The purpose of carried out investigations was to determine the digestibility of nutrients in wild boars, swine · wild boars hybrids and in swine fed mixtures containing different level of crude fibre. Mixture given to group I-st was treated as control and was characterized by a fibre concentration at level of 4%. In mixtures IInd and IIIrd the level of fibre was increased up to about 5 and 7 percent. As an result of performed investigation it was stated that the increase of crude fibre concentration (over 5%) in diets given to all groups of animals negatively affected the nutrients conversion, particularly decreased the protein digestibility. Obtained results indicate also that similarly to the increasing of fibre concentration the decrease of NDF and ADF digestibility appeared. The NDF fraction was better digested than ADF in all experimental animals.

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