The use of whole-room calorimetry (WRC) in young children can increase our understanding of children's energy balance. However, studies using WRC in young children are rare due to concerns about its feasibility. To assess the feasibility of WRC in young children, forty children, aged 4–6 years, were asked to follow a graded activity protocol while in a WRC. In addition, six children participated in two additional resting protocols to examine the effect of diet-induced thermogenesis on resting energy expenditure (REE) measures and the reliability of REE measurement. Refusals to participate and data loss were quantified as measures of practical utility, and REE measured after an overnight fast and after a 90-min fast were compared. In addition, both were compared to predicted BMR values using the Schofield equation. Our results showed that thirty (78·9 %) participants had acceptable data for all intensities of the activity protocol. The REE values measured after a 90-min fast (5·07 (sd 1·04) MJ/d) and an overnight fast (4·73 (sd 0·61) MJ/d) were not significantly different from each other (P= 0·472). However, both REE after an overnight fast and a 90-min fast were significantly higher than predicted BMR (3·96 (sd 0·18) MJ/d) using the Schofield equation (P= 0·024 and 0·042, respectively). We conclude that, with a developmentally sensitive approach, WRC is feasible and can be standardised adequately even in 4- to 6-year-old children. In addition, the effect of a small standardised breakfast, approximately 90 min before REE measurements, is likely to be small.

Human breast milk (BM) is the best source of nutrition in early life, particularly during the first 6 months. Nevertheless, human BM composition is variable, and more insight in the exact factors contributing to this variability is warranted. In this review, we explored the impact of maternal dietary intake and nutritional status (e.g. anthropometric measures, BMI, bioimpedance) on human milk macronutrient composition. PubMed, Scopus and Cochrane were systematically searched till November 2019. In total, 4946 publications underwent title–abstract screening; 101 publications underwent full-text screening. Eventually, fifty publications were included in this review, investigating either associations between maternal dietary intake (n 29) and/or maternal nutritional status (n 29), and macronutrient composition of human BM. Reported energy composition ranged from 213 to 301 kJ/100 ml, and 67 % and 54 % of the studies reported associations between with maternal nutritional intake and status, respectively. Protein content ranged from 0·8 to 3·3 g/100 ml, and four studies suggested a negative association with nutritional status. Fat content ranged from 2·1 to 9·8 g/100 ml, and 68 % of the studies reported positive associations with nutritional status. Carbohydrate content ranged from 5·8 to 7·5 g/100 ml, and 67 % of the included studies did not report an association between intake and status. Literature investigating associations of maternal dietary intake and nutrition status with BM composition of macronutrients and energy content is diversified, both in terms of used methodology and results. Further studies using well-defined and standard parameters are essential to aid the formulation of scientific recommendations.

Fruit and vegetable (FV) intake is associated with reduced risk of a number of non-communicable diseases. Research tends to focus on antioxidants, flavonoids and polyphenols contained in FV as the main beneficial components to health; however, increasing FV may also alter overall diet profile. Extra FV may be substituted for foods thought to be less healthy, therefore altering the overall macronutrient and/or micronutrient content in the diet. This analysis merged dietary data from four intervention studies in participants with varying health conditions and examined the effect of increased FV consumption on diet profile. Dietary intake was assessed by either diet diaries or diet histories used in four FV randomised intervention studies. All food and drink intake recorded was analysed using WISP version 3.0, and FV portions were manually counted using household measures. Regression analysis revealed significant increases in intakes of energy (172 kJ (+41 kcal)), carbohydrate (+3·9 g/4184 kJ (1000 kcal)), total sugars (+6·0 g/4184 kJ (1000 kcal)) and fibre (+0·8 g/4184 kJ (1000 kcal)) and significant decreases in intakes of total fat (−1·4 g/4184 kJ (1000 kcal)), SFA (−0·6 g/4184 kJ (1000 kcal)), MUFA (−0·6 g/4184 kJ (1000 kcal)), PUFA (−0·1 g/4184 kJ (1000 kcal)) and starch (−2·1 g/4184 kJ (1000 kcal)) per one portion increase in FV. Significant percentage increases were also observed in vitamin C (+24 %) and -carotene (+20 %) intake, per one portion increase in FV. In conclusion, pooled analysis of four FV intervention studies, that used similar approaches to achieving dietary change, in participants with varying health conditions, demonstrated an increase in energy, total carbohydrate, sugars and fibre intake, and a decrease in fat intake alongside an expected increase in micronutrient intake.

The present randomised trial investigated the effects of feeding Zambian infants from 6 to 18 months old either a richly or basal micronutrient-fortified complementary/replacement food on gut integrity and systemic inflammation. Blood samples were obtained from all infants (n 743) at 6 and 18 months for the assessment of serum C-reactive protein (CRP) and α1-acid glycoprotein (AGP). A subsample of 502 infants, selected from the main cohort to include a larger proportion of infants with HIV-positive mothers, was assigned to lactulose/mannitol gut permeability tests. Lactulose:mannitol (L:M) ratio analyses were adjusted for baseline urinary L:M ratio, socio-economic status, mother's education, season of birth and baseline stunting, and stratified by maternal antenatal HIV status, child's sex, concurrent breast-feeding status and anaemia at baseline. There was no significant difference in geometric mean L:M ratio between the richly fortified and basal-fortified porridge arms at 12 months (0·47 (95 % CI 0·41, 0·55) v. 0·41 (95 % CI 0·34, 0·49); P = 0·16 adjusted). At 18 months, the richly fortified porridge group had a significantly higher geometric mean L:M ratio than the basal-fortified group (0·23 (95 % CI 0·19, 0·28) v. 0·15 (95 % CI 0·12, 0·19); P = 0·02 adjusted). This effect was evident for all stratifications, significantly among boys (P = 0·04), among the infants of HIV-negative mothers (P = 0·01), among the infants of HIV-negative mothers not concurrently breast-fed (P = 0·01) and among those who were not anaemic at baseline (P = 0·03). CRP, but not AGP, was positively associated with L:M ratio, but there were no significant effects of the diet on either CRP or AGP. In conclusion, a richly fortified complementary/replacement food did not benefit and may have worsened intestinal permeability.

Poor diet quality (DQ) is associated with poor cognition and increased neurodegeneration, including Alzheimer’s disease (AD). We are interested in the role of DQ on cognitive functioning (by sex and increasing genetic risk for AD), in a sample of African American (AA) middle-aged adults. We analysed a sub-group of participants (about 55 % women; mean follow-up time of about 4·7 years) from the Healthy Aging in Neighborhoods of Diversity across the Life Span study with a genetic risk score for AD (hAlzScore). The Healthy Eating Index-2010, Dietary Approaches to Stop Hypertension and the mean adequacy ratio computed at baseline (2004–2009) and follow-up visits (2009–2013) were used to assess initial DQ and change over time. Linear mixed-effects regression models were utilised, adjusting for select covariates, selection bias and multiple testing. DQ change (ΔDQ) was associated with California Verbal Learning Test-List A – overall (0·15 (se 0·06), P = 0·008) and in women (0·21 (se 0·08), P = 0·006), at highest AD risk, indicating protective effects over time. Greater AD risk was longitudinally associated with poorer Clock Command Test scores in men. Poor DQ was positively and cross-sectionally associated with Trails B scores, but in women only. Better-quality diet was associated with a slower decline in verbal memory among AA women, with greater AD risk. Insufficient clinical evidence and/or mixed findings dictate that more studies are needed to investigate brain morphology and volume changes in relation to DQ in an at-risk population for AD, over time.

COVID-19 has further exacerbated trends of widening health inequalities in the UK. Shockingly, the number of years of life lived in general good health differs by over 18 years between the most and least deprived areas of England. Poor diets and obesity are established major risk factors for chronic cardiometabolic diseases and cancer, as well as severe COVID-19. For doctors to provide the best care to their patients, there is an urgent need to improve nutrition education in undergraduate medical school training.

With this imperative, the Association for Nutrition established an Interprofessional Working Group on Medical Education (AfN IPG) to develop a new, modern undergraduate nutrition curriculum for medical doctors. The AfN IPG brought together expertise from nutrition, dietetic and medical professionals, representing the National Health Service (NHS), royal colleges, medical schools and universities, government public health departments, learned societies, medical students, and nutrition educators. The curriculum was developed with the key objective of being implementable through integration with the current undergraduate training of medical doctors.

Through an iterative and transparent consultative process, thirteen key nutritional competencies, to be achieved through mastery of eleven graduation fundamentals, were established. The curriculum to facilitate the achievement of these key competencies is divided into eight topic areas, each underpinned by a learning objective statement and teaching points detailing the knowledge and skills development required. The teaching points can be achieved through clinical teaching and a combination of facilitated learning activities and practical skill acquisition. Therefore, the nutrition curriculum enables mastery of these nutritional competencies in a way that will complement and strengthen medical students’ achievement of the General Medical Council (GMC) Outcome for Graduates.

As nutrition is an integrative science, the AfN IPG recommends that the curriculum is incorporated into initial undergraduate medical studies before specialist training. This will enable our future doctors to recognise how nutrition is related to multiple aspects of their training, from physiological systems to patient-centred care, and acquire a broad, inclusive understanding of health and disease. In addition, it will facilitate medical schools to embed nutrition learning opportunities within the core medical training, without the need to add in a large number of new components to an already crowded programme or with additional burden for teaching staff.

The undergraduate nutrition curriculum for medical doctors is designed to support medical schools to create future doctors who will understand and recognise the role of nutrition in health. Moreover, it will equip frontline staff to feel empowered to raise nutrition-related issues with their patients as a fundamental part of enhanced care and to appropriately refer on for nutrition support with a registered associate nutritionist/registered nutritionist (ANutr/RNutr) or registered dietitian (RD) where this is likely to be beneficial.

Babies born small-for-gestational age (SGA) have an increased risk of mortality, morbidity and adverse functional consequences. Studies suggest that pre-pregnancy maternal diet may influence newborns’ size. This study aimed to determine whether maternal pre-pregnancy dietary patterns (DP) are associated with delivering SGA newborns in the ProcriAr Cohort Study, Sao Paulo-Brazil. Pre-pregnancy DP of 299 women were investigated using factor analysis with principal component’s estimation, based on intake reported on a validated 110-item FFQ. Newborns were classified as SGA if their weight and/or length, adjusted by gestational age and sex, were below the 10th percentile of the INTERGROWTH-21st standards. Multivariate Poisson regression modelling with robust error variance was performed to examine associations between the different DP (in quintiles) and SGA. In a model adjusted by maternal sociodemographic and health behaviours, women who scored in the highest quintile of the DP ‘Snacks, sandwiches, sweets and soft drinks’ (in relation to the women who scored in the lowest quintile) were significantly more likely to deliver SGA babies (relative risk 1·92; 95 % CI 1·08, 3·39). This study verified that women’s pre-pregnancy dietary behaviour characterised by an energy-dense nutrient-poor food intake was a risk factor for delivering SGA newborns. Investments in education and improved access to healthful food and nutritional information before pregnancy should be prioritised due to their potential positive impact on child health. However, further studies are warranted to identify specific metabolic pathways that may be underlying these associations.

Fat-soluble vitamins during pregnancy are important for fetal growth and development. The present study aimed at exploring the association between vitamin A, E and D status during pregnancy and birth weight. A total of 19 640 women with singleton deliveries from a retrospective study were included. Data were collected by the hospital electronic information system. Maternal serum vitamin A, E and D concentrations were measured during pregnancy. Logistic regression was performed to estimate the association between the vitamin status and low birth weight (LBW) or macrosomia. Women with excessive vitamin E were more likely to have macrosomia (OR 1·30, 95 % CI 1·07, 1·59) compared with adequate concentration. When focusing on Z scores, there was a positive association between vitamin E and macrosomia in the first (OR 1·07, 95 % CI 1·00, 1·14), second (OR 1·27, 95 % CI 1·11, 1·46) and third (OR 1·28, 95 % CI 1·06, 1·54) trimesters; vitamin A was positively associated with LBW in the first (OR 1·14, 95 % CI 1·01, 1·29), second (OR 1·31, 95 % CI 1·05, 1·63) and third (OR 2·00, 95 % CI 1·45, 2·74) trimesters and negatively associated with macrosomia in the second (OR 0·79, 95 % CI 0·70, 0·89) and third (OR 0·77, 95 % CI 0·62, 0·95) trimesters. The study identified that high concentrations of vitamin E are associated with macrosomia. Maintaining a moderate concentration of vitamin A during pregnancy might be beneficial to achieve optimal birth weight. Further studies to explore the mechanism of above associations are warranted.

The present study was designed to investigate whether 3 d of high-fat, low-carbohydrate diet (with normal daily energy intake) affected the metabolic, cardiovascular and thermic responses to an oral glucose load (1.5 g/kg body-weight). Eight normal weight, healthy subjects (five male) consumed diets containing approximately 65 % by energy of carbohydrate (C) or fat (F), each for 3 d. Before and after glucose ingestion, continuous recordings of oxygen consumption and carbon dioxide production were made using indirect calorimetry, and metabolic rate (MR) and respiratory exchange ratio (RER) were calculated. Heart rate, blood pressure and limb blood flow were also measured. There was no significant change in baseline MR following the high-fat diet, but the fasting RER was reduced. The high-fat diet modified the responses to oral glucose, with a greater increase in MR (kJ/min; C + 0.38, F + 0.76), and an enhanced plasma insulin response (mU/l; C + 51.5, F + 85.0). There were no differences between the two diets with respect to the baseline blood glucose levels or the changes after glucose ingestion. Heart rate, systolic and diastolic blood pressures and blood flow responses to the glucose load were similar after the two diets. There was no plasma catecholamine response to glucose ingestion. It can be concluded that a high-fat diet alters the initial thermic response and insulin response but does not alter the other physiological responses to glucose ingestion.

Preliminary evidence suggests that consumption of Porphyridium cruentum (PC) biomass results in hypocholesterolaemic effects; however, mechanisms responsible have not been elucidated. The aim of the present study was to determine whether PC biomass lowers circulating cholesterol concentrations, dose dependently, in hamsters fed hypercholesterolaemic diets for 28 d and determine whether cholesterol biosynthesis is affected. Biomass added to diets at 2·5, 5 and 10 % resulted in 14, 38 and 53 % reductions (P < 0·001) in total plasma cholesterol, respectively, compared with a control diet. Similarly, non-HDL-cholesterol concentrations in the 5 and 10 % PC groups were reduced (P < 0·001) 28 and 45 %, respectively, v. controls. These effects were unrelated to cholesterol fractional synthesis rate (FSR), as this did not differ between either treatment or control animals. PC consumption had no effect on food intake, plasma glucose concentrations or energy expenditure, but percentage of body fat was lower (P < 0·001) in the 5 and 10 % PC groups compared with controls. These data show that PC reduces total plasma cholesterol and non-HDL-cholesterol when incorporated into the diet at levels as low as 2·5 %. The mechanism of action for this reduction may be related to increased excretion since food intakes and cholesterol FSR were not reduced in the animals receiving the PC. In conclusion, the use of PC biomass reduces circulating cholesterol, dose dependently, in hypercholesterolaemic hamsters but not via reductions in cholesterol FSR. There is potential for the use of this biomass as a functional ingredient to aid in the management of blood cholesterol concentrations.

Obesity caused by excessive deposited fat is generally classified as BMI ≥ 30 kg/m2. Research regarding the association between dietary advanced glycation end products (dAGE) and obesity is limited. The aim of the present study was to investigate the association between dAGE and obesity and body composition in Iranian adults. This cross-sectional study included 265 adults aged 18–75 years from Tehran, Iran. dAGE were estimated using a validated semi-quantitative FFQ, according to the published food carboxymethyl lysine–AGE database for 549 routinely consumed food items for the Northeastern American multiethnic urban population, and were reported by dividing total energy intake. Dietary intake, sociodemographic data and physical activity status were collected using validated questionnaires, and anthropometric characteristics were measured. Body composition was assessed by bioelectrical impedance analysis, and obesity was defined based on WHO guidelines. The intake of fat and meat was significantly increased in higher tertiles, compared with the first tertile of dAGE (P < 0·001). No association between dAGE and body composition measures and obesity was observed; however, there was a significant negative association between dAGE and BMI (BMI; P = 0·01), waist circumference (P = 0·01), waist:hip ratio (P = 0·03), fat-free mass (P = 0·02) and muscle mass index (P = 0·01) in non-linear models. In conclusion, higher consumption of dAGE was associated with increased intake of fat and meat and was negatively related to changes in body composition measurements. Therefore, dAGE may connect obesity to diet by energy imbalance.

The metabolic syndrome is common in older adults and may be modified by the diet. The aim of this study was to examine associations between a posteriori dietary patterns and the metabolic syndrome in an older New Zealand population. The REACH study (Researching Eating, Activity, and Cognitive Health) included 366 participants (aged 65–74 years, 36 % male) living independently in Auckland, New Zealand. Dietary data were collected using a 109-item FFQ with demonstrated validity and reproducibility for assessing dietary patterns using principal component analysis. The metabolic syndrome was defined by the National Cholesterol Education Program Adult Treatment Panel III. Associations between dietary patterns and the metabolic syndrome, adjusted for age, sex, index of multiple deprivation, physical activity, and energy intake were analysed using logistic regression analysis. Three dietary patterns explained 18 % of dietary intake variation – ‘Mediterranean style’ (salad/leafy cruciferous/other vegetables, avocados/olives, alliums, nuts/seeds, shellfish and white/oily fish, berries), ‘prudent’ (dried/fresh/frozen legumes, soya-based foods, whole grains and carrots) and ‘Western’ (processed meat/fish, sauces/condiments, cakes/biscuits/puddings and meat pies/hot chips). No associations were seen between ‘Mediterranean style’ (OR = 0·75 (95 % CI 0·53, 1·06), P = 0·11) or ‘prudent’ (OR = 1·17 (95 % CI 0·83, 1·59), P = 0·35) patterns and the metabolic syndrome after co-variate adjustment. The ‘Western’ pattern was positively associated with the metabolic syndrome (OR = 1·67 (95 % CI 1·08, 2·63), P = 0·02). There was also a small association between an index of multiple deprivation (OR = 1·04 (95 % CI 1·02, 1·06), P < 0·001) and the metabolic syndrome. This cross-sectional study provides further support for a Western dietary pattern being a risk factor for the metabolic syndrome in an older population.

Oral arginine supplements are popular mainly for their presumed vasodilatory benefit. Arginine is a substrate for at least four enzymes including nitric oxide synthase (NOS) and arginase, but the impact of oral supplements on its different metabolic pathways is not clear. Deficiencies of arginine-metabolising enzymes are associated with conditions such as hyperammonaemia, endothelial dysfunction, central nervous system and muscle dysfunction, which complicate the use of oral arginine supplements. We examined the effect of l-arginine (l-Arg) and d-arginine (d-Arg), each at 500 mg/kg per d in drinking water administered for 4 weeks to separate groups of 9-week-old male Sprague–Dawley rats. We quantified the expression of enzymes and plasma, urine and organ levels of various metabolites of arginine. l-Arg significantly decreased cationic transporter-1 expression in the liver and the ileum and increased endothelial NOS expression in the aorta and the kidney and plasma nitrite levels, but did not affect the mean arterial pressure. l-Arg also decreased the expression of arginase II in the ileum, arginine:glycine amidinotransferase in the liver and the kidney and glyoxalase I in the liver, ileum and brain, but increased the expression of arginine decarboxylase and polyamines levels in the liver. d-Arg, the supposedly inert isomer, also unexpectedly affected the expression of some enzymes and metabolites. In conclusion, both l- and d-Arg significantly affected enzymes and metabolites in several pathways that use arginine as a substrate and further studies with different doses and treatment durations are planned to establish their safety or adverse effects to guide their use as oral supplements.

1. Groups of three colostomized germ-free (GF) and conventional (CV) chickens aged 4 months were maintained for successive periods of 8 d on a diet containing 200 g casein/kg without and with sodium bicarbonate at the rate of 20 mmol/d and a nitrogen-free diet without and with NaHCO3 at 9 mmol/d. Urine and faeces were collected during the last 3 d of each period.

2. Total N, uric acid- and ammonia-N were determined in urine and total N in faeces. Amino acids were measured in hydrolysates of faeces collected during the periods when no NaHCO3 was included in the diets.

3. The CV birds excreted more N on the casein diets but less on the N-free diets than did their GF counterparts, the differences being mainly shown in the urine.

4. On both diets hydrolysates of the faeces of CV birds contained smaller amounts of amino acids. On the N-free diet the proportions (g/160 g N) of serine, proline and threonine were reduced, suggesting some conservation of endogenous N by micro-organisms, and the proportions of histidine, alanine, lysine and methionine increased, possibly through microbial synthesis; on the casein diet, proportions of most amino acids were less, probably because bacterial deamination had occurred.

5. Urinary excretion of total N, uric acid and ammonia was much greater on the casein than on the N-free diets. Inclusion of NaHCO3 caused a sharp fall in urinary ammonia on both diets and in both environments.

6. It was concluded that the level of dietary protein and the regulation of acid-base balance have more effect than microbial activity on the urinary ammonia excretion.

Excessive iodine induces thyroid dysfunction. However, the effect of excessive iodine exposure on maternal–fetal thyroid hormone metabolism and on the expression of genes involved in differentiation, growth and development is poorly understood. Since a thyroid hormone receptor response element was found in the Hoxc8 promoter region, Hoxc8 expression possibly regulated by excessive iodine exposure was firstly investigated. In the present study, Balb/C mice were given different doses of iodine in the form of potassium iodate (KIO3) at the levels of 0 (sterile water), 1·5, 3·0, 6·0, 12·0 and 24·0 μg/ml in drinking water for 4 months, then were mated. On 12·5 d postcoitum, placental type 2 and type 3 deiodinase activities and fetal Hoxc8 expression were determined. The results showed that excessive iodine exposure above 1·5 μg/ml resulted in an increase of total thyroxine and a decrease of total triiodothyronine in the serum of maternal mice, which was mainly associated with the inhibition of type 1 deiodinase activity in liver and kidney. Placental type 2 deiodinase activity decreased, showing an inverse relationship with maternal thyroxine level. Hoxc8 mRNA and protein expression at 12·5 d postcoitum embryos were down regulated. Because Hoxc8 plays an important role in normal skeletal development, this finding provides a possible explanation for the skeletal malformation induced by excessive iodine exposure and also provides a new clue to study the relationship between iodine or thyroid hormones and Hox gene expression pattern.

1. Sheep with oesophageal fistulas were used in sham-feeding experiments to assess how sham intakes were affected by (a) physical form of straw (finely and coarsely ground; ground and pelleted), (b) type of food (straw pellets v. lucerne (Medicago sativa) hay pellets) and (c) additions of monosodium glutamate (MSG) with or without NaCl to the various straw diets. Normal animals were also fed on diets with and without MSG. Sham intakes of fine-ground loose straw (25 g/30 min) were markedly less (P = 0.002) than those of ground and pelleted straw (711 g/30 min). However, MSG at 5–40 g/kg fine and coarse ground straw increased sham intakes by 146 (P = 0.04) and 164% (P = 0.01) respectively. These findings indicated that the intakes of poor-quality diets can be increased by compacting them or by improving their palatability with MSG, or both. Sham intakes of straw pellets in two experiments were 32 (P = 0.02) and 45% (P = 0.008) of those of lucerne pellets (436 v. 1366 and 737 v. 1640 g/30 min). However, MSG at 20 g/kg straw pellets increased sham intakes from 674 to 1100 g/30 min (P = 0.05). When the MSG was mixed with NaCl (20 g/kg), the intakes of straw pellets were increased from 1089 to 1512 g/30 min (P = 0.02). Thus, the addition of MSG with or without NaCl increased the intakes of straw pellets. The highest intakes of the straw pellets treated with MSG were similar to those for lucerne pellets. When MSG-treated ammoniated barley straw (10 g/kg) was fed to normal sheep, the MSG increased DM intakes by 10 % (719–789 g/d; P = 0.04). MSG sprayed onto grass hay (10 g/kg) did not, however, affect daily DM intakes by these sheep. In general, the findings indicate that the intake of straw by ruminants may be increased by compressing it to form pellets or cubes and by adding MSG.

1. Surgical removal of the forestomach, the caecum or both the forestomach and the caecum, was performed on growing male golden hamsters (Mesocricetus auratus) given a low-or high-fibre diet.

2. In Expt J, 18 d after surgery, the hamsters which were given a concentrate before surgery were given an experimental low-fibre diet containing urea or [15N]urea (10 g/kg diet) for 9 d. In Expt 2, 5 d after surgery, the hamsters which were given a forage diet before surgery were adapted to an experimental high-fibre diet containing urea (10 g/kg) and dried Italian ryegrass (Lolium italicum) powder (400 g/kg diet) for 5 d, and 10 d after surgery, given a diet containing [l5N]urea (10 g/kg diet) for 9 d.

3. In both experiments, removal of the caecum resulted in a significant lowering of both weight-gain and the digestibility of the dry matter, and removal of the forestomach resulted in a significant decrease of both accumulation of 15N in the body protein and proportion of l5N retained in the body protein as a proportion of the administered dosage.

4. The effect of removal of the caecum on the utilization of [15N]urea was not apparent in Expt 1, but the utilization of [15N]urea was significantly lowered by removal of the caecum in Expt 2.

5. These results suggest that the caecum may play a more important role in food utilization than the forestomach. However, the forestomach of the golden hamster plays a significant role in the utilization of dietary urea. It is presumed that the role of the caecum in the utilization of urea may vary under different dietary conditions.

Six pigs were given a biotin-deficient diet (10 μg biotin/kg) for 14 weeks. The pigs were given the same diet for a further 42 d with one of three biotin treatments: no supplement, 400 μg biotin/d given orally, 400 μg biotin/d infused into the caecum. The concentrations of biotin in the liver, kidney and heart, at the conclusion of 42 d were greater in the pigs given the oral biotin supplement than in the unsupplemented pigs. The values for the pigs given the caecal infusion of biotin were intermediate. The excretion of biotin in faeces was increased from 35 to 101 μg/d by the caecal biotin infusion, and the urinary excretion was increased from 35 to 83 μg/d. The oral dose of biotin increased urinary biotin excretion from 35 to 345 μg/d, but there was no change in faecal biotin excretion. Two pigs were fitted with ileal cannulas and catheters in the vena cava. The pigs were given a dose of [14C] biotin either into the caecum, when the ileum was occluded by a bladder catheter, or orally. [14C] biotin was measured in the urine and plasma and showed that post-ileal biotin absorption was 8 % as efficient as the absorption of biotin after oral dosing.