Mini review on photosensitization by plants in grazing herbivores

Hepatogenic photosensitization in lambs supplemented with different levels of extruded urea in Brachiaria spp. pastures in the Brazilian Cerrado: Case report

The aim was to report cases and risk factors for hepatogenous photosensitization in lambs kept on Brachiaria spp. pastures and supplemented with levels of extruded urea (EU). The herd consisted of 69 Texel crossbred lambs with known parentage (fathers and mothers adapted to the consumption of forage of the genus Brachiaria), randomly divided into 5 groups and distributed in individual paddocks for each group. The animals were supplemented with increasing levels of EU (Amireia® 200S): 0, 6, 12, 18, and 24 g of EU per 100 kg-1 of body weight (BW). The concentration of protodioscin was estimated in the mixed pastures of Brachiaria spp. (cv. Marandu and cv. Basilisk), structural components (leaf, stem, and dead material), samples of each cultivar, and in the months of December (2018), February, and April (2019). The animals were examined daily, and when behavioral changes were identified, they underwent clinical examinations and anamnesis. Weighing was performed every 14 days, followed by necropsy and serum biochemical analysis, including gamma-glutamyltransferase (GGT). The highest concentrations of protodioscin (p < 0.0001) were found in the pastures used by animals supplemented without extruded urea (7.07 ± 0.56), in the Basilisk cultivar (11.35 ± 0.06), in the leaf blade components (2.08 ± 0.05), and thatch (2.20 ± 0.00), and in the month of April (7.34 ± 0.29) (the month with the lowest rainfall), respectively. Fourteen (20.29%) cases of photosensitization were observed in lambs, of which six recovered, and eight died. Serum GGT levels ranged from 42.2 to 225 IU/L; however, in animals that died, values ranged from 209.4 to 225 IU/L. The use of levels 12 g and 18 g per 100 kg-1 of body weight of extruded urea may contribute to the lower occurrence of photosensitization, as the animals selected pastures with lower protodioscin content, presenting a smaller number of cases.

Thermoregulatory response of black or red lactating Holstein cows in the hot and cold season in southern Brazil

Dairy cows in pasture-based systems are more susceptible to heat stress. Holstein cows have the black or red phenotypes, the latter having lower absorbance of solar radiation. Therefore, the study's objective was to evaluate whether cows with red (R) coats are more resistant than black (B) cows to hot weather in a subtropical climate. R and B lactating Holstein cows were evaluated during the cold and hot seasons for internal and surface temperature and sweating rate. In the cold season, body temperature (n = 9/group) did not differ between groups, but the average superficial temperature (n = 13/group) was lower in R cows (B: 30.9 ± 0.3 °C; RW: 29.6 ± 0.3 °C; p = 0.02). In the hot season, under mild to moderate heat stress, mean body temperature (n = 9/group) of R cows was lower (B: 38.75 ± 0.01 °C; R: 38.62 ± 0.1 °C; p=<0.0001), whereas no difference was observed in superficial temperature (n = 17/group). The maximum internal temperature and sweating rate (n = 11/group), measured in the hot season, and the number of evaluations in hyperthermia in both seasons did not differ. Therefore, there were differences in thermoregulation between phenotypes under mild to moderate heat stress conditions. However, considering that only discrete differences were observed, the red and white coat is unlikely to benefit the Holstein cow's welfare under mild to moderate thermal stress.

Evaluation of photocytotoxicity liposomal form of furanocoumarins Sosnowsky's hogweed

Sosnovsky's hogweed, Heracleum sosnowskyi has a high photosensitizing ability. Although Sosnovsky's hogweed is known as a poisonous plant, its chemical composition and phototoxicity are poorly studied. We analyzed the chemical composition of the Sosnovsky's hogweed juice that grew in natural conditions. It was found that the content of 8-methoxypsoralen in the juice is 1332.7 mg/L, and that of 5-methoxypsoralen is 34.2 mg/L. We have developed and analyzed liposomes containing furanocoumarins of Sosnovsky's hogweed juice and studied their photocytotoxicity in L929 mouse fibroblast cell culture. It was found that liposomes containing furanocoumarins of Sosnovsky's hogweed juice are more toxic for L929 cells in comparison with liposomal forms of pure substances 8-methoxypsoralen and 5-methoxypsoralen. It was found that when exposed to UV radiation at 365 nm at a dose of 22.2 J/cm², the liposomal form of furanocoumarins Sosnovsky's hogweed is 3 times more toxic to L929 cells than in the dark. It was found that the photocytotoxic effect of liposomal furanocoumarins Sosnovsky's hogweed is a strongly stimulation of apoptosis.The data obtained suggest that the raw material of Sosnovsky's hogweed claims to be a source of furanocoumarins, and the liposomal form, given the hydrophobic properties of furanocoumarins, is very suitable for creating a phototherapeutic drug.

Horses' rejection behaviour towards the presence of Senecio jacobaea L. in hay

BACKGROUND

Senecio jacobaea contains pyrrolizidine alkaloids that can induce severe hepatic intoxication in horses, either acute when ingested in high amounts or chronic when consumed over a long period. The aim of this study was to determine horses' rejection behaviour towards the presence of Senecio jacobaea in hay when fed ad libitum. We hypothesized that adult horses can sort Senecio jacobaea out of the contaminated hay when hay is fed ad libitum. Six warmblood geldings with a mean (±SD) age of 15 ± 2 years were included. In a randomized study, Senecio jacobaea contaminated hay (5% or 10% contamination level) was provided at several timepoints over the day for 1 hour to six. Hay was provided ad libitum for the rest of the day. The horses' rejection behaviour towards Senecio jacobaea was observed. If a horse ingested two Senecio jacobaea plants twice at different timepoints, then the horse was excluded from the experiment.

RESULTS

Two out of six horses had to be excluded from the study after three out of 12 observation periods due to repeated Senecio jacobaea intake. Two other horses had to be excluded after nine and 11 out of 12 observation periods. Only two horses were able to sort out the various amounts (5 and 10% contamination level) of Senecio jacobaea during the whole experiment.

CONCLUSIONS

Horses' intake of Senecio jacobaea cannot be avoided despite being fed with hay ad libitum. Due to the risk of chronic intoxication by pyrrolizidine alkaloids intake, feeding Senecio jacobaea contaminated hay must be avoided, and pastures with Senecio jacobaea growth are considered inappropriate for feed production.

Minimal Erythema Dose Determination in Holstein Friesian Cattle

Cattle on pasture are continuously exposed to solar UV radiation, which has been associated with biological effects such as sunburn, photosensitization, squamous cell carcinoma, and cutaneous vitamin D₃ production. The minimal erythema dose (MED) required to produce first-degree sunburn (erythema) is poorly researched in cattle. Since cattle are naturally covered with dense hair coats, the MED is influenced by the UV protection offered by the hair. The objective of this study was to determine the MED on intact-hair-covered (MED-H) and shaved white skin (MED-S) of Holstein Friesian cattle. Twenty-one Holstein Friesian cows and heifers were MED tested using a narrowband UV-B LED light (peak irradiance at 292 nm) on eight hair-covered and eight shaved areas over white skin previously unexposed to direct sunlight. Erythema was visually assessed after 24 h. The mean MED-H and MED-S were 5,595 and 329 J/m², respectively. Heifers had a higher MED-H compared to cows, 7,600 and 4,969 J/m², respectively. The mean UV transmittance of white cattle hair was 6.7%. MED-H was correlated with hair length (Spearman's rho = 0.76). A linear regression model showed that each millimeter of hair coat length increased the MED-H by 316 J/m². In conclusion, this study provides a MED testing protocol for cattle and reports standardized values of MED for cattle on intact-hair-covered and shaved areas.

Removal of chlorophyll and pheophorbide from Chlorella pyrenoidosa by supercritical fluid extraction: potential of protein resource

This study tried to quantitatively clarify the usefulness of supercritical fluid extraction for removal of chlorophyll and pheophorbide from Chlorella pyrenoidosa. C. pyrenoidosa powder was subjected to supercritical fluid extraction, and chlorophyll a and pheophorbide a in its extracted fractions were measured by HPLC-UV. Chlorophyll a and pheophorbide a in residue after supercritical fluid extraction became below of detection limit.

Plant-Induced Photosensitivity and Dermatitis in Livestock

Whether poisoned by grazing certain toxic plants, by eating contaminated feed, or by topical contact with plant toxins, certain plants poison livestock causing photosensitivity and dermatitis. These dermal lesions are rarely fatal, and with appropriate therapy and protection from additional exposure most lesions heal with few permanent sequelae. However, these lesions often result in costly production losses and missed opportunities. The objectives of this review are to briefly introduce toxic plants that result in photosensitivity and dermatitis, review the toxins and pathogenesis of plant-induced skin disease, and summarize treatments and recommendations to avoid poisoning.

The aetiology, prevalence and morbidity of outbreaks of photosensitisation in livestock: A review

BACKGROUND

Photosensitisation is a clinical condition occurring in both humans and animals that causes significant injury to affected individuals. In livestock, outbreaks of photosensitisation caused by ingestion of toxic plants are relatively common and can be associated with significant economic loss.

OBJECTIVES

The agents that are most commonly implicated in outbreaks of photosensitisation have not been formally investigated on a global scale. To address this question, a systematic review of the literature was undertaken to determine the most common causative agents implicated in outbreaks of photosensitisation in livestock in Australia and globally, as well as the prevalence and morbidity of such outbreaks.

METHODS

A systematic database search was conducted to identify peer-reviewed case reports of photosensitisation in livestock published worldwide between 1900 and April 2018. Only case reports with a full abstract in English were included. Non peer-reviewed reports from Australia were also investigated. Case reports were then sorted by plant and animal species, type of photosensitisation by diagnosis, location, morbidity and mortality rate and tabulated for further analysis.

RESULTS

One hundred and sixty-six reports qualified for inclusion in this study. Outbreaks were reported in 20 countries. Australia (20), Brazil (20) and the United States (11) showed the highest number of peer-reviewed photosensitisation case reports from this analysis. Hepatogenous (Type III) photosensitisation was the most frequently reported diagnosis (68.5%) and resulted in higher morbidity. Panicum spp., Brachiaria spp. and Tribulus terrestris were identified as the most common causes of hepatogenous photosensitisation globally.

CONCLUSIONS

Hepatogenous photosensitisation in livestock represents a significant risk to livestock production, particularly in Australia, Brazil, and the United States. Management of toxic pastures and common pasture weeds may reduce the economic impact of photosensitisation both at a national and global level.