I . Four rumen-cannulated sheep were given a forage mixture (F) of chopped hay-ground, pelleted, dried grass (92:8, w/w) and two concentrate mixtures (C and S) of ground barleyground hay-flaked maize (46: 24: 3 0 and 56: 24: 20, by wt respectively) in hventy-four hourly meals each day. Each of the diets was offered in successive periods of 16 d to give a feeding sequence F-S-C-S for one pair of shcep and C-S-F-S for the other pair.2. T h e average composition (mol/Ioo mol) of the mixture of short-chain fatty acids, acetic, propionic and butyric, in the rumen was respectively 70.1, 18.5 and 7.5 with diet F, and 55.8, 24.8 and 13.6 with diet C. With diet S, the pattern of fermentation varied both between animals and in the same animal for different periods having either 'high' (28-39 mol/roo mol) or 'low' (16-21 mol/roo mol) proportions of propionic acid. On average when diet S followed diet F there was less propionic acid in the fermentation mixture than when diet S followed diet C (j9.3 acetic, 22.2 propionic and 14.1 butyric as compared with 52.7, 29.4 and 13.1 respectively) but this trend was not significant and there was evidence of intcractions between the feeding sequences and the individual sheep.j. T h e mean concentrations of ammonia, sodium, potassium and chloride were similar for all diets but the pH and concentrations of calcium, magnesium and phosphorus tended to he higher and the buffering capacity loner for diet F than for diets C or S. In animals receiving diet S there was no relationship between the concentrations of minerals, the pH or buffering capacity and the pattern of fermentation except for ammonia, the concentration of which was high when the molar proportion of propionic acid was low.4. Rumcn volume, outflow rate and clearance rate, determined using polyethylene glycol, were higher for diet F than for diets C and S but within each diet, particularly for diet S, values varied considerably bet-een shcep and between periods. 5 . There was evidence of an interrelationship behveen the molar proportion of propionic acid in the fermentation products and the clearance rate, which indicated that the clearance rate may be an important factor influencing the pattern of fermentation in the rumen.Ishaque, Thomas & Rook (1971) found that for sheep given a diet of (g/kg): 560 ground barley, 240 ground hay and 200 flaked maize, there were wide variations in the composition of the mixture of short-chain fatty acids in the rumen between animals, or in the same animals on different occasions. In eight of their experiments animals were introduced to the experimental diet after receiving a diet of chopped hay, and in five of these experiments the mixture of fatty acids contained a low proportion of propionic acid (13-18 mol/roo mol). In the remaining three experiments, and in two additional experiments where the pre-experimental diet was of ground barley, ground hay and flaked maizc, the molar proportion of propionic acid was high (28-38 mol/ IOO mol). T h e precise influence of the 'pre-experimental' diet o...
Background:The value of carotid surgery is largely dependent on the safety of the procedure. With changes in population life expectancy, increasing numbers of elderly patients are being considered for surgery. Methods:In the present paper, the results of I13 patients (octogenarians: > 80 years of age) who underwent carotid endarterectomy in the 17 years prior to 1994 are reported. This group composed 6.2% of the 1818 patients treated in the period, 665 (36.6%) operations were performed on patients 50-65 years inclusive and 1040 (57.2%) on patients aged 66-80 years inclusive. Results: The overall peri-operative stroke rate was 2.5% and the postoperative mortality was 1.9% with no statistical difference apparent between the age groups despite hemispheric strokes being the most common indication for operation in the octogenarian group (29.5%) and the least common indication in the youngest age group (16.2%, P < 0.01).Long-term follow up (2-7 years) of octogenarian patients undergoing carotid surgery suggested maintenance of pre-operative levels of living independence. Conclusions:The results of the study indicated that octogenarian patients should not be denied carotid endarterectomy on the basis of age alone and that results comparable to those of younger patients can be anticipated.
The main object of the experiment was to assess the effect of the relative proportion of nonprotein nitrogen (NPN) to total nitrogen in silage on digestion in the sheep. Four unwilted perennial ryegrass silages were made with the addition of formic acid at 0, 2-3, 4-6 and 5-9 litres t"' to provide foods with NPN proportions reducing from 0-56 to 0 40 of the total N, The digestion of the silages was studied in a 4 x 4 Latin Square experiment with sheep cannulated in the rumen, proximal duodenum and terminal ileum.Results for organic matter (OM), cellulose and N showed no major difference between silages in their digestion in the rumen, small intestine and caecum and colon, though small differences (/'<0 05) in rumen fermentation pattern and in the proportion of digestible OM disappearing in the small intestine were observed. Concentrations of ammonia N in the rumen and rates of rumen bacterial protein synthesis did not differ significantly between silages and there were no treatment effects on the passage of individual amino acids to the small intestine. The results indicate that the proportions of NPN to total N in the silages examined had little influence on the efliciency of silage N utilization in the rumen or on the passage of undegraded dietary protein to the small intestine.
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