Ruminant Nutrition

Steps in obtaining nutrients

• Ingestion: taking food into body

• Digestion: mechanical and chemical breakdown of food

• Absorption: passage of nutrients from digestive tract to bloodstream

“True” stomach

Abomasum, enzymatic digestion

Foregut

Rumen, reticulum, omasum; microbial digestion/fermentation

Hardware disease occurs in the

Reticulum

What are the 4 mechanical factors of digestion

• mastication

• Degluttion

• Rumination

• Eructation

What are the 4 phases of rumination?

• Regurgitation

• Remastication

• Reinsalivation

• Redegluttion

1 contraction every 1-2 minutes =

Rumination

Fermentation digestion takes place in the

• Rumen

• Reticulum omasum

• Large intestines

Enzymatic digestion takes place in the

Abomasum and small intestines

Ruminant digestion = microbial digestion, where the en goal is

Microbial population growth

Primary nutrients

1. Protein

2. Carbohydrates

3. Fats

4. Water

5. Vitamins and minerals

Protein

• Requirements vary

• Crude protein: quantity of nitrogen

  • Indicates if a feed will satisfy and animal’s protein needs

  • Not actual protein

• Rumen microbes synthesize microbial protein from all nitrogen containing substances ingested

At least what amount of CP intake should be natural protein?

2/3

No more than ___ or CP should be non-protein nitrogen (NPN) sources

1/3; urea’s - synthetic, made of two ammonia molecules

NPN should not constitute more than ____% of the diet

2

Ruminant nutrition requirement is met by

Microbes

Bacteria contain ____% protein

65%, >80% utilize ammonia as N source for growth

Ruminants prefer cooler weather because

They produce a lot of heat from their rumen

Structural vs non-structural carbohydrates

• Structural:

  • Fermented by microorganisms

    • Fiber

      • Cellulose

      • Hemocellulose

      • Pectin

• Non-structural:

  • Digested by enzymes

    • Concentrates

      • sugars

      • Starches

Rumen bacteria break down fatty acids via

• hydrolysis

• Hydrogenation

• Liver synthesis

• Small intestine absorption

Fats can come from

Corn oil, vegetable oil in feed

Dry matter content + moisture content =

100% fresh weight feedstuff

On average, cattle eat ___% of the BW in dry matter per day

2-3%

On fresh weight basis, cattle eat more ____ than ______ per day

• Silage (20-30% DM)

• Hay (80-90% DM)

Neutral detergent fiber (NDF)

• measures total plant fiber

  • Total plant cell wall components (cellulose, hemicellulose, lignin)

  • High NDF = lower DM intake

Neutral detergent soluble (NDS)

• Measures plant cell contents

  • CP, sugars, starches, organic acids

Acid detergent fiber (ADF)

• Measures indigestible parts of a plant

  • Cellulose, lining

  • High ADF = low energy, low digestibility

Total digestible nutrients (TDN)

• Measure of digestible components

  • Digestible protein and carbohydrates + 2.25x digestible EE

  • % of dry matter

  • Higher % TDN = higher digestibility

Forage analysis consists of

• Neutral detergent fiber (NDF)

• Neutral detergent soluble (NDS)

• Acid detergent fiber (ADF)

• Total digestible nutrients (TDN_

Gross energy

Total energy released through oxidation

Digestible energy

gross energy - energy lost in feces

Metabolizable energy

digestible energy - energy lost in urine and methane gas (Approximately 81% in ruminants)

Ruminants have a minimum/maximum energy value requirement

Minimum

Low energy concentration =

Can’t eat enough to meet energy demand

Low digestibility feeds are even less well digested with

Deficiencies of vitamins and minerals ; restrict microbe growth and ferment feed efficiently; grain vs cellulose

Ration formulation

• If you feed corn with CP of 9 but growth requirement is 12, you can add a supplement to the 9% that would increase it to an acceptable required level