peripheral blood immune evaluation of broilers by flow cytometry is commonly used in avian research. However, indicative immune parameters in healthy animals have not yet been determined. In this trial, confidence intervals were determined for several circulating immune cell subsets.

2. The intervals were determined from over 1,000 healthy broilers from commercial lines. To verify the usefulness of the data, they were compared to animals under salmonellosis or mycotoxin challenges.

3. Confidence intervals were determined for several immune cells in the peripheral blood of broilers. The importance of some immune cells in discriminating diseased from healthy controls was demonstrated.

4. This work initiated the construction of reference values for cellular parameters in broilers as a tool for the avian immunology community. Accordingly, the entire dataset of healthy animals was made available for use with other analyses and for improvement by others.     

Effect of diet on composition of cecal contents and on excretion and composition of soft and hard feces of rabbits

A total of 260 New Zealand White growing rabbits were used to study the effect of diet on chemical composition of cecal contents and on production and composition of soft and hard feces. Eight diets varying in their acid detergent fiber (9.8% to 32.7%) and starch (13% to 30%) levels were evaluated. The diet affected (P less than .01) all the variables studied, except dry matter (DM) and molar proportions of volatile fatty acids on cecal contents. An increase of dietary crude fiber increased crude fiber level in cecal contents (from 11.58% to 26.53%). However, a relatively lower proportion of fibrous material was found in the cecal contents when rabbits were fed the more fibrous diets. This suggests that dietary fiber has a direct influence on the efficiency of particle separation in the digestive tract. Crude protein and volatile fatty acid concentrations of cecal contents decreased (from 30.14% to 19.65% and from 47.8 to 36.7 mmol/liter, respectively) when dietary crude fiber increased. This could be related to availability of energy to cecal microorganisms. Ammonia concentration of cecal contents was not affected by dietary crude fiber. Daily production of soft feces varied from 14.98 to 29.59 g DM/d, and the contribution of soft feces to total DM and to crude protein intake ranged from 10.6% to 15.0% and from 12.8% to 20.5%, respectively; these values were the smallest and the largest for the least and the most fibrous diets, respectively. From this study we conclude that dietary fiber has a major effect on the digestive processes in the rabbit and that dietary starch level has no influence on any of the variables studied.     

Antigenic relationships of Moraxella bovis isolates recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina, Brazil, and Uruguay between 1983 and 2000

Cross-reactivity indices (CRIs) of 28 isolates of Moraxella bovis recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina (A, 11 isolates), Brazil (B, 7), and Uruguay (U, 10) between 1983 and 2000 were estimated. Hyperimmune sera were produced in rabbits and antibody titres determined with each isolate. Isolates showing CRIs³ 70 were placed in the same group. Group I had 13 isolates (A, 1; B, 6; U, 6); group II had 6 isolates (A, 4; U, 2); groups III, IV, and V had 2 isolates each, recovered in Argentina; group VI had 2 isolates, from Uruguay; and group VII had 1 isolate, from Brazil. The CRIs³ 70 between vaccine strains and isolates recovered before and after 1990 were 58% and 42%, 50% and 50%, and 33% and 67% with vaccine strains 2419, 2358, and 2439, respectively. Isolate 273, from Uruguay, showed CRIs > 70 with 78% of the isolates and is recommended as the vaccine strain.     

Thinking outside the patch: a multi-species comparison of conceptual models from real-world landscapes

Context

When modeling a species’ distribution, landscapes can alternatively be conceptualized following patch- or gradient-based approaches. However, choosing the most suitable conceptualization is difficult and methods for empirical validation are still lacking.

Objectives

To address the conditions under which a given conceptual model is more suitable, taking into account landscape context and species trait dependency effects. Patch- and gradient-based conceptualizations were built based on two structurally different landscapes: variegated and mosaic. We hypothesize that: (H1) gradient-based models better describe variegated landscapes while patch-based models perform better in mosaic landscapes; and (H2) gradient-based models will fit generalist species better while patch-based models will suit specialists better.

Methods

We modeled the distribution of eleven bird species in each landscape using each conceptualization. We determined the suitability of each conceptual model to fit statistical models by looking for cross-species responses and deviations from best models.

Results

We found no clear support for our hypotheses. Although patch-based models performed better in mosaic landscapes (H1), they also provided useful conceptualizations in variegated landscapes. However, when patches showed high heterogeneity, gradient-based approaches better fit specialist species (H2).

Conclusions

The suitability of a given conceptual model depends on the interaction between species habitat specialization, and the intrinsic spatial heterogeneity of the landscape and the ability of each conceptualization to capture it. Gradient-based models provide better information on resource allocation, while patch-based models offer a simplified perspective on landscape attributes. Future research should consider the nature of both species and landscapes in order to avoid bias from inadequate landscape conceptualizations.

     

Landscape-scale modelling of agroforestry ecosystems services in Swiss orchards: a methodological approach

Context

Agroforestry systems in temperate Europe are known to provide both, provisioning and regulating ecosystem services (ES). Yet, it is poorly understood how these systems affect ES provision at a landscape scale in contrast to agricultural practises.

Objectives

This study aimed at developing a novel, spatially explicit model to assess and quantify bundles of provisioning and regulating ES provided by landscapes with and without agroforestry systems and to test the hypothesis that agroforestry landscapes provide higher amounts of regulating ES than landscapes dominated by monocropping.

Methods

Focussing on ES that are relevant for agroforestry and agricultural practices, we selected six provisioning and regulating ES—“biomass production”, “groundwater recharge”, “nutrient retention”, “soil preservation”, “carbon storage”, “habitat and gene pool protection”. Algorithms for quantifying these services were identified, tested, adapted, and applied in a traditional cherry orchard landscape in Switzerland, as a case study. Eight landscape test sites of 1 km?×?1 km, four dominated by agroforestry and four dominated by agriculture, were mapped and used as baseline for the model.

Results

We found that the provisioning ES, namely the annual biomass yield, was higher in landscape test sites with agriculture, while the regulating ES were better represented in landscape test sites with agroforestry. The differences were found to be statistically significant for the indicators annual biomass yield, groundwater recharge rate, nitrate leaching, annual carbon sequestration, flowering resources, and share of semi-natural habitats.

Conclusions

This approach provides an example for spatially explicit quantification of provisioning and regulating ES and is suitable for comparing different land use scenarii at landscape scale.

     

Nutritional planning for Nellore heifers post-weaning to conception at 15 months of age: performance and nutritional,metabolic, and reproductive responses

Tropical Animal Health and Production - The objective of this study was to evaluate the effects of strategic supplementation in the dry period and dry/rainy transition period on the performance and...     

Intake,digestibility, microbial protein production,and nitrogen balance of lambs fed with sorghum silage partially replaced with dehydrated fruit by-products

Tropical Animal Health and Production - The objective of this study was to evaluate intake, digestibility, microbial protein production, and nitrogen balance of lambs fed with different dehydrated...     

Ingestive behaviour of steers grazing Brachiaria brizantha cultivar Marandu and in feedlot in Brazil

Tropical Animal Health and Production - The objective of this study was to evaluate the ingestive behaviour of steers grazing Brachiaria brizantha cv. Marandu and in feedlot regimen in Brazil....