Zinc availability and digestive zinc solubility in piglets and broilers fed diets varying in their phytate contents, phytase activity and supplemented zinc source

The study was conducted to evaluate the effects of dietary zinc addition (0 or 15 mg/kg of Zn as inorganic or organic zinc) to three maize-soybean meal basal diets varying in their native Zn, phytic P contents and phytase activity (expressed in kg of feed: P− with 25 mg Zn and 1.3 g phytic P, P+ with 38 mg Zn and 2.3 g phytic P or P+/ENZ being P+ including 500 units (FTU) of microbial phytase per kg) in two monogastric species (piglets, broilers). Measured parameters were growth performance, zinc status (plasma, and bone zinc) and soluble zinc in digesta (stomach, gizzard and intestine). The nine experimental diets were fed for 20 days either to weaned piglets (six replicates per treatment) or to 1-day-old broilers (10 replicates per treatment). Animal performance was not affected by dietary treatments (P > 0.05) except that all P− diets improved body weight gain and feed conversion ratio in piglets (P < 0.05). Piglets fed P− diets had a better Zn status than those fed P+ diets (P < 0.05). In both species, Zn status was improved with supplemental Zn (P < 0.05), irrespective of Zn source. Phytase supplementation improved piglet Zn status to a higher extent than adding dietary Zn, whereas in broilers, phytase was less efficient than supplemental Zn. Digestive Zn concentrations reflected the quantity of ingested Zn. Soluble Zn (mg/kg dry matter) and Zn solubility (% of total Zn content) were highest in gizzard contents, which also presented lower pH values than stomach or intestines. The intestinal Zn solubility was higher in piglet fed organic Zn than those fed inorganic Zn (P < 0.01). Phytase increased soluble Zn in piglet stomach (P < 0.001) and intestine (P = 0.1), but not in broiler gizzard and intestinal contents. These results demonstrate (i) that dietary zinc was used more efficiently by broilers than by piglets, most probably due to the lower gizzard pH and its related higher zinc solubility; (ii) that zinc supplementation, irrespective of zinc source, was successful in improving animal's zinc status; and (iii) suggest that supplemented Zn availability was independent from the diet formulation. Finally, the present data confirm that phytase was efficient in increasing digestive soluble Zn and improving zinc status in piglets. However, the magnitude of these effects was lower in broilers probably due to the naturally higher Zn availability in poultry than in swin

Bioavailability of zinc sources and their interaction with phytates in broilers and piglets

Zinc (Zn) is essential for swine and poultry and native Zn concentrations in feedstuffs are too low to meet their Zn requirement. Dietary Zn bioavailability is affected by phytate, phytase and Zn supplemented in organic form is considered as more bioavailable than inorganic sources. A meta-analysis using GLM procedures was processed using broiler and piglet databases to investigate, within the physiological response of Zn, (1) the bioavailability of inorganic and organic Zn sources (Analysis I); (2) the bioavailability of native and inorganic Zn dependent from dietary phytates, vegetal and supplemental phytase activity (Analysis II). Analysis I: the bioavailability of organic Zn relative to inorganic Zn sources ranged, depending on the variable, from 85 to 117 never different from 100 (P > 0.05). The coefficients of determination of the regressions were 0.91 in broilers and above 0.89 in piglets. Analysis II: in broilers, bone Zn was explained by supplemental Zn (linear and quadratic, P 0.05). The coefficients of determination of the regressions were 0.92 in broilers and above 0.92 in piglets. The results from the two meta-analyses suggest that (1) broilers and piglets use supplemented Zn, independent from Zn source; (2) broiler use native Zn and the use is slightly enhanced with supplemental phytase; (3) however, piglets are limited in the use of native Zn because of the antagonism of non-hydrolyzed dietary phytate. This explains the higher efficacy of phytase in improving Zn availability in this speci

In vivo validation of the unified BARGE method to assess the bioaccessibility of arsenic antimony, cadmium and lead in soils

The relative bioavailability of arsenic, antimony, cadmium, and lead for the ingestion pathway was measured in 16 soils contaminated by either smelting or mining activities using a juvenile swine model. The soils contained 18 to 25 000 mg kg–1 As, 18 to 60 000 mg kg–1 Sb, 20 to 184 mg kg–1 Cd, and 1460 to 40 214 mg kg–1 Pb. The bioavailability in the soils was measured in kidney, liver, bone, and urine relative to soluble salts of the four elements. The variety of soil types, the total concentrations of the elements, and the range of bioavailabilities found were considered to be suitable for calibrating the in vitro Unified BARGE bioaccessibility method. The bioaccessibility test has been developed by the BioAccessibility Research Group of Europe (BARGE) and is known as the Unified BARGE Method (UBM). The study looked at four end points from the in vivo measurements and two compartments in the in vitro study (“stomach” and “stomach and intestine”). Using benchmark criteria for assessing the “fitness for purpose” of the UBM bioaccessibility data to act as an analogue for bioavailability in risk assessment, the study shows that the UBM met criteria on repeatability (median relative standard deviation value 0.6) for As, Cd, and Pb. The data suggest a small bias in the UBM relative bioaccessibility of As and Pb compared to the relative bioavailability measurements of 3% and 5% respectively. Sb did not meet the criteria due to the small range of bioaccessibility values found in the samples

Connaissance du devenir des éléments à risques dans les différentes filières de gestion des effluents porcins

Cet article résume les apports du programme "Porcherie verte" dans la connaissance et la maîtrise du devenir de l'azote, du phosphore et des éléments traces métalliques qui ont, à des titres divers, un impact sur l'environnement. La diminution de la teneur en protéines de l'aliment permet de réduire fortement les quantités d'azote excrétées par les animaux. Une part importante de l'azote est éliminée sous forme gazeuse lorsque les animaux sont placés sur litière ou lorsque le lisier est composté. L'importance de ces pertes d'azote peut cependant varier fortement selon les techniques utilisées et la nature des substrats. Le traitement biologique abat la majeure partie de l'azote et certains types de stations permettent de capter le reste dans des coproduits potentiellement exportables. La bonne valorisation agronomique des effluents nécessite de bien connaître leur valeur fertilisante azotée, ce que facilite l'approche typologique mise au point dans le cadre du programme. Un certain nombre de leviers alimentaires permettent de diminuer la fraction du phosphore alimentaire qui est excrétée dans les effluents: ajustement des apports alimentaires grâce à une meilleure connaissance des besoins des animaux, amélioration de la digestibilité du phosphore alimentaire par une meilleure connaissance de sa disponibilité dans les diverses matières premières ou via l'adjonction de phytase exogène. Les traitements biologiques avec séparation de phases permettent de capter le phosphore dans des coproduits potentiellement exportables et la valeur fertilisante phosphatée des effluents est en général très élevée et facile à prédire. Les éléments traces métalliques (cuivre et zinc) sont souvent ajoutés dans l'aliment à des concentrations dépassant largement les besoins stricts des animaux (pour éviter les carences) afin de bénéficier de leur effet protecteur vis-à-vis des pathologies digestives. La supplémentation par des éléments traces métalliques est utile pendant la phase de post-sevrage, mais pas au-delà et l'adjonction de phytase microbienne à l'aliment améliore la disponibilité du zinc pour l'animal. Les traitements biologiques avec séparation de phases permettent de capter le zinc et le cuivre dans des coproduits potentiellement exportables. Après épandage, les éléments traces métalliques sont peu mobiles dans le sol alors que les apports au sol excèdent en général largement les capacités d'exportation par les plantes, ce qui peut conduire à des situations de phytotoxicité à plus ou moins long terme. En fin de compte, la manière la plus simple et la plus économique de gérer les effluents d'élevage reste d'utiliser au mieux leur valeur fertilisante, ce qui s'obtient par un bon équilibre entre la quantité d'animaux produits et la capacité des sols à recevoir leurs effluents. En l'absence d'un tel équilibre, l'abattement de l'azote excédentaire par l'utilisation de litières ou par le compostage du lisier a un impact environnemental important alors même que ces solutions ne résolvent rien en termes de phosphore et d'éléments traces métalliques. Les traitements biologiques les plus sophistiqués permettent d'éliminer le phosphore et une partie des éléments traces métalliques dans des coproduits potentiellement exportables, mais ils ont un coût économique et écologique très élevé. (Résumé d'auteur

Metal stressors consistently modulate bacterial conjugal plasmid uptake potential in a phylogenetically conserved manner.

Published onlineJOURNAL ARTICLEThe environmental stimulants and inhibitors of conjugal plasmid transfer in microbial communities are poorly understood. Specifically, it is not known whether exposure to stressors may cause a community to alter its plasmid uptake ability. We assessed whether metals (Cu, Cd, Ni, Zn) and one metalloid (As), at concentrations causing partial growth inhibition, modulate community permissiveness (that is, uptake ability) against a broad-host-range IncP-type plasmid (pKJK5). Cells were extracted from an agricultural soil as recipient community and a cultivation-minimal filter mating assay was conducted with an exogenous E. coli donor strain. The donor hosted a gfp-tagged pKJK5 derivative from which conjugation events could be microscopically quantified and transconjugants isolated and phylogenetically described at high resolution via FACS and 16S rRNA amplicon sequencing. Metal stress consistently decreased plasmid transfer frequencies to the community, while the transconjugal pool richness remained unaffected with OTUs belonging to 12 bacterial phyla. The taxonomic composition of the transconjugal pools was distinct from their respective recipient communities and clustered dependent on the stress type and dose. However, for certain OTUs, stress increased or decreased permissiveness by more than 1000-fold and this response was typically correlated across different metals and doses. The response to some stresses was, in addition, phylogenetically conserved. This is the first demonstration that community permissiveness is sensitive to metal(loid) stress in a manner that is both partially consistent across stressors and phylogenetically conserved.The ISME Journal advance online publication, 2 August 2016; doi:10.1038/ismej.2016.98.We thank J Magid for access to the CRUCIAL field plot, LK Jensen for technical assistance in the laboratory and SM Milani for assistance in FACS sorting. This work was funded by the Villum Kann Rasmussen Foundation Center of Excellence CREAM (Center for Environmental and Agricultural Microbiology). UK is currently supported through an MRC/BBSRC grant (MR/N007174/1)