*2.8. Chemical Analysis*

Chemical analyses of the experimental rations and feces samples were carried out according to AOAC [51] for crude protein (CP, method 968.06), ether extract (EE, method 920.39), crude fiber (CF, method 932.09), and ash (method 967.05). The nitrogen-free extract (NFE) was calculated according to the next equation:

$$\text{NFE (\%)}=100-\text{ (CP\%}+\text{EE\%}\text{\%}+\text{CF\%}+\text{Assh\%}).\tag{5}$$

Organic matter (OM) was calculated as the difference between 100% DM and ash. Gross energy (GE, kcal/kg) of the experimental diets was calculated based on 5.64, 4.11, and 9.44 kcal GE/g CP, NFE, and EE, respectively NRC [52].

Digestible energy (DE) of the experimental diets was calculated according to the equation described by Cheeke [53], as follows:

$$\text{DE (kcal/kg)} = 4.36 - 0.0491 \times \text{NDF\%} \tag{6}$$

$$\text{where}\\
\text{as}, \text{NDF}\% = 28.924 + \text{(0.657 \times CF\%)} \text{ and } \text{ADF}\% = 9.432 + 0.912 \text{ (CF\%)}\tag{7}$$

The concentration of hemicellulose was estimated as the difference between NDF and ADF. Nitrogen in urine was determined by the micro-Kjeldahl method [51].
