FEEDING FAT TO DAIRY COWS

FEEDING FAT TO DAIRY CATTLE

Adding fat to the diet of dairy cows has become a common practice for most high

production herds.

Why?

Energy demands exceed energy intake for the first 80 to 100 days in milk (DIM).

FEEDING FAT TO DAIRY CATTLE

FEEDING FAT TO DAIRY CATTLE

Severe weight loss can lead to:

Ketosis

Fatty liver disease

Reduced reproductive performance

Decreased milk yield

FEEDING FAT TO DAIRY CATTLE

In times of energy deficiencies, grains can provide an economical source of energy.

But fibre minimums and excessive levels of fermentable carbohydrates limit the amount

that can be fed.

Fats on the other hand can provide over 2 times the amount of energy that carbohydrate's

can.

SOURCES OF FAT

• Fat sources in a dairy cows diet can be broken down into 3 main categories:

1. Naturally occurring fat (grains & forages).

2. Commodity fats (oils seeds and animal and vegetable fat).

3. Specialty or ruminally inert fats.

SOURCES OF FAT

SOURCES OF FAT

All dairy rations will naturally contain 2.5-3%.

Commodity fats can affect rumen fermentation by coating bacteria and feed particles lowering fermentation.

Specialty fats such as Megalac & Booster Fat, are ruminally inert and frequently are referred to as by-pass fat. They tend to be very expensive.

SOURCES OF FAT

RESPONSES TO FEEDING FAT

Typically one or more of the following responses will be seen when fat is added to

a dairy ration:

1. Milk yield may increase on average by 3 to 8% (1 to 2.5 kg).

2. Fat test can be maintained or increased by 0.2 to 0.3 percentage points.

3. Reproductive performance can be enhanced because cows return to positive energy balance sooner.

RESPONSES TO FEEDING FAT

4. Cows often lose >120 kg of body weight in early lactation.

It can be very difficult to gain lost body condition before the next lactation; this will affect future milk production and reproduction. Fats can reduce this affect.

5. Ketosis is a serious metabolic problem in early lactation. Cows that lose more than one BCS will be at risk of ketosis, fatty liver disease and death.

Energy status can be improved with fat supplementation without risking excessive starch levels and low fibre levels in the ration (acidosis).

BASAL FAT LEVEL 2.5-3.0%

COMMODITY FATS 2.0-3.0%

SPECIALITY FATS 2.0-3.0%

TOTAL 7.0-8.0%

HOW MUCH FAT CAN BE FED?

WHAT TYPE OF ADDED FAT SHOULD BE FED?

The choice or combination of fats used will depend on several factors:

1. Supplemental nutrient needs.

For example, if added protein is needed, whole soy beans would be a good choice.

If fibre is lacking, fuzzy cotton seed would be ideal.

2. Facility constraint and handling.

For example, fuzzy cotton seed will not flow or auger in most automated feed systems

3. Palatability of the fat product.

Most fat supplements are very palatable and readily consumed by cows.

4. Cost of the fat supplement will have a strong influence over its usage.

WHAT TYPE OF ADDED FAT SHOULD BE FED?

Nutritional Considerations When Feeding Fat

1. Adequate fibre form and level are needed to maintain rumen digestion, particularly with unsaturated fats.

2. Ca should be increased to about 1% of the ration dry matter to compensate for the formation of Ca soaps.

Mg should be increased to about 0.35% of ration DM, for the same reason

3. Fat cannot be used by the rumen microbes. All fat “by-passes” the rumen resulting in no additional microbial synthesis. Therefore higher by-pass protein levels must be fed in fat containing rations.

4. Added fats should be gradually increased in the ration to allow for palatability changes and microbial adjustments.

Nutritional Considerations When Feeding Fat

5. Supplemental fat should be limited in early lactation (3 to 5 weeks post partum). High levels of fat can depress total ration dry matter intake.

6. Milk protein % is often lower when supplemental fat is fed.

This could be due to the effect on rumen microbes (less microbial protein); reduced uptake of amino acids by the mammary system; less blood flow to the udder or dilution of protein by increased milk yield.

7. Liquid fats should be added to the concentrate prior to adding to the TMR, rather than adding it to silage or the final base TMR. Lower DMI and digestibility have ben reported when fat is added to the forage.