Carbohydrates – Basics
What is the most abundant nutrient class in animal diets?
Carbohydrates
Which enzyme breaks down starch in the small intestine?
Amylase
Where does carbohydrate fermentation occur in ruminants?
Rumen
Which chemical element is unique to proteins compared to carbohydrates and lipids?
Nitrogen
What are the two main protein fractions in the rumen?
RDP (rumen degradable protein) and RUP (rumen undegradable protein)
Which brain region regulates hunger and satiety?
Hypothalamus
What are the two main structural carbohydrates in plants?
Cellulose and hemicellulose
Which enzyme do ruminants lack for sucrose digestion?
Sucrase
Which volatile fatty acid is mainly produced from fiber fermentation?
Acetate
What is the formula used to estimate crude protein from nitrogen?
CP = N × 6.25
What is a common non-protein nitrogen source used in ruminant diets?
Urea
Which hormone stimulates appetite during fasting?
Ghrelin
Which monosaccharide is the main building block of hemicellulose?
Xylose
Which type of starch is more digestible due to its branched structure?
Amylopectin
Which volatile fatty acid serves as the main precursor for gluconeogenesis?
Propionate
What are amino acids that cannot be synthesized by the body called?
Essential amino acids
What protein is synthesized by rumen microbes from ammonia and energy?
Microbial protein (MCP)
How does dietary energy density affect feed intake?
Higher energy density reduces feed intake
What are the volatile fatty acids (VFAs) that provide 70–80% of the ruminant’s energy?
Acetate, propionate, and butyrate
What thermal processing method increases starch digestibility in corn and sorghum?
Steam-flaking
What disorder can occur when high-starch diets cause low rumen pH?
Acidosis
What environmental issue is associated with excess dietary protein?
Nitrogen pollution (ammonia, nitrate leaching)
What is the total absorbable protein in the small intestine called?
Metabolizable protein (MP)
What is the main physical factor limiting feed intake in ruminants fed high-forage diets?
Rumen fill (NDF content)
Which compound in legumes reduces fiber digestibility?
Lignin
Where does most glucose absorption occur in ruminants?
Small intestine (jejunum)
What energy compound is mainly produced from butyrate oxidation in the rumen epithelium?
Ketone bodies (BHBA)
What is the process that removes the amino group from an amino acid?
Deamination
What happens when protein degradation and carbohydrate fermentation are not synchronized?
Nitrogen loss as ammonia
How does heat stress affect feed intake?
It decreases feed intake