Effects of grain processing, forage to concentrate ratio, and forage particle size on rumen pH and digestion by dairy cows

Citation
Wz. Yang et al., Effects of grain processing, forage to concentrate ratio, and forage particle size on rumen pH and digestion by dairy cows, J DAIRY SCI, 84(10), 2001, pp. 2203-2216
Citations number
27
Categorie Soggetti
Food Science/Nutrition
Journal title
JOURNAL OF DAIRY SCIENCE
ISSN journal
00220302 → ACNP
Volume
84
Issue
10
Year of publication
2001
Pages
2203 - 2216
Database
ISI
SICI code
0022-0302(200110)84:10<2203:EOGPFT>2.0.ZU;2-L
Abstract
Dietary factors that alter the intake of effective fiber were evaluated for their effects on rumen fermentation, digestion, and milk production using a double 4 x 4 quasi-Latin square design with a 2(3) factorial arrangement of treatments. The dietary factors were extent of barley grain processing, coarse (1.60 mm) or flat (1.36 mm); forage-to-concentrate (F:C) ratio, low (35:65) or high (55:45) (dry matter basis); and forage particle length, lon g (7.59 mm) or short (6.08 mm). Eight lactating cows with ruminal and duode nal cannulas were offered ad libitum access to a total mixed diet and milke d twice daily. Dry matter intake was increased by increasing the extent of grain processing. Mean rumen pH was lower for cows fed flatly rolled barley than for cows fed coarsely rolled barley, whereas F:C ratio or forage part icle size had no effect on rumen pH. Rumen pH was not correlated with effec tive NDF intake but tended to be correlated with digestibility of starch in the rumen. Total tract digestibilities of dry matter, organic matter, star ch, and neutral detergent fiber were increased by feeding flatly rolled bar ley or low F:C ratio diets. Milk yield and milk protein content were higher in cows fed flatly rolled barley or low F:C ratio diets. Milk fat content tended to increase with high F:C ratio or long forage particle length but w as reduced by feeding flatly rolled barley. In this study, extent of grain processing and intake of ruminal available starch were the most influential factors affecting milk production. Reducing the ratio of F:C improved tota l digestion and actual milk production. Forage particle length had minimal impact on digestibility and milk production.