Particle size alterations of feedstuffs during in situ neutral detergent fiber incubation

Abstract

Particle size alterations during neutral detergent fiber (NDF) determination and in situ rumen incubation were analyzed by dry sieving and image analysis to evaluate the in situ procedure for estimation of NDF degradation parameters and indigestible NDF concentration in terms of particle size. Early-cut and late-cut grass silages, corn silage, alfalfa silage, rapeseed meal, and dried distillers grains were examined. Treatments were (1) drying and grinding of forage samples and grinding of concentrates; (2) neutral detergent-soluble (NDS) extraction; (3) machine washing and NDS extraction; (4) 24-h rumen incubation, machine washing, and NDS extraction; and (5) 288-h rumen incubation, machine washing, and NDS extraction. Degradation profiles for potentially degradable NDF were determined and image analysis was used to estimate particle size profiles and thereby the risk for particle loss. Particle dimensions changed during NDF determination and in situ rumen incubation and variations depended on feedstuff and treatment. Corn silage and late-cut grass silage varied most in particle area among feedstuffs, with an increase of 139% between 0 and 24h and a decrease of 77% between 24 and 288 h for corn silage and a decrease of 74% for late-cut grass silage between 24- and 288-h in situ rumen incubation. Especially for late-cut grass silage residues after 288 h in situ rumen incubation, a high mass proportion in the critical zone for escape was found. Particle area decreased linearly with increasing incubation time. Particle loss during in situ rumen incubation cannot be excluded and is likely to vary among feedstuffs.

Passage of stable isotope-labeled grass silage fiber and fiber-bound protein through the gastrointestinal tract of dairy cows

“…Digesta particle size was not measured in this study but effects of particle size on K 1 have been reported in the literature. For grass silage in particular, advancing plant maturity was observed to increase K 1 in line with a reduced digesta particle size and increased particle breakdown rate for the small particle pool in the rumen for a late-cut compared with an early-cut grass silage (Rinne et al, 2002;Krämer et al, 2013). Similarly, advancing maturity stage of grass silage considerably decreased the proportion of large particles (>1.0 mm) and increased that of small particles (0.2-0.5 mm) in feces (Jalali et al, 2012).…”

Review: Recent advances in evaluation of bags made from different textiles used in situ ruminal degradation

“…However, according to the results of this study, this recommendation seems not to be valid when F57 is used. By considering the maximal estimate of critical time for NDF (274.5 h) and adopting a multiple of 24 h to build an analytical recommendation, at least 288 h (12 d) are necessary to obtain a reliable estimate of the undegradable fraction of NDF, according to the results of and Kra¨mer et al (2013). Second, the greater critical times obtained with F57 and NWT compared with nylon were directly caused by lower degradation rates (Fig.…”

“…Different particle sizes are used in such procedures (Bowman and Firkins 1993;Nocek and Kohn 1988;Kra¨mer et al 2013). Nocek (1988) suggested using screen sieves of 2 mm and 5 mm for concentrate and forage to compensate the lack of rumination of samples.…”

Comparison of methods for estimating herbage intake in grazing dairy cows

“…Furthermore, lignin can be modified through the passage in the digestive tract (Fahey and Jung, 1983), and this can cause differences in recovery rate. Indigestible NDF can be lost from the dacron bags as particles during determination of INDF, and the particle loss might differ between feeds, and this might also lead to differences in recovery rate (Krämer et al, 2013). Simultaneous use of two internal markers could be an advantage in studies with part time grazing, but marker ratio must deviate substantially between herbage and barn feed, and furthermore recovery of markers should be known.…”