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The use of near infrared reflectance spectroscopy to predict protein fractions in free-ranging cattle
Abstract
Research was conducted to assess the feasibility of using near infrared reflectance spectroscopy (NIRS) technology to predict fractional protein utilization in cattle on forage based diets. Forage samples were obtained from esophageal and ruminal cannulated cattle grazing native forage (warm and cool season), while fecal samples were acquired from non-fistulated animals grazing the same pastures as the fistulated animals Laboratory analysis for crude protein (CP), 20-hr in vitro protein digestibility, and acid detergent fiber nitrogen (ADFN) were conducted on extrusa, and calculated on a percent dry matter (%DM) basis. Indigestible intake protein (IIP) was considered to be the nitrogen (N) content in the residue from the ADF procedure. Degraded intake protein (DIP) and digestible undegraded protein (DUP) were calculated from ADFN, 20-hr in vitro, and CP content. Fecal sample spectra and forage laboratory analysis provided the dependent and independent variable data needed to conduct stepwise regression analysis and obtain predictive NIRS equations. Standard error of calibration (SEC) for warm-season DIP, DUP, and IIP were 0.96, 0.36, and 0.25, respectively. While coefficients of determination (W) for the same fractions were 0.81, 0.94, and 0.97, respectively. Wavelengths selected were biologically explainable, therefore the equations were deemed satisfactory for first generation predictive technology. Cool-season equations were found to be less encouraging and yielded le values for DIP, DUP, and IEP of 0.90, 0.39, and 0.78, respectively, while SEC values were 0.95, 0.50, and 0.24, respectively. The cool-season calibrated equations for DLTP and IIP were deemed unsatisfactory and need future work. A more robust dataset with greater standardization of lab technique and stricter sampling methods will be required to improve the DUP and IIP cool-season equations. NIRS technology proved to be a feasible means of providing estimations for protein utilization of distinct protein fractions in the gastrointestinal tract of freeranging cattle. However, the stability of these predictions is heavily dependent on forage type. These equations serve as first-generation predictive equations and should be upgraded through enhanced research to provide cattle producers with answers to increasing questions about the nutritional status of cattle on grazinglands.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references: p. 104-112.
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Citation
Whitley, Evan Micah (1996). The use of near infrared reflectance spectroscopy to predict protein fractions in free-ranging cattle. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1996 -THESIS -W538.
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