Plant Nutritive Quality

Presentation 2 of Module 3

Recall that ruminants have a symbiotic relationship with microbes (i.e., bacteria and protozoa) that are housed in their rumen and allow them to digest cellulose. Non-ruminants do not have the ability to digest cellulose.

**Slide 3 - Energy

  • Gross -
  • Digestible -
  • Metabolizable -
  • NE Maintenance -
  • NE Productions -

**Slide 4 Cellulose vs Starch

  • Difference in bonds?
  • Cellulose is the major source of energy in plants that is used by grazing animals.

**5 Cell Walls vs Cell Contents

  • Hard to digest compounds in walls:
  • Easy to digest compounds in interiors

**6 -Neutral Detergent fiber

  • NDS --
  • NDF --
  • ADF ---

**7 What dose high NDF mean in terms of forage quality?

**8 How is NDF related to intake?

**9 What is ADF?

**10 What is In Vitro Digestible Dry Matter (IVDMD)?

**11&12 - In basic terms, what is NIRS?

**13 Protein - affect of age maturity

**14 Protein - forbs & shrubs vs grasses

Legumes vs other plants

**15 Why is crude protein "crude” instead of "true"?

**17 Vitamins -

What vitamin is the only commonly limiting vitamin?

**18 Minerals

Macro =

Micro =

**20 Grass vs Forbs

How do forbs, shrubs, and grasses compare in terms of protein value and digestibility?

**21 Herbaceous vs Wood

Important point -- wood is a indigestible complex of lignin and cellulose. Lignin is totally indigestible. And, lignin binds with cellulose making it indigestible.Because of this, woody stems are much less digestible and provide less energy than the stem of grasses or forbs.But remember, even the stems of herbaceous plants get "woody" as they matures.

Why do stems become less digestible as they mature?

**22 Cool vs Warm Season grasses

**23 Temperature

Are plants more nutritious if grown in mild temperatures or high temperatures?

**24 Soil Moisture

How does soil moisture affect forage quality?

Note -- I disagree with the presentation that drought often reduces forage quality. Plants growing dry conditions often concentrate nutrients in cells and can be more nutritious and digestible than in wet years. Thus, in drought ranchers often record surprisingly high weights of calves and lambs at the end of the season. In drought conditions, forage quantity is the problem, not quality.

**25 States of Maturity

Why do plants decrease in nutritive value as they mature?

**26 States of Maturity

Note that annual grass is a grass, (of course) filaree is forb, and bur clover is a legume

**27 States of Maturity

  • Early vegetative =
  • Late vegetative =
  • Early flowering =
  • Late flowering =
  • Mature =
  • Dry =
  • Dry, leached =

**28, 29, 30 -- Examples . Get main concepts, don't worry about details.

**31&32, Summary - make sure you understand the points in the summary