The Magical, Mystical Rumen

Dr. L. E. ChaseDept. of Animal Science

Cornell University

Objectives of Feeding Dairy Cattle

Balanced Total Ration and Good Feed Management Maximize dry matter intakes Optimize milk production Good health and

reproduction PROFITABILITY!! Growth

Dairy Cattle Nutrition

What are we feeding?

A dairy cow?

Rumen bugs?

Bug Managers

Don’t think of it as feeding the cow,

you are feeding the bacteria or “bugs”

that live in the cow’s rumen.

The bugs in the rumen take the nutrients in

the feed and turn it into milk, milk fat & protein,

growth, and to nourish their growing calf.

The Rumen Environment

AnaerobicConstant temperature = 39 CpH = 6 to 6.6Buffered by saliva10-15 % dry matterConstant mixing = motility

Generalized equation for ruminal fermentation and metabolism

Carbohydrates + Rumen bugs +

Fiber fermentors Starch + sugar

fermentors Nitrogen sources +

Ammonia, peptides, and AA

Anaerobic environment + Good environment to

grow (pH, water, temperature)

Volatile Fatty Acids + Acetate, propionate,

butryate More rumen bugs +

Microbial protein Methane (CH4) + CO2 + H2O + Heat

=

Rumen Bacteria

109 - 1011 per gram 0.3 - 50 um in size60-65% CP80% of CP is true protein

Fiber digesting bacteriaConvert fiber to VFA’s (mainly

acetate) - Cellulose, hemicelluloseLike a higher rumen pH (>6)Require ammonia as a nitrogen

sourceSlow generation interval

- 8 – 10 hours to double

Sugar % Starch Digesting Bacteria

Convert sugars and starches to VFA’s- mainly propionate

Like a lower rumen pH (5.5 to 6)Rapid generation interval

- Can double in < 1 hourUse ammonia, amino acids or

peptides as nitrogen sources

Rumen protozoa

105 - 106 per gram20 - 200 um in sizeMay account for 50% of the total

rumen microbial massNot well understood

Cows & Rumens - A Symbiotic Relationship

Stage 1 - The cow provides housing & nutrients for microbial growth

Stage 2 - The host animal utilizes the rumen microorganisms passing to the intestines as a source of nutrients

What Does the Cow Provide?

Low oxygen environmentConstant temperature (99 - 106 0 F)Food for the bugsNeutral environmentGarbage removal

What Do the Bugs Provide?

Fiber digestionHigh quality proteinVFA’s for energy and building blocks

for milk synthesisSynthesis of B vitaminsAmino acid balancing

% of Protein Requirement from Microbial Protein

0

20

40

60

80

100

g N/g OM

55 77 99

Milk, lbs/day

203040

Rumen CHO/Protein Balance

Good amino acid management begins with good CHO management in order to produce a high & consistent amount of AA from microbes

Hoover

What’s the Economics of Microbial Protein?

Ration A Ration BCorn sil. – DM 16.2 20Alf. Hay 2.2 2.7Oat sil. 3.5 5Wet brewers 4.8 5Cracked corn 9.5Ground corn 10.9

Economics of Microbial Protein

Ration A Ration BSBM – 48 8 7.5HT SBM 0.5Soy Hulls 6Anim. Prot. .5Bypass Fat .75

Economics of Microbial ProteinMilk, lbs/day 97 100MP – bact., g 1369 1582MP –RUP., g 1694 1591Feed cost, $ 4.05 3.52IOFC, $ 9.33 10.73

Microbial Composition

62.5%21.1%

12.0%4.4%

ProteinCHOFat Ash

FeedCrude Protein

Rumen

Ammonia

Microbes

Escape Feed Protein

Urine

Manure

Recycled

CarbohydratesVFA

Liver

UreaMilk

Excess Protein

Recycled

Production & Maintenance

AbsorbedProtein

Dr. M. B. Hall - Univ. of Florida

Ration, Eating Rate & Saliva Production

Feed Eating,lb/ minute

Saliva,teaspoons/ lb

Pellets 0.79 1.0Fresh grass 0.62 1.5

Silage 0.55 2.0Dried grass 0.18 5.0

Hay 0.15 6.0

Forage Particle Size and Chewing - Corn Silage

0

5

10

15

20

25

30

min/lb. NDF

3/4 inch 1/2 inch 1/4 inch

Particle Size - Case Study

900 cow dairyThings going wellThen a large number of fresh cow

DA’s within 1-2 weeksFeed company was called by the

producer and asked what was wrong with the ration

Corn Silage Particle Size

0

10

20

30

40

50

60

%

Top Middle Pan

BunkerTower

“To Feed the Cow, You Need to First Feed the Bugs”

“Happy” Bugs = Milk, Health and Profit

The Manure is Your Mirror

What To Look For:

1. Corn Kernels

2. Grain

3. Long Pieces of Fiber

4. Consistency - shaving cream

The Big Balancing Act...

Effective fiber

Salivary buffersRuminal mixing

RumenFermentableCarbohydrates

Acid production

Environment

Stall comfort standing vs lyingHeat stressOver-crowdingDiet consistency Dr. W. Stone - Cornell University

Conclusion

Need a balanced ration of carbohydrates, protein, vitamins, minerals, fiber & effective fiber for optimal rumen function, microbial growth=maximum VFA production Milk yields Good health Milk components