scholarly journals COMPARISON OF NEAR INFRARED CALIBRATIONS FOR ESTIMATING IN VITRO DIGESTIBILITY IN WHOLE-PLANT CORN HYBRIDS

1987 ◽  
Vol 67 (2) ◽  
pp. 557-562 ◽  
Author(s):  
E. V. VALDES ◽  
R. B. HUNTER ◽  
G. E. JONES

A comparison of two near infrared (NIRA) calibrations (C1 and C2) for the prediction of in vitro dry matter digestibility (IVDM) in whole-plant corn (WPC) was conducted. C1 consisted of 40 WPC samples collected from four locations across Ontario (Brucefield, London, Guelph and Elora). C2 consisted of 90 samples and included the above locations plus Pakenham and Winchester. Nine wavelengths were used in both equations but only three were common in C1 and C2 equations. These wavelengths were 2139 nm, 2100 nm, and 1445 nm, respectively. The predictions of IVDM utilizing both C1 and C2 were good. Coefficients of determination (r2) and standard error of the estimate (SEE) for calibration and prediction sets were 0.91, 1.7; 0.85, 1.7 for C1 and 0.88, 1.6; 0.77, 1.6 for C2 respectively. Regression analysis within location, however, showed low r2 values for the prediction of IVDM for Pakenham and Winchester in both calibrations. The more mature stage of harvest at these locations might be the cause of the poorer predictions. Key words: In vitro digestibility, whole-plant corn, near infrared reflectance

1989 ◽  
Vol 69 (3) ◽  
pp. 833-839 ◽  
Author(s):  
S. S. BUGHRARA ◽  
D. A. SLEPER ◽  
R. L. BELYEA ◽  
G. C. MARTEN

Little information is available on estimating in vitro dry matter digestibility (IVDMD) of alfalfa (Medicago sativa L.) herbage by a prepared cellulase solution (PCS) and then using these IVDMD estimates to calibrate near infrared reflectance spectroscopy (NIRS) equations. Objectives were to compare PCS digestion to that by two rumen fermentation procedures, including true in vitro digestibility (TIVD), and develop NIRS equations to estimate TIVD, neutral detergent fiber, and acid detergent fiber of alfalfa hay. Seventy-eight alfalfa samples, having a wide range in herbage quality, were analyzed for IVDMD using five different PCS procedures and two rumen fermentation procedures (true and apparent in vitro digestibility). The best NIRS calibration equation for TIVD had R2 of 0.92 and a standard error of selection of 20.7 g kg−1. Correlations between IVDMD and TIVD obtained by the various PCS assays ranged from 0.91 to 0.96 (P < 0.01), with regression coefficients ranging from 0.94 to 0.98. We concluded that PCS gave rapid and accurate estimates of TIVD and that NIRS could accurately estimate TIVD of a wide range of alfalfa herbage quality.Key words: Acid detergent solubles, fungal cellulase solubles, in vitro digestible dry matter, Medicago sativa L., neutral detergent solubles, alfalfa


1987 ◽  
Vol 67 (3) ◽  
pp. 747-754 ◽  
Author(s):  
E. V. VALDES ◽  
R. B. HUNTER ◽  
L. PINTER

The prediction of quality parameters by near infrared reflectance analysis (NIRA) in whole-plant corn (Zea mays L.) was studied. Quality parameters included percent protein and in vitro dry matter digestibility (IVDMD). Calibrations were developed using two types of NIRA instruments: (a) a Neotec 51A, a six-tilting-filters type instrument and (b) a Technicon InfraAlyzer 400R, a 19-fixed-filters type instrument. Plant samples were collected from four locations across Ontario (Brucefield, London, Guelph and Elora). Forty samples were used in the calibration sets (C) for each quality parameter and for each instrument. A second group of samples, a prediction set (P) consisting of 200 samples, was used to validate the calibration equations. Regression analysis between NIRA predicted and IVDMD, indicated that this parameter was well predicted in both C and P sets and with the two instruments. Coefficients of determination (r2) for C and P sets were 0.91 and 0.85 for the InfraAlyzer 400R and 0.92, and 0.81 for the Neotec 51A, respectively. A standard error of the estimate (SEE) of 1.70 was observed for the prediction of IVDMD in both C and P sets with the InfraAlyzer 400R. Values of SEE for IVDMD using the Neotec 51A were 1.76 and 1.73 for C and P sets, respectively. NIRA predictions of percent protein showed differences between instruments. The r2 for C and P sets were 0.95 and 0.81 for the InfraAlyzer 400R and 0.90 and 0.58 for the Neotec 51A, respectively. The low r2 value for percent protein in the P set might be related to the mathematical treatment of the reflectance data chosen for the analysis. The SEE for the prediction of percent protein varied between 0.25 and 0.56.Key words: Corn (whole-plant), quality, infrared reflectance


1981 ◽  
Vol 61 (1) ◽  
pp. 45-51 ◽  
Author(s):  
J. E. WINCH ◽  
HELEN MAJOR

A Technicon Infra Alyzer 2.5, near infrared reflectance analyzer equipped with the six filters (1.68, 1.94, 2.10, 2.15, 2.23, 2.31 μm) which are used for the estimation of percent nitrogen, oil and moisture of grain crops was evaluated for the analyses of percent total nitrogen, in vitro and in vivo dry matter digestibility in grasses, legumes and grass-legume mixtures. Of the three quality parameters, only percent nitrogen was estimated with an acceptable degree of accuracy. The analyzer, therefore, has a potential for rapid nitrogen analysis of grasses, legumes and grass-legume mixtures. Correlation coefficients of 0.90 and above were obtained between infrared and Kjeldahl nitrogen when the nitrogen content of grasses or legume test samples was derived on either a grass or a legume calibration. A slight decrease in the standard error of prediction occurred when grass and legume calibrations were used to estimate nitrogen content of grass and legume samples, respectively. To insure accuracy, samples used to develop calibrations as well as those to be analyzed should be finely ground. In addition, the moisture content of the samples must be kept within the moisture range of the calibration.


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