四个实验室应用滤袋技术检测阿根廷反刍饲料酸性和中型洗涤纤维的变异性

AGRICULTURAL MATERIALSVariability Among Four Laboratories of the Filter Bag Technique to Determine Acid and Neutral Detergent Fiber Contents in Ruminant Feeds from ArgentinaJ OSÉP.F AY and M ARÍA S.G UAITANational Institute of Agricultural Technology,Balcarce Agricultural Experiment Station,CC276,Balcarce,7620Argentina J OSÉL.D ANELÓNUniversity of Buenos Aires,College of Agronomy,Av.San Martín4453,Ciudad de Buenos Aires,1417ArgentinaS ONIA C HIFFLETCatholic University of Argentina,College of Agricultural Sciences,Ramón Freire183,Ciudad de Buenos Aires,1426 ArgentinaM ARISA W A WRZCKIEWICZUniversity of Buenos Aires,College of Agronomy,Av.San Martín4453,Ciudad de Buenos Aires,1417ArgentinaC AROLINA DÍAZCatholic University of Argentina,College of Agricultural Sciences,Ramón Freire183,Ciudad de Buenos Aires,1426 ArgentinaD EBORAH A.R OSSCornell University,Department of Animal Science,Ithaca,NY14853HÉCTOR M.F ERNÁNDEZNational Institute of Agricultural Technology,Balcarce Agricultural Experiment Station,CC276,Balcarce,7620ArgentinaThe objective of this work was to evaluate the filter bag technique(FBT)in an ANKOM200fiber analyzer to assess its accuracy for the determination of acid and neutral detergent fiber (ADF and NDF,respectively)contents in common ruminant feeds from the temperate region of Argentina.The evaluation was done in a ring test of4laboratories.The3Argentine laboratories were from the College of Agronomy,University of Buenos Aires,the College of Agricultural Sciences of the Catholic University of Argentina,and the Balcarce Agricultural Experiment Station of the National Institute of Agricultural Technology (INTA).The fourth laboratory was from the Department of Animal Science of Cornell University,Ithaca,NY.The feeds utilized were soybean meal expeller,whole sunflower seed,corn grain,herbages of alfalfa,ryegrass,tall wheatgrass,weeping lovegrass,guinea and barley grasses,and silages of corn and of a natural grassland.Results indicated that values obtained in the4laboratories were consistent regardless of the laboratory where the analyses were performed. It was concluded that the FBT in the ANKOM instrument gave satisfactory results when used for the determination of both ADF and NDF across samples having a wide range of fiber contents,and that the among-laboratories variability of this methodology was low.I n the United States and other countries,the methodologyof analysis of neutral detergent fiber(NDF)and acid detergent fiber(ADF)by the filter bag technique(FBT)in an ANKOM instrument(ANKOM Technology,Macedon, NY)has proven to be rapid and accurate(1,2).It involves a treatment with a thermally stable amylase(for NDF only),and in samples with high contents of lipids,a pretreatment with acetone.This technique has been tested with numerous feeds of different characteristics and origins(3).However,results obtained when ruminant feeds from the temperate region of Argentina are analyzed by this technique have not been reported.Due to the interest shown by several Argentine laboratories to adopt the FBT,the objective of this cooperative study was to evaluate the consistency of results for NDF and ADF obtained in4laboratories that are currently using this analytical methodology.ExperimentalLaboratoriesThe3participating laboratories from Argentina were from the College of Agronomy of the University of Buenos Aires (UBA),the College of Agricultural Sciences of the Catholic University of Argentina(UCA),and the Balcarce Agricultural Experiment Station(BAL)of the National Institute ofF AY ET AL.:J OURNAL OF AOAC I NTERNA TIONAL V OL.92,N O.2,2009371 Received May19,2008.Accepted by EB September4,2008.Corresponding author’s e-mail:pfay@.ar372F AY ET AL.:J OURNAL OF AOAC I NTERNA TIONAL V OL.92,N O.2,2009Table1.Neutral detergent fiber contents of11feeds as obtained in4different laboratoriesFeedNDF,average%±standard deviationLaboratoryUBA a UCA b BAL c COR dSoybean meal expeller12.07±0.1011.38±0.1610.71±0.1511.73±0.43 Sunflower seed45.72±0.3450.10±0.6944.17±0.1244.93±0.51 Alfalfa26.92±0.5526.82±0.6125.45±0.2126.65±0.37 Ryegrass47.30±0.8545.92±0.7943.69±0.1945.16±0.12 Tall wheatgrass68.34±0.4469.05±0.1967.94±0.1469.68±0.17 Corn silage50.52±0.1249.55±0.2345.16±0.7145.71±0.31 Grassland silage39.95±0.6838.95±0.8635.50±0.5135.26±0.59 Weeping lovegrass76.26±0.9176.24±0.1074.23±0.3376.00±0.37 Corn grain9.66±0.3010.07±0.108.22±0.539.03±0.50 Guinea grass68.69±0.1470.09±0.1168.60±0.4369.72±0.71 Barley grass60.00±0.5859.41±0.1256.54±0.4958.19±0.71a College of Agronomy,University of Buenos Aires,Argentina.b College of Agricultural Sciences,Catholic University of Argentina.c Balcarce Agricultural Experiment Station,National Institute of Agricultural Technology(INTA),Argentina.d Department of Animal Science,Cornell University,Ithaca,NY.Table2.Acid detergent fiber contents of11feeds as obtained in4different laboratoriesADF,average%±standard deviationLaboratoryFeed UBA a UCA b BAL c COR dSoybean meal expeller9.44±0.189.52±1.127.62±1.709.72±2.65 Sunflower seed35.17±0.5336.46±7.3034.63±0.1035.81±0.48 Alfalfa20.76±0.9921.16±0.8218.93±0.3622.44±1.04 Ryegrass27.53±0.3026.80±0.3225.61±0.3426.89±0.30 Tall wheatgrass38.98±0.2040.34±0.5638.09±0.5040.38±0.52 Corn silage30.28±0.7331.47±0.6128.49±0.6129.60±0.92 Grassland silage29.22±0.3431.77±1.3326.67±1.0029.61±0.95 Weeping lovegrass44.49±0.2646.63±1.2843.59±0.7346.24±0.44 Corn grain 3.43±0.28 3.99±0.25 2.80±0.47 4.29±0.32 Guinea grass46.06±0.6948.48±0.2845.89±0.3349.05±0.49 Barley grass35.67±0.9335.37±0.1733.81±0.5436.37±0.47a College of Agronomy,University of Buenos Aires,Argentina.b College of Agricultural Sciences,Catholic University of Argentina.c Balcarce Agricultural Experiment Station,National Institute of Agricultural Technology(INTA),Argentina.d Department of Animal Science,Cornell University,Ithaca,NY.Agricultural Technology(INTA).The laboratory of the Department of Animal Science of Cornell University at Ithaca,NY(COR)was the fourth source of data.This last laboratory was included in this ring test evaluation to have reference results obtained in an internationally renowned laboratory.FeedsEleven feeds in widespread use in Argentina were used: soybean meal expeller(an agroindustrial by-product)and whole sunflower seed(high lipid content).Other feeds included in the comparison were corn grain,herbages of alfalfa,ryegrass,tall wheatgrass(Thinopyum ponticum), weeping lovegrass(Eragrostis curvula),and silages of corn and of a natural grassland.These feeds were chosen because of the wide differences in their ADF and NDF contents. Guinea and barley grasses,2feed standards from the United States,were also incorporated in this study.The samples were dried at105°C to constant weight and ground in a Wiley mill to pass a1mm sieve.All samples were carefully homogenized,and the material was distributed in equal parts among the4laboratories(4,5).TechniqueThe FBT was performed utilizing a semi-automatic ANKOM200fiber analyzer,which allowed the simultaneous processing of11samples and2blank bags(6).The sunflower seeds were pretreated with acetone since they had a lipid content(301.6g/kg)greater than the50g/kg limit set in the method.Although the corn grain sample used also had a rather high lipid content(49.4g/kg),it was not pretreated with acetone since this value did not exceed the established limit. All the values of NDF and ADF were expressed as percent of the dry matter.Statistical AnalysisIn each laboratory,for each feed and type of analysis(NDF or ADF),4sets of duplicates were run in different periods (days)under the usual working conditions in the laboratory.Due to the lack of homogeneity of variances,an analysis of variance(ANOV A)was performed for each feed to test differences among laboratories.Mean results of each laboratory were compared with those obtained from BAL, which was the laboratory that systematically showed the lowest NDF and ADF values.The differences were considered significant when P<0.01.Finally,correlations among the results obtained in the4laboratories were estimated.Results and DiscussionThe results obtained in the4laboratories involved in this ring test comparative study are shown in Tables1and2.From the ANOV A of the NDF contents of each feed,it was observed that there were differences among the laboratories for the majority of the feeds except for tall wheatgrass(P=0.011), guinea grass(P=0.116),and solvent-extracted soybean meal (P=0.029).Regarding ADF,the differences among the laboratories were significant for all the feeds except for solvent-extracted soybean meal(P=0.194)and sunflower seeds(P=0.020).These differences did not respond to a common pattern in relation to the chemical composition of the feeds since this group included feeds with very different NDF and ADF contents.It is more likely that the high sensitivity of the ANOV A,due to the small coefficient of variation of results (<6%),could explain the significance of the differences observed.However,the magnitude of such differences would have little practical relevance in ruminant nutrition.For all of the feeds,the NDF and ADF values from BAL were systematically lower(P<0.01)than those obtained in the other laboratories,the exception being NDF grassland silage;also,the standard errors were generally lower at BAL. These differences could be attributed to the chemical composition of the tap water used to wash the fiber residues, which obviously was not the same in all of the laboratories, because in Argentina contents of salts in tap water vary considerably according to location.This,in turn,could have affected the weight of the washed residues due to differentF AY ET AL.:J OURNAL OF AOAC I NTERNA TIONAL V OL.92,N O.2,2009373 Table3.Pearson’s coefficients of correlation(r)among NDF values of the4laboratoriesLaboratoryLaboratoryUBA a UCA b BAL c COR dUBA1UCA0.9981BAL0.9970.9981COR0.9960.9960.9991a College of Agronomy,University of Buenos Aires,Argentina.b College of Agricultural Sciences,Catholic University of Argentina.c Balcarce Agricultural Experiment Station,National Institute of Agricultural Technology(INTA),Argentina.d Department of Animal Science,Cornell University,Ithaca,NY.Table4.Pearson’s coefficients of correlation(r) among ADF values of the4laboratoriesLaboratoryLaboratoryUBA a UCA b BAL c COR d UBA1UCA0.9981BAL0.9990.9971COR0.9970.9970.9981a College of Agronomy,University of Buenos Aires,Argentina.b College of Agricultural Sciences,Catholic University of Argentina.c Balcarce Agricultural Experiment Station,National Institute of Agricultural Technology(INTA),Argentina.d Department of Animal Science,Cornell University,Ithaca,NY.amounts of salts retained by the same feeds when analyzed in laboratories that were located in different places,as was the case in this work.For the4participating laboratories,standard errors oscillated within a range of0.27to1.25for NDF and from 0.37to 1.02for ADF.This shows that,in general,the variability was low.The correlations among laboratories are presented in Tables3and4.These values suggest that results obtained for NDF and ADF with the ANK were highly correlated(P<0.01)among the laboratories included in this evaluation.In each laboratory,samples were processed in different periods and in the same manner that all samples are routinely processed.Therefore,the absence of systematic errors or periodic variations(across a laboratory),and also the repeatability of results within laboratories,could be assumed. Further,uncontrolled variations within laboratories were small compared with variations among laboratories. Differences among laboratories were comparatively stable, despite the important differences in the means of NDF and ADF for the different feeds.Results indicate that values obtained in the4laboratories were consistent,independent of the laboratory where the analyses were performed.It is concluded that the FBT with the ANKOM200instrument produced satisfactory results with feed samples from Argentina.The interlaboratory variability for either the NDF or the ADF contents of these feeds was similar to the variability reported in previous studies in which other feeds from different regions were analyzed. AcknowledgmentsWe thank ANKOM Technology,Macedon,NY,for providing the reagents and filter bags and for the equipment calibration in the Argentinean laboratories.References(1)Komarek,A.R.(1993)Publication No.101,ANKOMTechnology,Macedon,NY,pp1–10(2)V ogel,K.P.,Pedersen,J.F.,Masterson,S.D.,&Toy,J.J.(1999)Crop Sci.39,276–279(3)Berchielli,T.T.,Paziani,S.F.,Oliveira Sader,A.P.,Tonani,F.L.,&Andrade,P.(2001)Proceedings of the XVII Meetingof the Latin-American Association of Animal Production,Article NA036,Havana,Cuba(4)Dux,J.P.(1990)Handbook of Quality Assurance for theAnalytical Chemistry Laboratory,V an Nostrand Reinhold,New York,NY(5)Johnston,R.K.,&V alente,R.M.(2001)Specifying andEvaluating Analytical Chemistry Quality Requirements forEcological Risk Assessments,/Docs/MESO-01-TM-01.pdf(Scirus08/27/03)(6)Komarek,A.R.,Robertson,J.B.,&V an Soest,P.J.(1994)J.Dairy Sci.77(Suppl.1),114374F AY ET AL.:J OURNAL OF AOAC I NTERNA TIONAL V OL.92,N O.2,2009。