The Magical, Mystical
Rumen
Dr. L. E. Chase
Dept. 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
Anaerobic
Constant temperature = 39 C
pH = 6 to 6.6
Buffered by saliva
10-15 % dry matter
Constant 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 size
60-65% CP
80% of CP is true protein
Fiber digesting bacteria
Convert fiber to VFA’s (mainly acetate)
- Cellulose, hemicellulose
Like a higher rumen pH (>6)
Require ammonia as a nitrogen source
Slow 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 hour
Use ammonia, amino acids or peptides as
nitrogen sources
Rumen protozoa
105 - 106 per gram
20 - 200 um in size
May account for 50% of the total rumen
microbial mass
Not 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 environment
Constant temperature (99 - 106 0 F)
Food for the bugs
Neutral environment
Garbage removal
What Do the Bugs Provide?
Fiber digestion
High quality protein
VFA’s for energy and building blocks for
milk synthesis
Synthesis of B vitamins
Amino acid balancing
% of Protein Requirement
from Microbial Protein
100
80
g N/g OM
60
20
40
30
20
40
0
55
77
Milk, lbs/day
99
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?
Corn sil. – DM
Alf. Hay
Oat sil.
Wet brewers
Cracked corn
Ground corn
Ration A
16.2
2.2
3.5
4.8
9.5
Ration B
20
2.7
5
5
10.9
Economics of Microbial
Protein
SBM – 48
HT SBM
Soy Hulls
Anim. Prot.
Bypass Fat
Ration A
8
6
.5
.75
Ration B
7.5
0.5
Economics of Microbial
Protein
Milk, lbs/day
MP – bact., g
MP –RUP., g
Feed cost, $
IOFC, $
97
1369
1694
4.05
9.33
100
1582
1591
3.52
10.73
Microbial Composition
4.4%
12.0%
21.1%
62.5%
Protein
CHO
Fat
Ash
Urine
Liver
Milk
Recycled
Feed
Crude Protein
Urea
Recycled
Ammonia
Carbohydrates
VFA
Manure
Excess
Protein
Microbes
Escape
Feed
Protein
Dr. M. B. Hall - Univ. of Florida
Rume
n
Absorbed
Protein
Production
&
Maintenance
Ration, Eating Rate &
Saliva Production
Feed
Pellets
Eating,
Saliva,
lb/minute teaspoons/lb
0.79
1.0
Fresh grass
0.62
1.5
Silage
0.55
2.0
Dried grass
0.18
5.0
Hay
0.15
6.0
Forage Particle Size and
Chewing - Corn Silage
30
25
20
min/lb.
NDF
15
10
5
0
3/4 inch
1/2 inch
1/4 inch
Particle Size - Case Study
900 cow dairy
Things going well
Then a large number of fresh cow DA’s
within 1-2 weeks
Feed company was called by the producer
and asked what was wrong with the
ration
Corn Silage Particle Size
60
50
40
Bunker
% 30
Tower
20
10
0
Top
Middle
Pan
“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...
Environment
Effective
fiber
Rumen
Fermentable
Carbohydrates
Salivary buffers
Ruminal mixing
Acid production
Stall comfort
standing vs lying
Heat stress
Over-crowding
Diet 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