Responses to sugars in dry or liquid form vary from study to study. To explain some of this variation and prioritize when sugars are more likely to have a benefit in diets for high producing dairy cattle, microbial function that influences susceptibility to low ruminal pH or a limitation in growth factors needed for efficient ruminal fiber degradation is discussed in this paper. When fed in pro...

INTRODUCTION When feeding grains to feedlot cattle, the goal is to maximize starch digestion while managing acidosis in order to provide optimal economic utilization of the finishing diet. Starch, the main component of grains, is digested primarily in the rumen with some digestion occurring in the small intestine and cecum. The small intestine is the preferred location of starch digestion to oc...

Succinic acid is a major end product of two cellulose-fermenting bacteria isolated in pure culture from the rumen of cattle and sheep. Ruminococcus flavefaciens, isolated by Sijpesteijn (1948, 1949, 1951), produced some 0-5 m-mole succinic acid per m-mole cellulose (calculated as glucose) fermented. Bacteroides succinogenes, isolated from the bovine rumen by Hungate (1950), was found by this au...

OBJECTIVE This study aims to identify the relationship between odd- and branched-chain fatty acids (OBCFAs) and microbial nucleic acid bases in the rumen, and to establish a model to accurately predict microbial protein flow by using OBCFA. METHODS To develop the regression equations, data on the rumen contents of individual cows were obtained from 2 feeding experiments. In the first experime...

The kinetics of allantoin metabolism were studied in rumen-cannulated sheep by means of a single intravenous injection of [4,5-(14)C]allantoin. The decline in the specific radioactivity of allantoin in plasma following the injection of tracer was best described by a double exponential function, indicating that allantoin moves in and out of two or more kinetically distinct compartments. Sequeste...

The objective of this experiment was to quantify ruminal digestive processes that could help to identify factors limiting DMI when silages differing in grass maturity were fed to dairy cows. Four silages were harvested at 1-wk intervals from a primary growth of a timothy-meadow fescue sward, resulting in feeds with digestible OM content in DM (D-value) of 739, 730, 707, and 639 g/kg in the orde...

Goat living in harsh environments represents a climax in the capacity of domestic ruminants to adjust to such areas. This ability is multifactorial: low body mass, and low metabolic requirements of goats can be regarded as an important asset to them for it minimise their maintenance and water requirements, in areas where water sources are widely distributed and food sources are limited by their...

We evaluated the effect of feed additives on the risk of ruminal acidosis in Holstein heifers (n = 40) fed starch and fructose in a challenge study. Heifers were randomly allocated to feed additive groups (n = 8 heifers/group): (1) control (no additives); (2) virginiamycin (VM); (3) monensin + tylosin (MT); (4) monensin + live yeast (MLY); and (5) sodium bicarbonate + magnesium oxide (BUF). Hei...

Elsden (1945) has shown that the volatile acids in the rumen fluid of sheep are chiefly acetic, propionic, and butyric. Barcroft, MoAnally, and Phillipson (1944) showed that the concentration of volatile acids in the blood draining the rumen was higher than that in the entering blood, indicating absorption from the rumen. Elsden postulated that propionic acid did not arise directly in cellulose...

The capacity of the rumen microbiota to produce volatile fatty acids (VFAs) has important implications in animal well-being and production. We investigated temporal changes of the rumen microbiota in response to butyrate infusion using pyrosequencing of the 16S rRNA gene. Twenty one phyla were identified in the rumen microbiota of dairy cows. The rumen microbiota harbored 54.5±6.1 genera (mean ...