مقايسه روشهاي مختلف پيش بيني قابليت هضم در گوسفند

Comparison of different techniques for predicting digestibility in sheep

In this study, five methods ot DM and OM digestibility of four rations were compared using sixteen Zel rams. Diets were: 1- alfalfa hay (ad libitum), 2- alfalfa hay and barley grain (60:40), 3- wheat straw and barley grain (60:40) and 4- wheat straw and barley grain (80:20). Diets 2, 3 and 4 were each offered at the level of 40 g DM/Kg W° 75. The digestibility methods which been conducted were total collection of faeces, lignin (as an internal marker), acid insoluble ash (AIA), chromic oxide and in vitro techniques for all rations, there were a significant different (p<0.01) between the DMD and OMD of total collection method and lignin, AIA and in vitro techniques. However, no signicant difference (p<0.05) were noted between the chromic oxid method and total collection method, for all rations , the recoveries were 88, 112 and 101% For lignin. AIA and chromic oxide respectively, for all diets, a high correlation coefficient (r) was obtained between total collection method and lignin, chromic oxid and in vitro techniques. That is mean, lignin, chromic oxid and in vitro methods may be used to estimate the DMD and OMP of all ration; however AIA method can not be used to estimate the DMD and OMD af all ration.