## 2 Materials and Methods
### Chemical Analysis  
Chemical analysis was performed during the initial stage, before the start of rearing, to select the appropriate amounts of each component within the framework of the birds' demand for nutrients in order to determine the chemical composition of individual diets. Metabolisable energy (ME) for each component of the diet was calculated based on the equations presented in the European Tables of Energy Values for Poultry [43]. After an evaluation of ME in the components, the diets were prepared with their metabolisable energy, nutrients, and minerals in accordance with The Polish Requirements of Poultry Nutrition [44]. In terms of nutrition, starter and grower diets were used. The first starter diet was used on the chickens' 20 th day of life. In each treatment, diet per 1 kg of feed was 12.5 MJ ME/kg and about 220 g/kg of crude protein (Table 1). The second grower diet was given to chickens from 21 to 35 days of life (Table 2). The use of the mixtures was deliberately changed over time to also determine whether the additional source of DF would significantly affect the growth of the birds, or whether it would have no significant effect and would affect the health of the birds.  
The chemical composition of individual components and diets was determined using the Official Methods of Analysis (AOAC) [45]. During the analysis, the following constituents were determined: dry matter (DM, AOAC; 934.01), crude protein (CP, Kjeldahl method, AOAC 984.13), crude ash (CA, AOAC 942.05), ether extract (EE, Soxhlet method, AOAC, 920.39A), and crude fibre (CF, Hennenberg and Stohmann method, AOAC 978.10). On the other hand, the contents of TDF, IDF, and SDF in the feed components were determined as the average value from previous studies [19; 29; 46; 47]. Then, the fibre fraction content in the ingredients was used to calculate the total content for individual diets (Figure 1).  
\begin{table}
\begin{tabular}{l c c c c c} \hline
**Item** & **Control** & **3\% OH** & **3\% SH** & **3\% SBP** & **3\% WB** \\ \hline Chalk & 14.2 & 14.6 & 14.6 & 14.0 & 14.9 \\ DL-methionine (98\%) & 2.39 & 2.39 & 2.39 & 2.41 & 2.38 \\ HCI-L-lysine (78\%) & 2.82 & 2.95 & 2.81 & 2.89 & 2.82 \\ Premix DKA grower 0.5\% & 5.0 & 5.0 & 5.0 & 5.0 & 5.0 \\ \hline Chemical composition (g/kg) & & & & & \\ \hline Metabolisable energy, MJ & 13.03 & 12.96 & 13.00 & 13.02 & 12.99 \\ Crude protein, g & 200.0 & 199.9 & 200.2 & 200.0 & 200.3 \\ Crude fibre & 28.9 & 36.8 & 42.7 & 34.4 & 31.8 \\ Total dietary fibre & 176.82 & 193.71 & 198.34 & 190.93 & 187.30 \\ Insoluble dietary fibre & 151.65 & 168.87 & 150.14 & 151.14 & 148.78 \\ Soluble dietary fibre & 25.12 & 24.79 & 48.17 & 39.74 & 38.49 \\ Calcium & 9.2 & 9.2 & 9.2 & 9.2 & 9.2 \\ P\({}_{\text{available}}\) & 4.0 & 4.0 & 4.0 & 4.0 & 4.0 \\ Sodium & 1.7 & 1.7 & 1.7 & 1.7 & 1.7 \\ L-lysine & 11.44 & 11.57 & 11.51 & 11.50 & 11.51 \\ DL-methionine & 5.24 & 5.20 & 5.20 & 5.21 & 5.23 \\ \hline \end{tabular} The premix provided the following amounts of nutrients per kilogram of diet: vitamin A, 9500 IU; vitamin D\({}_{3}\), 4000 IU; vitamin E, 35 mg; vitamin K, 2 mg; vitamin B1, 2 mg; vitamin B2, 5 mg; vitamin B6, 3 mg; vitamin B12, 0.015 mg; nicotinic acid, 40 mg; pantothenic acid, 14 mg; folic acid, 1.6 mg; biotin, 0.18; choline chloride, 300 mg; Mn, 100 mg; Fe, 40 mg; Zn, 100 mg; Cu, 15 mg; I, 1 mg; and Se, 0.3 mg. Abbreviations: OH—ad hull; SH—sunflower hull; DSBP—dry sugar beet pulp; WB—wheat bran.  
\end{table}
Table 2: _Cont._