Formulating feed rations for pigs

Feed rations for pigs are primarily made of grains, legumes, vitamins and minerals. Many pig farmers still allow pigs to forage on pasture and supplement with any available farm waste. Some offer maize and other grains without considering the amounts and economic returns. This type of feeding program is very inefficient and the best feed to gain ratio that can be achieved is normally in the range of 5:1.

In advanced systems pigs are totally kept in confinement and provided a well balanced diet. To provide such a well balanced diet the nutritional requirements of different classes of pigs must be known and met. The main considerations for feed ration for pigs should therefore consist of meeting biological needs with appropriate combination of feed ingredients and pure sources of limiting nutrients to provide a nutritionally balanced diet. This information must be accurate so as to make a cost effective diet when you take into account that feed cost contributes about 55 to 70% of the total cost of production

Daily nutrients requirement for pigs

There various nutrients required by pigs and other farm animals which include water, energy, proteins, fats, vitamins, minerals and additives. Under practical feeding conditions whereby natural feedstuffs are used some of the required nutrients are likely to be deficient. Lack of these nutrients are manifested in various forms such as impaired growth, weak pigs, weight loss, skin problems, rickets, problems with blood, hypersensitivity, reproductive problems, cracked hooves, lameness and sometimes death.

In addition the daily nutrients required by the pig for maintenance, growth and reproduction depend on the size and physiological state of the pig. Nutrient interaction also plays an important role. It refers to a situation whereby the presence of a certain nutrient in the diet affects the availability of another required nutrient. The feeding standards as provided by NRC, ARC or KEBS are minimum requirements and should be considered as starting points in diet formulation.

Procedure for formulating rations

Due to the complexity of this procedure which any farmers might not be able to perform it is prudent to use already prepared rations from reliable commercial sources. Mixing the rations at home after getting the formula can also be very tricky. Experienced farmers use complex computer programs to come up with accurate diets and mix the feed ingredients with complex equipment. However, there are those who use trial and error methods with varying degrees of success.

The following information is required to be able to formulate a pig ration.

1.      Recommended nutrient levels for various categories of pigs.

An example is given on the table below.

 

 

Liveweight in Kg

10 – 20

20 – 50

50 – 110

Expected daily intake (g/day)

950

1900

3100

Energy intake (Kcal DE/Kg diet)

3400

3400

3400

Protein (%)

18

15

13

Amino acids (%)

 

 

 

Lysine

0.95

0.75

0.60

Methionine + Cystine

0.48

0.41

0.34

Threonine

0.56

0.48

0.40

Tryptophan

0.14

0.12

0.10

Minerals

 

 

 

Calcium (%)

0.40

0.60

0.50

Phosphorous (%)

0.60

0.50

0.40

Zinc (mg/Kg diet)

0.80

0.60

0.50

Vitamins

 

 

 

B12 (µg/Kg diet)

15

10

5

A (IU)

1750

1300

1300

D (IU)

200

150

150

E (IU)

11

11

11

 

2.      Nutrient composition of various feedstuffs

For example

Nutrient

DE

CP

Ca

P

Reject wheat

3400

12

0.4

0.2

Barley

3100

10

0.05

 

Soya bean

3220

44

0.3

0.65

Dicalcium phosphate

 

 

23

18

Limestone

 

 

38

 

Once this information is available various methods of calculation can be employed. The simplest is the Pearson square method. A portion of the ration is fixed and the variable part is calculated using the square.

For example to formulate a pig diet for finisher pigs which has Crude Protein (CP) of 13 – 14% with calcium requirements of 0.5% and phosphorous 0.4%:

Step 1: Fix the important feeds.

Trial and error method is used to fix the important feedstuff. An important guide is to know the maximum inclusion rates of particular feedstuffs because if they exceed a certain level they may become toxic to the animal or interfere with the digestive process. In this example we fix the following feedstuffs at the percentages given on the table; limestone, dicalcium phosphate, trace elements and barley.

 

Feedstuff

%

Barley

10

Limestone

0.5

Dicalcium phosphate

2

Trace minerals

1

Total

13.5

Balance

86.5

 

Step 2: Calculate the composition of the remaining feedstuff using CP levels

The balance should form the bulk of the feedstuff; in this case it is 86.5%. Normally two feed sources are considered at this level, one with high energy content and another with high protein content. In this example reject wheat has high energy content and soya bean has high protein content.

The overall feed composition should have a minimum 13% CP. This percentage is needed in the remaining portion of the ration. This translates to 13 / 0.865 = 15% CP. Put this figure in the middle of the square then the respective CP% of the remaining two feedstuffs at the corners on the left of the square.

Pearson square

Then subtract the figures diagonally across the square only indicating the positive sum on the right. Get the sum of the figures on the right of the square and use it to calculate the percentages of the respective feedstuff. In this case the percentage of reject beans in the balance is (29/32) 100 = 90.6% and soya beans (3/32) 100 = 9.4%

Finally convert these percentages to total ration.

E.g. reject wheat forms 90.6% of 86.5% of ration = 78.4% of total ration.

Soya beans forms 9.4% of 86.5% of ration = 8.1% of total ration.

When you bring all the percentages together you get the following feed composition:

 

Ingredient

%

Reject wheat

78.4

Soya bean

8.1

Barley

10

Limestone

0.5

Dicalcium phosphate

2

Trace minerals

1

Total

100

So the final composition of this diet is as follows:

 

Ingredient

% in diet

DE

CP

Ca

P

Reject wheat

78.4

2665.60

9.408

0.313

0.16

Soya bean

8.1

260.82

3.564

0.024

0.05

Barley

10

310.00

1.000

0.005

0

Limestone

0.5

0.00

0.000

0.190

0

Dicalcium phosphate

2

 

 

0.460

0.36

Trace minerals

1

 

 

 

 

 

100

3236.42

13.972

0.992

0.57

 

As I said before, a number of commercial feed manufacturers have well balanced diets and it may not be necessary to undergo this complex procedure to make your own diet. There are always chances of getting it wrong. In Kenya there are three types of pig feeds in the market; creep feed, sow and weaner and finisher ration. These feeds have been formulated to meet the nutritional demands of the various categories of pigs.


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