The Rumen & the (TMR)

Wagon Part II

Chemical & Effective Fibres

When dairy nutritionist talk about chemical & effective fibres nutrition they are generally

referring to:

ADF, NDF, NSC and eNDF.The names refer to the types of detergent solutions

that are used to measure the forage fibre in an analysis laboratory

ADF & NDF: The Chemical Fibres

The ADF fraction contains a higher proportion of true indigestible or slowly digestible

cellulose & lignin.

ADF is a good indicator of plant or dry matter digestibility. The higher the ADF, the less

digestible the forage or ration will be.

ADF & NDF: The Chemical Fibres

The NDF fraction contains all of the fibre components that represent “bulk”.

NDF is a good indicator of the “dry matter intake” ability of a forage or feed. The higher

the NDF, the less an animal can consume.

ADF & NDF: The Chemical Fibres

ADF & NDF: The Chemical Fibres

NSC (Non structural carbohydrate)

NSC describes the non-NDF fraction and is composed primarily of sugar, starch and

pectin.

In rations for high production groups (i.e. >30-35 kg/head/day), I like to see NSC %

between 35% and 40%.

Ideally I do not like to see NSC > 37%

ACIDOSIS!!!

ACIDOSIS!!!

Diets that are rapidly fermented in the rumen lead to rapid production of VFA (i.e. NSC>

38% or deficient in eNDF).

When VFA production exceeds the ability of the rumen environment to neutralize or

absorb the acids, sub-acute ruminal acidosis occurs.

An episode of ruminal acidosis occurs when the pH in the rumen drops 5.8.

ACIDOSIS!!!

I am extremely cautious with my herds to avoid acidosis.

The recovery period is 1-3 years and the cost to the producer in terms of herd health and

productivity is huge!

Effective Fibre: The Physical Fibre (eNDF)

When nutritionist talk about the physical attributes of fibre they refer to it as the

“effective fibre”.

Historically, fibrousness was related to chewing activity and effectiveness was

related to milk fat depression.

Effective Fibre: The Physical Fibre (eNDF)

When eNDF is decreased or inadequate: Less chewing by animal Less salivary buffer secreted More rumen acid produced Reduced ruminal pH Shift in microbial populations & end

products of fermentation (>propionic acid,<acetic acid)

Milk fat depression Acidosis, sick & unproductive animals

(long term!)

Effective Fibre: The Physical Fibre (eNDF)

This tenuous situation is further complicated by the trend towards finely cut and

processed forages, and a range of by-products that offer very little chemical or

effective fibre

Penn State Shaker Box

Particle Sizing: A Tool for Evaluating Forages & TMR’s

There are many steps between the ration on paper and the ration consumed by the cow

that can cause “ration break down”.

These would include:

1. Loading and delivery accuracy

2. Mixer design

3. Loading sequence

4. Mixing time

5. Animal sorting

Particle Sizing: A Tool for Evaluating Forages & TMR’s

An important point, which in my experience, is too often forgotten, is mixer maintenance and

cleaning. Worn, broken or missing parts do not allow the

mixer to function uniformly. A schedule must be in place to sharpen, replace or

rotate knives. Drastic changes in forage particle break down can occur if they are done all at once.

Build-up of wet feed stuffs can also impair mixer function and inhibit uniform distribution of nutrients.

Particle Sizing: A Tool for Evaluating Forages & TMR’s

Reducing particle size has been shown to improve the dry matter intake potential of diets, particularly if

poor quality forages are involved.

However, adequate particle size in the ration is necessary to avoid depressed milk fat and to

maintain a healthy rumen.

What, exactly, are they eating?

We've looked at the producers role in TMR’s, we’ve considered the nutritionist’s perspective.

What role does the cow play?

Nutritionist refer to 3 rations that exist:1. The ration formulated on paper.2. The ration offered to the cow3. The ration eaten by the cow

There can be huge differences between these 3 depending on mixing accuracy and cow behaviour.

What, exactly, are they eating?

What, exactly, are they eating?

The previous tables show results when researchers fed cows a well balanced and mixed TMR.

By sorting, cows ate finer forage and concentrates almost exclusively during the first 12 hours, setting

themselves up for acidosis.

During the last 6 hours the cows were forced to eat more of the longer particles that had been sorted out

earlier.

What, exactly, are they eating?

So what's the big deal? Less rumination and cud chewing. Digestive upsets and fluctuation in intake. A drop in milk production and reproduction. Low or erratic butterfat tests. Laminitis, sole ulcers, white line disease etc. Higher incidences of displaced abomasums. Depressed immune system, body abscesses.

What, exactly, are they eating?

How can we prevent “sorting”? Ensure total ration moisture is between 46 to 55%. If

too dry, add water or products such as wet brewers grains.

Limit dry hay (or straw in the case of heifers and FAD cows) to 1 to 2 kg/hd/day.

Limit maximum fibre length to 5 cm or less. Processed corn silage helps; the presence of husks

and cobs in the TMR promotes sorting. Provide free choice sodium bicarb.

The Rumen & the (TMR) Wagon

A balanced ration will allow forproper digestibility, good dry matter

intakes, and satisfactory feed utilization.A ration should be developed with

profitable levels of milk and components inmind.

TMR designers, nutritionists and producers should not overlook the physical aspects of the ration, such as

minimum forage required, maximumlevels of concentrate to feed, eNDF, and palatability.