Trends in feed evaluation for poultry with emphasis on in vitro techniques

Accurate knowledge of the actual nutritional value of individual feed ingredients and complete diets is critical for efficient and sustainable animal production.For this reason,feed evaluation has always been in the forefront of nutritional research.Feed evaluation for poultry involves several approaches that include chemical analysis,table values,prediction equations,near-infrared reflectance spectroscopy,in vivo data and in vitro digestion techniques.Among these,the use of animals(in vivo)is the most valuable to gain information on nutrient utilization and is more predictive of bird performance.However,in vivo methods are expensive,laborious and time-consuming.It is therefore important to establish in vitro methods that are reliable,rapid and practical to assess the nutritional quality of feed ingredients or complete diets.Accuracy of the technique is crucial,as poor prediction will have a negative impact on bird performance and,increase feed cost and environmental issues.In this review,the relevance and importance of feed evaluation in poultry nutrition will be highlighted and the various approaches to evaluate the feed value of feed ingredients or complete diets will be discussed.Trends in and practical limitations encountered in feed evaluation science,with emphasis on in vitro digestion techniques,will be discussed.

Influence of main dietary chemical constituents on the in vitro gas and methane production in diets for dairy cows

Background： Modification of chemical composition of diets fed to dairy cows might be a good strategy to reduce methane（CH4） production in the rumen. Notable reductions of CH4 production compared to conventional highroughages rations were more frequently observed for very concentrated diets or when fat supplements were used. In these cases, the reduction in the gas emission was mainly a consequence of an overall impairment of rumen function with a reduction of fiber digestibility. These strategies do not always comply with feeding standards used in intensive dairy farms and they are usually not applied owing to the risks of negative health and economic consequences.Thus, the present study evaluated the effects of seven commercial diets with contents of neutral detergent fiber（NDF）,protein and lipids ranging 325 to 435 g/kg DM, 115 to 194 g/kg DM, and 26 to 61 g/kg DM, respectively, on in vitro degradability, gas（GP）, and CH4 production.Results： In this experiment, changes in the dietary content of NDF, crude protein（CP） and lipids were always obtained at the expense or in favor of starch. A decreased of the dietary NDF content increased NDF（NDFd） and true DM（TDMd） degradability, and increased CH4 production per g of incubated DM（P 〈 0.001）, but not that per g of TDMd. An increase of the dietary CP level did not change in vitro NDFd and TDMd, decreased GP per g of incubated DM（P 〈 0.001）, but CH4 production per g of TDMd was not affected. An increased dietary lipid content reduced NDFd, TDMd,and GP per g of incubated DM, but it had no consequence on CH4 production per g of TDMd.Conclusions： It was concluded that, under commercial conditions, changes in dietary composition would produce small or negligible alterations of CH4 production per unit of TDMd, but greater differences in GP and CH4 production would be expected when these amounts are expressed per unit of DM intake. The use of TDMd as a standardizing parameter is proposed to account for possible difference in DM intake and productivity.

IgY technology: Methods for developing and evaluating avian immunoglobulins for the in vitro detection of biomolecules

The term“IgY technology”was introduced in the literature in the mid 1990s to describe a procedure involving immunization of avian species,mainly laying hens and consequent isolation of the polyclonal IgYs from the“immune”egg yolk(thus avoiding bleeding and animal stress).IgYs have been applied to various fields of medicine and biotechnology.The present article will deal with specific aspects of IgY technology,focusing on the currently reported methods for developing,isolating,evaluating and storing polyclonal IgYs.Other topics such as current information on isolation protocols or evaluation of IgYs from different avian species are also discussed.Specific advantages of IgY technology(e.g.,novel antibody specificities that may emerge via the avian immune system)will also be discussed.Recent in vitro applications of polyclonal egg yolk-derived IgYs to the field of disease diagnosis in human and veterinary medicine through in vitro immunodetection of target biomolecules will be presented.Moreover,ethical aspects associated with animal well-being as well as new promising approaches that are relevant to the original IgY technology(e.g.,development of monoclonal IgYs and IgY-like antibodies through the phage display technique or in transgenic chickens)and future prospects in the area will also be mentioned.

How old is too old? In vivo engraftment of human peripheral blood stem cells cryopreserved for up to 18 years-implications for clinical transplantation and stability programs

BACKGROUND Peripheral blood stem cells(PBSC)are commonly cryopreserved awaiting clinical use for hematopoietic stem cell transplant.Long term cryopreservation is commonly defined as five years or longer,and limited data exists regarding how long PBSC can be cryopreserved and retain the ability to successfully engraft.Clinical programs,stem cell banks,and regulatory and accrediting agencies interested in product stability would benefit from such data.Thus,we assessed recovery and colony forming ability of PBSC following long-term cryopreservation as well as their ability to engraft in NOD/SCID/IL-2 Rγnull(NSG)mice.AIM To investigate the in vivo engraftment potential of long-term cryopreserved PBSC units.METHODS PBSC units which were collected and frozen using validated clinical protocols were obtained for research use from the Cellular Therapy Laboratory at Indiana University Health.These units were thawed in the Cellular Therapy Laboratory using clinical standards of practice,and the pre-freeze and post-thaw characteristics of the units were compared.Progenitor function was assessed using standard colony-forming assays.CD34-selected cells were transplanted into immunodeficient mice to assess stem cell function.RESULTS Ten PBSC units with mean of 17 years in cryopreservation(range 13.6-18.3 years)demonstrated a mean total cell recovery of 88%±12%(range 68%-110%)and post-thaw viability of 69%±17%(range 34%-86%).BFU-E growth was shown in 9 of 10 units and CFU-GM growth in 7 of 10 units post-thaw.Immunodeficient mice were transplanted with CD34-selected cells from four randomly chosen PBSC units.All mice demonstrated long-term engraftment at 12 wk with mean34%±24%human CD45+cells,and differentiation with presence of human CD19+,CD3+and CD33+cells.Harvested bone marrow from all mice demonstrated growth of erythroid and myeloid colonies.CONCLUSION We demonstrated engraftment of clinically-collected and thawed PBSC following cryopreservation up to 18 years in NSG mice,signifying likely successful clinical transplantation of PBSC following long-term cryopreservation.

Establishment of an in vitro model using the rat alveolar macrophage cell line NR8383

OBJECTIVE:To establish an in vitro model of radiation-induced lung injury using rat lung alveolar macrophages(NR8383).METHODS:Using a medical electronic linear accelerator,cells were irradiated with either 0 Gy or 6 Gy X-rays.At 6,12,24,30 and 48 h,the DNA damage index(8-OHd G)and lipid damage index(MDA)were measured in the two groups.We also determined the levels of tumor necrosis factor-alpha(TNF-α),interleukin-6(IL-6)and transforming growth factor-β(TGF-β).RESULTS:The levels of 8-OHd G and MDA in the 6 Gy irradiation group were higher than those in the0 Gy group at 6,12,24,30 and 48 h after irradiation.The levels reached the highest value-6 h after irradiation,and then gradually decreased.The levels of the inflammatory factors TNF-α,TGF-βand IL-6 were higher in the 6 Gy irradiation group than those in the 0 Gy group at 6,12,24,30 and 48 h after irradiation.CONCLUSION:Six Gy X-ray irradiated NR8383 cells can be used to establish an in-vitro model of radiation-induced lung injury.The levels of 8-OHd G,MDA,TNF-α,TGF-βand IL-6 can be used as effective evaluation indicators.

Effect of New Dayuan powder on methicillin-resistant Staphylococcus aureus biofilms in vitro

OBJECTIVE:To observe the effects of New Dayuan powder(NDYP)on Methicillin-resistant Staphylococcus aureus(MRSA)biofilms and the embedded bacteria in vitro.METHODS:2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2 H-tetrazolium-5-carboxanilide(XTT)assays were used to study the effects of NDYP on developing MRSA biofilms:100μL of bacterial culture and100μL drug solution were added to wells of96-well plates.After 24 h of incubation,the plates were washed and XTT-phenazine methyl sulfate(PMS)was added to enable counting of the number of live bacteria in biofilms using a microplate reader.XTT assays were also used to explore the effects of NDYP on mature MRSA biofilms:100μL of bacterial culture were added to wells of 96-well plates.Bacteria were cultured in the plates for 24 h,and then drug solution was added.The plates were cultured for another 24 h,and then XTT-PMS was added to detect the number of live bacteria in the biofilms.Scanning electron microscopy(SEM)was used to observe the effects of NDYP on mature MRSA biofilms:washed and sterilized glass coverslips were added to 24-well plates.Bacterial culture was added.After 24 h of incubation,drug solution was added.After another 24 h of incubation,the samples were observed by SEM.RESULTS:XTT assays showed that the number of live bacteria in both developing and mature MRSA biofilms decreased significantly(P<0.01)after the administration of NDYP.SEM images showed that NDYP could destroy the structure of the bacteria and resulted in uneven thickness of MRSA biofilms.CONCLUSION:In vitro,NDYP has obvious inhibitory effects on the formation of MRSA biofilms and on mature biofilms.

Rumen liquor from slaughtered cattle as inoculum for feed evaluation

Use of nonlinear mathematical models has been majorly based on in vitro gas production(GP) data generated when substrates are incubated with rumen liquor from fistulated steers. However,existing evidence suggests that rumen liquor from slaughtered cattle of unknown dietary history also generates quantifiable in vitro GP data. Fitting and description of GP data obtained from 4 diets incubated with rumen liquor from slaughtered cattle was evaluated using single-pool exponential model with discrete lag time(EXPL), logistic(LOG), Groot's(GRTS) and Gompertz(GOMP) models. Diets were formulated by varying proportions of Rhodes grass(Chloris gayana) hay and a concentrate mixed on dry matter basis to be: 1,000 g/kg Rhodes grass hay(RGH) and 0 of the concentrate(D1), 900 g/kg RGH and 100 g/kg concentrate(D2), 800 g/kg RGH and 200 g/kg concentrate(D3), 700 g/kg RGH and 300 g/kg concentrate(D4). Dietary kinetics for the models were determined by measuring GP at 2,4.8,10.18,24.36,48.72,96 and 120 h. Model comparison was based on derived GP kinetics, graphical analysis of observed versus predicted GP profiles plus residual distribution and goodness-of-fit from analysis of root mean square error(RMSE), adjusted coefficient of determination(Adj-R^2) and Akaike's information criterion(AIC). Asymptotic GP, half-life and fractional rate of GP differed(P < 0.001) among the 4 models. The RMSE, Adj-R^2 and AIC ranged from 1.555 to 4.429,0.906 to0.984 and 2.452 to 15.874, respectively, forall diets compared across the 4 models. Based on the goodness-of-fit statistical criterion, GP profiles of D1 were more appropriately fitted and described by GRTS and GOMP than the EXPLand LOG models. The GRTS model had the lowest AIC value for D2(2.452). Although GRTS model had the most homogenous residual dispersion for the 4 diets, all the 4 models exhibited a sigmoidal behavior.Therefore, rumen liquor from slaughtered cattle of unknown dietary history can be used to derive nutritionally important feed parameters, but choice of the most appropriate model should be made based on fitting criteria and dietary substrates incubated.