Comparative digestibility studies with hens and rats

Abstract

Abstract. Trials were made to compare the digestibility of feeds in hens and rats. In the comparison particular attention was paid to the true digestibility of the feeds. The digestibility of rusks made of wholewheat meal was compared in hens and rats. The rats digested 62.1 % of the cell wall substances of the whole wheat meal, while the value for the hens was 16 %-units lower. The true digestibility of the other N-free organic matter was also clearly lower in the hen trial than in the rat trial. In the rat trials the digestibility of wholewheat meal was compared with that of bark meal. The true digestibility of the organic matter of the bark meal was only 23.6 %, while that of the wholewheat meal was 92.4 %. The digestibility of the cell wall substances of the bark meal was 18.5 % and of the wholewheat meal 62.1 %.It is rather difficult to compare the digestibility of feeds in hens and rats, owing to the great differences in the digestive tract and excreta of these animals. If the comparison is based on the apparent digestibility values, the results can be deceptive. This is due to the fact that the quantity and quality of the endogenous and bacterial materials of faeces vary considerably in the different animal species, and also in the same species when different rations are given. With poultry the uric acid of the excreta also leads to inaccurate digestibility results, if these are based only on the apparent digestibility. If the efficiency of digestion in different animal species is to be compared, the true digestibility of the feeds of these animals has to be known. The same applies if widely differing feeds are given to the same animal species (Syrjälä 1967). In this paper the word faeces means also the excreta of the hens.The purpose of this study was to investigate and compare the efficiency of digestion in hens and rats by estimating the true digestibility of their feeds. The feeds used in the digestibility trials were wholewheat meal and bark meal. The latter is made from the inner bark of pine. Experimental procedureFeeds. The digestibility of wholewheat meal was studied in hens and rats; the digestibility of bark meal only in rats.