ARS | Publication request: Use of Near Infrared Reflectance Spectroscopy to Predict Intake and Digestibility in Bulls and Steers

Submitted to: Journal of Animal Science
Publication Type: Research Notes
Publication Acceptance Date: November 15, 2010
Publication Date: February 20, 2011
Citation: Huntington, G., Leonard, E.S., Burns, J.C. 2011. Use of Near Infrared Reflectance Spectroscopy to Predict Intake and Digestibility in Bulls and Steers. Journal of Animal Science. 89:1163-1166.

Interpretive Summary: Near infrared reflectance can be used to assess the chemistry of intact feed and fecal samples. The nature of feed and fecal samples reflect their nutritive value revealing how they (feed) may be consumed and digested or how they were process (fecal) by the animal. This study makes the application of the use of near-infrared reflectance spectroscopy (NIRS) to feed and fecal samples to back predict dry matter intake (DMI) and dry matter digestion (DMD). Bulls and steers were quantitatively feed a corn-silage based total mixed ration and estimates of DMD were calculate based on estimates of fecal output. These actual estimates of DMI and DMD were used to calibrate the NIRS to generate a calibration data set. The known data set was then used to predict DMI and DMD of another known data set based on the NIRS spectra of feed and fecal samples. It was evident that calibration must include some direct measures from the population to be predicted. The application of the technique would include collection of fecal samples from the population of interest, using NIR spectral criteria to identify and quantify how many direct measures need to added to the calibration data set. One would then proceed with obtaining fecal samples for those direct measures as well as fecal samples for prediction of the rest of the population. Proper calibration will provide an estimate of DMI and DMD of animals based solely on fecal grab samples weather on pasture or in dry-lot.

Technical Abstract: Fecal samples were collected from 282 growing Angus bulls over 4 yr to predict DMI of corn-silage-based diet. Contemporaneous digestion trials were conducted with the same diet in 12 steers for 3 yr and 12 bulls in 1 yr. Near-infrared spectra (n = 735 for growing bulls, n= = 240 for digestion trials) were obtained from dried and ground fecal samples, and were regressed against measured DMI and DMD. Although predicted DMI (7.66± 0.05 kg/d or 22.9 ± 0.1 g/kg BW) was within 3% of , measured DMI (7.84 ± 0.06 kg/d or 23.3 ± 0.1 g/kg BW) the difference (0.18 ± 0.04 kg/d or 0.4 ± 0.1 g/kg BW) was greater (P < 0.01) than zero. Measured DMD (72.3 ± 0.5 %) was identical (P < 0.97) to predicted DMD (72.3 ± 0.5 %), and DMD for bulls did not differ (P < 0.27) from DMD for steers. Near-infrared spectroscopy provided reliable predictions of DMI and DMD in bulls and steers.