Effects of sample size on neutral detergent fiber digestibility of triticale forages using the Ankom Daisy II Incubator system.
| Autor: | Coblentz WK; USDA-Agricultural Research Service, US Dairy Forage Research Center, Marshfield, WI 54449. Electronic address: wayne.coblentz@ars.usda.gov., Akins MS; Department of Dairy Science, University of Wisconsin, Madison 53706., Ogden RK; USDA-Agricultural Research Service, US Dairy Forage Research Center, Marshfield, WI 54449., Bauman LM; University of Wisconsin Soil and Forage Laboratory, Marshfield 54449., Stammer AJ; University of Wisconsin Soil and Forage Laboratory, Marshfield 54449. |
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| Jazyk: | angličtina |
| Zdroj: | Journal of dairy science [J Dairy Sci] 2019 Aug; Vol. 102 (8), pp. 6987-6999. Date of Electronic Publication: 2019 Jun 20. |
| DOI: | 10.3168/jds.2019-16681 |
| Abstrakt: | Accurate and precise determinations of fiber digestibility are essential for proper diet formulation for dairy cows. Our objectives were 3-fold: (1) regress in vitro neutral detergent fiber digestibility (NDFD) values from 48 triticale forages determined at multiple endpoints ranging from 12 to 240 h with Ankom Daisy II Incubator system (Ankom Technology Corp., Macedon, NY) methods using 0.25- or 0.50-g sample sizes on concentrations of fiber-related analytes or growth stage; (2) directly compare NDFD values determined with 0.25- or 0.50-g sample sizes by Ankom methods after 12-, 24-, 30-, 48-, 144-, or 240-h incubations; and (3) compare NDFD values determined by Ankom methods after 30 and 48 h of incubation with those determined by traditional sealed-tube procedures obtained from a commercial laboratory. Generally, plant growth stage, which was quantified with a linear model suitable for serving as an independent regression variable, proved to be a better predictor variable for NDFD than neutral detergent fiber or acid detergent lignin. For direct comparisons of 0.25- and 0.50-g sample sizes using Ankom methods, the regression relationship for a 30-h incubation was explained by a linear model [Y = 1.206x - 1.1; coefficient of determination (R 2 ) = 0.933], in which the slope differed from unity, but the intercept did not differ from 0. After a 48-h incubation, a linear model (Y = 1.014x + 7.1; R 2 = 0.964) indicated that the slope did not differ from unity, but the intercept was >0. A linear regression (Y = 1.040x - 1.8; R 2 = 0.861) of the 30-h incubation results obtained by Ankom methods using the 0.25-g sample size on those from the commercial laboratory indicated the slope and intercept did not differ from unity or 0, respectively. A similar relationship was obtained from the 48-h incubation (Y = 1.021x - 3.4; R 2 = 0.866). Relationships were poorer when the 0.50-g sample size was used by Ankom methods, particularly for the 30-h incubation, where the slope (0.824) was less than unity. Generally, NDFD values were greater for the 0.25-g sample size by Ankom methods, especially with 24-, 30-, and 48-h incubation times, and agreement with traditional sealed-tube methods was improved with the smaller sample size. Synchronization of results between Ankom and traditional methods needs to be further verified across a wider range of forages and harvest/preservation methods before definitive recommendations can be made. (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.) |
| Databáze: | MEDLINE |
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