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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #131725
Title: RELATIONSHIP OF FORAGE FIBER CONTENT AND MECHANICAL STRENGTH TO PARTICLE SIZE REDUCTION DURING INGESTIVE MASTICATION BY STEERS

Author
item Jung, Hans Joachim
item BAKER, S - CSIRO PERTH AUSTRALIA

Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2002
Publication Date: 7/22/2002
Citation: JUNG, H.G., BAKER, S.K. RELATIONSHIP OF FORAGE FIBER CONTENT AND MECHANICAL STRENGTH TO PARTICLE SIZE REDUCTION DURING INGESTIVE MASTICATION BY STEERS. JOURNAL OF ANIMAL SCIENCE. 2002. V. 80 (SUPPL. 1) ABSTRACT P. 361.

Interpretive Summary:

Technical Abstract: Forage fiber content and mechanical toughness have been proposed as factors that limit particle size reduction and feed intake of ruminants. Three coarsely chopped forages were available ad lib to six mature rumen- fistulated steers. The oaten and mature alfalfa hays were similar in NDF concentration (42.4 and 41.5 % DM, respectively); the immature alfalfa hay contained less NDF (34.2 % DM). Acid detergent lignin content of the NDF fraction was higher for both the immature and mature alfalfa hays (12.3 and 12.8 % NDF, respectively) than the oaten hay (2.1 % NDF). Compression energy was higher for the mature alfalfa hay (3.86 kJ/kg DM) than for the oaten and immature alfalfa hays (3.64 and 3.57 kJ/kg DM, respectively). Shear energies were similar among the hays (7.34 kJ/m2). Hays were fed in a cross-over design. Ingestive boli were collected from each steer. Hay intake did not differ among the oaten and immature and mature alfalfa hays (9.4, 11.1, and 12.4 kg/d, respectively). Hay and boli samples were sieved into large, medium, and small particle fractions. The percentage of particles in the large particle fraction in the ingestive boli compared to the hays declined more for the mature alfalfa and oaten hays (-31.3 and -37.7 %, respectively) than for the immature alfalfa (-11.6 %). No differences for boli compared to hays were observed for the medium size fraction (4.2 % change), but the change in percentage of small particles in the boli of mature alfalfa and oaten hays (52.4 and 54.4 %, respectively) increased more than was observed for the immature alfalfa (13.4 %). Lower compression energy and reduced fiber concentration of immature alfalfa, but not fiber lignification, were associated with greater particle size reduction during ingestive mastication.