Serving Society through Food Animal Agriculture

January 2001                                                                                            

 

FEED AND ANIMAL MANAGEMENT FOR SWINE[*]

 

Swine operations may include a complete farrow to finishing unit, or various combinations of separate units for feeder pig production, finishing pigs or the breeding herd. Distinctly different diets are required for each of these stages of the life cycle resulting in great differences in the volumes and nutrient composition of the manure produced. This fact sheet briefly highlights some factors affecting nutrient excretion, including potential dietary adjustments that can be used to minimize excess nutrient excretion.  Selected nutrient requirements for pigs of different sizes are listed in Table 1 (NRC, 1998).  Reference to the NRC (1998) is imperative for a thorough evaluation of all swine diets, including the breeding herd, on a commercial operation.

 

Table 1. Selected nutrient requirements of pigs (adapted from NRC, 1998)1.

Nutrient

 

Pig Weight

3-5 kg

(7-11 lb)

Pig Weight

5-10 kg

(11-22 lb)

Pig Weight 10-20 kg

(22-44 lb)

Pig Weight 20-50 kg

(44-110 lb)

Pig Weight 50-80 kg

(110-176 lb)

Pig Weight

80-120 kg

(176-265 lb)

Crude Protein, %

 

26.0

 

23.7

 

20.9

 

18.0

 

15.5

 

13.2

Lysine,

 % total

 

1.5

 

1.35

 

1.15

 

0.95

 

0.75

 

0.60

Lysine, % appt. ileal dig

 

1.26

 

1.11

 

0.94

 

0.77

 

0.61

 

0.47

Calcium, %

0.90

0.80

0.70

0.60

0.50

0.45

Phosphorus, % total

 

0.70

 

0.65

 

0.60

 

0.50

 

0.45

 

0.40

Phosphorus, % avail.

 

0.55

 

0.40

 

0.32

 

0.23

 

0.19

 

0.15

Potassium, %

0.30

0.28

0.26

0.23

0.19

0.17

Sodium, %

0.25

0.20

0.15

0.10

0.10

0.10

Copper, mg

6

6

5

4

3.5

3

Zinc, mg

100

100

80

60

50

50

1Adapted from Table 10-1 and 10-5 Nutrient Requirements of Swine. 10th Revised Edition, 1998. National Research Council, National Academy of Sciences, National Academy Press, 2101 Constitution Ave, Washington, DC 20418 (G. L. Cromwell, Chair, Subcommittee on Swine Nutrition).

 

Phase Feeding and Split-Sex Feeding.  Dividing the growth period into several periods with a smaller spread in body weight allows producers to provide diets that more closely meet the pig’s nutrient requirements.  Also, since gilts require more protein and amino acids than barrows, penning barrows separate from gilts allows the feeding of lower protein and amino acid levels to barrows without compromising the leanness and performance efficiency of the gilts.  In addition, as the lean gain potential for the pig increases, the crude protein level and amino acid requirements in the diet will increase. The level in the diet may be modified according to the feed intake and nutrient  needs of the genetic line.  Therefore, the amount of nutrients required and consumed daily by the pigs is generally a more accurate indicator of whether the diet is meeting the pig’s requirements, and, therefore, minimizing nutrient excesses and excretion.  Feeding 3 or 4 diets during the grow-finish period compared with feeding only 2 diets during the G-F phase would reduce N excretion by at least 5 to 8%.  Refer to NRC (1998) and consult certified nutritionists to accurately evaluate current or planned diet compositions during the development of a CNMP.  The CNMP can be modified and “fine-tuned” later based upon data accumulated from the actual production operation.

Manage to Improve Feed Efficiency. Controlling feed wastage improves herd feed conversion and reduces nutrient losses.  Feed wasted in the manure pit can add considerably to the nutrients that need to be applied to cropland.  Wet-dry feeding systems can significantly reduce feed wastage and water wastage.  Current research has shown that manure volume per pig can be reduced from 30 to 50% using wet-dry feeding systems.  However, the nutrient concentrations in the manure from a wet-dry feeding system are generally significantly higher, therefore, routine manure analyses are needed to adjust application rates of such manure to cropland.  Maintaining pigs under comfortable environmental temperature and humidity conditions will improve feed utilization and can also reduce nutrient excretion.  Cold temperatures increase caloric requirements for body maintenance, and, therefore, increase feed intake and nutrient excretion.  Likewise, extremely hot temperatures reduce feed intake, decrease growth rate and increase time to market, thereby also increasing maintenance requirements and nutrient excretion.  Raising genetically lean pigs (rather than fat ones) on diets that meet their requirements, controlling diseases and parasites, and using good management practices are further examples of how one can improve feed conversion efficiency and reduce nutrient excretion.

Fine grinding and pelleting feed are also effective ways in improving feed utilization and decreasing dry matter (DM) and nutrient excretion.  By reducing the particle size, the surface area of the grain particles is increased allowing for greater interaction with digestive enzymes. Addition of enzymes, such as phytase, amylase, protease, glucanase, etc., may release nutrients that will enhance nutrient retention and reduce excretion.

Formulate Diets on an Available Nutrient Basis.  A high proportion (56 to 81%) of the P in cereal grains and oilseed meals occurs as phytate-P.  Phosphorous in this form is not well utilized by pigs because they lack intestinal phytase, the enzyme needed to cleave the phosphate groups from the phytate molecule. Therefore, supplemental P is added to the diet to meet the pig’s growth requirements. The non-digestible phytate-P and any excessive P added to the diet is excreted in the feces.   Because some feedstuffs are high in phytate, and because there is some endogenous phytase in certain small grains (wheat, rye, triticale, barley), there is wide variation in the bioavailability of P in feed ingredients.  For example, the P in corn is only 12% available while the P in wheat is 50% available.  The P in dehulled soybean meal is more available than the P in cottonseed meal (23 vs. 1%), but neither source of P is as highly available as the P in meat and bone meal (90%), fish meal (93%) or dicalcium phosphate (95-100%).  Similarly, the sources of Cu and Zn used in the diet can vary in availability for animal use. To reduce excretion levels, formulate these nutrients on an available basis according to NRC (1998) requirements and adjustments needed for farm specific animal performance.

Supplementing the diet with the enzyme, phytase, is an effective means of increasing the breakdown of phytate P in the digestive tract and reducing the P excretion in the feces.  Using phytase allows one to feed a lower level of supplemental inorganic P in the diet, because a portion (35%) of the unavailable phytate-P in the grains is released and made available by the phytase enzyme to help meet the pig’s P needs. The inclusion of phytase increases the availability of P in a corn-soy diet by three-fold, from 15% up to 45% and has resulted in reduced P excretion of 20 to 30%.

Some feed manufacturers are currently formulating swine feeds on an “ideal protein” basis.  An “ideal protein” is one in which the available amino acids closely match the animals requirements  for lean tissue protein synthesis and maintenance by reducing crude protein and adding synthetic amino acids.   Although nutritionists cannot prepare perfect amino acid balances from natural feed ingredients, the use of computers and having an array of different feed ingredients allows them to produce feeds that have reduced amino acid excesses. Reduced excesses of amino acids results in  less N being excreted. Recent research has shown a 20 to 40% reduction in N excretion using this technology.

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[*] Prepared by the FASS Environment, Waste Management and Ecosystems Committee.