Chickens were fed on diets containing either 12.8 MJ, 150 g crude protein (nitrogen x 6.25)/kg or 12.8 MJ, 200 g crude protein/kg to determine differences in metabolism. The diet containing 12.8 MJ, 150 g crude protein/kg contained either 8 or 12 g lysine/kg. Treatment variables examined in vitro were lipogenesis, glucose production and hepatic enzyme activities to compare metabolism in chicks fed on a low-protein, lysine-supplemented diet and a diet formulated to contain the required amount of lysine from intact protein. Growth was similar in chicks fed on diets containing either 12.8 MJ, 154 g crude protein with 12 g lysine/kg or 12.8 MJ, 200 g crude protein/kg. Net glucose production was greater (p < 0.05) in liver explants from chickens fed on diets containing either 12.8 MJ, 154 g crude protein with 12 g lysine/kg or 12.8 MJ, 200 g crude protein/kg than in explants from chickens fed on 12.8 MJ, 150 g crude protein with 8 g lysine/kg. Pyruvate use for glucose production was greater (p < 0.05) in chickens fed on a diet containing 12.8 MJ, 150 g crude protein with 8 g lysine/kg. The findings from the present study suggest that crystalline and ‘natural’ lysine additions to chick diets may influence metabolism differently.

The aim of the present study was to investigate whether oral potassium supplementation during food deprivation could stimulate rumen electrolyte absorption and maintain plasma electrolyte concentration. Eight goats were subjected to food deprivation in combination with intrarumen loads of potassium chloride or, as a control, mannitol in a change-over design. In addition, four KCI- and four mannitol-treated goats were given an extra KCI load towards the end of the experiment. Food-deprived goats which were given KCI maintained their plasma concentration of Na and CI, while plasma K concentration increased from 3.6 mM to 4.4 m.M. In control goats receiving mannitol during food deprivation, the plasma concentration (mM) decreased from 144 to 140 for Na, 105 to 100 for CI and from 3.8 to 3.6 for K, but concentrations were restored when these goats were given a load of KCI. The plasma renin activity was suppressed in food-deprived goats receiving KCI, while those given mannitol showed increased activity. It is suggested that the hyponatraemia which occurs in food-deprived ruminants is mainly caused by diminished K intake.

Estimates of iron status in a random sample (218 men, 283 women) of the Northern Ireland population (aged 18–64 years) were obtained from blood measurements. Multiple criteria were used to determine Fe deficiency and body Fe stores were calculated as an index of Fe sufficiency. Three distinct groups with respect to Fe stores were identified on the basis of sex and menstrual status. Estimates of body Fe stores, mean (and SD), were 13.4 (SD 5.97), 5.3 (SD 6.09) and 8.5 (SD 6.72) mM for men, women aged 18–44 years and women aged 45–64 years respectively. The prevalence of Fe-deficincy was low. ranging from 0.5% in men to 6.6% and 4.6% in the younger and older women respectively. The prevalence of Fe deficiency was low in men (1.4%) and older women (5.7%) rising to 11.0% in the younger group of women. The disproportionately elevated serum ferritin relative to transferrimn saturation supported the suggestion that chronic inflammation might have influenced Fe status measurements in men and older women.

Techniques have been developed to produce microbial phytase for addition to diets for simple-stomached animals, with the aim to improve phosphorus availability from phytate-P in plant sources. The activity of the crude microbial phytase showed pH optima at pH 5.5 and 2.5. The enzyme was able to degrade phytate in vitro in soya-bean meal, maize and a liquid compound feed for pigs. When microbial phytase was added to low-P diets for broilers the availability of P increased to over 60% and the amount of P in the droppings decreased by 50%. The growth rate and feed conversion ratio on the low-P diets containing microbial phytase were comparable to or even better than those obtained on control diets. Addition of microbial phytase to diets for growing pigs increased the apparent absorbability of P by 24%. The amount of P in the faeces was 35% lower.

Inositol compounds with three to five phosphate groups (IP3–IP5) were produced by hydrolysis of phytate (inositol hexaphosphate, IP6) and their binding affinities for calcium and zinc investigated at neutral pH with relative concentrations that had been found in a range of students' meals. Zn solubility was negligible at many of these concentrations, with less Zn bound to precipitates of Ca-IP6 than Ca-IP5. The capacity to precipitate Zn at these ratios fell between IP5 and IP3. Zn was partially desorbed by soluble chelators (histidine and picolinate), especially when it had been adsorbed to preformed Ca-IP precipitates. A lower proportion of Zn was accessible to soluble chelators from Ca-IP4 than the other compounds. IP3-IP4 were hydrolysed. by phytase more readily than IP5–IP6.

Iron absorption from three typical West African meals was measured in fourteen subjects using the extrinsic-tag technique with 59Fe and 55Fe. All meals consisted of maize as the staple food. Meals were prepared in Benin under realistic conditions from locally grown foods. Of the non-haem-Fe in the meals 39–73% did not exchange with the added inorganic radio-Fe tracer, depending on the degree of Fe contamination of meals. Non-haem-Fe absorption was low in each maize meal, but was even lower for those eaten with a vegetable sauce than for those eaten with a fish sauce. When haem-Fe absorption was included, 70.0–160μg Fe was absorbed. Expressed on an energy basis, the bioavailable nutrient density was 3.2–7.0 μ/100 kJ (13.4–29.5 μ/100 kcal). These findings suggest that total Fe available in the typical diets of West African countries does not meet the physiological requirements of large proportions of the population.

The addition of 1 g sugar-beet fibre (Beta Fibre) to 3 g semi-synthetic diet resulted in a 54% increase in iron and a 39% increase in zinc absorption in rats. The same amount of non-starch polysaccharides fed as wheat bran (1.9 g) had no effect on Fe absorption but reduced Zn absorption by 9%. The inhibitory effect of wheat bran is probably due to its high phytate content, but there is, as yet, no explanation for the enhancement of Fe and Zn absorption caused by Beta Fibre. If the effect also occurs in man, it will have important implications for high-fibre diets and mineral nutrition.

Two studies were conducted to investigate the possibility that pteroylmonoglutamic acid supplementation would alleviate teratogenesis in zinc-deficient rats. Pregnant rats of the Wistar strain were fed on Zn-deficient (< 0.5 mg Zn/kg) or Zn-supplemented (75 or 95 mg Zn/kg) diets from mating until day 18.5 of gestation. The basal level of pteroylmonoglutamic acid added to all diets (0.56 mg/kg) was supplemented with 30–200 mg/kg in selected diets. Dietary Zn deprivation resulted in fetal resorption, fetal growth retardation and reduced concentrations of Zn in fetuses and maternal plasma and tibia. Low maternal body-weight at conception emerged as an important determinant of risk of resorption in Zn-deficient rats. Dietary Zn deficiency resulted in reduced maternal plasma folate concentrations and these values were inversely correlated with litter size or weight in Zn-deficient rats. Pteroylmonoglutamic acid supplementation increased maternal plasma folate concentrations, but did not reduce the high incidence of teratogenesis which occurred in Zn-deficient rats. Supplementation of Zn-deficient rats with pteroylmonoglutamic acid significantly increased the incidence of clubbed foot and tended to increase the incidence of brain or meningeal abnormalities, or both, and cleft palate, but did not reduce maternal or fetal Zn status. Pteroylmonoglutamic acid supplementation also increased the weights of Zn-supplemented control fetuses.

The purposes of the present study were to determine whether caffeine has an effect on zinc absorption and tissue levels of Zn. Under anaesthesia, one side of the intestine of female rats was connected to infusion pumps and an infused solution (first caffeine and later Zn solution) was collected from the other side of the intestine using either 300 mm or the whole small intestine to determine Zn absorption. In a further study, different doses of caffeine solution were injected directly into the femoral vein and a saline or Zn solution was infused into the intestine to measure Zn absorption and tissue Zn concentrations. The results consistently showed that the caffeine solution infused into the intestine did not affect intestinal Zn absorption nor was absorption affected by the direct injection of caffeine into the vein. In contrast, injection of different doses of the caffeine solution significantly decreased Zn tissue levels for the heart only. Calcium concentrations in the heart tissue were also decreased, but not magnesium concentrations. Tissue Zn levels recovered immediately on infusion of a Zn solution into the intestine.

Damage to skeletal muscles may be mediated via free radicals or intracellular calcium overload. To look for inter-relationships between these pathways we have examined the effect of intracellular Ca overload on muscles from rats fed on either a vitamin E-deficient or vitamin E-sufficient diet and assessed the non-enzymic lipid peroxidation in these muscles by examining the production of thiobarbituric acid reactive substances by homogenates. Vitamin E-deficient muscles were more susceptible to Ca-induced intracellular enzyme efflux and this was acutely corrected by supplementation of the external medium with 230 μmol α-tocopherol/l. Vitamin E-deficient muscles showed increased levels of basal lipid peroxides and were more susceptible to iron-catalysed lipid peroxidation. Addition of the Ca ionophore A23187 increased lipid peroxidation in vitamin E-deficient muscle homogenates, but had the opposite effect in vitamin E-sufficient muscles. These results demonstrate that vitamin E-deficient muscle has an increased susceptibility to intracellular Ca overload, but that this effect cannot be explained by a direct stimulatory effect of the ionophore on non-enzymic lipid peroxidation.

Measurement of peroxyl-radical trapping capacity (TRAP) were made in plasma from patients with malaria from a rural and an urban Thai community. The results were compared with those from control subjects living in the same areas and chosen to match the patients closely. Measurements were also made of various antioxidants including nutritional indices vitamin C and α-tocopherol and the non-nutritional indices urate and protein-sulphydryl. Parasite counts, temperature on examination and the duration of illness were recorded together with measurements of plasma caeruloplasmin (EC 1.16.3.1), retinol and malondialdehyde (MDA). In general, most measurements made in the villagers were lower than those in the comparable urban groups. The exceptions were caeruloplasmin and MDA when the latter was expressed as MDA: cholesterol ratio. TRAP values were extremely low in 50% of the villagers and 25% of the urban patients with malaria and these results correlated with retinol and vitamin C and inversely with malonaldehyde. The results suggested that low TRAP values are associated with lipid peroxidation and that vitamin C and possibly retinol may be destroyed by the oxidative conditions present in the plasma in this disease.

The purpose of the present study was to determine the levels of zinc in the hearts of growing post-weaning offspring, fetuses and their dams chronically fed caffeine. A further study was conducted to determine the distribution of Zn in subcellular heart fractions affected by acutely injecting caffeine into the veins of the adult rats. After delivery pups were raised on a 200 g protein/kg diet until day 22 of weaning. On day 22 randomly selected male offspring from each litter were divided into two groups. Group 1 was fed continuously on the same diet as a control, whereas in the experimental group offspring were fed on a 200 g protein/kg diet supplemented with caffeine (20 mg/kg). On day 49 the animals were killed and Zn, calcium and magnesium concentrations of the hearts were measured. In the second series of studies pregnant dams were randomly divided into two groups. Group 1 was fed on a 200 g protein/kg diet from day 3 of gestation, whereas in the experimental group dams were fed on the diet supplemented with caneme. On day 22 of gestation the fetuses were surgically removed. The Zn, Ca and Mg concentrations of hearts of fetuses and dams were determined. In the third phase a caffeine solution was injected into the vein. After 45 min the hearts were removed and Zn levels in the subcellular fractions determined. The hearts of the growing offspring fed on a caffeine-supplemented diet consistently showed decreased Zn and Ca levels compared with the non-caffeine group. In contrast, Zn and Ca concentrations of the hearts of fetuses and dams showed no difference between caffeine and non-caffeine groups. In the various fractions studied, the Zn contents affected by caffeine were in the supernatant (cytoplasmic) fraction. This fraction contained 30% of the Zn concentration of the homogenates. Current findings suggest that caffeine intake and heart Zn levels are closely correlated.

Eighteen different infants' drinks from five manufacturers were examined for their carbohydrate, calcium, phosphorus and acid contents, and their attack on tooth mineral. Seven of the drinks were compared with nine varieties of adults' soft drinks, and demineralization was studied with and without the presence of a cariogenic oral streptococcus. The influence of the acids already in the drinks in dissolving Ca and P outstripped that of any acid generated in these studies in vitro by microbial fermentation of the sugars they contained, giving an indication of their relative erosiveness rather than their cariogenic action. Various other features of the drinks relevant to dental health were identified. Titratable acid was a better guide than pH to their dental properties. Although there were considerable differences between the various infants' drinks taken as a group, their acidity levels and demineralizing powers were generally lower than those of the adults' drinks.

The digestion of non-starch polysaccharides (NSP) was studied in rats given semi-purified diets containing 0-500 g raw peas (Pisum sativum)/kg. NSP were equally well digested at all inclusion levels with digestibilities for individual constituents ranging from 0.58 for xylans to 0.99 for arabinose-containing polymers with a total NSP digestibility of 0.79. Increasing the dietary pea inclusion rate increased the amount of substrate flowing to the large bowel (LB) and this was associated with marked increases in caecal tissue and contents masses, a reduction in caecal transit time from 0.88 to 0.43 d and a threefold increase in faecal bacterial biomass output. Caecal pH fell as did the molar proportions of acetate, isobutyrate, isovalerate and valerate whilst butyrate increased when peas were included in the diet. Possible mechanisms for these fermentation end-product changes are discussed. Pea inclusion in the diet was associated with increased volatile fatty acid and 3-hydroxy butyrate concentrations in portal and heart blood. It was concluded that peas are a rich source of fermentable polysaccharides which produce a LB fermentation pattern of potential health benefit.

Starch that is resistant to human amylases forms during the cooking and subsequent cooling of some foods, and may therefore be a substrate for the bacterial flora of the colon. It is thus possible that resistant starch (RS) will affect colon function in a similar manner to non-starch polysaccharides. To test this theory, a group of eight volunteers took two diet supplements for 1 week each in a random order with a 1 week separation. One supplement comprised mainly 350 g Cornflakes/d and the other 380 g Rice Krispies/d, providing 10.33 and 0.86 g RS/.d respectively. The amounts of amylase-digestible starch, non-starch polysaccharides, total carbohydrate, energy, protein and fat were balanced between the two periods by giving small amounts of Casilan, wheat bran, butter and boiled sweets. The volunteers made faecal collections during day 3 to day 7 of each period. Whole-gut transit time was calculated using the continuous method. Stool consistency and ease of defaecation were assessed by the volunteers. All episodes of flatulence noticed were recorded in a diary, along with food intake. Serial breath hydrogen measurements were made at 15 min intervals for 8 h on day 1 of each supplement. Questionnaires regarding colon function were completed at the end of each dietary period. There were no significant differences in the stool mass, frequency or consistency, ease of defaecations, transit time or flatulence experienced during the two supplements (P > 0.05). Significantly more H2 (area under curve) was produced while eating Cornflakes than Rice Krispies (P < 0.05). The difference of 9.47 g RS/d between the two diets was over three times the calculated normal daily RS intake of 2.76 g/d. As the only significant difference observed was in the breath H2 excretion on day 1, we suggest that either RS is rapidly and completely fermented to end-products including H2 gas, which is subsequently excreted via the lungs and has little influence on colon function, or that bacterial adaptation removed any observable effect on faecal mass and transit time by day 3.

The site where osmotically active substances act to depress food intake was determined in sheep. After 5 × 5 h of food deprivation, solutions of sodium chloride or polyethylene glycol-200 (PEG-200) were added to either the reticulo-rumen or the abomasum. The sheep were then immediately offered pelleted lucerne (Medicago sativa). Water was withheld during the first 60 min of feeding but was available from 60 to 90 min. There was a linear inhibition in food intake in the first 10 min after loading 2.37, 6.25, 12.5, 25.0 or 50.0g NaCI into the rumen according to a 5.5 Latin square design (P = 0.0001). The intake reduction was 3.49 g food/g NaCI. An osmotic load of PEG-200 equivalent to 50 g NaCI also significantly inhibited food intake in the first 10 min of the meal compared with a control treatment. The inhibition of food intake after loading 55 g NaCI into the rumen was not affected by injecting lidocaine hydrochloride into the reticulum immediately before NaCI loading. NaCI injected into the abomasum did not significantly affect food intake in the first 10 min of feeding even though the tonicity of abomasal digesta was increased to unphysiological levels. There was no consistent relationship between food intake and the change in the tonicity of jugular plasma following solute loading and drinking. The sensing site of hypertonicity was localized to the wall of the reticulo-rumen where neuronal receptors appear to be capable of detecting osmotic pressure within the physiological range to depress food intake. These receptors should be identified and characterized because of their possible significance in limiting food intake by ruminants.