1. A number of dietary sugars are known to mediate the effects of copper deficiency. The effects of lactose (compared with sucrose) and a dietary Cu deficiency on hepatic and cardiac antioxidant enzyme activities and tissue mineral element status were investigated in the rat.

2. Groups (n 6) of male weanling Wistar rats were provided ad lib. with deionized water and diets containing sucrose (580 g/kg) or sucrose and lactose (387 g/kg and 193 g/kg respectively) with either control (12.0 mg/kg) or deficient (1.5 mg/kg) quantities of Cu for 77 d.

3. Animals consuming the low-Cu diets exhibited significantly decreased tissue Cu levels (P < 0.01), hepatic and cardiac cytochrome c oxidase (EC 1.9.3.1, CCO) activities (P < 0.01 and P < 0.001 respectively) and hepatic Cu-zinc superoxide dismutase (EC 1.15.1.1, CuZnSOD) activity (P < 0.05). The low-Cu diets also significantly decreased cardiac manganese superoxide dismutase (EC 1.15.1.1, MnSOD), catalase (EC 1.11.1.6) and glutathione peroxidase (EC 1.11.1.9, GSH-Px) activities (P < 0.01, P < 0.05 and P < 0.001 respectively).

4. Hepatic Mn was significantly increased in both lactose-fed (P < 0.001) and Cu-deficient (P < 0.01) animals. These increases were unrelated to hepatic MnSOD activity. Cardiac Zn was significantly (P < 0.01) increased in Cu-deficient animals.

5. Lactose feeding resulted in significantly increased cardiac CCO activity (P < 0.001) but significantly decreased hepatic CuZnSOD (P < 0.05), catalase (P < 0.01) and GSH-Px (P < 0.001) activities.

6. The activities of lactose dehydrogenase (EC 1.1.1.27, LDH) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6PDH) were found to be significantly (P < 0.05 and P < 0.01 respectively) increased in Cu-deficient animals and G6PDH activity was significantly (P < 0.01) decreased as a result of lactose consumption.

7. The observed changes in antioxidant enzyme activities associated with both Cu deficieny and lactose consumption may have important implications for the development of free radical mediated cell damage. However, no significant differences in either hepatic or cardiac levels of thiobarbituric acid reactive substances, a measure of lipid peroxidation, were found.

1. Fifteen normal premenopausal women followed a low-fat diet for a period of 2 months.

2. Daily fat intake was reduced from 81 g on their customary diet to 36 g on the low-fat diet. A significant reduction in total energy intake and an increase in the dietary polyunsaturated fat: saturated fat ratio was also observed. There was a significant decline in body-weight, percentage body fat and total serum cholesterol, but no significant change in high-density-lipoprotein-cholesterol.

3. Luteal-phase prolactin concentrations were not altered, but there was a significant decline in oestradiol concentrations on the low-fat diet. The proportion of erythrocyte inositol-phospholipid was increased on the low-fat diet and there was a significant increase in the 20:4ω6 (arachidonate) content of inositol-phospholipids. No significant changes in the content or fatty acid compositions of other phospholipid fractions were observed.

4. Further investigation of the effect of level and type of dietary fat on the content and fatty acid composition of membrane inositol-phospholipids are required. Long-term studies investigating the response of both prolactin and oestradiol to dietary fat reduction are also warranted.

1. The relative importance of excretory routes in the removal of recently stored 67Cu following tetrathiomolybdate (TTM) administration was studied. Lambs fed on either 5 mg Cu/kg dry matter (DM) or 35 mg Cu/kg DM, were primed intravenously (iv) with 67Cu and challenged 27 h later with 99Mo-labelled TTM given either iv or intraduodenally (id). The profiles of 67Cu and 99Mo and of Cu and Mo in blood, bile, urine and faeces were measured.

2. Level of dietary Cu and route of administration of 99Mo-TTM affected the amplitude of blood, bile and urine profiles of 67Cu and stable Cu, but not the pattern of the responses observed.

3. The present study describes for the first time increased excretion of endogenous 67Cu through gastrointestinal secretions other than bile due to TTM administration.

4. Administration of TTM resulted in the immediate release of 67Cu from storage compartments in the body into the blood circulation. Changes in stable Cu levels in blood, bile, urine and faeces, and gut and systemic effects were evident. Biliary and urinary Cu excretion due to TTM was rapid and maximal within 24 h of injection.

5. Administration of 67Cu iv resulted in the immediate excretion of 67Cu in bile in a pulsatile, constant pattern. A similar pattern of 67Cu excretion into bile in synchrony with that of 99Mo was observed after 99Mo-labelled TTM administration.

6. The similar pattern of biliary 67Cu excretion observed after injection of 67Cu and after injection of 99Mo-labelled TTM 27 h later is discussed in relation to the times required to process the Cu through different hepatic pathways for excretion in bile.

1. The effectiveness of tetrathiomolybdate (TTM) in the removal of 67Cu from the long-term storage compartment in liver was studied. Lambs receiving 5 mg Cu/kg dry matter (DM) or 35 mg Cu/kg DM were primed intravenously (iv) with 67Cu and challenged 10 d later with 99Mo-labelled TTM given either iv or intraduodenally (id). The profiles of 67Cu and 99Mo and of Cu and Mo with time were measured in blood, bile, urine and faeces.

2. The level of dietary Cu affected the amplitude of profiles of 67Cu and Cu in blood, bile and urine after administration of 99Mo-labelled TTM. TTM administration increased liver Cu removal and this was most marked in sheep given TTM iv. The liver Cu removal from the long-term storage Cu compartment was low and was not affected by the route of administration of TTM. Endogenous Cu excretion was higher in lambs given TTM id.

3. Excretion of 67Cu in bile through the transhepatocellular pathway after TTM administration appeared absent, while the transbiliary and hepatolysosomal pathways were operative. The potential reasons for this change are discussed.

4. TTM predominantly enhances the removal of Cu from the short-term storage compartment, but effects on the long-term storage compartment may still be of significance.

1. Metabolic changes associated with Ramadan fasting were studied in eleven Asian pregnant mothers. This was compared with a group of control mothers undergoing a normal physiological fast.

2. At the end of the Ramadan fast day there was a significant fall in glucose, insulin, lactate and carnitine, and a rise in triglyceride, non-esterified fatty acid and 3-hydroxybutyrate. When compared with the control group, none of the Ramadan mothers had a completely normal set of biochemical values at the end of the fast day.

3. Pregnancy outcome in the two groups was comparable.

4. We are wary of the metabolic departures from normal observed in the Ramadan fasting mothers. If asked we advise mothers to take up the dispensation from fasting during pregnancy which is allowed.

1. A group of six cattle, three of which had a non-bloating history (group A) and had been ruminally cannulated for the previous 2 years, and three with a history of being bloat-prone (group B) and which had been ruminally cannulated only 3 months before the study, were fed ad lib. on chopped lucerne (Medicago sotiva) hay, lucerne pellets, or a 100 g chopped hay and 900 g rolled barley grain/kg diet over three periods of 30 d each. Flow of rumen digesta, by reference to CoEDTA and chromium-mordanted fibres, and foam production from samples of rumen contents were measured.

2. Samples of rumen contents (50 ml) from group A produced foam heights of 150 and 60 mm, 2 and 4 h after feeding respectively, compared with 240 and 150 mm for group B (P < 0.05).

3. The fractional passage rate of the 1-2 mm particles mordanted with Cr did not differ (P > 0.05) between groups.

4. The fractional outflow rates (FOR) for CoEDTA 0-2 h and 2-7 h after feed was offered were 0.205 and 0.160/h for group A and 0.093 and 0.086/h for group B respectively (P < 0.05).

5. Rumen-fluid FOR 0-2 h and 2-7 h after provision of feed were significantly (P < 0.05) inversely correlated (r -0.74 and -0.85 respectively) with the amount of foam produced from rumen contents at these times.

1. An in vitro method, using duodenal and ileal digesta and faeces from pigs as inocula for the preparation of three incubation media for simulating the digestive processes in the pig, was proposed. The kinetics of degradation in these three media of three feed samples (pig-grower diet, sugar-beet pulp and wheat bran) with crude protein (nitrogen × 6.25) contents varying from 111 to 196 g/kg, starch contents from 10 to 446 g/kg and dietary fibre contents from 168 to 686 g/kg, were studied.

2. The method was investigated by incubating the feeds in the three media for up to 96 h, and determining the rate and extent of disappearance of feed components.

3. For each feed the 96 h dry matter disappearance was almost equal for all media, although the rate of disappearance varied considerably, with ileal digesta the most potent, particularly for the high-fibre feeds, and duodenal digesta the least. The patterns of disappearance of individual components were similar in all media, with the exception of crude protein which was apparently less degraded in ileal and especially faecal media.

4. Results suggest that a combination of a short (6–12 h) and a long (48–72 h) in vitro incubation could be employed to simulate digestion in the small and large intestine respectively of the pig.

1. In hay-fed, cannulated sheep the apparent degradation in and outflow from the rumen were determined for graded doses of mixtures of the amino acids lysine, threonine and methionine, administered intraruminally and using polyethylene glycol (PEG) as a liquid marker. The doses ranged between 2.5 and 15 g for each amino acid in the mixtures.

2. Relative rate of apparent degradation in the first 4 h was highest for lysine, and lowest for methionine. The apparent degradation in 24 h was highest for lysine and lowest for threonine. Conversely the fraction flowing out of the rumen in intact form in 24 h was highest for threonine and lowest for lysine. Rates of apparent degradation as well as outflow were dose-dependent.

3. The validity of the estimated outflow of amino acids from the rumen was corroborated by measurements of concentrations of the amino acids in duodenal contents and in blood plasma which were also dose-dependent.

4. It was concluded that part of the requirement for the essential amino acids threonine and methionine may be met, even when these amino acids are delivered in unprotected form, given as a feed supplement.

1. An in vitro method involving incubation of feed samples with buffered duodenal digesta for 12 h or with buffered ileal and faecal inocula for 48 h was compared with in vivo ileal or faecal apparent digestibilities in pigs.

2. The five diets investigated had crude protein (nitrogen × 6.25) contents from 164 to 185 g/kg, starch contents from 296 to 463 g/kg and dietary fibre contents from 176 to 347 g/kg.

3. In vitro disappearances with duodenal inocula were correlated (P < 0.05) with in vivo ileal apparent digestibilities for crude protein, ash, starch, energy and dry matter, but not for dietary fibre.

4. In vitro disappearances with the ileal and faecal inocula were generally correlated (P < 0.1) with in vivo faecal apparent digestibilities for dietary fibre, energy and dry matter, but not for ash or crude protein. The patterns of degradability of fibre polysaccharide residues in vitro and in vivo were also similar.

5. Results indicate that this in vitro method could be used to predict the availability of starch and crude protein for digestion in the small intestine, and the degradability of dietary fibre, and thus for comparing the nutritive value of pig feeds.

1. The relations between food intake, reticulo-ruminal motility and abomasal digesta outflow were investigated in ewes receiving lucerne (Medicago sativa) v. orchard grass (Dactylis glomerata) hay. Abomasal digesta outflow was recorded continuously by means of an electromagnetic flowmeter probe inserted into a duodenal T-shape cannula and the motility using strain-gauge force transducers. Volumes and turnover rates of both rumen and abomasal liquid phases were measured by CrEDTA dilution.

2. The voluntary intake of lucerne was higher (60%) than that of orchard grass hay, and paralleled by an increased abomasal outflow (65%) corresponding to an increased number of gushes of digesta through the flowmeter probe: 129/h instead of 78/h on orchard grass hay. Abomasal motor activity was enhanced (35%), and periods of regular spiking activity were seen passing along the duodenum at a higher velocity for the lucerne diet than for the orchard grass diet. The increased abomasal outflow with lucerne hay was associated with a higher reticulo-ruminal turnover rate, but not abomasal turnover rate. Abomasal, but not reticulo-ruminal volume, was increased (30%) when lucerne hay was fed ad lib.

3. The total number of reticulo-ruminal contractions was increased by 6.6% when the dry matter entering the duodenum was increased by 70.6%, suggesting the level of voluntary intake, rather than reticulo-ruminal motility, as a major factor governing abomasal outflow in sheep.

4. More frequent passages of digesta, unrelated to duodenal contractions, were recorded in ewes receiving lucerne compared with orchard grass. Both a higher viscosity of the contents due to the addition of guar gum and the impairment of antroduodenal motility by 5-hydroxytryptophan were able to reduce the flow rate of orchard grass digesta, but did not affect the higher flow rate of lucerne digesta. The findings suggest that the high abomasal outflow in sheep fed on lucerne ad lib. is related to a low viscosity of the contents that are propelled, even in the case of antral contractions of low magnitude.

1. Five rumen-fistulated cows were given freshly cut ryegrass (Lolium perenne L.) and lucerne (Medicago sativa L.), on separate occasions, to compare rates of particle breakdown and aspects of rumen fermentation.

2. Cattle were required to consume their daily allowance (offered ad lib.) in two 2 h feeding periods daily.

3. During the first 2 h feeding period, dry matter (DM) intakes of ryegrass (4.75 kg) and lucerne (4.85 kg) were similar. Eating reduced 46% of ryegrass and 61 % of lucerne to a size able to pass a 2 mm sieve (P < 0.001). Rumen DM particles retained on the 2 and 4 mm sieves had a low probability of passage out of the rumen, and accounted for only 6 % of faecal DM with both feeds.

4. Ryegrass was cleared from the rumen more slowly than lucerne. During eating, rumen DM particles which could not pass the 2 mm sieve increased from 323 to 511 g/kg for ryegrass and from 201 to 389 g/kg for lucerne. The rate of particle size reduction for lucerne stem was similar to that for ryegrass.

5. When lucerne was eaten the increases in rumen volatile fatty acid (VFA) and ammonia concentrations were much greater than for ryegrass (P < 0.001). The proportions of plant chlorophyll released during eating were similar for both feeds (0.570 and 0.607), but 2 h after eating 22.3 g had been released from lucerne (79.1 %) compared with 15.0 g from ryegrass (63.8%). The flux of water from the rumen to the omasum was similar for ryegrass (10.2 litres/h) and lucerne (12.7 litres/h) during eating, but declined to 6.0 litres/h after eating with the lucerne diet.

1. The absorption rates of calcium, inorganic phosphate (P1) and magnesium were determined from buffered solutions placed in the temporarily isolated and washed reticulo-rumen of conscious sheep. The basic composition of these solutions was similar to that found in supernatant fractions of ultracentrifuged rumen contents.

2. The Pi concentrations studied in these solutions were 2, 8·7, 14, 17·3 and 38 mmol/l. The initial concentration of Ca was 2·0 mmol/l and that of Mg was 2.5 mmol/l in all experiments.

3. Increasing the Pi concentration in the rumen solution from 2 to 38 mmol/l resulted in increases in the net absorption rates of both Ca and Pi, and a decrease in the potential difference across the wall of the rumen.

4. Similarly, increasing the Pi concentration from 2 to 17·3 mmol/l resulted in an increase in the net absorption rate of Mg from the rumen.

5. Mineral analysis of strained rumen fluid or a 30000 g centrifugate of strained rumen fluid revealed a reduced Pi concentration in sheep fed on frozen spring grass as opposed to the pellet + hay diet. The values obtained were within the range studied.

1. Liquid-associated bacteria (LAB) were harvested from the liquid phase (LAB1) and from the solid phase of rumen contents after washing and manual shaking (LAB2). Solid-adherent bacteria (SAB) were recovered after washing and pummelling the total particles (SAB1). The distribution and the chemical composition of these three bacterial compartments were investigated in four dairy cows fitted with rumen fistulas. The animals received successively a diet consisting of one part hay and one part barley-based concentrate (diet C) and the same diet containing free soya-bean oil (79 g/kg dry matter (DM); diet So).

2. The efficiency of removal of SABI from total particles of rumen digesta collected I h after feeding, was calculated from the diaminopimelic acid content in particles and of the corresponding detached bacteria. It was 24% on diet C and 18% on diet So (P < 0.05), using a combination of homogenizing and ‘stomaching’ treatments in saline (9 g sodium chloride/1) (reference treatment). For diets C and So respectively it was lowered by Tween in saline solution (1 g/l; 22.7 and 17.8 %, not significant), but was increased when using a previous chilling (6 h at 4°) of homogenized particles before stomaching in saline (28.8 and 24.7%, P < 0.05) and in Tween 80 in saline (1 g/l; 26.6 and 20.8%, P < 0.05).

3. The extent of removal of SABI from the solid fraction of rumen digesta by the reference treatment decreased with decreasing particle size; it was at the highest for particles retained on 4 and 2 mm sieves (62.1–82.1 %) and still elevated for particles retained on 0.8, 0.4 and 0.1 mm sieves (41.3–57.9%). It was very much reduced for particles smaller than 0.1 mm (11.7–14.5 %), suggesting the occurrence of favourable conditions for the adhesion of SAB firmly resistant to removal (SAB2).

4. The concentration of total SAB (SABI +SAB2) in particles collected l h after feeding was lower (P < 0.05) in diet C (190 g/kg DM) than in diet So (234 g/kg DM). Values averaged 595–645 g/kg DM for particles smaller than 0.1 mm, but only 61 and 81–98 g/kg DM for particles retained on 4 and 0.4 mm sieves, and on a 0.1 mm sieve respectively. No significant differences were noted between diets but the effect of particle size was highly significant (< 0.1 mm v. others).

5. Postprandial variations of concentrations of total SAB on total particles exhibited a large increase I h after feeding in diet So (P < 0.05). Similar but amplified variations were observed for LAB in both diets (P < 0.05).

6. Total bacterial mass amounted to 213 and 231 g DM/kg whole-rumen contents DM in diets C and So respectively 6 h after feeding. Mean percentages of total SAB (69.8), LAB1 (7.3) and LAB2 (22.9) in total rumen contents were not significantly modified by the lipid level of the diet.

1. The inhibitory effects of inorganic and organic sulphur-containing compounds, copper and tungsten on nitrate reduction by mixed rumen micro-organisms were investigated in two in vitro studies.

2. Coarsely strained rumen fluid from nitrate-adapted (Expt 1) or non-adapted (Expt 2) Suffolk Down wethers maintained on lucerne (Medicago sativa) cubes was used as an inoculum. In Expt 1, anaerobic incubation was carried out for 24 h for each medium supplemented with 10 mM-sodium nitrate and the following chemicals: 0, 1, 2, 3, 5, 8 and 10 mM-sodium sulphide, 1 and 10 mM-sodium sulphite, 1 and 10 mM-sodium sulphate, 1 and 10 mM-L-cysteine, 1 and 10 mM-DL-methionine, 1 mM-sodium tungstate and I mM-copper sulphate. In Expt 2, 1 and 10 mM-Na2S, 1 and 10 mM-L-cysteine, 1 mM-Na2WO4, and 1 mM-CuSO4 were added to incubation media to test for chemical inhibition of microbial reduction of nitrate.

3. In Expt 1, the amount of nitrite formed decreased with increasing concentration of sulphide-S added. The additions of L-cysteine, W and Cu suppressed nitrite formation in media from both nitrate-adapted and non-adapted sheep.

4. In contrast to the effects of sulphide, L-cysteine and W counteracted, to some degree, nitrate-induced reduction of volatile fatty acid (VFA) production. Addition of Cu to the media resulted in a further depression of VFA production.