Influence of the diet on the morphology of ruminal and intestinal mucosa and on intestinal carbohydrase levels in cattle

This study examined the effects of extensive and intensive feeding on the morphology of the gastrointestinal tract as well as on the level of carbohydrase activity in the small intestine of growing cattle. Fourteen growing male bulls aged 5 months were divided into two feeding groups. The extensively fed animals were kept on pasture in the summer and in a stall in the winter whereas the intensively fed group was housed all the year long. The bulls were slaughtered 16 h after the last feeding at the age of 18 months. Rumen fluid samples and mucosa samples from the ventral ruminal sac and the intestinal tract (duodenum, jejunum, ileum) were subjected to analyses. Evaluation of rumen fermentation did not reveal significant differences between the groups, however, the molar proportions of propionic acid were increased in the intensively reared bulls. As to the activity of the individual carbohydrase enzymes (maltase, cellobiase, lactase) no significant differences could be stated between the groups. Comparison to the extensively reared group revealed that the length and width of papillae of the ventral ruminal sac was significantly increased in the intensively reared animals (P < 0.001) and so was the papillar surface per cm2 of mucosa (P < 0.001). The length of duodenal villi in the intensive group was singnificantly increased (P = 0.026) whereas that of the jejuenal villi approached the limits of significance (P = 0.052) when compared to the extensive group. There were no significant differences in the depth of crypts, however, the crypts of the intensively reared animals were somewhat deeper. The length of jejunal villi positively correlated both with the length (r = 0.658; P = 0.011; n = 14) and with the absorption surface of the rumen papillae (r = 0.636; P = 0.015; n = 14). Our results confirm that high concentrate rations increase both the absorption surface of the rumen papillae and the height of villi in the small intestine of intensively fed cattle.