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Photosensitivity in Cattle Grazing Brassica Crops

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Fast-growing Brassica forage crops, comprising turnip, rape, rutabaga, and kale varieties or interspecies crosses, are important in the provision of high-quality, easily digestible animal feed in many countries. The feeding of Brassica is associated with a number of potential problems, including photosensitization. This photosensitivity ranges from mild to severe. This article reports data on the implicated Brassica cultivars, as well as clinical observations, serum chemistry findings, skin biopsy and liver biopsy histopathology, gross necropsy and histopathological observations of spontaneous cases of Brassica (in particular turnip) photosensitivity in dairy cattle, and treatment and prevention strategies. In cattle, Brassica photosensitization is associated with increased activities of γ-glutamyl transferase and glutamate dehydrogenase, and raised phytoporphyrin (phylloerythrin) concentrations in serum. Thus, it is classified as a hepatogenous, or secondary, photosensitization. Histopathological lesions in the skin and liver of affected animals and bile duct changes, distinctly different from those seen in facial eczema (sporidesmin toxicosis), are described for the first time. In contrast to the situation with many cases of chronic facial eczema, the biliary and fibrotic changes appear to regenerate and not become relentlessly progressive. The toxin(s) responsible for the hepato-and cholangiotoxicity in cattle grazing Brassica is unknown. On the basis of a brief review of the literature on Brassica secondary compounds, and work done in rats, it appears possible that toxicity may be caused by degradation products of glucosinolates, in particular the nitrile or isothiocyanate derivatives.
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... biennis) and swedes (rutabaga, B. napus ssp. napobrassica) has been reported from Australia (Morton & Campbell 1997) and New Zealand (Collett & Matthews 2014). This bovine clinical entity is now referred to as Brassica-associated liver disease (BALD) (Matthews, Parton & Collett 2020). ...
... This bovine clinical entity is now referred to as Brassica-associated liver disease (BALD) (Matthews, Parton & Collett 2020). The incidence, clinical signs, blood chemical and histological changes were first described by Collett and Matthews (2014). The Brassicaceae family of plants is also associated with various well-known clinical syndromes, including haemolytic anaemia, polioencephalomalacia, abortion, nitrate toxicity, ruminal acidosis, constipation or diarrhoea, goitre, fog fever and bloat as a result of choke, as well as the problem of Brassica milk taint (Cote 1944;Westwood & Nichol 2009;Wikse, Leathers & Parish 1987). ...
... In some cows, skin lesions are mild and confined to the teats and limited areas of nonpigmented skin. In others, more severe and extensive nonpigmented skin lesions, characterised by epidermal and superficial dermal necrosis leading to sloughing, as well as oedema of the extremities may lead to dehydration and death or necessitate culling on welfare grounds (Collett & Matthews 2014). ...
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Holstein cows on a farm in the Humansdorp district, Eastern Cape province, South Africa, developed reddened, painful teat skin 3 days after grazing a mixed forage crop dominated by bulb turnip (Brassica rapa, Barkant cultivar). The crop was grazed 45 days after planting and 10% of the herd developed symptoms. More characteristic non-pigmented skin lesions started manifesting 1–2 days after the appearance of the teat lesions. Affected cows had elevated serum activities of gamma-glutamyl transferase, glutamate dehydrogenase and aspartate aminotransferase. These blood chemistry findings confirmed a secondary (hepatogenous) photosensitivity. As a result of the severity of the teat and skin lesions, seven cows were slaughtered and tissue samples from five of them were collected for histopathological examination. Liver lesions in cows that were culled 3 or more weeks after the onset of the outbreak showed oedematous concentric fibrosis around medium-sized bile ducts and inflammatory infiltrates in portal tracts. Characteristic lesions associated with other known hepatobiliary toxicities were not found. No new cases were reported 5 days after the cattle were removed from the turnips. The sudden introduction of the cows, without any period of transitioning or adaptation to grazing turnips, as well as the short latent period, clinical signs of photosensitisation, blood chemistry and histopathology, confirmed a diagnosis of Brassica-associated liver disease, a condition seen in New Zealand but not previously described in South Africa. Brassica forage crops are potentially toxic under certain conditions and farmers must be aware of these risks.
... acephala), introduced from Europe, North America and Asia, are now cultivated across temperate and subtropical regions of Australia and have become sporadically naturalized in southern regions [57]. These plants can cause a number of diseases in cattle and are implicated in cases of secondary photosensitization, referred to as brassica-associated liver disease (BALD) [113]. Morbidity rates and disease severity vary between outbreaks; however, severe photosensitization is a common feature and typically develops three to four days after introduction to brassica forage [113]. ...
... These plants can cause a number of diseases in cattle and are implicated in cases of secondary photosensitization, referred to as brassica-associated liver disease (BALD) [113]. Morbidity rates and disease severity vary between outbreaks; however, severe photosensitization is a common feature and typically develops three to four days after introduction to brassica forage [113]. Hematological and biochemical changes take a number of days to develop and are characterized by marked elevations in cholestatic enzyme activities and total bilirubin and marked but often less severe elevations in hepatocellular enzyme activities [40,113]. ...
... Morbidity rates and disease severity vary between outbreaks; however, severe photosensitization is a common feature and typically develops three to four days after introduction to brassica forage [113]. Hematological and biochemical changes take a number of days to develop and are characterized by marked elevations in cholestatic enzyme activities and total bilirubin and marked but often less severe elevations in hepatocellular enzyme activities [40,113]. Changes consistent with inflammation, such as a left shift neutrophilia and hyperfibrinogenemia, may also be seen [114]. ...
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Plant- and fungus-derived hepatotoxins are a major cause of disease and production losses in ruminants in Australia and around the world. Many are well studied and described in the literature; however, this is not the case for a number of hepatotoxicities with economic and animal welfare impacts, such as acute bovine liver disease (ABLD), brassica-associated liver disease (BALD) and Trema tomentosa, Argentipallium blandowskianum and Lythrum hyssopifolia toxicity. Additionally, significant overlap in the clinical presentation and pathology of these conditions can present a diagnostic challenge for veterinarians. This review summarizes the current and most recently published knowledge of common plant- and fungus-associated hepatotoxins affecting cattle in Australia, with a focus on the mechanisms of toxicity and distinguishing diagnostic features. Consolidation of the current understanding of hepatotoxic mechanisms in cattle provides insight into the potential mechanisms of lesser-known toxins, including cellular and subcellular targets and potential metabolic pathways. In the absence of specific etiological investigations, the study of epidemiological, clinical and pathological features of hepatotoxicity provides valuable insights into potential toxic mechanisms and is integral for the successful diagnosis and management of these conditions.
... Given the high digestibility and ME content of the forage brassicas relative to the forage oats in this study, there is considerable potential for forage brassicas to reduce ruminant-derived carbon emissions. Despite the range of livestock production benefits, there are challenges to maximising production in brassica-fed livestock, including early suppression of intake, possibly associated with anti-nutritional factors (Nichol 2003), the risk of ruminal acidosis induced by insufficient neutral detergent fibre content (Westwood and Mulcock 2012), and the risk of photosensitisation where livestock intakes are not appropriately managed, such as break-feeding, as done in dairy systems (Collett and Matthews 2014). These issues can reduce the feeding value of forage brassicas and complicate their grazing management (Barry 2013), especially in extensive systems where greater livestock numbers and paddock size limit the rigorous monitoring of animals. ...
... These issues can reduce the feeding value of forage brassicas and complicate their grazing management (Barry 2013), especially in extensive systems where greater livestock numbers and paddock size limit the rigorous monitoring of animals. Furthermore, lowyielding crops grown under hot, dry 'drought stressed' conditions such as those that occur in Australia's mixed farming zone may also increase the risk of higher concentrations of anti-nutritional compounds and associated health disorders such as photosensitisation (Morton and Campbell 1997;Collett and Matthews 2014). ...
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In many areas of Australia’s mixed farming zone, cropping rotations are dominated by cereals and some areas have few suitable broadleaf alternatives. Forage brassicas are widely used in high rainfall livestock systems, but this study shows that several genotypes offer an alternative to forage oats in drier environments within Australia’s mixed farming zone. We compared a diverse set of forage brassica genotypes sown in autumn and winter with benchmark species, principally oats, across 10 experimental site-years. In both early (800–1300 growing degree days after sowing) and late (1600–2100 growing degree days after sowing) grazing windows, several forage brassica genotypes had forage production similar or superior to oats and dual-purpose canola. Many forage brassica genotypes produced higher yields of metabolisable energy (ME) and crude protein (CP), particularly in the late grazing window. In the early grazing window, Rival and Green globe turnips and HT-R24 forage rape consistently produced ~15% above the site mean for all productivity measures, whereas kale produced ~40% less than the site mean. In the late grazing window, oats produced the greatest amount of edible biomass (~44% higher than the site mean); however, Goliath and HT-R24 forage rapes, Pallaton raphanobrassica and dual-purpose canola had the highest yields of ME and CP (~16% higher than the site mean). Green globe turnip, Hunter leafy turnip and Regal kale produced ~22% less than the site mean in this late grazing window. Multi-environment analyses revealed no genotype × environment interactions within the early grazing window. In the late grazing window, there were several genotypic adaptations, particularly for Pallaton, which performed better in low–medium production environments than the other genotypes. We show that forage brassicas offer superior yields of ME and CP, indicating that they may be better able to meet the energy and protein demands of grazing livestock than forage oats.
... Toxicity was observed over a period of approximately 1 month (July-August) and the affected cattle came from multiple farms (Dalley et al. 2015). Photosensitisation was the most outstanding clinical presentation of many of the cows and was secondary to liver disease as indicated by elevated activities of liver enzymes in serum (Collett and Matthews 2014). Histopathological lesions of the liver in many of the cows that died or that were euthanised, showed distinctive but subtle lesions in small interlobular bile ducts, variable portal fibrosis and bile duct hyperplasia, as well as mild fatty change or patchy necrosis in the parenchyma (Collett et al. 2015). ...
... These lesions closely resembled those seen in photosensitisation caused by bulb turnip (B. rapa) (Collett and Matthews 2014). Lesions in the kidneys were variable and comprised tubular dilation and cast formation, with scattered tubules showing epithelial necrosis (Collett et al. 2015). ...
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Aim: To investigate the direct in vitro toxicity in human and bovine liver cells, and inhibition of activity of ATP-binding cassette transporter G2 (ABCG2) and cytochrome P450 3A4 (CYP3A4) by five nitrile and epithionitrile derivatives from swede (Brassica napus). Methods: The following compounds were investigated: 1-cyano-2-hydroxy-3-butene (CHB, epithionitrile derivative of progoitrin), 1-cyano-2-hydroxy-3,4-epithiobutane (nitrile derivative of progoitrin), 3-butenenitrile (nitrile from sinigrin), 4-pentenenitrile (nitrile from gluconapin), and 5-hexenenitrile (nitrile from glucobrassicanapin). Direct cytotoxicity was assessed by incubating the compounds (at 100 mM, 200 mM, 2 M) with human (HepG2) hepatocellular carcinoma cells or bovine primary hepatocytes for 24 hours. Cell viability was then assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytotoxicity in Hep2G cells was also assessed after incubation for 72 hours at sub-chronic concentrations (1, 2.5, 5, 10, 15, 20 µM) and for combinations of compounds (20 µM). The ability of compounds to inhibit activity of the ABCG2 transporter and the CYP3A4 enzyme were assessed using human ABCG2 vesicles and demethylation of erythromycin by rat liver microsomes, respectively. Results: No reduction of cell viability compared to control assays was observed when the tested compounds were incubated with Hep2G cells or bovine liver cells at concentrations up to 2 mM for 24 hours or with Hep2G cells at concentrations up to 20 µM for 72 hours. None of the five tested compounds inhibited the ability of the ABCG2 transporter to transport the fluorescent substrate at concentrations up to 2 mM. Furthermore, no inhibition of CYP3A4 activity (measured as N-demethylation of erythromycin) was observed for CHB up to 2 mM. Conclusion: This study suggests that under these conditions, the selected nitrile or epinitrile derivatives of glucosinolates are not hepatotoxic in vitro.
... Liver disease and photosensitisation in cattle grazing brassica forage crops, especially turnips (Brassica rapa ssp. rapa), have been previously described [1]. The disease associated with the consumption of swedes (rutabaga, B. napus ssp. ...
... Brassica spp. are known to contain a large variety of specialised metabolites, with the principal ones being the sulphur-containing glucosinolates (GSLs) [1]. GSLs (mustard oil glucosides) are stable, nontoxic compounds that are found in all plant tissues of Brassica spp. ...
Article
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Cattle occasionally develop brassica-associated liver disease (BALD) and photosensitisation when grazing turnip or swede (Brassica spp.) forage crops. The liver toxin in these brassica varieties has yet to be discovered. Progoitrin is the dominant glucosinolate in incriminated crops. Apart from goitrin, progoitrin hydrolysis yields the nitrile, 1-cyano-2-hydroxy-3-butene (CHB), and the epithionitrile, 1-cyano-2-hydroxy-3,4-epithiobutane (CHEB). The two compounds were custom-synthesised. In a small pilot trial, New Zealand White rabbits were given either CHB or CHEB by gavage. Single doses of 0.75 mmol/kg of CHB or 0.25 mmol/kg of CHEB were subtoxic and elicited subclinical effects. Higher doses were severely hepatotoxic, causing periportal to massive hepatic necrosis associated with markedly elevated serum liver biomarkers often resulting in severe illness or death within 24 h. The possibility that one or both of these hepatotoxic nitriles causes BALD in cattle requires further investigation.
... rapa ssp. rapa), has been described (Collett and Matthews, 2014). The disease associated with swede consumption appears to be the same as that caused by turnips, hence we refer to the condition as brassica-associated liver disease (BALD). ...
... Brassica spp. are known to contain a large variety of secondary compounds, with the principal ones being the sulphur-containing glucosinolates (GSLs) (Collett and Matthews, 2014). Nearly 130 unique GSLs have been discovered so far. ...
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A large outbreak of liver toxicity in dairy cows that were consuming swede (rutabaga, Brassica napus ssp. napobrassica) crops in Southland and Otago, New Zealand in 2014 prompted the search for the toxin(s) responsible for brassica-associated liver disease (BALD). Analysis of swede plant material showed that the ultra-dominant glucosinolate was progoitrin. The two nitrile derivatives of progoitrin, 1-cyano-2-hydroxy-3-butene (CHB, also known as crambene) and 1-cyano-2-hydroxy-3,4-epithiobutane (CHEB), were custom-synthesised. In this pilot trial, individual progoitrin nitriles were administered by gavage to rats in order to establish a “subtoxic” dose, i.e. the dose where apparently clinically normal rats show liver injury based on altered serum biochemical indicators and histological lesions. We found that consecutive daily doses of 1 mmol/kg CHB produced severe pancreatic and mild liver histological lesions in the absence of notable biochemical changes in clinically normal rats. No evidence of a cumulative effect was seen. Single doses of 1 mmol/kg of CHEB caused elevated concentrations of serum creatinine and distinctive renal and stomach histological lesions in apparently clinically normal rats. Consecutive daily 1 mmol/kg doses of CHEB had a considerable cumulative effect and proved severely hepato- and nephrotoxic with creatinine concentrations peaking after three daily doses. Three other commercially available nitriles (3-butenenitrile, 4-pentenenitrile and 5-hexenenitrile) derived from minor glucosinolates in the swedes were also investigated in this pilot trial. Single combined 1 mmol/kg doses of both progoitrin nitriles as well as these two nitriles plus small doses of the other three failed to demonstrate any synergism, however, the characteristic and apparently dominant effects of CHEB were consistently demonstrated. The results of this pilot study confirmed the previously reported pancreatotoxicity of CHB and nephrotoxicity of CHEB. CHEB also caused intraepithelial pustules, submucosal oedema, erosions and ulcers in the squamous portion of the stomach. These stomach lesions, as well as the renal lesions, appear identical to those caused by another epithionitrile, 1-cyano-3,4-epithiobutane, derived from gluconapin, which was a minor glucosinolate in the swedes. Because of the fact that cyanide can be released with the metabolism of some nitriles, we analysed cyanide in the livers of treated rats. The liver of a rat dosed with 1 mmol/kg of 3-butenenitrile contained 0.5 μg/g of cyanide. The hypothesis that BALD is due to nitrile toxicity requires further testing. Keywords: Brassica-associated liver disease, Progoitrin, 1-Cyano-2-hydroxy-3-butene, 1-Cyano-2-hydroxy-3,4-epithiobutane, Toxicity in rats
... Esto ha hecho posible la observación de casos frecuentes de fotosensibilización hepatógena a causa de las lesiones hepáticas provocadas por F. hepatica. Los signos clínicos que presentaron los animales de este estudio, correspondieron a un cuadro de fotosensibilización, tales como: desprendimiento de la piel del morro y párpados, edema alrededor de los ojos, lagrimeo bilateral, movimiento de cabeza, fotofobia (Collett y Matthews, 2014). Estos signos de fotosensibilización se podrían atribuir al acúmulo de filoeritrina (producto de la metabolización de la clorofila), causada por la estasis biliar provocada por la colangitis y obstrucción biliar que producen las lesiones crónicas de F. hepatica (Perusia y Rodriguez, 2017;Cardona et al., 2015;Olaechea et al., 2011;Smith et al., 1997). ...
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Veterinaria (Montevideo) Volumen 56 Nº 214 (2020 Jul-Dic) e20205621403 Bovine hepatogenic photosensitization can be caused by several causes, such as hepatocellular damage due to by Fasciola he-patica. Hepatogenic photodermatitis is one of the clinical signs that can be observed in chronic fasciolasis, caused by hepatic fibrosis and cholangitis with bile stasis. The objective of this work was to describe two outbreaks of hepathogenic photosen-sitization in cattle in the counties of Tacuarembó and Soriano (Uruguay). The disease affected a herd of Hereford and crossbreed cows and a herd of crossbreed heifers. In both outbreaks the animals grazed in damp forest fields. The main clinical signs observed were weight loss, scabs and peeling on the snout, pho-tophobia, hypersalivation and ocular bleeding. In all necropsies performed, the relevant macroscopic findings were bilateral ne-crotic dermatitis of the eyelids, ulcers on the ventral surface of the tongue. In the liver, there was thickening of the Glisson's capsule, diffuse fibrosis, and chronic cholangitis with calcifica-tion of the bile canaliculi. Histopathologically the main lesion was liver fibrosis and canalicular obstruction with the presence of F. hepatica. Based on the clinical signs, macro and microscopic findings, the photosensitization observed in the animals of both outbreaks was directly related to the chronic liver alterations caused by F. hepatica.
... For one animal, these were the only dietary species observed in the scat and in four others, they exceeded 80%. Excessive intake of glucosinolates has been associated with several health problems in livestock, notably including reduced feed intake and growth, hepatic lesions (bile duct hyperplasia, megalocytosis, zonal hepatocyte necrosis, and hepatic fibrosis), photosensitivity and anemia [44,45]. All wombats examined from Portee showed signs of severe weight loss, alopecia and changes in hair color and quality. ...
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Habitat degradation and summer droughts severely restrict feeding options for the endangered southern hairy-nosed wombat (SHNW; Lasiorhinus latifrons). We reconstructed SHNW summer diets by DNA metabarcoding from feces. We initially validated rbcL and ndhJ diet reconstructions using autopsied and captive animals. Subsequent diet reconstructions of wild wombats broadly reflected vegetative ground cover, implying local rather than long-range foraging. Diets were all dominated by alien invasives. Chemical analysis of alien food revealed Carrichtera annua contains high levels of glucosinolates. Clinical examination (7 animals) and autopsy (12 animals) revealed that the most degraded site also contained most individuals showing signs of glucosinolate poisoning. We infer that dietary poisoning through the ingestion of alien invasives may have contributed to the recent population crashes in the region. In floristically diverse sites, individuals appear to be able to manage glucosinolate intake by avoidance or episodic feeding but this strategy is less tractable in the most degraded sites. We conclude that recovery of the most affected populations may require effective Carrichtera management and interim supplementary feeding. More generally, we argue that protection against population decline by poisoning in territorial herbivores requires knowledge of their diet and of those food plants containing toxic principles.
Article
Case history: : Fifteen lambs from a flock of 1000, 5-month-old Romney lambs in the Manawatū region of New Zealand, developed unusual postural and gait abnormalities during the Summer of 2020. In mid-January, the lambs were grazing a raphanobrassica crop (xRaphanobrassica; Brassica oleracea x Raphanus sativus) but were removed from this crop soon after as they developed dermal lesions on the pinnae consistent with photosensitisation (colloquially known as 'rape scald'). The lambs were placed onto a shaded paddock containing a pasture of predominantly perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). One week following removal from the crop (late January), the 15 lambs developed abnormal postures and gaits that were described by farm staff as 'neurological' and 'swayback-like'. Clinical findings: : From a distance, all 15 lambs exhibited remarkably similar abnormal posture and gait whereby their weight was borne on their carpi, and they appeared to crawl while walking due to crouched hindquarters and prominent lordosis. Of the affected lambs, five were submitted for clinical examination. All five had normal vital signs. The results of neurological examinations were within normal limits. In response to palpation of the dorsum, the lambs performed an exaggerated and unusual dipping motion, particularly when pressure was applied over the lumbar spine. Parting of the fleece over the dorsum revealed thickened, indurated skin that cracked and tore easily. Pathological findings: : The shorn pelt of a euthanised lamb revealed a large (100 cm x 40 cm), locally extensive, irregular ovoid region of the skin of the dorsum that was markedly thickened, indurated and crusted. Impression smears of the lesions revealed long filamentous chains of plump coccoid bacteria separated by transverse and longitudinal septa, consistent with Dermatophilus congolensis. Histopathology of the lesions revealed severe, chronic-active, locally extensive, necrosuppurative dermatitis with marked acanthosis, orthokeratotic and parakeratotic hyperkeratosis, ulceration, filamentous bacteria and coccoid zoospores. Diagnosis: : Cutaneous dermatophilosis due to Dermatophilus congolensis. Clinical relevance: : Painful dermal lesions due to severe dermatophilosis of the dorsal skin of sheep are capable of causing postural and gait abnormalities that may be misinterpreted as neurological signs. Such dermal lesions may be concealed by an apparently normal fleece.
Preprint
Cattle occasionally develop brassica-associated liver disease (BALD) and photosensitisation when grazing turnip or swede (Brassica spp.) forage crops. The liver toxin in these brassica varieties has yet to be discovered. Progoitrin is the dominant glucosinolate in incriminated crops. Apart from goitrin, progoitrin hydrolysis yields the nitrile, 1-cyano-2-hydroxy-3-butene (CHB), and the epithionitrile, 1-cyano-2-hydroxy-3,4-epithiobutane (CHEB). The two compounds were custom-synthesised. In a small pilot trial, New Zealand White rabbits were given either CHB or CHEB by gavage. Single doses of 0.75 mmol/kg of CHB or 0.25 mmol/kg of CHEB were subtoxic and elicited subclinical effects. Higher doses were severely hepatotoxic causing periportal to massive hepatic necrosis associated with markedly elevated serum liver biomarkers often resulting in severe illness or death within 24 h. The possibility that one or both of these hepatotoxic nitriles causes BALD in cattle requires further investigation.
Article
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Glucosinolates with Brassica genus as secondary metabolites have a lot of functions and effects. Glucosinolates form less than 2% of the overall sulphur content at the beginning of vegetation in different parts of the plants and during growth their content is decreasing and forms less than 0.1%. This low representation doubts their storage function. With its chemical composition, they are ranked among natural pesticides with active and passive resistance against diseases and pests. They show repellent effects and properties of natural biofumigators in soil after ploughing in their biomass as green fertilizing, or after ploughing in after harvest the leftovers of rape. The principle of these effects is decomposition products of glucosinolates - bioactive isothiocyanates. Very important from this point of view are turnip rape Rex and Brassica juncea, whose content of these compounds is the highest one and they are resistant against the attack of Ceutorrhynchus pleurostigma. The same effect showed also when attacked by Phoma lingam. With other winter Brassicas either hybrid or linea and summer rape is this defensive system suppressed because of their lowered content due to breeding interferences, leading to limitation of their anti-nutritional negative effects. It is possible to state the final result after finding out the production of the above matter, roots, and after evaluation of the sorbal characteristics of the soil and evaluation of the state of health of the following crop or vegetable. After this overall analysis, it will be possible to evaluate the biofumigation properties of accessible varieties of the Brassica genus.
Conference Paper
Forage brassicas are a group of annual crops commonly grown as a feed source for ruminants in temperate regions around the world. Swedes, forage rape, kale, turnips and raphanobrassica are grazed in situ, delivering a valuable feed source. Animal health challenges may occasionally necessitate the involvement of the veterinarian. This paper backgrounds the agronomy and farm systems placement for forage brassicas and outlines a diagnostic approach for veterinarians involved in treating and preventing cases of brassica-associated disease and poor performance by sheep, cattle and deer grazing forage brassicas.
Article
Twenty-nine cultivars of turnip [Brassica campestris L. ssp. rapifera (Metzg.) Sinsk.] and twelve of rutabaga [Brassica napus L. ssp. rapifera (Metzg.) Sinsk.] were analyzed for fourteen glucosinolates. Major glucosinolates in turnip roots are 2-hydroxy-3-butenyl, 2-phenylethyl, and 3-indolylmethyl glucosinolates; in rutabaga roots there are these three plus 4-(methylthio)butyl glucosinolate. Only a few small turnips show a negative correlation between glucosinolate concentration and root weight. Whereas the amounts of individual glucosinolates within a cultivar fluctuated from year to year, there was little change in the relative proportions of these glucosinolates. Both 4-(methylthio)butyl and 5-(methylthio)pentyl glucosinolates are lower in peelings and tops (above-ground parts) of turnips than in peeled roots, whereas 3-butenyl and total glucosinolates were higher. However, 2-phenylethyl and 3-indolylmethyl glucosinolates are concentrated in turnip peelings. Other glucosinolate distributions within the plant are also discussed.