[Studies on the effect of nutritional factors on the rumen mucosa. 2. Report. Morphological conditions after feeding with fattening rations in various physical forms].

3 groups of fattening cattle (DSR breed) were fed rations of nearly identical composition for a period of 395-455 days. The rations consisted of either crushed (group I), finely ground (group II) or finely ground and pelleted material (group III). Samples of the ruminal mucosa from 26 animals were investigated macroscopically, microscopically and histologically. All samples from animals of group I were found to be normal whereas clumping of the villi, hyperkeratosis, atrophy and loss of villi over 40%-50% of the surface of the ruminal mucosa were observed in the animals from group II, and, to a larger extent in animals of group III. The main reason for the mentioned changes of that kind are the very fine foodstuff particles, less than 0.05 to 0.5 mm in length, which form extraneous deposits in the mucosa or act as cement substances between neighbouring villi. This leads to hyperkeratosis because these particles prevent desquamation of the corneal cells and at the same time produce conditions of compression; these, in turn, result in a hardening of the newly formed stratum corneum. Hypertrophy of the undamaged villi was observed in animals of group III receiving the pelleted ration (thickness of villi group III: 243 mum as compared with group I:196 mum). The unfavourable morphological state of the ruminal mucosa in animals of group III was associated with a reduced rate of daily weight gains and increased food consumption.