Sulfur-associated polioencephalomalacia in cattle grazing plants in the Family Brassicaceae

Transient methemoglobinemia suspected secondary to ingestion of Brassica species in a dog

This case report describes methemoglobinemia in a dog suspected to be the result of consumption of a large volume of fermented bok choy. The patient presented with clinical signs and co-oximetry consistent with methemoglobinemia without ingestion of a known toxin. A large volume of fermented bok choy had been ingested earlier that day and decontamination procedures were performed as a result. Supportive care led to resolution of clinical signs and appropriate clearance of methemoglobin. While erythrocyte oxidant damage is a consequence of ingestion of plants in the genus Brassica (such as bok choy) in ruminant species due to rumen microbiota producing sulfur-containing compounds, specifically dimethyl disulfide, there are potential pathways that can lead to similar effects in monogastric animals. The methemoglobin formation in this patient may have resulted from the large volume consumed with the natural fermentation releasing dimethyl disulfide and leading to oxidant damage analogous with that in ruminants. This case report provides additional mechanisms for methemoglobin formation in dogs and to direct the clinician toward methemoglobinemia in patients with compatible clinical signs with ingestion of specific plant species.

Forages and pastures symposium: cover crops in livestock production: whole-system approach. Can cover crops pull double duty: conservation and profitable forage production in the Midwestern United States?

Data from a recent survey suggest that the major reasons Nebraska farmers plant cover crops are to improve soil organic matter, reduce erosion, improve soil water holding capacity, produce forage, and increase soil microbial biomass. Many of these benefits appear to be positively correlated with production of above-ground biomass. Thus, selecting species that will produce the greatest biomass should be beneficial for both soil conservation and forage production. Furthermore, the limited data available suggest that grazing of cover crops does not have large negative crop production, soil, or environmental impact. In the Midwestern United States, the production window following wheat harvest, male row destruction in seed corn, and to a lesser extent following corn silage harvest is long enough to produce 2,500 to 4,500 kg DM per hectare of high-nutritive value, fall forage. In the past 4 yr, we have conducted eight trials using predominantly oats and brassicas planted in mid- to late-August. Forage nutritive value of oats and brassicas is extremely high in early November (70% to 80% IVDMD; 14% to 23% CP) and remains high through December with only a 4% to 7% unit decrease in IVDMD and no change in CP concentration. Thus, it appears that delayed grazing could be an option to maximize potential forage yield. Fall-weaned calves (200 to 290 kg BW) grazing oats with or without brassicas in November and December (48 to 64 d) at stocking rates of 2.5 to 4.0 calves per hectare have ADG between 0.60 and 1.10 kg. The cost of gain has ranged from $0.53 to $2.08/kg when accounting for seed costs plus establishment ($60 to 117/ha), N plus application ($0 to 58/ha), fencing ($11/ha) and yardage ($0.10 calf-1 d-1). Although soybeans and corn harvested for grain do not provide a large enough growing window to accomplish fall grazing, similar dual purpose cover crop practices are often accomplished by planting winter-hardy small grain cereal grasses, such as cereal rye or winter triticale in the fall and grazing in the spring. However, traditional planting dates for corn and soybean result in a 30 to 45 d grazing period prior to corn and a 45 to 60 d period prior to soybean planting. Planting cover crops to provide late fall or early spring grazing has potential. However, incorporating forage production from cover crops into current cropping systems greatly increases the need for timeliness of management since the window of opportunity for forage production is quite narrow.

Discrimination between Synthetically Administered and Endogenous Thiouracil Based on Monitoring of Urine, Muscle, and Thyroid Tissue: An in Vivo Study in Young and Adult Bovines

Thiouracil (TU), synthesized for its thyroid-regulating capacities and alternatively misused in livestock for its weight-gaining effects, is acknowledged to have an endogenous origin. Discrimination between low-level abuse and endogenous occurrence is challenging and unexplored in an experimental setting. Therefore, cows (n = 16) and calves (n = 18) were subjected to a rapeseed-supplemented diet or treated with synthetic TU. Significant higher urinary TU levels were recorded after TU administration (<CC_α, 15 642 μg L^-1) compared to rapeseed supplementation (<CC_α, 65.8 μg L^-1), however, with overlapping values. TU was not detected in the edible meat; however, concentrations between the CC_α and 10 μg kg^-1 were noted in thyroid tissue of calves and cows following rapeseed supplementation. The latter concentrations were significantly higher in thyroid tissue of calves (22.9-41.8 μg kg^-1) and cows (16.9-36.7 μg kg^-1) after synthetic TU administration. These results strongly point toward thyroid analysis as a discriminatory tool.

Retrospective study of cattle poisonings in California: recognition, diagnosis, and treatment

In this retrospective study all suspect bovine intoxications submitted to the California Animal Health and Food Safety Laboratory between January 1, 2000 and December 31, 2011 were reviewed. A total of 1199 cases were submitted, but a diagnosis of intoxication was only established in 13.5% of cases. In these cases, overexposures to minerals, metals, and poisonous plants were determined as the most commonly diagnosed poisonings in cattle in California. Nitrate/nitrite poisoning was the most commonly diagnosed plant-associated intoxication, followed by gossypol and oleander. This study details the diagnostic challenges and treatment options for the most commonly diagnosed intoxications. To ensure proper treatment and prevention of new cases, accurate diagnosis is necessary, and therefore this review provides an essential tool for the food animal practitioner. Available toxicological analyses are offered at select laboratories, which can be time consuming and expensive, yet the potential for residues in consumed animal products and implications for human health necessitate testing and consultation. Any potential exposure to a toxicant in cattle should be reviewed to determine whether a residue hazard exists. Therapy focuses on immediate removal of the toxicant from the environment and from the gastrointestinal tract. With few antidotes available, most are cost prohibitive to treat numerous affected cattle. In addition, most antidotes will require extra-label drug use and establishment of meat and milk withdrawal times.

Effects of high-sulphur water on hepatic gene expression of steers fed fibre-based diets

Sulphur-induced polioencephalomalacia (sPEM), a neurological disorder affecting ruminants, is frequently associated with the consumption of high-sulphur (S) water and subsequent poor performance. Currently, there is no economical method for S removal from surface water sources, and alternative water sources are typically neither readily available nor cost-effective. Determination of genes differentially expressed in response to high-S water consumption may provide a better understanding of the physiology corresponding to high dietary S and ultimately lead to the development of treatment and prevention strategies. The objective of this study was to determine changes in gene expression in the liver, an organ important for S metabolism, of fibre-fed steers consuming high-S water. For this study, liver tissues were collected on the final day of a trial from yearling steers randomly assigned to low-S water control (566 mg/kg SO4 ; n = 24), high-S water (3651 mg/kg SO4 ; n = 24) or high-S water plus clinoptilolite supplemented at either 2.5% (n = 24) or 5.0% (n = 24) of diet dry matter (DM). Microarray analyses on randomly selected healthy low-S control (n = 4) and high-S (n = 4; no clinoptilolite) steers using the Affymetrix GeneChip Bovine Genome Array revealed 488 genes upregulated (p < 0.05) and 154 genes downregulated (p < 0.05) in response to the high- vs. low-S water consumption. Real-time RT-PCR confirmed the upregulation (p < 0.10) of seven genes involved in inflammatory response and immune functions. Changes in such genes suggest that ruminant animals administered high-S water may be undergoing an inflammation or immune response, even if signs of sPEM or compromised health are not readily observed. Further study of these, and other affected genes, may deliver new insights into the physiology underlying the response to high dietary S, ultimately leading to the development of treatments for high S-affected ruminant livestock.

Polioencefalomalacia experimental em bovinos induzida por toxicose por enxofre

O presente trabalho teve como objetivos avaliar os sinais clínicos, as concentrações do sulfeto de hidrogênio ruminal e as alterações anatomopatológicas associadas à intoxicação experimental por enxofre em bovinos. Foram utilizados dez bezerros mestiços leiteiros, sendo que quatro bovinos ingeriram ração sem sulfato de sódio (G1) e seis consumiram ração com sulfato de sódio (G2). Exames clínicos (temperatura retal, frequência cardíaca e respiratória e motricidade ruminal) e laboratoriais (hemograma, fibrinogênio, proteína plasmática, pH do fluido ruminal, concentração do sulfeto de hidrogênio ruminal, líquido cerebrospinal e histopatológico) foram realizados. A temperatura retal, frequência cardíaca, hemograma, fibrinogênio, proteína plasmática, pH do fluido ruminal e os valores do líquido cerebrospinal estavam dentro dos valores de referência para a espécie. Taquipnéia, hipomotricidade ruminal e elevados valores de sulfeto de hidrogênio ruminal foram observados nos bezerros do grupo G2. Um bezerro do grupo G2 apresentou sinais neurológicos e lesões histopatológicas de PEM. Dois animais de cada grupo foram eutanasiados. Lesões microscópicas foram observadas nos bezerros do G2. Histologicamente as alterações observadas foram necrose neuronal cortical e lesões hemorrágicas nos núcleos basais, tálamo, mesencéfalo, ponte e bulbo. O protocolo experimental constituído por uma dieta rica em carboidrato de alta fermentação, baixa quantidade de fibra efetiva e altos níveis de enxofre (0,52%) ocasionou alterações clinicas e histológicas e elevadas concentrações de sulfeto de hidrogênio ruminal compatíveis com quadro de intoxicação por enxofre.

Polioencefalomalacia em ruminantes

Polioencefalomalacia (PEM) de ruminantes é uma doença complexa. O termo indica um diagnóstico morfológico em que necrose neuronal grave resulta em amolecimento da substância cinzenta do cérebro. Interpretada no início como uma doença única, causada por deficiência de tiamina, acredita-se hoje que várias causas e diferentes mecanismos patogênicos, ou um único mecanismo patogênico disparado por diferentes agentes, sejam responsáveis pelo aparecimento da doença. Neste artigo, as possíveis causas e a patogênese de PEM em ruminantes são criticamente revisadas e discutidas. Também são revisadas a epidemiologia, os sinais clínicos, os achados macro e microscópicos e os métodos de diagnóstico, tratamento e controle.