Dairy data processing

The data from the dairy farms for feedstuff and direct energy consumption indicated the year-ly farm consumption, according to the purchase bills. This consumption and usage of ma-chinery and building area were used without distinguishing between cattle categories. The number and average mass of different types of cattle at the beginning and at the end of each year, and also those for sold cattle, were declared by the farmers. However, the sale dates for the sold cattle or calves, the replacement dates for old cows with heifers, and the birth dates for the calves were not determined. Given that information, the following data pro-cessing was performed:

Feedstuff

The feedstuff consumption data were checked by calculating the cattle demand for feed en-ergy intake on the basis of animal nutrition knowledge. The standard cattle enen-ergy intake requirements, as reported by Kirchgeßner et al. (2008), and the data on cattle live mass (LM), growing rates and milk yield from the investigated farms were obtained from these cal-culations. The energy demand for the maintenance (EDM) of dairy cattle was calculated from the live body mass by using equation 17 (Kirchgeßner et al., 2008). To calculate the lactation energy requirement (MJ NEL), a value of 3.15 MJ kg^-1 ECM was used, which is equal to the HHV of the resulting ECM. The total dairy cattle energy requirement was calculated by add-ing the energy requirement for maintenance and for lactation. Kirchgeßner et al. (2008) used a value of 1.66 to convert the NEL to the ME (q value). The NEL and ME of all feedstuffs consumed at each farm for each year were calculated by using the energy values shown in table 10 (p. 36).

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For the other cattle categories, the cattle growing period was divided into different categories.

The live mass, average daily mass gain and average metabolisable energy requirement in each category are summarised in table 16 according to Kirchgeßner et al. (2008).

Table 16 Average daily mass gain and metabolisable energy intake for different types of cattle at different ages and live masses.

Live mass (LM) Calves born at 38 kg (male or female)

38-150 0-5 730 29.4

a According to Kirchgeßner et al. (2008).

b Average value for cattle data in this category by Kirchgeßner et al. (2008).

The number of days that cattle from each category stayed on the farms was calculated using the mass gain values given in table 16 and the farm data on the live mass of each type of cattle at the beginning / end of each year and also those sold or bought from each farm. A prediction model was established to allocate the growing period of the existing cattle to the categories listed in table 16. Then, the standard ME requirements were calculated for each cattle category.

These calculated standard ME requirements were compared with the farm data of the ME consumption of each farm for each year. This comparison helped to rectify the feedstuff con-sumption data by again contacting the farmers for an iterative approach, as advised by LCA analysis (ISO 14040, 2006).

Based on the calculated ME requirements for each cattle category and the derived feedstuff rations, the embodied energy in the consumed feedstuff were allocated to the cattle catego-ries for each farm and year of investigation.

Concentrated feed

The farms were designated according to whether they were preparing concentrated feed inside the farm or buying it from other companies. Some of the farms had no mixing ma-chines and were buying the feedstuffs and having them mixed by their neighbours. For the direct buying case, the energy embodied in concentrated feed was calculated according to

the mixture of the single feedstuffs indicated by the ration receipts and the data from the oth-er farms, which woth-ere mixing the concentrated feed by themselves. The extra enoth-ergy input from machinery and electrical consumption was added according to the average mass and usage hours of the mixing machinery, the average mixing capacity (1 t h^-1), and the nominal motor power, assuming 50% use of nominal power.

Energy embodied in dairy facilities

In the absence of an exact separation between the cattle categories in the barns and the use of machinery and consumed direct energy, the energy embodied in the facilities was calcu-lated and allocated to each category in several ways.

The energy embodied in the buildings, silos and open areas (concrete and fences) was allo-cated to each cattle category according to the days for each category in the farm and the required area inside the barns for cattle in each category. Using a scoring system in which the area requirement was 1 for a calf, 2 for heifers and bulls, and 4 for dairy cattle, this sys-tem indicates that dairy cattle need 4 times more land than a calf.

The embodied energy in milking machines and milk coolants were allocated only to the dairy cattle. For the other machines, e.g., feed mixers, tractors, and water pumps, the embodied energy was allocated with the same ratios used in the allocation of the energy embodied in the feedstuffs.

The electricity consumed by milking machines and milk coolants was allocated only to dairy cattle. This consumption was estimated by recording the nominal power of their motors and their hours of use and by assuming 50% use of nominal power. The electricity consumed by mixers and water pumps was allocated according to the allocated feedstuff in each category.

The electricity, diesel or gas consumption consumed for lighting, households and tractors (for excrement gathering and feedstuff displacement) was allocated according to the ratios used in building energy allocations.

Energy embodied in live cattle

The energy embodied in live cattle was the sum of the allocated energies to each cattle cat-egory from different energy input resources.The average number of cattle from each catego-ry on the farms was determined according to the mass gain of cattle and estimations made by model predictions. The first cattle category was that in which the calves weighed less than 150 kg. Each calf was an energy input for a heifer with less than 400 kg of body mass, be-sides the other inputs. In addition, a heifer with less than 400 kg of mass was an energy input for a heifer of up to 550 kg. A heifer was also an energy input for a cow. The energy from the manure of each cow was subtracted from the total energy input.

For the bull cattle, an individual with less than 400 kg body mass and a bull over 400 kg was used to calculate the energy input in cattle. The newborn calves were not considered in the energy analysis.