Male broiler chickens growing from 7 to 35d were fed on a diet containing 150g crude protein (N × 6·25)/kg diet supplemented with lysine to equal that in diets containing 166, 183 and 200g crude protein/kg diet (Expt 1). A second group of male broiler chickens growing over the same period were fed on a diet containing 120g crude protein/kg supplemented with lysine, arginine, tryptophan, threonine and isoleucine equal to that in diets containing 144, 172 and 200g crude protein/kg diet (Expt 2). Growth was improved by lysine supplementation but not to the level attained by feeding 200g crude protein/kg (Expt 1). Lysine, arginine, tryptophan, threonine and isoleucine supplementation of a low-protein diet also improved growth, but growth again fell short of that attained by feeding a diet containing 200g crude protein/kg. Plasma insulin-like growth factor-1 and thyroxine concentrations increased and triiodothyronine decreased as the crude protein level increased from 150 to 200g/kg diet. Supplemental lysine did not affect plasma levels of these hormones. Although dietary crude protein levels noticeably changed rates of in vitro lipogenesis, changing either the level of a single limiting amino acid or the levels of several limiting amino acids did not change lipogenesis.

Four steers were maintained wholly by intragastric infusion of volatile fatty acids (VFA) and protein, together with a mineral–vitamin supplement. The infusion was given at three levels of energy, namely 450, 675 and 900 kJ/g live weight0·75, calculated to supply energy at 1·0,1·5 or 2·0 times that required for maintenance. The VFA provided 0·837 and the protein 0·163 of the energy infused. The molar proportions of individual VFA were varied so that the infusate contained 0·36–0·91 of acetic acid, 0·56–0·01 of propionic acid and a constant 0·08 of butyric acid. Heat production was measured in respiration chambers. Urine was analysed for N, urea, β-hydroxybutyrate and VFA. Blood plasma was analysed for β-hydroxybutyrate, free fatty acids, insulin and glucose. As the proportion of acetic acid was increased, and propionic acid reduced, there was no change in blood or urine metabolites or in heat production until acetic acid exceeded a proportion of about 0·75. At higher proportions β-hydroxybutyrate increased in plasma and urine, blood glucose and insulin tended to fall and urinary N excretion rose. At a proportion of acetic acid of > 0·80, acetate appeared in the urine and at > 0·86 heat production declined. The effect of level of infusion on the molar proportion at which plasma and urine metabolites changed was less clear. There was a tendency for the increase in β-hydroxybutyrate to occur at a slightly lower proportion of acetic acid at the highest level of infusion. It is concluded that differences in heat production that are observed between diets are probably not caused by differences in rumen VFA proportions. The reaction to a highly elevated proportion of acetic acid is to excrete β-hydroxybutyrate and acetate in the urine and so decrease rather than increase heat production. Regardless of level of infusion a metabolic crisis occurred when the proportion of acetic acid was above the levels found in the rumen content of normally-fed animals.

A large variation in seasonal weight loss between individuals exists in rural communities in developing countries. Therefore, it was investigated whether some individuals show a metabolic adaptation and, through that, prevent large body-weight losses during the preharvest season. Basal metabolic rate (BMR), energy intake and physical activity level (PAL) of rural Beninese women were measured in three seasons. Groups of subjects were: women with a body mass index (BMI) < 18 (n 18), and a BMI > 23 (n 16), and women who had shown small (n 18) and large (n 15) preharvest weight loss. All groups of subjects decreased energy intake during the preharvest season by 0·66–1·09 MJ/d. PAL did not show significant seasonal changes in any of the four groups. Only subjects with a BMI < 18 decreased BMR during the preharvest season with 2·9 (SD 6·7) J/kg per min (P < 0·05), with a decrease of 0·8 (SD 1·4) kg (P < 0·05) in body weight. In very thin women with a BMI < 17 (n 5) BMR expressed per unit body weight decreased even more during the preharvest season (by 12 %).

The effects of body size and feed intake on N digestibility, pancreas and liver weight, and digestive enzyme activities in male broiler chicks were compared with those induced by dietary tannins. Four groups (SSM, ad lib., pair-fed and young) of sixteen birds each (2 weeks old) were used as experimental animals. They were fed on experimental diets for 4 weeks, except the young group which were fed from age 15 d to 24 d only. Two isonitrogenous and isoenergetic diets with (SSM) or without salseed (Shorea robusta) meal (CONTROL) were used. SSM diet was fed ad lib. to SSM group and control diet was fed ad lib. to ad lib. and young birds and to pair-fed birds at same intake level as SSM birds. Birds fed ad lib. utilized their diet more efficiently than the SSM and pair-fed birds. Digestibility of N, both apparent and ileal, was substantially lower with SSM diet than with the control diet. Each of the treatments induced enlargement of the pancreas (g pancreas/kg live weight) when compared with ad lib. birds. There was no difference between the relative liver weights of SSM and ad lib. birds; however, pair-fed and young birds had comparatively bigger livers. In pair-fed birds the trypsinogen activity of pancreatic tissue (U/g pancreatic tissue) was significantly depressed but there was a significant elevation in trypsinogen (U/kg live weight) activity in SSM birds; again pair-fed birds exhibited the lowest value for this variable. Compared with control birds all the other treatments resulted in significant depression of α-amylase (EC 3.2.1.1) activity in pancreatic tissue (U/g) and jejunal digesta (U/g), but because of pancreatic enlargement α-amylase activity per kg live weight was significantly lower only in SSM birds. The activity of trypsin (EC 3.4.21.4) in jejunal digesta was very low in SSM birds, but it was slightly higher in the young birds. Dipeptidase (EC 3.4.13.11) and disaccharidases in duodenal and jejunal mucosa were markedly depressed by the diet containing salseed meal, with the exception of maltase (EC 3.2.1.20) which was unaffected in jejunal mucosa. Enterokinase (EC 3.4.21.9) activity was not inhibited by the presence of tannins in the diet, rather it increased in the duodenal mucosa of SSM birds.

An experiment was conducted to determine the utilization of ileal digestible methionine by growing pigs. Three methionine-deficient diets (0·09 g ileal digestible methionine/MJ digestible energy (DE)) were formulated using cottonseed meal, meat-and-bone meal and soya-bean meal respectively as the only source of methionine in the diet. An additional three diets were formulated with supplements of methionine to confirm that methionine was limiting in the first three diets. The growth performance and retention of methionine by pigs given the six diets over the 20–45 kg growth phase was then determined. Growth rates (g/d) of pigs given the three diets formulated to 0·09 g ileal digestible methionine/MJ DE were significantly different (P < 0·01): cottonseed meal 411, meat-and-bone meal 442, soya-bean meal 496 (SED 24·6). The response of pigs to the addition of methionine confirmed that methionine was limiting in these diets. Crude protein (N × 6·25) deposited by the pigs (g/d) was significantly higher (P < 0·05) for those given soya-bean meat (61) and meat-and-bone meal (57) relative io cottonseed meal (47; SED 3·3). The proportion of ileal digestible methionine retained by pigs given the three protein concentrates was: cottonseed meal 0·39, meat-and-bone meal 0·45, soya-bean meal 0·47 (SED 0·019). These results indicate that values for the ileal digestibility of methionine in protein concentrates do not reflect the proportion of methionine that can be utilized by the pig. It appears that, with heat-processed meals, a considerable proportion of the methionine is absorbed in a form(s) that is (are) inefficiently utilized.

The question addressed is whether an increased intake of cholesterol affects esterase-1 (EC 3.1.1.1; ES-1) and butyrylcholinesterase (EC 3.1.1.8) activity in plasma. Rats were fed on a purified diet either without or with cholesterol (10 g/kg) added at the expense of the carbohydrate source. Dietary cholesterol significantly decreased plasma butyrylcholinesterase activity, but raised plasma ES-1 activity. Evidence is discussed, suggesting that plasma butyrylcholinesterase is involved in plasma cholesterol metabolism, whereas esterase-1 is involved in intestinal cholesterol absorption.

Although there have been a number of studies of effects of diet and hormones on lipoprotein lipase (EC 3.1.1.34; LPL) activity and levels of LPL mRNA (Raynolds et al. 1990), there have been no studies which have investigated effects of different dietary fatty acids on LPL gene expression. In the present study male Wistar Albino rats were pair-fed diets containing 50 g fat/kg of different fatty acid composition for 2 weeks. The diets fed were (1) a mixed oil (450 g saturated fatty acids, 420 g monounsaturated fatty acids, 130 g polyunsaturated fatty acids/kg; n 8), (2) maize oil (n 8), or (3) fish oil (n 8). Animals were killed, RNA was extracted from liver and perirenal and epididymal fat pads, and analysed by ‘Northern methodology’. Samples were hybridized to a human cDNA probe for LPL (Gotoda et al. 1989). Two transcripts were identified in epididymai and perirenal adipose tissue which were approximately 3·7 and 1·7 kb in size. The results suggested that (1) fish oil-fed animals had significantly greater production of LPL mRNA in epididymai adipose tissue compared with maize oil-fed animals (P < 0·05), (2) maize oil-fed animals had significantly greater production of LPL mRNA in perirenal fat compared with the other dietary groups (P < 0·05), (3) expression in the liver was not significant. Rats fed on a fish oil diet had significantly reduced plasma triacylglycerol concentrations compared with the mixed-oil group (P < 0·05), but there were no significant differences in plasma cholesterol. The differences in LPL could not be explained directly by the changes in plasma immunoreactive-insulin and glucose-dependent insulinotrophic polypeptide levels in the three groups.

Adult laca mice were dosed orally with 150 μl whole milk containing 2·5 μCi of either labelled stearic acid ([1-14C]18: 0; n 20) or labelled linoleic acid ([1 − 14C]18: 2; n 20). The mice were killed in groups of four at 6, 12, 24, 48 and 96 h following dosing and samples of perirenal and epididymal fat pads were taken from both inner and outer sites at each location. Significant differences in the rate of loss of label between sites were found. No differences (P = 0·018) between fat pad locations (epididymal v. perirenal) were found. A significant interaction between rate of loss of labelled fatty acid and site (P = 0·019) reflected the fact that between-site variations in this context were confined to labelled linoleic acid. In a second study weanling adult (n 10) and adult (n 10) mice were killed and their epididymal and perirenal fat pads prepared for histological examination. Both transverse and longitudinal sections were taken at the inner and outer sites of each fat pad location. Following staining, both the size and number of blood vessels were measured using computer-linked microscopy. In all instances there were significant differences between sites with the inner site consistently showing greater numbers and areas of blood vessels. In general the number of blood vessels in the inner site tended to be greater in older mice, while the reverse was seen for younger mice. The results lend support to the concept of multiple pools of triacylglycerol-fatty acids in adipose tissue such that the main determinant of shortterm supply of essential fatty acids is the quantity recently ingested.

The hypothesis was tested that dietary lactose v. glucose stimulates Mg absorption in rats because lactose lowers pH of the ileal lumen, which improves Mg solubility which in turn enhances Mg availability for transport across the ileal epithelium. For comparison, the effects of lactulose were studied because it shares with lactose the characteristic of being poorly digestible. Replacement of glucose by lactose (100 g/Kg) significantly stimulated apparent absorption of Mg. Apart from Mg absorption, lactulose also significantly enhanced absorption of Ca and phosphate. Lactose v. glucose lowered the pH of the ileal lumen from 7·5 to 7·2, whereas lactulose significantly reduced it to 7·0. In in vitro incubations a decrease in pH within the range of fluctuation in vivo was found to cause an improved solubility of Mg, and to a lesser extent also of Ca and phosphate. The smaller fall of ileal pH induced by feeding lactose instead of lactulose may explain why lactose improved Mg absorption only. For all individual rats combined there were negative relationships between ileal pH and apparent absorption of minerals, the relationship being strongest for Mg. Neither lactose nor lactulose was found to raise ileal solubility of minerals, which could relate to the possibility that the time of sampling was not appropriate. It is suggested that lactose-induced stimulation of Mg absorption in rats is caused by a lowering of ileal pH.

The effect of addition of sugar-beet fibre to the diet on sterol excretion from the small intestine was studied in nine ileostomy subjects. A constant low-fibre diet was given in two 3 d periods with and without 32 g sugar-beet fibre/d in random order. Care was taken to minimize bacterial alteration of the ileostomy contents. The addition of sugar-beet fibre increased net cholesterol excretion by 52 (SE 9)%(P < 0·01), from 294 (SE 99) to 451 (SE 124) mg/d, and decreased bile acid excretion by 26 (SE 15)% (P < 0·01), from 764 (SE 118) to 567 (SE 96) mg/d. The increased cholesterol and decreased bile acid excretion found with sugar-beet fibre addition is different from the pattern associated with fibre sources such as pectin and oat fibre. The interaction between dietary fibre and sterol metabolism may be mediated, therefore, by different mechanisms depending on the fibre source.

Oat bran concentrated with respect to both soluble and insoluble dietary fibre was fed to adult rats, and its effects on serum cholesterol and liver fat infiltration were studied. The feeds contained 15, 30 or 45 g β-glucan/kg, except in control groups where the fibre of the feed was cellulose. Half the experimental groups received the feeds with an addition of 10 g cholesterol and 2 g cholic acid/kg in order to create an hypercholesterolaemic condition. In normocholesterolaemic rats the concentrated oat bran did not cause any significant changes in serum cholesterol concentrations, but reduced liver weight compared with control group rats fed on the cellulose-containing diet. In hypercholesterolaemic rats the concentrated oat bran reduced serum total cholesterol and increased high-density-lipoprotein cholesterol concentration. The effect was seen already at the 15 g/kg concentration of β-glucan, the higher doses tested did not significantly improve the effect. Infiltration of fat into liver cells, especially in the periportal areas, was observed only in hypercholesterolaemic animals. The fat infiltration was accentuated in proportion to the amount of oat-bran concentrate fed.

Severe vitamin A deficiency in rats is known to cause anaemia associated with growth retardation and impaired water retention. However, study of the effect of marginal vitamin A intake is of more interest because such intake may mirror the situation in humans in many developing countries. Therefore, in two experiments, the effect of marginal vitamin A deficiency on Fe status was investigated in male rats. After 28 d of feeding either low- or high-vitamin A diets (0 or 120 v. 1200 retinol equivalents/kg feed), body weight and feed intake were not influenced by the level of vitamin A in the diet. Liver weight was lowered by vitamin A deficiency. Water intake was not influenced in rats fed on a low-vitamin A diet. Plasma retinol concentrations were decreased in rats fed on diets low in vitamin A. Marginal vitamin A deficiency produced slightly lower blood haemoglobin concentrations; it did not systematically affect packed cell volume. The concentration of Fe in liver was significantly higher when diets low in vitamin A were fed, but hepatic Fe mass was not affected. Significantly lower Fe levels were observed in femurs of rats with vitamin A deficiency. The effects on liver and femur Fe concentrations were seen with diets adequate in Fe but not with diets deficient in Fe. The efficiency of apparent Fe absorption was significantly increased by low intakes of vitamin A, provided that the dietary Fe concentration was adequate. It is speculated that depressed uptake of Fe by bone marrow is the primary feature of altered Fe status in rats with marginal vitamin A deficiency.

The present study investigates the prevalence and type of anaemia in Chinese female cotton mill workers. The prevalence of anaemia is reported in 447 non-pregnant female workers aged between 19 and 45 years. The mean value for haemoglobin (Hb) was 123 (SD 15) g/l and 150 of the total 447 subjects had Hb values below 120 g/l; thus 34% of the population was anaemic according to World Health Organization (WHO, 1975) criteria. The mean value for free erythrocyte protoporphyrin (FEP) was 419 (SD 215) μg/l; 55% of the total population had FEP values higher than 350 μg/l and 72% among the anaemic subjects. Serum ferritin (SF) was tested in all the women with a Hb value less than 120 g/l and 71 % of them had SF values below 12·0 μg/ls. Eighty women diagnosed as either Fe deficient or with Fe-deficient anaemia were selected for a diagnostic supplementation trial. They were randomly assigned to FeSO4 (60 or 120 mg Fe/d) or placebo treatment for 12 weeks. Fe supplementation increased mean Hb values from 114 to 127 g/l (P < 0·001) and SF levels from 9·7 to 30·0 μg/l (P < 0·001), and decreased mean FEP values from 570 to 277 μg/l (P < 0·001). The response rate of Hb in the whole Fe-treated group or Fe-treated subjects with an Hb level less than 120 g/1 was 90 % or 92 % respectively. These findings indicate that the type of anaemia in this population was mainly Fe deficiency. It was also found that in this population the severity of anaemia, not the prevalence, was significantly related to the use of intra-uterine devices (IUD).

The tripeptide glutathione is proposed to be protective against a number of chronic diseases including cardiovascular disease and cancer. However, there have been few studies of plasma glutathione levels in humans and in those studies the numbers of participants have been very small. In an exploratory analysis the determinants of plasma total glutathione (GSHt) were investigated in a group of 100 volunteers aged 18–61 years in Atlanta, Georgia, USA during June and July 1989. Data on demographic and health-related factors were collected by interview and plasma GSHt was measured using a recently modified laboratory method. The mean concentration of plasma GSHt for all 100 participants was 761 μg/l, with a standard deviation of 451 μg/l, a range of 86–2889 μg/1 and a median of 649 μg/l. Men had significantly higher levels of plasma GSHt than women (924 v. 692 μg/l; P = 0·006). Seventh-day Adventists participating in the present study had higher plasma GSHt levels than other subgroups defined by race and/or religion. Among Seventh-day Adventists consumption of a vegetarian diet was associated with increased plasma GSHt concentration (P = 0·002). Plasma GSHt levels also appeared to vary by race, but relationships with race could not be clearly disassociated from relationships with religion. Among white participants plasma GSHt concentration decreased with age in women but increased with age in men (P = 0·05). Few other factors were associated with plasma GSHt concentration, although use of oral contraceptives (P = 0·10) was somewhat associated with decreased plasma GSHt levels. These findings suggest that plasma GSHt levels may vary with several demographic and health-related attributes and support the need for further research on this potentially important disease-preventive compound.