Technical note: A comparison of alkali treatment methods to improve neutral detergent fiber digestibility of corn stover

Abstract

The objective of this study was to compare neutral detergent fiber (NDF) digestibility of corn stover that had been treated by 2 alkali treatment methods. Two experiments were conducted to test a sodium hydroxide (NaOH) treatment method that uses an ethanol/water co-solvent (NaOH/ethanol-HO, United States Patent No. 20140220228) and a calcium hydroxide (CaOH) treatment method, which uses water as a solvent (CaOH/HO). An in situ trial was conducted to compare NDF digestion kinetics between NaOH/ethanol-HO-treated stover, CaOH/HO-treated stover, untreated corn stover, and soy hulls. The digestion rate of potentially digestible NDF (k) of NaOH/ethanol-HO-treated corn stover (5.36%/h) was higher than CaOH/HO-treated stover (2.27%/h), or untreated corn stover (1.76%/h) and similar to the k of soy hulls (4.93%/h). The indigestible NDF (iNDF) fraction of untreated corn stover (35.1% of NDF) was reduced by CaOH/HO treatment (27.3% of NDF) and by NaOH/ethanol-HO treatment (2.8% of NDF). The iNDF fraction in soy hulls (3.6% of NDF) was similar to iNDF of NaOH/ethanol-HO-treated stover. An in vivo digestibility trial was also conducted to compare fiber digestibility of diets supplemented with untreated corn stover, NaOH/ethanol-HO-treated corn stover, or soy hulls. Total-tract apparent dry matter (DM) and NDF digestibility were measured with 8 lactating Holstein cows in a replicated 4 × 4 Latin square with four 21-d periods. Apparent DM digestibility (DMD) was improved when supplemental soy hulls were added to the base diet (60.0% DMD) compared with the base diet with no supplemental fiber (57.7% DMD). Apparent DM digestibility was reduced when diets were supplemented with untreated stover (52.4%). Dry matter digestibility of NaOH/ethanol-HO-treated stover was similar (54.8% DMD) to all other treatments. Digestibility of NDF was lowest when cows were fed the diet with supplemented untreated stover (35.5% of NDF), and improved when soy hulls (40.6% of NDF) or NaOH/ethanol-HO-treated stover (43.8% of NDF) were added to the diets. The NaOH/ethanol-HO treatment process improves the DM and NDF digestibility of corn stover to values similar to those of soy hulls.

Adjusting for 30-hour undigested neutral detergent fiber in substitution of wheat straw and beet pulp for alfalfa hay and corn silage in the diet of high-producing cows

“…An in situ study was conducted to measure undigested NDF and NDFD in forages, BP, and TMR, according to the method described by Bender et al (2016) and Donnelly et al (2018;Table 1). Two ruminally cannulated nonlactating Holstein dairy cows were used and fed a high forage TMR diet (25% AH, 25% CS, 25% WS, 4.2% BP, 20.8% concentrate mix; DM basis) as recommended by Krizsan and Huhtanen (2013).…”

“…Dried samples were ground to pass a 1-mm Wiley mill (Arthur H. Thomas, Philadelphia, PA) screen, and 0.5 g of each sample was weighed into an Ankom F57 bag (Ankom Technology, Macedon, NY) with a pore size of 25 μm (Bender et al, 2016). This particular bag was selected so that digestibility estimates would be comparable with previously reported methods (Bender et al, 2016;Su et al, 2017;Donnelly et al, 2018) and the result replicable for practice condition. Samples were incubated in the rumen for 30, 240, and 288 h in triplicate along with 3 blank bags for each time point.…”

“…A log-residue value less than −3 was discarded as an invalid result (Bender et al, 2016). A linear regression based on the natural log residual values versus time was then fit to the data, and kd was determined as the slope of the regression (Donnelly et al, 2018).…”

Performance of dairy cows fed diets with similar proportions of undigested neutral detergent fiber with wheat straw substituted for alfalfa hay, corn silage, or both

“…An in situ study was conducted to measure uNDF and NDFD in forages, BP, and final TMR according to the method described by Bender et al (2016) and Donnelly et al (2018;Table 1). Two ruminally cannulated, nonlactating Holstein dairy cows were fed a high-forage TMR diet (25% AH, 25% CS, 25% WS, 4.2% BP, 20.8% concentrate mix; DM basis) as recommended by Krizsan and Huhtanen (2013).…”

“…Dried samples were ground to pass the 1-mm screen of a Wiley mill (Arthur H. Thomas, Philadelphia, PA), and 0.5 g of each sample was weighed into an Ankom F57 bag (Ankom Technology, Macedon, NY) with a pore size of 25 μm (Bender et al, 2016). This particular type of bag was selected so that digestibility estimates would be comparable with previous reports (Bender et al, 2016;Su et al, 2017;Donnelly et al, 2018). Samples were incubated in the rumen for 30, 240, and 288 h in triplicate along with 3 blank bags for each time point.…”