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Irish Farmers Journal - 2nd April 2008

Cost of Producing Excess Pig Manure

By Michael McKeon, Teagasc

The pig industry in recent months has come under financial pressure from all angles- the spiraling cost of energy, high feed prices and poor sales returns etc. In the current economic climate, all the principal inputs (feed, energy etc) are been examined in order to increase efficiency thereby maximizing the economic return. Unfortunately the pig producer has no control over the economic market forces driving many of these costs and therefore at best can only try to minimize their effects. However one cost that the pig producer has control over is the water cost associated with pig manure.

This may not be considered an important cost at first, but excess water usage on the unit will incur a water charge and this water must then be transported away after use in the form of manure.  This is a doubling of the cost of an important input that usually goes unaccounted.

How much manure does a unit produce?

The table below shows the minimum amount of neat manure a unit is likely to produce. It is calculated onthe basis of the minimum daily drinking water requirement less metabolic losses for a sow and progenyon a per 100 sow integrated basis..

Table 1. Neat manure produced per 100 sows on integrated unit (litres)

Type Number /100 sow Litres/head/week Total / week Total / year %
Suckling Sow 18 135 2430 126,360 10
Dry Sow/boar 82 70 5740 298,480 23
Gilt 12 53 630 32,720 2.5
Weaner 400 12 4800 249,600 19.5
Finisher 550 20 11000 572,000 45
      Total 1,279,160 100
                                 Total volume produced per sow (including progeny) = 12.8 M3 (2,816 gls)

Additional water may also be used for washing and cleaning. The volume used will vary greatly between units depending on the structure, system used etc. French research (IFIP 2003) has a shown a usage figure of 2 M3 / sow/year for washing and disinfecting a unit.

Table 2. Total manure volume produced per sow + progeny

Volume produced M3
Neat excreta produced per sow + progeny 12.8
Additional washing water 2
Total volume produced 14.8

The 14.8M3/sow/yr is the minimum target a unit may be using and does not include any additional water from leakages or rainwater entering storage tanks. In reality the water usage on units will vary from a low of 15M3/sow/yr to a high of 25 M3/sow/yr due to a number of factors as outlined below.

Factors affecting volume produced:

The volume of manure produced may be increased due to the following factors

  • High dietary protein levels,
  • High dietary salt levels,
  • High ambient temperature,
  • Health status
  • Feed is presented as meal rather than pellets.
  • Washing system
  • Water leakages
  • Water:feed ratio’s

On a wet feed system, the water:feed ratio of the various diets will have a very significant effect on the volume produced. This is particularly relevant for the finisher pigs as this is where nearly 50% of the unit’s manure is produced. The table below shows the effect on manure volume produced by increasing the finisher water:feed ratio