Blümmel, Michael

Dutta, N.

Pattanaik, A.K.

Prasad, K.V.S.V.

Sharma, K.

Viraktamath, B.

Prasad, Kodukula V.S.V.

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Prasad, K.V.S.V.1 , Pattanaik A.K.2, Dutta, N.2, Viraktamath,Prediction of the efficiency of in vitro ruminal microbialproduction of different cultivars of rice straw byNear Infrared Spectroscopy (NIRS)B.3, Sharma, K.2 and Blümmel, M1.1International Livestock Research Institute, South Asia Project, Patancheru 5023242Indian Veterinary Research Institute, Izatnagar 2431223Directorate of Rice Research, Hyderabad 500030Variable R2 SECt1/2 0.910 0.706PFOM 0.988 0.051TDOM 0.924 0.950ResultsMaterials and MethodsConclusionsInternational Livestock Research InstituteP.O. Box 307709, Nairobi, Kenyawww.ilri.orgPF analysis at t½ is quite laborious requiring first determinations of kinetics of in vitro gasproduction to obtain t½. Second the gas volume and TDOM (by NDS – refluxion) at t½need to be determined. The results presented in this work suggest that NIRS can besuccessfully used for the prediction of variations in the efficiency of microbial productionby PF analysis. This will result in considerable time and resource savings in laboratoryinputs.NIRS is successfully used in crop improvement programs to reduce often-laboriousconventional laboratory analyses. Chemical measurements, in vitro digestibilitymeasurements and more recently extent and rate of in vitro gas production were accuratelypredicted by NIRS. The present work explored the use of NIRS for the prediction of theefficiency of in vitro ruminal microbial production – an important fodder quality trait - incrop improvement programs.IntroductionNIRS instrument, scanning, calibration and validationThe NIRS instrument used was a FOSS Analyzer 5000 with software package WinISI II.After scanning the samples for their NIRS spectra, calibration – validation procedureswere developed in that half of a given set of sample was used to develop calibrationequations  from conventional laboratory analysis. These calibration equations werevalidated by predicting the laboratory measurements of  the second half of samples(blind-predictions). Agreement between NIRS predicted and actually measured laboratoryvalues were assessed by the coefficient of determination (R2) and by the standard errorof prediction (SEP). Outlier samples were reanalyzed.Crop residues investigatedA total of 108 rice straws from 32 cultivars consisting of leaves (36), stems (36) andwhole plants (36) were split into a NIRS calibration and validation set each consisting of54 straw samples.Estimation of  variations in the efficiency of microbial production by partitioningfactor (PF)Efficiency of ruminal microbial production was estimated by combined analysis of in vitrogas volumes  and true organic matter degradability measurements at times of microbialpeak production (Figures 1 and 2)  as the ratio of mg of organic matter truly degraded toml gas produced by it (partitioning factor, PF). Time of microbial peak production wasestimated as the time of half-maximum gas production (t½ ) using a derivation of thesigmoidal Gompertz model y = AS * exp(-exp[(2.718 MR *)*(LAG-t) + 1]). Proportional to the amountof substrate truly degraded low gas production, that is a high PF, indicates high efficiencyof microbial production and vice versa.The relationships between measured and NIRS blind-predicted halftime of gas production,true degradable organic matter and partitioning factor are presented in Figures 3, 4 and5. The range in t½ was 13.6 to 23.7 hrs (mean 18.4), in TDOM 46.2 to 60.1% (mean 52.4)and in PFOM 3.00 to 4.64 mg\ml (mean 3.71).The goodness of fit of calibration equations for halftime of gas production (t½), truedegradable organic matter (TDOM) and partitioning factor (PFOM)are reported in Table 1.Table 1: Goodness of NIRS calibration equations for variables t Ω, PFOM and TDOM

Prediction of the efficiency of in vitro ruminal microbial production of different cultivars of rice straw by Near Infrared Spectroscopy (NIRS)

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Prediction of the efficiency of in vitro ruminal microbial production of different cultivars of rice straw by Near Infrared Spectroscopy (NIRS)

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