Table 1.1.4 Ratio of COD, P, and N produced by various animals to that produced
by a 1,000 pound slaughter steer.
Young Dairy Stock
Interpolation of values should be based on the maximum weight animals would be expected to reach.
Data from Midwest Plan Service (1975) except for swine, which is from American Society of Agricultural
Determine percent manure pack:
In areas of high animal unit density (AUD) (Young et al., 1982), almost all of the rainfall and
runoff in and from the lot comes in contact with animal wastes before leaving the lot. Where AUD is
low, some of the runoff may escape contact with animal waste and thus contain no fecal contamination.
Sweeten and Reddell (1976) assumed uniform spreading of cattle manure over a feedlot area over a
given time period to estimate percent manure pack. If one beef animal (1,000 lbs) covered
approximately 0.001 acres per day, assuming animal waste scraping or waste removal (cleaning)
frequency of 10 days, an AUD of 100 head of beef cattle per acre will result in 100 percent manure
pack, Figure 1.1.7. Where feedlot systems include outdoor exercise areas, AUDs should be adjusted
for the percent time spent in these areas. P, in percent manure pack below 100, from 85, 4500 and
300 mg/1 respectively (Young et al., 1982, 1987).
Determine runoff volume from Area 2 (V2 acre-in) by the CNE (Section 1.1.3.) by summing runoff
volumes from each subarea.
For Area 2, if runoff volume (V2) is greater than 30 acre-inches, the pollutant concentration
(C2) in mg/1 at the feedlot edge is calculated by: