| Bioconversion of Organic Residues for Rural Communities (1979) |
|Indian experience with treated straw as feed|
Annex 2. Method of calculating the value presented in table 2 for the efficiency of NaOH energy usage
The MJ of NaOH energy input per MJ additional energy stored as body-weight gain was calculated as follows.
1,000 kg untreated straw provided for
1,000 kg treated straw provided for
In 222 days a calf fed untreated straw also consumed
222 x 0.8 = 178 kg oilcake
In 167 days a calf fed treated straw also consumed
167 x 1.0 = 167 kg oilcake
In 222 days a calf fed untreated straw gained
222 x 0.25 = 55.5 kg
In 167 days a calf fed treated straw gained
167 x 0.42 = 70.0 kg
Therefore, the treatment of straw increased weight gain by 70.0 - 55.5 = 14.5 kg/1,000 kg straw. (This figure is conservative, because a calf fed treated straw consumed slightly less oilcake/1,000 kg straw than the one fed untreated straw.) The energy value of this bodyweight gain is taken as 9.6 MJ/kg (calves about 1-year-old gaining at a rate of 0.40 kg/day), or 139.2 MJ for 14.5 kg. The manufacturing energy cost of NaOH is estimated to be 51 MJ/kg;
1,000 kg straw x 3.3 kg NaOH/100 kg x 51 = 1,683.