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