Separate spreadsheets were developed for production and meat and of eggs from poultry. Additional worksheets are included for swine, dairy, beef and sheep. Other species (e.g., goats), although important, were not included due to time constraints. For each species, the entire production chain is included, the rationale being that even though the reproductive and growing phases may take place on different farms, all must be accounted for in the production system. The user may also define the type and amount of pasture (for poultry and swine the default is zero), and diet compositions. All the production worksheets are linked to a single feeds worksheet, which has separate sections to account for the dietary requirements of different types of animals. In the future, each spreadsheet should include error-checking equations to ensure that dietary inputs match the levels of production set by the user. At present, caution must be exercised to avoid unrealistic input-output relationships.
Poultry
In the case of eggs, only domestic chickens were included, but for meat production the user may select among broilers, turkeys, ducks and geese. Selection of species then sets up the appropriate input and output defaults, taken from standard livestock production handbooks and texts (e.g., Acker & Cunningham, 1998; Gillespie, 1997). Costs of construction, equipment, temperature control and ventilation are extremely variable. Default values were obtained from Collins & Walpole (1977); Ostrander (1980); and Stout (1984). An example worksheet is appended to this document.
Swine
The default swine herd is a 100-sow farrow-to-finish operation. The user may give actual input and output values, including a provision for pasture amount and type and feeds as for poultry. are extremely variable. Default costs of construction, equipment, temperature control and ventilation were obtained from Bloome & Williams (1980); Driggers (1976); and Reid et al. (1980).
Dairy
The default dairy operation is a 100-cow dairy; at this stage there is no provision for dual-purpose cattle, although the spreadsheet could be modified to accommodate this system. In addition to pasture, there is provision for three forages (either alone or in mixtures) and three concentrates, to accommodate different feeding strategies within the herd. Default values for building, equipment and operating costs were taken from Oltenacu & Allen (1980).
Beef
The default is a 100-cow herd producing weaned calves, with provision for subsequent growing and finishing phases of the offspring. Separate pasture, feed and operating sections are included for each phase. Default values for costs of construction, fencing, water and on-farm transportation were obtained from Cook (1976); Cook et al. (1980); Heitschmidt et al. (1996); Hoveland (1980); and Ward et al. (1977).
Sheep
The default sheep farm is a 1,000 ewe range lambing operation, with production of meat and wool. Separate pasture, feed and operating sections are included for ewes and for finishing lambs. Default values for costs of construction, fencing, water and on-farm transportation were obtained from Cook (1976); and Gee (1980).
