Allocations in this study

3.3.7.1 Allocated energy for feedstuffs

The feedstuff energy content can be quantified depending on the animal species to which it is fed. For dairy cattle, the NEL indicates the energy available in feedstuff for milk production and body maintenance. The MEV can be used for all ruminants. Therefore, the MEV is used to compare or to sum the energy content of feedstuffs for different animal categories, such as calves, heifers, bulls and cows. Energy input in feedstuff production can be allocated to dif-ferent parameters, thereby giving the energy content of the feedstuffs (e.g., MEV or NEL).

Furthermore, energy allocation is needed if a feedstuff is not the only product of a process, i.e., if a feedstuff is one of several products and/or by-products.

In this study, three cases were used in the allocation of production energy to different feedstuff products in dairy farms and described in the following.

Case A) Products and by-products are both used as feedstuffs:

When both the products and by-products are or can be used as feedstuffs, the production energy is allocated with the relationship of their feeding values (MEV or NEL). The energy in product A (EEVA) is found by multiplying the actual energy in the total products (EEVT) by the ratio of metabolisable energy of product A (MEVA) to the metabolisable energy of total prod-ucts (MEVT), as shown in equation 10.

T T

A A

EEV

MEV

= MEV

EEV ×

This method was used for the allocation of production energy to sugar beets by products, straw and grain in cereals, and also the bran of wheat grain, which are all used as feedstuffs.

This case was also used for soya beans and sunflower meal, and the metabolisable energy value of whole sunflower seed and rapeseed is reported.

Case B) The product is used as foodstuff and the by-product is used as feedstuff:

In some processes, the main aim is the production of foodstuff, and by-products can be used as feedstuff. Rapeseed meal, tomato pomace, poultry offal, meat and bone meal, and fat are

by-product feedstuffs from main products which are foodstuff. In this case, when there is no information about the MEV of the main product, the HHV of the main product and by-product are used for allocation.

T

Extra necessary energy consumed in the preparation of by-product as feedstuff (e.g., milling of meat and bone) is included in the energy demand of by-product.

Case C) Product is used as material and by-product is used as feedstuff:

In the case that the main product is used for purposes other than bio-energy, food, or feedstuff (such as the cotton lint used in the textile industry), but by-products are used as feedstuff, the substitution method was used to credit the by-product according to the amount of displaced feedstuff. In this study, the simple substitution method was used, by crediting the replacer according to the ratio of the MEV of the replacer (MEVA) to the MEV of replaced feedstuff (MEVB).

In the case of products such as sugar beets and oilseeds, there is an extra consumed energy in the sugar or oil extraction processes. This energy was assigned to the energy demand of sugar or oil and not to the energy demand of molasses, pulps, and meals, which were con-sidered by-products. This argument shows that the extra energy is not necessary for the feedstuff and has no influence on the feeding specification of the feedstuff. In other words, prior to the consumption of this extra energy, the main product could be fed to the cattle, and the extraction energy belongs to the food production.

The EEV allocation of cotton example:

When allocating the consumed energy from cotton production, cases C and B were com-bined. Considering that cotton fuzz can be fed to ruminants without being crushed, all the extra energy requirements are from ginning, de-linting, de-hulling and oil extraction and are excluded from the energy required for the feedstuff.

As reported in the petition of the National Cottonseed Products Association (Anonymous, 2011), the average energy embodied in cotton production with mechanised cultivation in Asia is 13.0 MJ kg^-1 whole cottonseed and lint.During recent years, the lint to seed ratio in im-proved cultivars has been 1.43 (i.e., lint is 59% of the mass of fresh-picked cotton.)

(Anony-mous, 2011). Cottonseed consists of 16% oil, 45% meal and 39% hull, linter and waste (Blasi

& Drouillard, 2002). The feeding characteristics of whole cottonseeds are very similar to soya beans, and both have a similar proportion of oil. In addition, their meals also seem to be simi-lar in terms of feeding value, especially for MEV (table 10, p. 36). In this study, the allocation of energy, cottonseed and cottonseed meal are used as replacements for soya bean meal. In reference to the energy values presented in table 10 and also considering the 9.17 MJ kg^-1 soya bean energy reported by Mandal et al. (2002), the allocation of embodied energy in cotton by-products was performed as detailed below:

The allocated cottonseed EEV was calculated by substituting it with the soya bean values and comparing their MEVs using equation 13 (case C).

)

Allocated EEV in cottonseed meal was calculated by comparing its MEV with the MEV of cottonseed (case A) and calculating the allocated EEV (9.59 MJ kg^-1) with the following:

)

In the same way, the cottonseed hull MEV was compared with the MEV of cottonseed (case A); the energy allocated to cottonseed hulls was found as follows:

)

Allocation by substituting soya bean meal with cottonseed meal (instead of soya bean with cottonseed) and then allocating embodied energy to cottonseed and other cottonseed by-products produces the same results because this method is simply the reverse of the above calculations.

Considering the allocation methods for the products and by-products consumed as feedstuffs by the study farms (listed in table 10), the embodied energy is allocated as follows:

- Alfalfa, maize corn, maize silage, and grass silage cultivation have no useful

by-- Barley, wheat, soya bean, tomato, and sugar beet cultivation have byby--products. Thus, the production energy was allocated to grain, straw and bran in wheat and barley, pulp and molasses in sugar beet, and as well oil and meal in oilseeds, according to the ration of their MEV to the total MEV of the products and by-products (case A).

- Assuming the substitution of soya bean meal (as the main oilseed meal consumed in the investigated farms) with cottonseed, rapeseed and sunflower meal, the embodied energy in the replacement was calculated by multiplying the EEV of soya bean meal with the ratio of the MEV of the replacement to the MEV of soya bean meal (corre-spondent to “case A”).

3.3.7.2 Allocated energy for dairy products

The energy allocated to excrement was 0.33 MJ kg^-1 offresh manure as discussed in section 2.6.2.6.4.

The energy output from manure was subtracted from the energy input in a cow. Thereafter, the remained energy input was allocated to the milk and meat produced by the cow. The energy input allocation between the milk and meat was carried out according to the caloric value (MJ kg^-1) produced by the milk and meat yield (kg cow^-1) of a cow.