A total of 14740 schoolchildren in seven provinces of Shoa Administrative Region in Central Ethiopia were surveyed for the prevalence of goitre, xerophthalmia and anaemia. Haemoglobin and packed cell volume were assessed in 966 children in one province while an in-depth study was conducted on 344 children in the same province and two others. Goitre, xerophthalmia (Bitot's spots) and clinical anaemia were observed in 34·2, 0·91 and 18·6% respectively of the children. Most biochemical variables were within the normal range while those of haemoglobin (Hb), mean corpuscular Hb concentration (MCHC) and urinary I excretion were lower, and mean corpuscular volume, mean corpuscular Hb (MCH), and immunoglobulins G and M were higher. Hb was strongly correlated with retinol. ferritin, MCHC, MCH, packed cell volume and erythrocyte count while retinol formed a triad with transthyretin (TTR) and retinol-binding protein (RBP) which were all correlated with one another. Total and free thyroxin and total and free triiodothyronine were positively correlated as were the concentrations of the total and free hormones. Thyrotropin (TSH) was negatively correlated with total and free thyroxin and positively correlated with free triiodothyronine. Thyroxin and triiodothyronine in both free and combined forms were all correlated with thyroxin-binding globulin which in turn was negatively correlated with the triad retinol, RBP and TTR. The triad was also negatively correlated with C-reactive protein. Urinary I excretion was positively associated with total thyroxin and negatively associated with TSH. The anaemia found was not nutritional in origin but due to the effect of infestation with intestinal parasites and malaria.

The influence of the source of dietary Fe (ferric citrate alone or mixed with bovine blood at a proportion of 1:1) (v/v) on the digestive utilization of Fe, P, Ca and Mg, and on haemoglobin regeneration efficiency (HRE) was investigated in control and Fe-deficient rats. Diet A contained (by analysis) 43·5 mg Fe/kg diet (as ferric citrate), and diet B contained 44·3 mg Fe/kg diet (ferric citrate—bovine blood). In Fedeficient rats fed on diet A or B the apparent digestibility coefficient (ADC) of Fe increased by 42·3 and 45·7% respectively. The ADC of Ca and Mg decreased significantly in Fe-deficient rats regardless of the source of dietary Fe. The HRE increased by 72·9% in Fe-deficient rats fed on diet A, and by 91·1% in Fe-deficient animals fed on diet B. In Fe-deficient rats fed on Fe for 10 d the values of haematological variables approached normality. However, serum Fe remained low, indicating that Fe reserves were still depleted. A deficient dietary supply of Fe for 30 d did not significantly modify the numbers of circulating leucocytes.

Feeding diets depleted of vitamin E and Se to cattle can induce a disease known as nutritional degenerative myopathy. It is believed that an increased peroxidative challenge in muscle is involved in the pathogenesis of this disease. A number of species can up-regulate the activity of some antioxidant enzymes, including glutathione reductase (EC 1.6.4.2), glutathione transferase (EC 2.5.1.18), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), catalase (EC 1.11.1.6), and superoxide dismutase (EC 1.15.1.1), in an attempt to mitigate the effects of a peroxidative challenge. A 2 × 2 factorial study was set up to examine possible changes in the activities of these antioxidant enzymes in muscles of ruminant calves fed on diets low in either vitamin E or Se. Four groups of four calves each were fed on a basal diet of NaOH-treated barley which was supplemented with α-tocopherol or Se or both for a total of 50 weeks. Calves fed on diets depleted of vitamin E, but not those ted on diets low in Se, developed subclinical myopathy, as judged by increases in the activity of plasma creatine kinase (EC 2.7.3.2), and had increased muscle concentrations of two indices of lipid peroxidation, namely thiobarbituric acidreactive substances, with and without ascorbate activation. Feeding diets depleted of vitamin E and diets low in Se both increased muscle activities of glucose-6-phosphate dehydregenase in heart, biceps and supraspinatus. This change may have occurred in an attempt to maintain intracellular pools of reduced glutathione. No other changes in antioxidant enzyme activity were observed.

Glucosinolates, such as sinigrin, and S-methyl cysteine sulphoxide (SMCO), which are found in forage brassica species have been implicated in the low intakes observed among lambs consuming such diets. To test both the individual and interactive effects of these compounds in sheep, all combinations of the sinigrin breakdown products, allyl cyanide (ACN) and allyl isothiocyanate (AITC; 10 mmol/d), and the SMCO metabolite dimethyl disulphide (DMDS; 25 mmol/d) were orally administered twice daily for 5 weeks to forty sheep offered dried grass pellets ad lib. As well as measuring voluntary food intake (VFI), a number of haematological and clinical function tests were conducted to assess the physiological effects of the compounds. VFI was significantly depressed by both ACN and AITC but not by DMDS. DMDS significantly ameliorated the effects of ACN on VFI (P < 0.001). Concentrations of reduced glutathione in the blood were depressed by ACN and AITC and elevated by DMDS but no significant interactions were evident. Elevated plasma γ-glutamyl transpeptidase (EC 2.3.2.1) activity on ACN and AITC treatments indicated possible liver damage. DMDS elicited a rise in Heinz bodies to 11 % by week 2 but this was not reflected in packed cell volume and blood haemoglobin levels which were unaffected by treatment. The increased Heinz body count caused by DMDS was not further influenced by ACN or AITC. In conclusion, the depressive effects of sinigrin breakdown products on VFI were not compounded by the additional presence of DMDS which, on the contrary, lessened the depression of VFI caused by ACN.

Two experiments were conducted with sheep fed on fresh Lotus pedunculatus containing 50–55 g condensed tannin (CT)/kg dry matter. Effects of CT were assessed by comparing control sheep (CT operating) with sheep receiving a continuous intraruminal infusion of polyethylene glycol (PEG) to bind and inactivate CT. Digestion of methionine and cystine was determined using a continuous intraruminal infusion of indigestible markers, whilst plasma irreversible loss (IRL) of methionine, cystine and inorganic sulphate was determined using 35S labelling. The proportion of microbial non-NH3-N (NAN) in whole rumen digesta NAN and the IRL of reducible S from the rumen were determined using a continuous intraruminal infusion of (NH4)235SO4. The proportion of microbial NAN in whole rumen digesta NAN (0·44 v. 0·71) and the IRL of reducible S from the rumen (0·84 v. 2·49 g S/d) were lower in control than PEG sheep. PEG sheep lost 30% of ingested methionine and cystine across the rumen, whereas the control sheep lost no methionine and cystine across the rumen. Apparent absorption of methionine from the small intestine was 27% higher in control than PEG sheep, but both groups had a similar apparent absorption of cystine. The apparent digestibility of cystine in the small intestine was lower in control (0·42) than PEG (0·53) sheep, whereas the apparent digestibility of methionine was similar (0·78) for both groups. CT had no effect on plasma methionine IRL, but markedly increased the IRL of cystine (39·8 v. 22·4 μmol/min) and reduced the IRL of plasma inorganic sulphate (35·9 v. 50·2 μmol/min). A three-pool model comparing interconversions between the three plasma metabolites showed that CT increased the flow of cystine to body synthetic reactions (36·5 v. 17·3 μmol/min). This was due to trans-sulphuration of methionine to cystine being greater in control than in PEG sheep, whilst the oxidation of both methionine and cystine were reduced in control sheep. It was concluded that CT reduced the proteolysis of forage protein and the degradation of S amino acids to inorganic sulphide in the rumen, resulting in increased net absorption of methionine and increased utilization of cystine for body synthetic reactions in sheep with a high capacity for wool growth (and, hence, high cystine requirement).