This trial was conducted to study the effects of dietary rapeseed cake (RSC) containing high glucosinolates (GLS) on rumen fermentation, nutrient digestion and the rumen microbial community in steers. Eight growing steers and four rations containing RSC (GLS 226·1 μmol/g DM) at 0·00, 2·65, 5·35 and 8·00 % DM were assigned in a replicate 4 × 4 Latin square design. The results indicated that increasing RSC levels increased the ruminal concentration of thiocyanate (SCN) (P < 0·01), decreased the ruminal concentration of ammonia nitrogen (NH3-N) and the molar proportion of isovalerate (P < 0·05), did not affect the ruminal concentration of total volatile fatty acids (P > 0·05), decreased the crude protein (CP) digestibility (P < 0·05) and increased the ether extract (EE) digestibility (P < 0·01). Increasing RSC levels tended to decrease the abundances of ruminal Ruminobacter amylophilus (P = 0·055) and Ruminococcus albus (P = 0·086) but did not affect methanogens, protozoa, fungi and other bacteria (P > 0·05). Increasing RSC levels in the ration did not affect the ruminal bacterial diversity (P > 0·05), but it increased the operational taxonomic units and the bacterial richness (P < 0·05) and affected the relative abundances of some bacteria at the phylum level and genus level (P < 0·05). In conclusion, RSC decreased the ruminal concentration of NH3-N and the CP digestibility, increased the EE digestibility and partly affected the ruminal bacterial community. SCN, as the metabolite of GLS, could be a major factor affecting these indices.

Weed control in organic onion production is often difficult and expensive, requiring numerous cultivations and extensive hand weeding. Onion safety and weed control with mustard seed meal (MSM) derived from Sinapis alba was evaluated in greenhouse and field trials. MSM applied at 110, 220, and 440 g m−2 severely injured onions and reduced onion stand by 25% or more when applied from planting to the one-leaf stage of onions in greenhouse trials. MSM derived from mustard cultivars ‘IdaGold’ and ‘AC Pennant’ reduced plant dry weight of redroot pigweed with an effective dose that provided 90% weed control (ED90) of 14.5 and 3.2 g m−2, respectively, in greenhouse trials, whereas the ED90 of MSM from a low-glucosinolate cultivar ‘00RN29D10’ was 128 g m−2, suggesting that glucosinolate content and ionic thiocyanate (SCN−) production contribute to phytotoxicity of MSM. In field trials, weed emergence, onion injury, and onion yield were recorded following single or three sequential applications of MSM from 1.1 to 4.5 MT ha−1 beginning at the two-leaf stage of onions in 2008, 2009, and 2010. By 8 wk after treatment (WAT), onion injury following MSM sequential applications was 10% or less in all 3 yr. Combined over 2008 and 2009, 48 and 68% fewer weeds emerged 3 WAT with MSM at 2.2 and 4.5 MT ha−1, respectively. In 2010, MSM at 2.2 and 4.5 MT ha−1 reduced the number of weeds emerged 4 WAT by 91 and 76%, respectively. MSM treatment did not significantly affect onion yield or size in 2008 and 2009, but in 2010 onion total yield was reduced by 29% by three sequential applications of MSM at 2.2 MT ha−1. MSM has potential to be used as a weed-suppressive amendment in organic production systems, but the risk of crop injury is substantial.

Thiocyanate content and lactoperoxidase activity of individual cow's milk of different breeds were determined, and the effects of different lactoperoxidase system (LP-s) activation strategies were compared. Lactoperoxidase activity varied significantly between Friesian and both Ayrshire and Tanzania Short Horn Zebu (TSHZ), but differences between Ayrshire and TSHZ were not significant. There was no significant variation in SCN− content between breeds. The LP-s was activated using three strategies based on SCN−: namely; equal concentrations of SCN− and H2O2 (7:7, 10:10, 15:15 mg/l), excess SCN− concentrations (15:10, 20:10, 25:10 mg SCN−:H2O2/l), and excess H2O2 concentrations (10:15, 10:20, 10:25 mg SCN−:H2O2/l), plus a fourth strategy based on I− (15:15 mg I−:H2O2/l). The keeping quality (KQ) was assessed using pH, titratable acidity, clot on boiling and alcohol stability tests. All activation strategies enhanced the shelf life of milk (typically increasing KQ from around 10 to around 20 h), but it was clear that the effectiveness of the LP-s depends on the type and concentrations of the activators of the system. The LP-s activated using I− as an electron donor was more effective than the LP-s activated using SCN− as an electron donor, increasing the KQ by a further 6–8 h compared with SCN−.

Plasma thiocyanate has been reported to be high among cassava-eating populations such as that in Nigeria because of the cyanide content of cassava. Thiocyanate, which is secreted into the stomach contents of animals, has been demonstrated to catalyse the formation of nitrosamines (potent carcinogens) in the stomach from secondary amines and nitrite. The main source of the nitrite precursor in this environment is vegetables, primarily eaten as the chief supplier of proteins. The present study attempts to analyse the levels of nitrate and nitrite in vegetables commonly grown and consumed in Delta State, Nigeria. The nitrate and nitrite contents in green vegetable (Amaranthus spp.), bitter leaf (Vernonia amygdalina), pumpkin (Telfaria occidentalis) and water leaf (Talinum triangulare) grown in different localities of the state were determined by standard analytical procedures. The results show that those vegetables grown in the industrialised urban centres of the state had higher nitrate (223 (sd 71) mg/kg dry weight; P<0·05) and nitrite (12·6 (sd 1·7) mg/kg dry weight; P>0·05) levels when compared with the same species (188 (sd 77) mg nitrate/kg dry weight and 10·9 (sd 1·1) mg nitrite/kg dry weight) cultivated in less industrialised suburbs. We conclude that frequent consumption of such vegetables whose nitrate and nitrite contents are high by cassava-eating individuals might put them at risk of developing stomach cancer and other possible results of nitrate and/or nitrite toxicity. In order to avoid an outbreak in our communities, appropriate agencies should monitor and regulate the release of chemicals into the environment. In the meantime, the cultivation and consumption of vegetables grown in industrialised areas of the state should be discouraged.

I deficiency is the leading cause of preventable mental retardation. A number of surveys in Afghanistan show goitre prevalence rates more than 20% amongst children and women. Access to iodised salt remains low, with disparate coverage by region, despite the recent implementation of a national salt iodisation programme. The objectives were to identify whether the presence of goitre is a satisfactory marker of I deficiency and to examine the relationship between goitre and thyroid function. A case–control study was carried out in children and women of childbearing age, stratified on the presence of goitre. Adequate levels of urinary I were observed in 6·8% of all the subjects, and amongst the subjects without goitre, this figure was only 9%. The presence of goitre was significantly associated with severe urinary I deficiency; however, the difference between the cases and controls was not as great as expected. An association between the presence of goitre and elevated thyroid-stimulating hormone (TSH) levels was observed, but 14% of the children without palpable goitre also showed abnormal TSH levels.Given that the majority of subjects showed some degree of I deficiency and that children without goitre may have elevated TSH levels, the absence of goitre is an insufficient indicator to determine adequate I status. The risk of subsequent development of goitre, in the currently non-goitre population, is elevated. This suggests that short-term I supplementation should be considered independently of the presence of goitre or urinary I level, until the access to and consumption of iodised salt is generalised.

Lactoperoxidase activity and thiocyanate content were monitored in the milks of seven individual cows and six goats during lactation. Lactoperoxidase activity exhibited a cyclic pattern with alternating peaks and troughs throughout lactation. Extremely large variations were observed between and within animals. For example, lactoperoxidase activity ranged from 0·05–5·60 U/ml for one cow on different sampling days. Variations between cows were also large, ranging from 0·98–5·1 U/ml on a specific sampling day. Mean lactoperoxidase activity in cows ranged from 1·5–2·7 U/ml with an overall mean of 2·3±1·0 U/ml while the thiocyanate concentration ranged from 6·0–10·2 μg/ml with an overall average of 8·5±5·1 μg/ml. Lactoperoxidase activity means for goats ranged from 0·04–0·16 U/ml with a grand mean of 0·1±0·06 U/ml while the thiocyanate content means ranged from 6·6–8·2 μg/ml with a grand mean of 7·0±2·59 μg/ml. There was no correlation between lactoperoxidase activity and thiocyanate content in either cows' (R2 = 0·011) or goats' (R2 = 0·015) milk. These experiments have revealed that lactoperoxidase activity is affected by many factors including the individual animals, species, feed and stage of lactation. Therefore the exogenous supply of thiocyanate and hydrogen peroxide needed to activate the lactoperoxidase system for raw milk preservation will vary in quantity depending on these factors.

A thyroid-hormonal evaluation of thirty-five women consuming commercially packed milk containing thiocyanate was carried out. The mean serum thiocyanate concentration, which was measured by the FeCl3 colour test, was significantly higher (P < 0.01) than that of control subjects. Serum thyroxine (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) concentrations of exposed women were compared with those of thirty-five control subjects. Thiocyanate ingestion was associated with lower levels of T4 (P <0.01) and higher levels of TSH (P < 0.01) compared with the control subjects. T3 was found to be higher in the women consuming thiocyanate-containing milk but the difference was not significant. The serum T4 level was found to be negatively correlated (r −0.359, P <0.05) while the TSH level was positively correlated (r 0.354, P < 0.05) with thiocyanate concentration in the exposed group. From this study, it appears that ingestion of milk with added thiocyanate impairs thyroid function.