Effect of forage particle size and concentrate level on chewing activity, ruminal fermenta-tion, digestibility and passage in dairy cows fed slightly restricted

Publication Type

Contribution to conference

Authors

Weber I., Zebeli Q., Tafaj M., Steingass H., Drochner W.

Year of publication

2007

Published in

Proc. Soc. Nutr. Physiol.

Editor

Gesellschaft für Ernährungsphysiologie

Pubisher

DLG-Verlags-GmbH , Frankfurt/M

Series/labeling

Proc. Soc. Nutr. Physiol.

Page (from - to)

64

Conference name

61. Tagung

Conference location

Göttingen

Conference date

06.-08.03.2007

Keywords

concentrate level, dairy cow, digestibility, forage particle size, rumen fermentation

Objectives: This study was designed to investigate the effects of varying dietary forage particle size on chewing activity, ruminal fermentation, total tract digestibility and passage in slightly restricted fed dairy cows at a low and high concentrate inclusion. Results: Altering the particle size of hay from 6 to 30 mm in a diet containing high concentrate amount increased by 4.5% the proportion of dietary DM retained on screen 1.18 mm and extended daily chewing or rumination time (Table 1). However, this treatment could not avoid ruminal pH dropping below 5.8 and acetate to propionate ratio declining (P = 0.02). This was also reflected by an increased fractional passage rate of solid digesta from reticulorumen and increased retention time in hindgut (P = 0.08), which in turn indicate a shift of fiber digestion from the reticulorumen to the lower digestive tract. Conclusion: It can be concluded that inclusion of coarsely chopped hay to the high concentrate diets does not appear to bring the expected advantages concerning the physical effectiveness in slightly restricted dairy cows. Chewing activity alone seems to be insufficient to assess dietary physical effectiveness, when dairy cows are fed high-concentrate diets, as offered in the present study.