Effects of structural and non-structural carbohydrates on the development of rumen fermentation and ruminal mucosa in calves were examined during the weaning period. Barley/soybean meal (SBM) group was fed a concentrate starting from 2 weeks of age, whereas alfalfa group received a mixture of concentrate and alfalfa hay in which the proportion of the latter was gradually increased from 20% to 70% between weeks 2 and 9 of age. The total volatile fatty acid concentration in rumen fluid of calves increased with age, but at 9 weeks there were no significant differences between the two diets (barley/SBM group 153 mmol/l, alfalfa group 150 mmol/l). Rumen papillae at 9 weeks of age, as compared to 6 weeks of age, were longer and fewer in number per square centimetre mucosa, with larger cut surface. This resulted in a higher surface of papillae per square centimetre mucosa at 9 weeks (barley/SBM group 286 mm2/cm2, alfalfa group 245 mm2/cm2) than at 6 weeks of age (barley/SBM group 217 mm2/cm2, alfalfa group 198 mm2/cm2). At 9 weeks of age, the pH (barley/SBM 5.0, alfalfa 5.7), the acetate to propionate ratio (barley/SBM 2.2, alfalfa 3.2) as well as the length of the papillae in the ventral ruminal sac (barley/SBM 1.96 mm, alfalfa 2.37 mm) were increased in the alfalfa group when compared to the barley/SBM group (P < 0.1). In the former group, the proportion of butyrate revealed significantly increased values at 4 and 6 weeks of age. In animals of the barley/SBM group at 9 weeks of age, characteristic protrusions with proliferated thick epithelium occurred on the papillae and increased the surface for absorption. On the epithelium (Stratum corneum) desquamating cells with parakeratosis could be observed. In the alfalfa group the papillae of the ventral ruminal sac were longer, without protrusions. The morphotypes of the adhering rumen microflora differed between the groups. It can be concluded that feeding greater amounts of non-structural carbohydrates increases the surface for absorption of the rumen epithelium in calves. The absence of hyperkeratosis and rumenitis in the barley/SBM group indicated that there is no reason to limit high starch diets in the early weaning period of calves.

Two bulls, each fitted with rumen and duodenal cannulas, received (in addition to a hay-grain diet) twice daily an infusion of 200 g glycerol into the rumen over a period of six days. During this preliminary in vivo investigation, the influence of a glycerol application on the rumen environment over a six-day adaptation period was examined. Samples of rumen fluid were collected daily, two hours after glycerol infusion. An additional 15N-urea application into the rumen was given on days 1 (without glycerol infusion), 3 and 7 (with glycerol infusion). Extra samples of rumen fluid and blood plasma (from puncture of vena jungularis) were taken through the 12th hour following urea application. Rumen fluid pH was reduced due to glycerol intake from 6.3 (day 1, without glycerol) to 5.4 by day 7. Molar proportion of acetic acid to propionic acid decreased from 3.5 (day 1) to 2.1 (days 6 and 7). Average glycerol disappearance rate from the rumen was 4.7 gl-1 h-1 for the first hour. Only small amounts of glycerol could be detected in the duodenal digesta. Blood plasma glycerol content was significantly higher after glycerol application (0.061 mmol l-1 vs. 0.019 mmol l-1). The incorporation of 15N into the rumen bacteria and the proportion of bacterial N (as percent of TCA-precipitable N in the rumen fluid) were lower after glycerol influsion. These results, coupled with the lower concentration of iso-acids (isobutyric and isovaleric acids) in the rumen fluid, indicate that the high amount of glycerol infusion (10% of DMI) reduced protein metabolism of rumen bacteria throughout the experimental period.

In ca�le, energy-rich feeding causes an increase in the size of rumen papillae and leads to considerable mucosa proliferation (Dirksen et al., 1984). In animals fed low and high energy diets rumen mucosa revealed progressive reduction and intensive proliferation, respectively (Dirksen et al., 1985). Intensity of rumen fermentation increases with the increasing intake of concentrate and simultaneously the occurring volatile fa�y acids promote the structural development of the rumen epithelium (Kauffold et al., 1977;Hofmann and Schnorr, 1982;Zitnan et al., 1998).So far, insufficient or no investigations at all have been carried out into the effects of the diet upon the development of small intestinal mucosa.According to Tivey and Smith (1989), changes in the development of enterocytes and in the structure of villi determine the digestive and absorptive capacity of the small intestine. Kreikemeier et al. (1990) studied the activity of carbohydrate digesting enzymes in Holstein and Longhorn bulls and observed it to be influenced by the type of diet and the level of feed intake. Mir et al. (1997) considered the length of villi and crypts and mucosal carbohydrase activity to be an important factor in nutrient absorption; they recorded differences in these parameters between different cattle breeds, of which Holstein bulls had the highest lactase activity and the longest villi in the middle part of the intestine. ABSTRACT: 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 ca�le. 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 a�er 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 cm 2 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 lengt...

Four Slovakian Black-and-white bulls (LW 410 +/- 12 kg; Exp. 1) and four Slovakian Black-and-white non lactating dairy cows (LW 475 +/- 14 kg; Exp. 2) with permanent ruminal cannulas, duodenal T-cannulas and ileal re-entrant cannulas were used in a 4 x 4 Latin square design to determine the postruminal capacity of starch digestion. In Exp. 1 bulls received 5.4 kg DM from corn silage and 3.6 kg DM from alfalfa hay, in Exp. 2 cows consumed only 2.1 kg DM corn silage and 1.9 kg DM alfalfa hay. Additionally, either 750 or 1500 g (Exp. 1) or resp. 1000 or 2000 g (Exp. 2) gelatinized corn or wheat starch per animal and day were applied as pulse doses or as infusion into the proximal duodenum. In both experiments the duodenal and ileal nutrient flow, as well as the faecal excretion without starch application, were measured in a pre-period. After starting starch application ileal digesta and faeces were sampled over 120 h after 9 or 23 days of adaptation respectively. Cr2O3 was used as a flow marker. It was shown, that the capacity of starch utilisation in the small intestine was limited. The effect of different doses of bypass-starch was more pronounced than the effect of different starch sources. Starch digestibility decreased with increasing amounts of starch in the intestine (Exp. 1: corn starch: from 74.3 to 68.0%, P < 0.001; wheat starch: from 76.7 to 67.4%, P < 0.001; Exp. 2: corn starch: from 71.4 to 50.3%. P < 0.001; wheat starch: from 73.8 to 53.1%, P < 0.001). Corn starch was 0.6 to 2.4% units (P < 0.05) and 2.4 to 2.8% units (P < 0.001) less digested than wheat starch in Exp. 1 and Exp. 2, respectively.

Most antibiotics are only partially metabolised by patients before being discharged into the municipal sewage system along with patient excreta. Studies have shown that the majority of antibiotics pass through sewage treatment and are then released into the environment. Accordingly, investigations conducted in various countries have detected a number of antibiotics in the low μg or ng per litre range in different environmental compartments. Studies connecting mass balances of use on a local scale and of input and analysis of the antibiotic concentrations present in municipal sewage treatment plants are scarce. Data on local use of antibiotics and their relation to nationwide consumption are not available. This study investigated the use, input, and fate of antibiotics on a local scale and this data were compared with the German nationwide consumption. 42 antibiotics and 15 antimycotics were used in the mass balance consideration over a period of one year. It was found that the local pattern of usage differed only little from that found nationwide. Seasonal changes were minor and the concentrations actually measured were found to be in the expected range. Differences in both the identified occurrence and the concentrations of the target compounds were observed within and between the three sampling periods.