Nitrogen fixation associated with sago (Metroxylon sagu) and some implications.

AIMS: To determine the presence and contribution of diazotrophic bacteria to nitrogen concentrations in edible starch derived from the sago palm (Metroxylon sagu). METHODS AND RESULTS: Isolation of diazotrophic bacteria and analysis of nitrogen fixation were conducted on pith, root and sago starch samples. Acetylene reduction showed that five of ten starch samples were fixing nitrogen. Two presumptive nitrogen-fixing bacteria from starch fixed nitrogen in pure culture and five isolates were positive for the nif H gene. Nitrogen concentrations in 51 starch samples were low (37 samples <0·2 g kg(-1); 14 ranging from 0·2 to 2·0 g kg(-1)). CONCLUSIONS: Nitrogen fixation occurs in sago starch, which undoubtedly plays a role in fermentation ecology. Nitrogen levels are considered too low to be of nutritional benefit and to protect against nutritional-associated illnesses. SIGNIFICANCE AND IMPACT OF THE STUDY: Sago starch does not add significantly to the protein calorie intake and may be associated with susceptibility to nutritional-associated illness.

Early harvest and ensilage of forage sorghum infected with ergot (Claviceps africana) reduces the risk of livestock poisoning.

Sorghum ergot produces dihydroergosine (DHES) and related alkaloids, which cause hyperthermia in cattle. Proportions of infected panicles (grain heads), leaves and stems were determined in two forage sorghum crops extensively infected 2 to 4 weeks prior to sampling and the panicles were assayed for DHES. Composite samples from each crop, plus a third grain variety crop, were coarsely chopped and half of each sealed in plastic buckets for 6 weeks to simulate ensilation. The worst-infected panicles contained up to 55 mg DHES/kg, but dilution reduced average concentrations of DHES in crops to approximately 1 mg/kg, a relatively safe level for cattle. Ensilation significantly (P = 0.043) reduced mean DHES concentrations from 0.85 to 0.46 mg/kg.

Nutritive value and non-toxicity of Botryosphaeria zeae-infected wheat for weaner pigs.

A novel fungal infection of wheat by Botryosphaeria zeae was identified on the Darling Downs of Queensland, Australia and called 'white grain' because of its bleached appearance. The only nutritional changes in the wheat grain infected with B. zeae were decreases in nitrogen and total amino acids (approximately 5%), and slight increases in the lysine, fibre and fat content, with starch unaffected. Nutrient digestibility and potential toxicity were assessed in weaner pigs housed in metabolism crates and fed this grain over a 4-week period, as they grew from 15 to 35 kg. Digestibility of energy and nitrogen in white grain was not different from that of normal wheat. The piglets were then bled for biochemical and haematological testing, slaughtered and the entire viscera subjected to gross pathological inspection, followed by histological examination of the liver, kidney, pancreas, spleen, heart, lung, muscle and intestine. White grain did not affect palatability of diets, pig growth rates; no abnormalities were detected in tissues, while biochemical and haematological parameters did not suggest any toxic effect. Hence, wheat with white grain appears suitable for use in pig diets, but the use of this wheat for human food should be restricted until additional longer term studies are conducted.

Spontaneous fermentation of traditional sago starch in Papua New Guinea.

Sago starch is an important dietary carbohydrate in lowland Papua New Guinea (PNG). An investigation was conducted to determine whether microbes play a role in its preservation using traditional methods. In 12 stored sago samples collected from PNG villages, lactic acid bacteria (LAB) were present (> or = 3.6 x 10(4)cfu/g) and pH ranged from 6.8 to 4.2. Acetic and propionic acids were detected in all samples, while butyric, lactic and valeric acids were present in six or more. In freshly prepared sago, held in sealed containers in the laboratory at 30 degrees C, spontaneous fermentation by endogenous microflora of sago starch was observed. This was evident by increasing concentrations of acetic, butyric and lactic acids over 4 weeks, and pH reducing from 4.9 to 3.1: both LAB and yeasts were involved. Survival of potential bacterial pathogens was monitored by seeding sago starch with approximately 10(4)/g of selected organisms. Numbers of Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus fell to < 30/g within 7 days. Salmonella sp. was present only in low numbers after 7 days (< 36/g), but Escherichia coli was still detectable after three weeks (> 10(2)/g). Fermentation appeared to increase the storability and safety of the product.

Effect of feeding sorghum ergot (Claviceps africana) to sows during mid-lactation on plasma prolactin and litter performance.

Diets containing 3% sorghum ergot (16 mg alkaloids/kg, including 14 mg dihydroergosine/kg) were fed to 12 sows from 14 days post-farrowing until weaning 14 days later, and their performance was compared with that of 10 control sows. Ergot-fed sows displayed a smaller weight loss during lactation of 24 kg/head vs. 29 kg/head in control sows (p > 0.05) despite feed consumption being less (61 kg/head total feed intake vs. 73 kg/head by control sows; p < 0.05). Ergot-fed sows had poorer weight gain of litters over the 14-day period (16.6 kg/litter vs. 28.3 kg/litter for controls; p < 0.05) despite an increase in consumption of creep feed by the piglets from the ergot-fed sows (1.9 kg/litter compared with 1.1 kg/litter by the control; p > 0.05). Sow plasma prolactin was reduced with ergot feeding after 7 days to 4.8 microg/l compared with 15.1 microg/l in the control sows (p < 0.01) and then at weaning was 4.9 microg/l compared with 8.0 microg/l (p < 0.01) in the control sows. Two sows fed ergot ceased lactation early, and the above sow feed intakes, body weight losses with litter weight gains and creep consumption indirectly indicate an ergot effect on milk production.

Mycotoxins and toxigenic fungi in sago starch from Papua New Guinea.

AIMS: To assay sago starch from Papua New Guinea (PNG) for important mycotoxins and to test fungal isolates from sago for mycotoxin production in culture. METHODS AND RESULTS: Sago starch collected from Western and East Sepik Provinces was assayed for aflatoxins, ochratoxin A, cyclopiazonic acid, sterigmatocystin, citrinin and zearalenone and all 51 samples were negative. Frequently isolated species of Penicillium (13), Aspergillus (five) and Fusarium (one) were cultured on wheat grain, and tested for the production of ochratoxin A, cyclopiazonic acid, sterigmatocystin, citrinin, patulin and penicillic acid. All 12 isolates of P. citrinin and one of two A. flavipes isolates produced citrinin. A single isolate of A. versicolor produced sterigmatocystin. No other mycotoxins were detected in these cultures. CONCLUSIONS: No evidence was found of systemic mycotoxin contamination of sago starch. However, the isolation of several mycotoxigenic fungi shows the potential for citrinin and other mycotoxins to be produced in sago stored under special conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Sago starch is the staple carbohydrate in lowland PNG and the absence of mycotoxins in freshly prepared sago starch is a positive finding. However, the frequent isolation of citrinin-producing fungi indicates a potential health risk for sago consumers, and food safety is dependant on promoting good storage practices.

Fungal colonization of sago starch in Papua New Guinea.

Sago starch is an important source of dietary carbohydrates in lowland Papua New Guinea. Over the past 30 years there have been sporadic reports of severe illness following consumption of sago starch. A common assumption is that fungal metabolites might be associated with the illness, leading to the need for a more thorough investigation of the mycoflora of sago starch. Sago starch was collected from areas of high sago consumption in Papua New Guinea for fungal analysis (69 samples). Storage methods and duration were recorded at the time of collection and pH on arrival at the laboratory. Yeasts were isolated from all samples except two, ranging from 1.2 x 10(3) to 8.3 x 10(7) cfu/g. Moulds were isolated from 65 of the 69 samples, ranging from 1.0 x 10(2) to 3.0 x 10(6) cfu/g. Of 44 samples tested for ergosterol content, 42 samples showed the presence of fungal biomass. Statistical analyses indicated that sago starch stored for greater than five weeks yielded significantly higher ergosterol content and higher numbers of moulds than sago stored for less than five weeks. The method of storage was also shown to influence mould numbers with storage in natural woven fibre containers returning significantly greater numbers than present in other storage methods tested. Potentially mycotoxigenic genera of moulds including Aspergillus and Penicillium were commonly isolated from sago starch, and as such storage factors that influence the growth of these and other filamentous fungi might contribute to the safety of traditional sago starch in PNG.

Feeding sorghum ergot (Claviceps africana) to sows before farrowing inhibits milk production.

OBJECTIVE: To assess the impact of feeding different amounts of sorghum ergot to sows before farrowing. DESIGN: Fifty-one pregnant sows from a continually farrowing piggery were sequentially inducted into the experiment each week in groups of four to seven, as they approached within 14 days of farrowing. Diets containing sorghum ergot sclerotia within the range of 0 (control) up to 1.5% w/w (1.5% ergot provided 7 mg alkaloids/kg, including 6 mg dihydroergosine/kg) were randomly allocated and individually fed to sows. Ergot concentrations were varied with each subsequent group until an acceptable level of tolerance was achieved. Diets with ergot were replaced with control diets after farrowing. Post-farrowing milk production was assessed by direct palpation and observation of udders, and by piglet responses and growth. Blood samples were taken from sows on three days each week, for prolactin estimation. RESULTS: Three sows fed 1.5% ergot for 6 to 10 days preceding farrowing produced no milk, and 87% of their piglets died despite supplementary feeding of natural and artificial colostrums, milk replacer, and attempts to foster them onto normally lactating sows. Ergot inclusions of 0.6% to 1.2% caused lesser problems in milk release and neo-natal piglet mortality. Of 23 sows fed either 0.3% or 0.6% ergot, lactation of only two first-litter sows were affected. Ergot caused pronounced reductions in blood prolactin, and first-litter sows had lower plasma prolactin than multiparous sows, increasing their susceptibility to ergot. CONCLUSION: Sorghum ergot should not exceed 0.3% (1 mg alkaloid/kg) in diets of multiparous sows fed before farrowing, and should be limited to 0.1% for primiparous sows, or avoided completely.

Sorghum ergot (Claviceps africana) associated with agalactia and feed refusal in pigs and dairy cattle.

OBJECTIVE: To establish the aetiology and define the main clinical features of a syndrome characterised by severe feed refusal, death of piglets and reduced milk production in pigs and dairy cattle. DESIGN: Clinical, pathological, toxicological and epidemiological examination of clinical cases in 10 piggeries and 4 dairies, located between 50 and 150 km south-west of Rockhampton. RESULTS: All cases were associated with the feeding of sorghum grain infected with sorghum ergot (Claviceps africana). There was mild to severe feed refusal when the sorghum was first offered. Sows fed ergot before farrowing had shrunken udders, produced no colostrum, and displayed signs of oestrus. All of their piglets died, apparently from starvation: necropsy of a few piglets showed that they were born alive and walked, but had ingested no milk. Sows fed the grain after farrowing had severe reductions in milk production despite aggressive sucking by piglets, leading to very poor growth of piglets. There were no signs of infectious disease. Ergot in sorghum samples ranged from 1 to 31% ergot sclerotes by weight. Total alkaloid concentrations in mixed feeds ranged from 5 to 40 mg/kg, with dihydroergosine accounting for approximately 90%. At the same time, in the same districts, there were reports of feed refusal and reduced milk production from 4 dairy farms. Grain samples from these farms contained up to 17% C africana ergot sclerotia. CONCLUSION: Agalactia and feed refusal are classical signs of poisoning by rye ergot (C purpurea), but this is the first time that sorghum ergot has been associated with a similar syndrome.

Cyclopiazonic acid in combination with aflatoxins, zearalenone and ochratoxin A in Indonesian corn.

The mycotoxin, cyclopiazonic acid (CPA), was detected at concentrations as high as 9 ppm in 21 of 26 corn samples from a Bogor poultry feedmill. This is the first demonstration of the natural occurrence of CPA in Indonesia. CPA was always accompanied by other mycotoxins, especially aflatoxins, suggesting that the interactive toxicity of these mycotoxins to poultry should be investigated.

Corn as a source of mycotoxins in Indonesian poultry feeds and the effectiveness of visual examination methods for detecting contamination.

Every truck load of corn (n = 52) entering and every batch of poultry feed (n = 290) leaving a Bogor feedmill over one year was analysed for aflatoxins, zearalenone, ochratoxin A and sterigmatocystin. Fifty loads of corn and 274 of the batches of chicken feed contained aflatoxins. Zearalenone was detected in 11 corn samples but was not found in the formulated feed. Ochratoxin A was detected in one corn sample, but not in feed. Corn can account for all of the aflatoxin in the feed since levels were always lower in the finished product. There was no quantitative association between the proportion of bright green-yellow fluorescent, purple or mouldy kernels and the mycotoxin contents of the composite samples. Nevertheless, the absence of abnormal kernels indicates higher quality corn since the highest levels of mycotoxins occurred in the abnormal kernels.

Identification of uroliths by infrared spectroscopy.

Wet chemical tests have deficiencies when applied to mixtures containing silica, which are common in the uroliths of some domestic animals. Consequently, the applicability of an infrared spectroscopic method was tested on 104 uroliths obtained from cattle, sheep, goats, horses, pigs, dogs, a chicken and a rabbit during diagnostic investigations. The following components were satisfactorily identified: silica, calcium oxalate, calcium carbonate, calcium phosphate, magnesium ammonium phosphate, magnesium phosphate and urates. The infrared characteristics of these compounds and their mixtures are described.

Rejection by pigs of mouldy grain containing deoxynivalenol.

Weaner pigs on a farm near Beaudesert in south eastern Queensland refused to eat feed comprised largely of wheat and barley. Older pigs consumed small amounts and some prepubertal gilts subsequently displayed enlarged and reddened vulvas. Wheat, barley and triticale were grown on the farm during 1983, which was unusually and persistently wet. The wheat and triticale were harvested and stored for about 3 weeks with moisture contents above 14% before being fed. Samples of the wheat and triticale contained pale pink grains, which can indicate infection by the fungus Fusarium graminearum Schw. On analysis 2 mycotoxins known to be produced by F. graminearum were detected, deoxynivalenol (vomitoxin) which causes feed refusal and vomiting, and zearalenone which causes oestrogenic effects. Concentrations of deoxynivalenol in the wheat, triticale and barley were 34, 10, and less than 0.1 mg/kg respectively. Concentrations of zearalenone were 6.2, 2.8 and 0.1 mg/kg respectively. Subsequently, F. graminearum was isolated from grains and crop residues. Although the wet weather contributed to F. graminearum infection of the crops before harvest, most of the toxins probably developed during storage.

Zearalenone intoxication of pigs.

Mycotoxicosis due to ingestion of zearalenone was detected on 2 pig farms on the Atherton Tableland in northern Queensland. In one herd of 200 pigs, this resulted from feeding maize which had been stored with a high moisture content. In the other herd of 1400 pigs, it resulted from feeding sorghum grain which was rain affected before harvest. Concentrations of zearalenone in the feeds ranged up to 8 mg/kg. Most prepubertal gilts in the herds displayed enlarged teats and signs of oestrus such as having red, swollen vulvas. In several cases both rectal and vaginal prolapses occurred. On one of the farms, 25 pigs died as a direct result of prolapses. Autopsy of a 3-month-old gilt revealed apparently enlarged ovaries and uterine horns. Sows and boars seemed to be unaffected. Four gilts failed to conceive following mating during the period of zearalenone ingestion, but apart from this and the deaths from prolapses, production of the herds appeared to be unaffected.

Field cases of aflatoxicosis in pigs.

Five cases of aflatoxicosis in pigs in southern Queensland are described. One peracute case where aflatoxin concentrations of up to 5000 micrograms aflatoxin B1/kg were demonstrated in stomach contents was presumed to be caused by consumption of mouldy bread. High levels of toxins were also present in the livers. Two cases of acute toxicity were caused by feeding mouldy peanut screenings containing 22000 micrograms aflatoxin B1/kg. One case of subacute and one of chronic toxicity were caused by sorghum grain based rations with lower aflatoxin levels (4640 and 255 micrograms/kg). Peracute toxicity caused collapse and deaths within several hours, acute toxicity caused deaths within 12 h and with subacute toxicity deaths occurred after 3 weeks on a toxic ration. Anorexia and ill thrift affecting only growing animals were seen with chronic toxicity. Extensive centrilobular liver necrosis and haemorrhage occurred with peracute toxicity and in cases of acute poisoning there was hepatic centrilobular cellular infiltration, hepatocyte swelling and bile stasis. With subacute toxicity hepatocyte vacuolation together with bile stasis and bile ductule hyperplasia were seen.