Effects of Grain Processing, Forage to Concentrate Ratio, and Forage Particle Size on Rumen pH and Digestion by Dairy Cows

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, long (7.59 mm) or short (6.08 mm). Eight lactating cows with ruminal and duodenal cannulas were offered ad libitum access to a total mixed diet and milked 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 particle size had no effect on rumen pH. Rumen pH was not correlated with effective NDF intake but tended to be correlated with digestibility of starch in the rumen. Total tract digestibilities of dry matter, organic matter, starch, and neutral detergent fiber were increased by feeding flatly rolled barley 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 was 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 total digestion and actual milk production. Forage particle length had minimal impact on digestibility and milk production.

Effect of rate of substitution of processed, urea-treated whole-crop wheat for grass silage on the intake, milk production and diet digestibility in dairy cows and ruminal metabolism in vitro

“…In general, feeding more rapidly digested starch sources such as wheat can cause a depression in ruminal pH and may lead to a reduction in DM intake (Grant, 1994). In the current study, despite starch intake increasing from approximately 1 kg/ day on W-0 to 4.6 kg/day on W-75, forage DM intake increased, although the highest level of starch intake recorded here was substantially lower than that reported in other studies (Overton et al, 1995;Yang et al, 2001).…”

Suitability of lupin and pea seeds as a substitute for soybean meal in high-producing dairy cow feed

“…However, the forage to concentrate ratio and DMI differed among diets. These factors are both negatively related to nutrient digestion [38] and, on the contrary to experiment 1, influenced digestibility measurements as well as the protein source. Similar nutrient digestibility in dairy cows receiving mixed diets with lupin or soybean meal as protein source were reported by Singh et al [35] where the forage to concentrate ratio, DM and CP intake did not differ.…”

“…In contrast to experiment 1, milk fat percentage was depressed with the lupin diet. This could be due to lower forage to concentrate ratios of lupinbased diets [38], inducing a modification of the rumen volatile fatty acid synthesis. However, milk fat depression was less pronounced with the lupin/pea diet.…”

<b>Performance of beef cattle bulls in feed lots and fed on diets containing enzymatic complex

“…It causes a greater ruminal digestion of starch with greater benefits in the diet (Yang et al, 2001;Zinn et al, 2002). The percentage of residual fecal starch was not influenced by supplementation with exogenous amylolytic enzymes of the treatments amylase and compound (Table 4).…”