CHO Metabolism. CHO Metabolism. CHO constitute 70% or more of the DM Major precursor of energy Partitioning CHO into fiber & non-fiber. CHO Metabolism. Optimal utilization of diets influenced by: - Chemical composition - Physical characteristics (particle size & density
- Chemical composition
- Physical characteristics (particle size & density
- Physical characteristics can influence: animal health, ruminal fermentation & utilization, &animal performance.
refer to ability of fiber to maintain milk fat production and animal health effectively
related to physical characteristics of fiber (primarily particle size) that influence chewing activity and the biphasic nature of ruminal contents (floating mat of large particles on a pool of liquid and small particles)
peNDF of a feed is the product of its NDF concentration and its physically effectiveness factor (pef)
peNDF is related to animal health and milk fat depression, because ruminal pH and the pattern of fermentation is a function of: production of salivary buffers during eating and rumination.
Chewing activity / Kg DM varies with: 1) breed, 2) size, 3) level of intake, 4) fiber content, and 5) particle size.
Effectiveness factor for NDF can vary from 0, when a feed has no ability to maintain milk fat percentage , to values greater than 1.0 when a feed maintain milk fat percentage more effectively than it maintain chewing activity.
Conversely, eNDF can be less than peNDF for feeds that detrimentally affect ruminal fermentation and milk fat production without affecting chewing activity (e.g., feeds containing sugars).
Because eNDF is related to intrinsic pH buffering and neutralizing capacity, fat concentration and composition, acid producing during fermentation, pH changes reflecting the balance of buffering capacity and acid production, shift in VFA amounts and ratio produced, and metabolic changes that influence secretion of milk fat
A simple system for estimating peNDF from chemical and physical measurements in the laboratory can be based on NDF concentration and the proportion of particles that are retained on a 1.18 mm sieve.
A hypothetical std that would result in the max amount of chewing/ Kg DM or NDF.
Chewing/ Kg of NDF increase as the NDF in long forage increase (Table 1).
Chopping forages to 4 cm reduced total chewing activity to 80% of the unchopped forage.
Total tract digestibility
direct: total fecal collection