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Better Nutrient use: Working it Out

After completing this section, you will know the amount of slurry and manure1 generated by your housed livestock.

Nutrient values in slurry and manures have been shown to differ from farm to farm, so it is recommended that slurry and manure samples are tested (as spread) in an approved laboratory which will give a more accurate nutrient value.

Calculating the amount of slurry produced by housed livestock

Using Tables 2 and 3, calculate the volume of excreta (slurry) produced by housed livestock:

  • Put the livestock type and number of housed livestock that produce the slurry into the first two columns in Table 3.
  • Multiply this by the typical quantity (volume) of slurry produced by that type of animal per week (using typical values from Table 2).
  • Multiply by the number of weeks each type of livestock is housed.

1 Values in this section refer to animal excreta only and do not take into account any additional water.

This will give the slurry produced in the housed period in m3. An example is included in the first line of Table 3 based on 26 weeks (6 months) housed period. The total volume of slurry (m3) in Table 3 gives an approximation of the amount of slurry produced and added to your store.

For example:

Production from 100 housed dairy cattle during October would be:

  • Average weekly production from each cow (0.45 m3taken from Table 2), multiplied by the number of cows in the herd (100) = 45 m3 weekly.
  • Monthly production is the daily production from the herd (45 m3), multiplied by the number of weeks in October (4 weeks) = 180 m3.

Over the housed period:

  • Housed period of 26 weeks (45 m3 weekly x 26 weeks) = 1,170 m3.

Table 2. Typical values of excreta produced by housed livestock per week (adapted from NVZ Action Programme Guidelines)2.

Livestock type Volume of excreta (slurry) produced per livestock type per week (m3) Volume of excreta (manure) produced per livestock type per week (m3)
1 Dairy cow (over 9000 litre milk yield) 0.45 0.45
1 Dairy cow (6000 and 9000 litre milk yield) 0.37 0.37
1 Dairy cow (up to 6000 litre milk yield) 0.29 0.29
1 Dairy heifer replacement (13 months to first calf) 0.28 0.28
1 Dairy heifer replacement (3 to 13 months) 0.14 0.14
1 Beef suckler cow (over 500kg) 0.32 0.32
1 Beef suckler cow (up to 500kg) 0.22 0.22
1 Steer/heifer (over 25 months) 0.22 0.22
1 Steer/heifer (13 to 25 months) 0.18 0.18
1 Steer/heifer (3 to 13 months) 0.14 0.14
1 Bull beef (3 months and over) 0.18 0.18
1 Bull for breeding (over 25 months) 0.18 0.18
1 Bull for breeding (3 to 25 months) 0.18 0.18
1 Calf (up to 3 months) 0.05 0.05
1 Lamb (6 to 9 months) - 0.01
1 Lamb/Hogg (9 months to first lambing, tupping or slaughter) - 0.01
1 Breeding ewe (to 60kg inc lamb to 6 months where applicable - 0.02
1 Breeding ewe (over 60kg inc lamb to 6 months where applicable - 0.04
1 Goat - 0.02
1 Breeding deer - 0.04
1 Deer (other) - 0.02
1 Horse - 0.17

2 Information on pigs and poultry is contained in Appendix 6

Table 3 – Volume of slurry produced over the housed period.

1 2 3 4 5
Type of livestock Number of livestock Volume (m3) of slurry produced per week (from Table 2) Number of weeks housed Volume of Slurry produced in housed period (m3)
Example - Dairy cows (over 9000l milk yield per year) 100 x     0.45 x    26 =     1,170
x x =
x x =
x x =
x x =
x x =
x x =
Total volume of slurry (m3) -

Calculating the amount of manure produced by housed livestock

Use the same method to calculate the potential amount of manure produced in m3 from housed livestock using Table 4 and the reference data from Table 2.

A ‘straw addition factor’ (1.3 for dairy cattle or 1.15 for all other types of livestock) has been included along with a correction factor (0.70) to allow for the density of manures.

  • Write the livestock type and number of housed livestock that produce the manure into the first two columns in Table 4
  • Multiply this by the typical quantity (volume) of manure produced by that type of animal per week (using values from Table 2).
  • Then multiply by the number of weeks each type of livestock is housed and multiply by the straw addition factor. Divide then by the manure density value which is 0.70.

This will give the manure produced over the housed period in m3.

An example is included in the first line of Table 4 based on 26 weeks (6 months) housing period using beef suckler cows over 500 kg, which will be multiplied by a straw addition factor of 1.15.

Table 4. Volume of manure produced over the housed period.

1 2 3 4 5 6 7
Type of livestock Number of housed livestock Volume (m3) of manure produced per week (from Table 2) Number of weeks housed Straw addition factor

(1.3 for dairy; 1.15 all other livestock)

 Manure density value (divide by 0.70) Volume of manure produced over the housed period (m3)
Beef suckler cow (over 500kg)           50 x       0.32 x          26 x       1.15 /       0.70 =    683.43
x x x / =
x x x / =
x x x / =
x x x / =
x x x / =
x x x / =
Total volume of manure (m3) =

The total volume of manure in Table 4 gives an approximation of the amount of manure produced over the housed period and added to your store.

For example:

Manure production from 50 housed beef suckler cows (over 500 kg) during October (4 weeks) would be:

  • Average weekly production from each cow (0.32 m3taken from Table 2), multiplied by the number of cows in the herd (50) = 16 m3 weekly.
  • Before the straw addition factor and manure addition factors are applied, the monthly production is the daily production from the herd (16 m3), multiplied by the number of weeks in October (4 weeks) = 64 m3 in October.
  • The October production (64 m3) is then multiplied by the straw addition factor of 1.15 which is for all other livestock (non-dairy) = 73.6 m3.
  • The total manure volume produced over October with the straw addition factor considered (73.6 m3) is then divided by the manure density factor (0.70) = 105.14 m3.

You can use these methods to calculate how much slurry and/or manure from your housed livestock is added to storage systems on a month by month basis or across the full housed period.

This information is updated and abridged from The 4 Point Plan (2003).

Download a pdf version of The 4 Point Plan: Better Nutrient Use, Working it Out