## 2 Materials and Methods  
### Animals and Diets  
This experiment on broiler chickens was approved by the Faculty Team for Animal Welfare of the Faculty of Biology and Animal Nutrition at the University of Life Sciences in Wroclaw, approval no. 0058 in the Register of Users of animals used in procedures, in accordance with the ordinance described in article no.3 of Dz.U.2021 position 1331, 2338 on the protection of animals used for scientific and educational purposes. In this experiment, 150 broiler chickens were kept in 30 metabolic cages during the digestibility trial. This experiment was planned for a standard broiler chicken rearing period of 35 days. The experiment was designed under the assumption of the use of a single experimental factor in the form of additional sources of DF in five diet treatments. Each treatment consisted of six replicates with five chickens each (n = 30 in each treatment). Similar average BW was taken into consideration and checked at the beginning of the experiment, allowing for changes between the treatments to be observed based on different experimental factors. The diets differed based on their structural components, with 3% being structural additives (OH, SH, SBP, and WB), except for the control group where a standard diet containing maize and soybean meal was used. Vaccinated, one-day-old Ross 308 chickens with an average body weight of 44.8 g were kept together for the first 7 days of life and fed a starter mixture based on wheat grain and soybean extraction meal (Table 1). \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Item** & **Control** & **3\% OH** & **3\% SH** & **3\% SBP** & **3\% WB** \\ \hline Maize & 50.2 & 11.9 & 7.9 & 11.1 & 10.3 \\ Wheat & 536.6 & 529.5 & 534.2 & 537.0 & 540.9 \\ Soybean meal & 320 & 325 & 327 & 322 & 318 \\ Soy oil & 53 & 63 & 61 & 61 & 61 \\ Oat hull & & 30 & & & \\ Sunflower hull & & & 30 & & \\ Dry sugar beet pulp & & & & 30 & \\ Wheat bran & & & & 30 & \\ NaCl & 2.2 & 2.2 & 2.2 & 2.2 & 2.2 \\ Sodium bicarbonate & 2.0 & 2.0 & 2.0 & 2.0 & 2.0 \\ Monocalcium phosphate & 12.5 & 12.6 & 12.6 & 12.5 & 12.6 \\ Chalk & 14.2 & 14.2 & 14.2 & 13.5 & 14.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Ingredient composition and chemical analysis of starter diets (g/kg). At 7 days of age, chicks weighing approximately 133 g were randomly assigned to the five treatments. The birds continued to be fed a starter-type diet until 21 days of age. From 21 to 35 days of age, the chicks received a grower mix with the same types and share of structural components as in the starter mixes (Table 2). The chicks were kept under standard rearing conditions. The temperature on the first day of the experiment was 32 \({}^{\circ}\)C; then, it was systematically lowered to 24 \({}^{\circ}\)C during the second week and to 20 \({}^{\circ}\)C during the last days of the chicks' life. The lighting program included 23 h of light and 1 h of darkness in the first few days; after day 7, the duration of daylight was shortened to 20 h, while from days 14 to 35, the duration of daylight was shortened again to 18 h. The diets were offered to the chickens ad libitum, taking into account uneaten food during the recording of feed intake. Water was provided to the chickens using nipple drinkers. Body weight, feed intake, and feed conversion ration were recorded on days 21 and 35. Humidity in the room was maintained in the range of 55-60% and was reduced with the age of the birds. \begin{table}