1. Twenty apparently healthy and normal Nigerian female students, resident at the University of Ibadan campus, were studied for seven consecutive days to assess their food energy intake and energy expenditure during sedentary and physical activities.

2. The mean age (years) of the group was 20.05 (SD 3.44, range 16–29), mean height (m) 1.62 (SD 0.07, range 1.47–1.74) and body-weight (kg) 51.28 (SD 3.21, range 46–58).

3. The food intake of each subject was obtained by direct weighing, and the energy value determined using a ballistic bomb calorimeter. Daily activities were recorded and the energy cost of representative activities was determined by indirect calorimetry.

4. Activities mainly involved sitting, mean (min/d) 354 (SD 84, range 253–475). Personal domestic activities took a mean of 162 (SD 73) min/d. Sleeping took a mean of 451 (SD 62) min/d.

5. The mean energy intake of the group was 8480 (SD 1316) kJ/d or 167 (SD 30.6) kJ/kg body-weight per d. This value is lower than that recommended by the Food and Agriculture Organization/World Health Organization (FAO/WHO) (1973) as the energy requirement for adult women engaged in light activities (9205 kJ/d), but it is higher than the FAO/WHO/United Nations University (UNU) (1985) recommended value of 8326 kJ (1990 kcal)/d for a housewife in an affluent society. It is lower than the recommended intake of 9350 kJ/d for rural women in developing countries (FAO/WHO/UNU, 1985).

6. The mean energy expenditure (kJ/d) of the female subjects was 6865 (SD 214, range 6519–7222). Mean energy expenditure was lower than mean energy intake.

7. The energy intake and expenditure values indicated that the subjects participating in the present study were not physically very active. It is suggested, for health reasons, that they might undertake more physical activity.

1. A Finnish national programme to fertilize crops with sodium selenate led us to compare the nutritional availability to rats of selenium in two Finnish spring wheats (Triticum aestivum L.), either fertilized or sprayed with sodium selenate, with that in an American winter bread wheat naturally high in Se.

2. Weanling male rats were given a Se-deficient Torula yeast diet for 4 weeks followed by either continued depletion or repletion for 4 weeks with graded levels of Se as sodium selenite (standard) or wheat (test food). Plasma and liver Se levels and plasma and liver glutathione peroxidase (EC 1.11.1.9; GSH-Px) activities were used as criteria of body Se status.

3. The availability of Se under these conditions was calculated with the point-slope technique at two dietary levels of Se (Expt 1) and with the slope-ratio method (Expt 2).

4. In the point-slope assay, the level of dietary Se fed had a considerable effect on the apparent availability values obtained which made interpretation of the results difficult. In the slope-ratio assay, no difference in the availability of Se from the various wheats was observed when plasma or liver Se levels were used as the response criteria.

5. The Se in the fertilized wheat was somewhat more available than that in the sprayed wheat when plasma or liver GSH-Px activities were the response criteria. Overall, availability values (% ) derived by averaging all four response criteria were 86, 77 and 73 for the fertilized and sprayed Finnish wheats and the American wheat respectively (sodium selenite 100).

6. These results show that wheat is a relatively available source of Se to rats regardless of whether its Se content is naturally high or is increased by fertilization or spraying.

1. The effects of the chemical composition of fruit juices and fruit on the absorption of iron from a rice (Oryza sativa) meal were measured in 234 parous Indian women, using the erythrocyte utilization of radioactive Fe method.

2. The corrected geometric mean Fe absorptions with different juices varied between 0.040 and 0.129, with the variation correlating closely with the ascorbic acid contents of the juices (rs 0.838, P < 0.01).

3. Ascorbic acid was not the only organic acid responsible for the promoting effects of citrus fruit juices on Fe absorption. Fe absorption from laboratory ‘orange juice’ (100 ml water, 33 mg ascorbic acid and 750 mg citric acid) was significantly better than that from 100 ml water and 33 mg ascorbic acid alone (0.097 and 0.059 respectively), while Fe absorption from 100 ml orange juice (28 mg ascorbic acid) was better than that from 100 ml water containing the same amount of ascorbic acid (0.139 and 0.098 respectively). Finally, Fe absorption from laboratory ‘lemon juice’ (100 ml orange juice and 4 g citric acid) was significantly better than that from 100 ml orange juice (0.226 and 0,166 respectively).

4. The corrected geometric mean Fe absorption from the rice meal was 0.025. Several fruits had little or no effect on Fe absorption from the meal (0.013–0.024). These included grape (Vitis vinifera), peach (Prunuspersica), apple (Malus sylvestris) and avocado pear (Persea americana). Fruit with a mild to moderate enhancing effect on Fe absorption (0.03 1–0.088) included strawberry (Fragaria sp.) (uncorrected values), plum (Prunus domestica), rhubarb (Rheum rhaponticum), banana (Musa cavendishii), mango (Mangifera indica), pear (Pyrus cornmunis), cantaloup (Cucumis melo) and pineapple (Ananas comosus) (uncorrected values). Guava (Psidium guajava) and pawpaw (Carica papaya) markedly increased Fe absorption (0.126–0.293).

5. There was a close correlation between Fe absorption and the ascorbic acid content of the fruits tested (rs 0.738, P < 0.0001). There was also a weaker but significant correlation with the citric acid content (rs 0.55, P < 0.03). Although this may have reflected a direct effect of citric acid on Fe absorption, it should be noted that fruits containing citric acid also contained ascorbic acid (rs 0.70, P < 0.002). Similarly, the negative correlation (rs –0.62, P < 0,008) between Fe absorption and the malic acid content of fruits may have been due to the fact that fruits with a high malic acid content tended to have low levels of ascorbic acid (rs–0.45, P < 0.06).

6. These various results suggested that most fruits have only a limited effect on overall Fe nutrition. However, the presence of citrus fruit, guava or pawpaw would be expected to increase Fe absorption markedly from diets of low Fe availability.

1. The absorption of iron from soya-bean (Glycine hispida)-based and milk-based infant formulas was assessed in 138 multiparous Indian women, using the erythrocyte utilization of radioactive Fe method.

2. Fe absorption was significantly greater from the basal milk formula (1.5 g protein) than it was from the basal soya-bean formula (2.3 g protein), with geometric mean values of 0.083 and 0.044 respectively.

3. Ascorbic acid markedly increased Fe absorption from the milk-based formula in a dose-dependent fashion. The increase was fivefold when the ascorbic acid: Fe ratio on a weight-for-weight basis was 6: 1 and over tenfold when it was 20:1. In contrast, ascorbic acid had a less-marked effect on the absorption of Fe from the soya-bean-based formula, with only a two- to threefold increase at an ascorbic acid: Fe ratio of 20: 1.

4. The geometric mean Fe absorption from the soya-bean formula (1.27 mg Fe, 2.3 g isolated soya-bean protein (ISP)) was somewhat less than that from the same amounts of ISP and ascorbic acid made up in milk (0.075 and 0.1 13 respectively). However, a direct comparison between the soya-bean formula in milk and in water showed no significant difference (0.043 and 0.060 respectively).

5. Fe absorption from a drink containing 10 g ISP and 30 mg ascorbic acid was significantly better than that from a similar drink containing the soya-bean flour from which ISP is extracted (0.044 and 0.027 respectively).

6. Heating ISP to 200° for 2 h before its use had no effect on Fe availability. When 2.3 g heated ISP (10 mg ascorbic acid) was compared with a similar formulation of untreated ISP, Fe absorption values were 0.135 and 0.099 respectively. Comparable values with 25 g ISP (no ascorbic acid) were 0.067 and 0.058.

7. Citric acid in amounts of 1 4 g had a dose related but limited enhancing effect on Fe absorption from 10 g ISP, with a rise from 0.01 1 (no citric acid) to 0.068 (4 g citric acid).

8. There was appreciable variability in the levels of Fe absorption in different studies, which suggested that unidentified manufacturing or preparative differences might be influencing the overall results.

1. Total methane excretion (CH4 in breath+flatus) was measured in two experiments with thirty-six castrated male pigs (Danish Landrace) during the growth period from 20 to 120 kg live weight (LW). In Expt A, twenty-eight pigs were fed on a commercial diet alternately at high (HFL; metabolizable energy (ME) 1234 (SE 41) kJ/kg LW0.75) or low (LFL; ME 784 (SE 31) kJ/kg LW0.75) feed levels in different weight classes. In Expt B, eight pigs were constantly fed on a semi-purified diet at HFL without (-oil) or with 90 g soya-bean oil/kg diet (foil) corresponding to daily intakes of ME of 1339 (SE 11) and 1413 (SE 8) kJ/kg LW0.75 respectively.

2. CH4 excretion was measured during 24 h respiration trials in open-air-circulation chambers.

3. About 1 litre CH4 was excreted per day at 20–25 kg LW increasing to a maximum of 12 litres at 120 kg LW, which corresponded to no more than 1.2% of dietary gross energy.

4. In Expt A, CH4 excretion increased linearly with LW, while in Expt B the increase was linear until about 70 kg LW, when it reached a plateau. On average LFL reduced CH, excretion by 23% compared with HFL. When related to dry matter (DM) intake, however, the pigs on LFL excreted 3.1 litres CH4/kg dietary DM and those on HFL 2.5 litres CH4/kg dietary DM, the difference being significant (P < 0.05). In Expt B the inclusion of soya-bean oil in the basal diet (+oil) reduced CH, excretion by 26% compared with the diet without oil (-oil). The pigs receiving the basal diet excreted 5.2 litres CH4/kg DM and the pigs receiving soya-bean oil 4.3 litres CH4/kg DM, the difference being highly significant (P < 0.001). All differences between Expt A and B in CH4 excretion based on DM intake were highly significant (P < 0.001).

5. The results are discussed in relation to gas production in ruminants, rats and humans. It is suggested that flatus production may not only be reduced by changing the composition of the dietary carbohydrates, but also by inclusion of a polyunsaturated oil in the diet of simple-stomached animals and humans.

1. Complete energy balance measurements were made in exercise-trained (treadmill running) rats subjected to 27 d of exercise detraining.

2. The 20% difference in body-weight that existed at the end of the training period between sedentary and trained rats was negated by detraining. Detrained rats had twice the body-weight gain of their untrained controls.

3. An elevation (12%) in metabolizable energy (ME) intake (relative to body-weight) was observed in detrained rats while their gross energetic efficiency was augmented by 60%.

4. Energy expenditure, excluding the estimated costs of fat and protein storage, was similar for detrained and untrained rats. Complementing the latter was the finding that thermogenesis in brown adipose tissue, a known energy buffering process, was also similar.

5. Elevated ME intake (relative to body-weight) largely contributed to the increased energetic efficiency of detrained rats.

1. Interrelations between bacterial metabolites (volatile fatty acids, lactate) in the gut contents and the blood in relation to the faecal excretory cycle (soft or hard faeces) were studied in anaesthetized rabbits.

2. It appeared that the level of organic acids in the alimentary tract varied cyclicly with the faecal excretion pattern. The lactate entering the portal circulation originates from the stomach, while the volatile fatty acids (VFA) originate from the hind-gut. Net absorption from the digestive tract and hepatic utilization of fermentation acids were greater when the rabbits produced hard faeces (hard-phase) compared with soft faeces (soft-phase). Propionate and butyrate reaching the liver were almost quantitatively removed; acetate and lactate were available for extra-hepatic tissue metabolism.

3. Whatever the excretion pattern the levels of VFA in the arterial circulation remained remarkably constant; blood lactate, however, was lower during the soft-phase.

4. Absorption of bacterial metabolites, like their metabolism in the liver, showed a circadian rhythm parallel to the changes in the activity of the adrenal glands, i.e. the activity was enhanced during the hard-phase.

1. The oxidation rates of lauric, myristic, palmitic, stearic, oleic, α-linolenic, linoleic, γ-linolenic, dihomo- γ-linolenic and arachidonic acids were studied by use of a radioisotope tracer technique in weanling rats at rest in a metabolism chamber over 24 h.

2. Of the saturated fatty acids, lauric acid (12:O) was the most efficient energy substrate: the longer the chain length of the saturated fatty acids, the slower the rate of oxidation.

3. Oleic acid (18:1) was oxidized at a remarkably fast rate, similar to that of lauric acid.

4. Of the ω6 essential fatty acids studied, linoleic acid (18:2ω6) was oxidized at a faster rate than any of its metabolites, with arachidonic acid (20:4ω6) being oxidized at the slowest rate.

5. The rate of oxidation of γ-linolenic acid (18:3ω3) was almost as fast as that of lauric and oleic acids.

1.Six Friesian heifers (250 kg live weight) with permanent cannulas in the rumen and abomasum were allocated at random into two groups of three. One group was treated with Teric GN9 (ICI (Aust.) Ltd) to defaunate the animals during the first two of the four periods of the experiment, after which they were refaunated. The second group was treated with Teric at the end of the first two periods. The dietary treatments were: paspalum (Paspalum dilatatum) hay (4.1 kg/d) given alone and the hay supplemented with urea (20 g/kg dry matter).

2. Defaunation was not complete but the approximate volume of protozoa in the rumen of treated animals was less than 6% of that in the untreated animals.

3. The amount of organic matter (OM) digested in the stomach was lower (P < 0.01) in animals with reduced fauna than in those with normal fauna. There were reductions in both the apparent OM digestibility in the total tract (from 0.56 to 0.52, P < 0.01) and the proportion of the digestible OM digested in the rumen (from 0.82 to 0.79, not significant) of animals with reduced fauna. Apparent digestibilities of acid-detergent fibre and neutral-detergent fibre were significantly lower (P < 0.01) in animals with reduced fauna.

4. The amount of nitrogen disappearing from the stomach was significantly higher (P < 0.01) with the urea supplement; effects due to concentrations of protozoa were not significant. The flow of non-ammonia-N from the abomasum was higher (P < 0.05) in animals with reduced fauna than in animals with normal fauna. The flows of bacterial N from the abomasum and the efficiencies of bacterial N synthesis were not significantly affected by the treatments. N retention was higher (P < 0.01) in animals receiving the urea supplement but differences due to protozoa were not significant.

5. Protozoal contribution to the microbial N flowing from the rumen of animals with normal fauna was estimated to be 24 and 27% with and without the urea supplement respectively.

6. Concentrations of rumen-fluid ammonia-N were reduced (P < 0.05) and those of volatile fatty acids were increased (P < 0.01) with reduction in protozoal numbers. Molar proportions of propionic acid increased (P < 0.05) and of butyric acid decreased (P < 0.01) with reduced rumen fauna.

7. Rumen water volume was lower (P < 0.05) and the mean retention time of indigestible acid-detergent lignin tended to be higher in animals with reduced fauna. Rumen dry-matter pool and mean retention time of CrEDTA were not significantly different between treatments.

1. A method was developed for extracting enzymes from micro-organisms closely associated with ammoniatreated straw (NH3-S) that had been incubated in nylon bags in the rumen. Incubation of washed straw with 125 ml carbon tetrachloride/l and 20 μg lysozyme/ml for 3 h at 37° gave carboxymethylcellulase (EC 3. 2. 1. 4; CMCase) and NAD-linked glutamate dehydrogenase (EC 1. 4. 1.2; GDH) activities greater than those extracted by sonication.

2. GDH associated with NH3-S increased with incubation time and was highest in sheep receiving a high-barley diet. Particle-bound CMCase activity reached a peak between 16 and 24 h and declined thereafter.

3. Particle-bound GDH activity showed no correlation with dry matter (DM) degradation in the rumens of sheep fed on a range of diets. In contrast, CMCase activity after 24 h was highly correlated with DM degradability of the same samples at 24 h (r 0.98) and 48 h ( r 0.94).

4. It was concluded that GDH and CMCase can be used as indices of the total population of colonizing rumen micro-organisms and of the fibre-degrading population respectively, and that these enzymes can therefore be used to assess rapidly and with great sensitivity variations in the rumen environment that affect the rate of fibre breakdown.

1. Twenty-two British Friesian bull calves were used in a comparative slaughter experiment to determine the effects of a β-agonist (clenbuterol) on body composition and energy retention. Four calves were slaughtered at 18 d of age and constituted the initial slaughter group. Of the remaining calves, eight (group A, controls) were given milk replacer only, and ten calves (groups B and C, five calves per group) were given milk replacer plus clenbuterol(O.1 and 1.0 mg clenbuterol/kg milk replacer equivalent to approximately 2 and 20 μg/kg body-weight respectively over the 105±3 d of the experimental period). Calves were slaughtered over the weight range 146–177 kg.

2. Clenbuterol had no significant effect on dry matter (DM) intake, daily live-weight gain or feed conversion ratio. DM digestibility of the milk replacer was not affected by treatment. Nitrogen balance was measured on three separate occasions starting when the calves weighed approximately 60, 110 and 130 kg. N retention was increased over the experimental period in clenbuterol-treated calves, although the effect only achieved significance in calves weighing approximately 110 kg live weight (P < 0.05).

3. Clenbuterol (20 μg/kg body-weight) increased estimated mean daily N retention in the carcass of the calves from 22 to 25 g whilst N retention in the non-carcass components decreased from 10 to 8 g/d. Effects of clenbuterol on N retention occurred mainly in skeletal muscle. Fat in both carcass and non-carcass components was reduced by treatment with clenbuterol. The total energy content of live-weight gain was reduced from 1077 to 897 MJ in clenbuterol-treated calves and mean daily heat production was estimated to increase from 23.1 in controls to 25.9 MJ/d in calves in group C.

4. In calves of mean live weight during balance of 120 and 136 kg, clenbuterol significantly increased daily urinary creatinine excretion and in 120 kg calves NT-methylhistidine was significantly decreased (P < 0.05). Based on estimates of muscle mass from urinary creatinine and protein degradation fromN7-methylhistidine NT-methylhistidine excretion, the fractional breakdown rate of muscle protein in clenbuterol-treated calves was only 0.66 of that in the controls when the calves weighed 120 kg.

1. Metabolism of L-[1-14C]methionine, DL-[l-14C]methionine and DL-[ 1-14C]2-hydroxy-4-methylthiobutanoic acid (DL-HMB) by broiler chicks which had been fasted overnight or given a methionine-deficient diet was compared with fed (control) birds.

2. The excretion of 14C-labelled material, total 14CO2 exhaled, 14C incorporation into tissue proteins and the 14C-labelled material in perchloric-acid-soluble tissue fractions were measured 6 h after injection of the 14C-labelled materials.

3. The incorporation of 14C into tissue proteins and the relative rates of conversion of D-methionine and DL-HMB to L-methionine in tissues under different nutritional regimens were compared using protein-bound 14C:protein-free 14C values.

4. Fasted birds exhaled more 14CO2 than control birds but excreted less 14C, while methionine-deficient birds behaved very similarly to the control animals in these respects.

5. Fasted birds incorporated much less 14C into proteins of tissues other than liver and kidney from all three labelled tracers. The values for protein-bound 14C: protein-free 14C were lower in all tissues.

6. Methionine-deficient birds had similar levels of 14C in tissue proteins but lower values for protein bound 14C: protein-free 14C.

7. Examination of the values for protein-bound 14C:protein-free 14C suggest that brain and probably liver tissues from fasted and methionine-deficient birds showed improved rates of conversion of D-methionine and DL-HMB to L-methionine compared with control animals.

1. The effects of a high-(HF) and a low-(LF) fibre diet on porto-arterial plasma concentration differences and plasma levels of urea and ammonia-nitrogen were compared in six Swedish Landrace x Yorkshire pigs (30–52 kg). Portal and arterial blood samples were drawn during 8 h following two consecutive meals, given at 08.00 and 16.00 hours.

2. The HF diet, in comparison with the LF diet, was found to produce significantly lower portal plasma urea levels. However, concomitant arterial plasma levels were equally depressed, consequently leaving the porto-arterial urea differences unchanged.

3. In no instance during the 16 h studied could negative porto-arterial urea differences clearly be observed. It was thus concluded that none of the diets induced an important net flux of plasma urea directly from the circulation into the gastrointestinal tract.

4. The significantly lower circulating plasma urea levels that were observed when the pigs received the HF diet were also associated with significantly lower urinary excretions of urea.

5. The HF and LF diets had similar effects on portal and arterial plasma levels of ammonia-N. This was also true with regard to porto-arterial ammonia-N differences.

1. A low-sodium diet was given to Blackface ewes over two reproductive seasons. This diet provided a total of 3–7 mmol/d except during lactation when the intake was about 11 mmol/d. Control ewes were given the same diet supplemented with sodium chloride to provide recommended levels which were about tenfold that of the experimental diet.

2. The output of Na in urine and faeces from ewes given the low-Na diet was very low, about 3 mmol/d, from early in the experiment and continued at about this level throughout.

3. Lambs born to low-Na ewes and given a low-Na diet similar to that of their dams during lactation, grew, after weaning, more slowly than corresponding lambs from control ewes, but at 6 months of age when six from each group were killed, tissue Na contents were only slightly lower in experimental than control lambs.

4. Fluids and tissues obtained at the end of the second lactation from four ewes of each group that had suckled twin lambs, were analysed for Na and potassium. The Na concentration in saliva and rumen fluid of low-Na ewes was about half that of control ewes and there were corresponding increases in K: the differences were significant. Although Na concentrations for experimental ewes were generally lower than those for control ewes in the tissues analysed (liver, kidney, heart, brain and bone), the difference was significant only for the heart (P < 0.05). Haemoglobin and packed cell volume were significantly elevated in low-Na ewes (P < 0.01), indicating decreased body fluid volume. Enlargement of the adrenal glands in low-Na ewes (P < 0.01) and specifically in the zona glomerulosa (P < 0.001), showed the marked hormonal response to Na status of experimental ewes given a very-low-Na diet over two reproductive cycles.

1. The effects of progressive reduction in food intake from 1.6 x maintenance (1.6 M) to approximately maintenance (M′) and then to zero (fasting) on energy expenditure and leucine kinetics were examined in Hereford x Friesian finishing beef steers.

2. Estimates of whole body protein synthesis and protein oxidation were obtained from the specific radioactivity of free leucine in blood and of exhaled carbon dioxide during continuous infusions of [I-14C]leucine. Protein synthesis contributed a minimum of 0.19 to total heat production across all three intakes.

3. The apparent efficiencies with which synthesized protein was retained were 0.28 between 1.6 M and M′ and 1.04 between M′ and fasting. The greater efficiency below M′ reflected probable use of amino acids as energy sources during fasting, which would be spared as soon as feed was available.

4. Nitrogen derived from protein oxidation made a minor contribution to urine N at both 1.6 M (0.45) and M′ (0.36) but provided a significant proportion to the increment in urine N between intakes (0.68).

5. Amino acid absorption, estimated indirectly as the sum of protein oxidation and protein retention, represented only 0.28 of N intake at M′ and 0.38 at 1.6 M but the contribution to the increment in N intake between these two diet levels was greater (0.56).

6. The estimated efficiency of utilization of absorbed amino acids between M′ and 1.6 M was 0.45.

1. Excreta were collected for four consecutive days from 4- to 18-week-old cockerels following subcutaneous injection of Nτ-[14CH3]methylhistidine.

2. The recoveries of radioactivity in excreta were incomplete and progressively decreased with increasing age.

3. Most of the radioactivity not recovered in excreta after 4 d was found in skeletal muscle where > 55% of the radioactivity present was in the Nτ-methylhistidine-containing dipeptide, balenine.

4. This peptide appeared to be relatively stable so that most of the labelled Nτ-methylhistidine incorporated was not released during the period of the recovery measurements.

5. The total pool of non-protein bound Nτ-methylhistidine (free Nτ-methylhistidine+balenine) in pectoral and mixed thigh muscles increased with age and relative to the daily excretion of Nτ-methylhistidine. At 18 weeks the pool was 3.3 times the daily excretion of Nτ-methylhistidine.

6. These observations account for the decreasing recoveries of radioactivity in excreta described previously, due to progressive dilution of labelled Nτ-methylhistidine in an expanding pool of non-protein-bound Nτ-methylhistidine, part of which was relatively stable.

7. It is concluded that excretion of Nτ-methylhistidine by 4- to 18-week-old cockerels cannot be used as a reliable index of muscle protein breakdown in vivo.

1. The absorption and secretion of 65Zn in the stomach and intestinal tract regions was studied in sets of two and three sheep which were exchanging digesta via re-entrant cannulas in the proximal duodenum. One sheep from each of the three three-sheep sets was dosed intraruminally with the radioisotope. One sheep from the three two-sheep sets received an intravenous dose.

2. Measurements of 65Zn in blood plasma from intraruminally dosed sheep showed that there was no apparent absorption from the stomach region. Measurements from sheep receiving radioactive digesta intraduodenally showed that mean apparent absorption of 65Zn was 0.07 and mean true absorption was 0.103. There was a large variation in endogenous recycling of 65Zn into the stomach region.

3. Secretion of 65Zn into the stomach and intestinal regions in the intravenously dosed sheep of the two-sheep sets was calculated on the basis of total recovery over 10 d in the digesta and faeces. The present study showed that for every 1 molecule Zn secreted into the stomach region, 2.1 molecules were secreted into the intestinal tract region.