Plant Secondary Compounds Research Articles

Bacteria Contribute to Plant Secondary Compound Degradation in a Generalist Herbivore System.

Herbivores must overcome a variety of plant defenses, including coping with plant secondary compounds (PSCs). To help detoxify these defensive chemicals, several insect herbivores are known to harbor gut microbiota with the metabolic capacity to degrade PSCs. Leaf-cutter ants are generalist herbivores, obtaining sustenance from specialized fungus gardens that act as external digestive systems and which degrade the diverse collection of plants foraged by the ants. There is in vitro evidence that certain PSCs harm Leucoagaricus gongylophorus, the fungal cultivar of leaf-cutter ants, suggesting a role for the Proteobacteria-dominant bacterial community present within fungus gardens. In this study, we investigated the ability of symbiotic bacteria present within fungus gardens of leaf-cutter ants to degrade PSCs. We cultured fungus garden bacteria, sequenced the genomes of 42 isolates, and identified genes involved in PSC degradation, including genes encoding cytochrome P450 enzymes and genes in geraniol, cumate, cinnamate, and α-pinene/limonene degradation pathways. Using metatranscriptomic analysis, we showed that some of these degradation genes are expressed in situ Most of the bacterial isolates grew unhindered in the presence of PSCs and, using gas chromatography-mass spectrometry (GC-MS), we determined that isolates from the genera Bacillus, Burkholderia, Enterobacter, Klebsiella, and Pseudomonas degrade α-pinene, β-caryophyllene, or linalool. Using a headspace sampler, we show that subcolonies of fungus gardens reduced α-pinene and linalool over a 36-h period, while L. gongylophorus strains alone reduced only linalool. Overall, our results reveal that the bacterial communities in fungus gardens play a pivotal role in alleviating the effect of PSCs on the leaf-cutter ant system.IMPORTANCE Leaf-cutter ants are dominant neotropical herbivores capable of deriving energy from a wide range of plant substrates. The success of leaf-cutter ants is largely due to their external gut, composed of key microbial symbionts, specifically, the fungal mutualist L. gongylophorus and a consistent bacterial community. Both symbionts are known to have critical roles in extracting energy from plant material, yet comparatively little is known about their roles in the detoxification of plant secondary compounds. In this study, we assessed if the bacterial communities associated with leaf-cutter ant fungus gardens can degrade harmful plant chemicals. We identify plant secondary compound detoxification in leaf-cutter ant gardens as a process that depends on the degradative potential of both the bacterial community and L. gongylophorus Our findings suggest that the fungus garden and its associated microbial community influence the generalist foraging abilities of the ants, underscoring the importance of microbial symbionts in plant substrate suitability for herbivores.

Male-lure type, lure dosage, and fly age at feeding all influence male mating success in Jarvis\u2019 fruit fly

Males of certain Dacini fruit flies are strongly attracted to, and feed upon, plant secondary compounds such as methyl eugenol, raspberry ketone and zingerone. The consumed lure is generally found to induce physiological and behavioural changes that enhance the mating performance of lure-fed males. Male Bactrocera jarvisi respond strongly to zingerone from a young age, but only weakly respond to raspberry ketone. We hypothesized that this selective lure-response would be reflected in the physiological importance of the lure to the fly. We found that zingerone feeding by young males resulted in significantly greater mating success in competitive mating trials with lure-deprived flies, but the mating advantage was lost in older males. Lure dosage had a significant effect on the duration of the mating advantage, for example when fed 20 µg of zingerone, the advantage lasted only 1 day post-feeding, but when fed of 50 µg zingerone the advantage lasted 7 days. Raspberry ketone feeding did not confer any mating advantage to males except at one dosage (50 µg) for 1 day after feeding. When given a choice, B. jarvisi females preferred to mate with zingerone-fed versus to raspberry ketone-fed males. This study revealed lure, dosage and age of fly at time of lure administration are all important factors for maximising lure-enhanced fruit fly mating performance. These findings contribute to a better theoretical understanding of the evolution of fruit fly-lure interactions and may help improve fruit fly pest management via the Sterile Insect Technique through semiochemical-mediated enhancement of sterile male mating performance.

Enterotypes of the Gut Microbial Community and Their Response to Plant Secondary Compounds in Plateau Pikas.

Animal gut microbiomes can be clustered into “enterotypes” characterized by an abundance of signature genera. The characteristic determinants, stability, and resilience of these community clusters remain poorly understood. We used plateau pika (Ochotona curzoniae) as a model and identified three enterotypes by 16S rDNA sequencing. Among the top 15 genera, 13 showed significantly different levels of abundance between the enterotypes combined with different microbial functions and distinct fecal short-chain fatty acids. We monitored changes in the microbial community associated with the transfer of plateau pikas from field to laboratory and observed that feeding them a single diet reduced microbial diversity, resulting in a single enterotype with an altered composition of the dominant bacteria. However, microbial diversity, an abundance of some changed dominant genera, and enterotypes were partially restored after adding swainsonine (a plant secondary compound found in the natural diet of plateau pikas) to the feed. These results provide strong evidence that gut microbial diversity and enterotypes are directly related to specific diet, thereby indicating that the formation of different enterotypes can help animals adapt to complex food conditions. Additionally, natural plant secondary compounds can maintain dominant bacteria and inter-individual differences of gut microbiota and promote the resilience of enterotypes in small herbivorous mammals.

Dragon fruit (Hylocereus undatus) peel pellet as a rumen enhancer in Holstein crossbred bulls.

ObjectiveAn experiment was conducted to assess the effect of dragon fruit peel pellet (DFPP) as a rumen enhancer of dry matter consumption, nutrient digestibilities, ruminal ecology, microbial protein synthesis and rumimal methane production in Holstein crossbred bulls.MethodsFour animals, with an average live-weight of 200±20 kg were randomly assigned in a 4×4 Latin square design to investigate the influence of DFPP supplementation. There were four different dietary treatments: without DFPP, and with 200, 300, and 400 g/h/d, respectively.ResultsResults revealed that dry matter consumption of total intake, rice straw and concentrate were not significantly different among treatments (p>0.05). It was also found that ruminal pH was not different among treatments (p>0.05), whilst protozoal group was reduced when DFPP increased (p<0.01). Blood urea nitrogen and NH3-N concentrations were increased at 400 g of DFPP supplementation (p<0.01). Additionally, volatile fatty acid production of propionate was significantly enhanced by the DFPP supplementation (p<0.05), while production of methane was consequently decreased (p<0.05). Furthermore, microbial protein synthesis and urinary purine derivatives were remarkably increased especially at 400 g of DFPP supplementation (p<0.05).ConclusionPlant secondary compounds or phytonutrients (PTN) containing saponins (SP) and condensed tannins (CT) have been reported to influence rumen fermentation. DFPP contains both CT and SP as a PTN. The addition of 400 g of DFPP resulted in improved rumen fermentation end-products especially propionate (C3) and microbial protein synthesis. Therefore, DFPP is a promising rumen enhancer and indicated a significant potential of DFPP as feedstuff for ruminant feed to mitigate rumen methane production.

In vitro digestibility of mountain-grown irrigated perennial legume, grass and forb forages is influenced by elevated non-fibrous carbohydrates and plant secondary compounds.

Perennial legumes cultivated under irrigation in the Mountain West USA have non-fibrous carbohydrate (NFC) concentrations exceeding 400 g kg-1 , a level commonly found in concentrate-based ruminant diets. Our objective was to determine the influence of NFC concentration and plant secondary compounds on in vitro rumen digestion of grass, legume and forb forages compared with digestion of their isolated neutral detergent fiber (NDF) fraction. Forages were composited from ungrazed paddocks of rotationally stocked, irrigated monoculture pastures between May and August 2016, frozen in the field, freeze-dried, and ground. The maximum rate (RMax ) of gas production was greater for the legumes alfalfa (ALF; Medicago sativa L.) and birdsfoot trefoil (BFT; Lotus corniculatus L.) than for the legume cicer milkvetch (CMV; Astragalus cicer L.) the grass meadow brome (MBG; Bromus riparius Rehm.) and the non-legume forb small burnet (SMB; Sanguisorba minor Scop.), and intermediate for the legume sainfoin (SNF; Onobrychis viciifolia Scop.). The RMax of isolated NDF was greatest for BFT and CMV, intermediate for ALF, SNF and SMB and least for MBG. More than 900 g of organic matter kg-1 dry matter of legumes was digested after 96 h. Across forages, the extent of whole-plant digestion increased with NFC and crude protein concentrations, decreased with NDF concentrations, and was modulated by secondary compounds. The extent of digestion of isolated NDF decreased with concentration of lignin and residual tannins. © 2020 Society of Chemical Industry.

Sheep and Goats Respond Differently to Feeding Strategies Directed to Improve the Fatty Acid Profile of Milk Fat.

Simple SummarySheep and goat milk, as well as dairy products, are considered good sources of high-quality nutrients, particularly proteins and fats. Many positive effects on human health have been attributed to the consumption of dairy containing specific fatty acids, including some compounds originating from the polyunsaturated FA (PUFA) biohydrogenation operated by rumen microbes. In this bibliographic review, several nutritional strategies able to improve the milk fatty acids (FA) profile, in terms of an increase in the concentration of fatty acids considered beneficial to human health, are presented and discussed, with special attention to the differences between the two species.This bibliographic review presents and discusses the nutritional strategies able to increase the concentration of beneficial fatty acids (FA) in sheep and goat milk, and dairy products, with a particular focus on the polyunsaturated FA (PUFA), and highlights differences between the two species. In fact, by adopting appropriate feeding strategies, it is possible to markedly vary the concentration of fat in milk and improve its FA composition. These strategies are based mostly on the utilization of herbage rich in PUFA, or on the inclusion of vegetable, marine, or essential oils in the diet of lactating animals. Sheep respond more effectively than goats to the utilization of fresh herbage and to nutritional approaches that improve the milk concentration of c9,t11-conjugated linoleic acid (c9,t11-CLA) and α-linolenic acid. Dietary polyphenols can influence milk FA profile, reducing or inhibiting the activity and growth of some strains of rumen microbes involved in the biohydrogenation of PUFA. Although the effectiveness of plant secondary compounds in improving milk FA composition is still controversial, an overall positive effect has been observed on the concentration of PUFA and RA, without marked differences between sheep and goats. On the other hand, the positive effect of dietary polyphenols on the oxidative stability of milk fat appears to be more consistent.

Selecting between iron-rich and clay-rich soils: a geophagy field experiment with black-and-white colobus monkeys in the Budongo Forest Reserve, Uganda.

Geophagy, the intentional consumption of soil, has been observed in humans and numerous other animal species. Geophagy has been posited to be adaptive, i.e., consumed soil protects against gastrointestinal distress and/or supplements micronutrients. We conducted a field experiment in the Budongo Forest, Uganda, to investigate geophagic behaviors, including soil preference, the quantity of soil eaten, and competition for access to preferred soils. We placed pairs of artificial tree stumps at two existing geophagy sites. One stump contained soil from the surrounding area, Sonso, that could supplement bioavailable iron. The other stump contained soil from a neighboring community, Waibira, that was richer in clay minerals, which could provide protection from plant secondary compounds. We monitored activity and engagement with the stumps for 10 days using camera traps. After 5 days, we reversed the type of soil that was in the stumps at both sites (i.e., a crossover design). Only Colobus guereza (black-and-white colobus monkeys) interacted with the stumps. These monkeys used visual and olfactory cues to select between the two soils and exclusively ate the clay-rich soil, consuming 9.67kg of soil over 4.33h. Our findings lend the greatest plausibility to the protection hypothesis.Additionally, monkeys competed for access to the stumps, and 13% of the videos captured aggression, including pushing, excluding, and chasing other individuals from the experimental stumps. Nine episodes of vigilance and flight behavior were also observed. Given that intentionally ingested soil is a valuable resource that may confer health benefits, geophagy sites should be conserved and protected.

UV-B absorbing and bioactive secondary compounds in lichens Xanthoria elegans and Xanthoria parietina: A review

Secondary metabolites are the bioactive compounds of plants which are synthesized during primary metabolism, have no role in the development process but are needed for defense and other special purposes. These secondary metabolites, such as flavonoids, terpenes, alkaloids, anthraquinones and carotenoids, are found in Xanthoria genus lichens. These lichens are known as lichenized fungi in the family Teloschistaceae, which grows on rock and produce bioactive compounds. A lot of secondary compounds in plants are induced by UV (100-400 nm) spectra. The present review showcases the present identified bioactive compounds in Xanthoria elegans and Xanthoria parietina lichens, which are stimulated by different amounts of UV-B light (280-320 nm), as well as the biochemistry of the UV-B absorbingcompounds.

Production of Secondary Metabolite Compounds of Gotu Kola (Centella asiatica) Under Salinity and Drought Stress

Gotu kola (Centella asiatica) is a traditional herbal plant that has been reported have a variety of pharmacological activities. The compounds of gotu kola that play a role on pharmacological activities are triterpene group compounds, namely madecasosside (MD), asiaticoside (AS), madecassic acid (AM), and asiatic acid (AA). Stress can affect the production of biomass and secondary metabolite compounds in plants. The aims of the study is to analyze the effect of salinity and drought stress on biomass and 4 compounds of triterpene in gotu kola. Harvesting is done when the plant is 8 weeks old. The yield of the biomass was analyzed and then extracted using methanol solvent to be analyzed secondary metabolite levels using the high performance liquid chromatography (HPLC) method. The lowest crop biomass was obtained at 50% of field capacity and 3,000 ppm salt content. The highest levels of MD and AS were established in conditions of 100% field capacity and 1,000 ppm salt content. The 50 and 100% field capacity and 1,000-3,000 ppm salt content did not affect the levels of AM and AA.

The effects of dissolved organic matter from a native and an invasive plant species on juvenile Daphnia survival and growth

Abstract Shifts in the composition of terrestrial plant communities could have significant effects on freshwater zooplankton due to changes in the quality of inputs of terrestrially derived dissolved organic matter (DOM). Leachate from native red maple (RM) and invasive Amur honeysuckle (AH) were used to explore the effects of DOM source on survival and growth of juvenile Daphnia ambigua. Prior research with both terrestrial and aquatic organisms indicates that AH-derived DOM has negative effects. Comparing bioassays in the presence and absence of algae with no additional DOM, RM- or AH-derived DOM, RM had stronger negative effects on both Daphnia survival and growth while AH only decreased growth. The negative effects seen in the presence and absence of algae provided evidence for both indirect and direct effects due to phytotoxicity and plant secondary compounds, respectively. DOM source may play a key role in regulating consumers in aquatic ecosystems.

A role for gut microbiota in host niche differentiation.

If gut microbes influence host behavioral ecology in the short term, over evolutionary time, they could drive host niche differentiation. We explored this possibility by comparing the gut microbiota of Madagascar's folivorous lemurs from Indriidae and Lepilemuridae. Occurring sympatrically in the eastern rainforest, our four, target species have different dietary specializations, including frugo-folivory (sifakas), young-leaf folivory (indri and woolly lemurs), and mature-leaf folivory (sportive lemurs). We collected fecal samples, from 2013 to 2017, and used amplicon sequencing, metagenomic sequencing, and nuclear magnetic resonance spectroscopy, respectively, to integrate analyses of gut microbiome structure and function with analysis of the colonic metabolome. The lemurs harbored species-specific microbiomes, metagenomes, and metabolomes that were tuned to their dietary specializations: Frugo-folivores had greater microbial and metagenomic diversity, and harbored generalist taxa. Mature-leaf folivores had greater individual microbiome variation, and taxa and metabolites putatively involved in cellulolysis. The consortia even differed between related, young-leaf specialists, with indri prioritizing metabolism of fiber and plant secondary compounds, and woolly lemurs prioritizing amino-acid cycling. Specialized gut microbiota and associated gastrointestinal morphologies enable folivores to variably tolerate resource fluctuation and support nutrient extraction from challenging resources (e.g., by metabolizing plant secondary compounds or recalcitrant fibers), perhaps ultimately facilitating host species' diversity and specialized feeding ecologies.

Tannin Supplementation in Animal Feeding; Mitigation Strategies to Overcome the Toxic Effects of Tannins on Animal Health: A Review

Optimum animal production depends on the type of feedstuffs available for the whole year. Plants such as trees and shrubs have significance in the animal production due to high nutritious values of tannins which reduce the rumen protein degradability and improve the feed digestibility as well as amino acid absorption in the small intestine. But, some of these plant materials are usually rich in anti-nutritional factors, known as tannins. Tannins are a complex group of plant secondary compounds widely distributed in the plant kingdom. Tannins have both deleterious and advantageous effects depending on the types, doses, composition and concentration of tannins. Rural farmers face fodder scarcity during the winter season. Therefore, tannins containing browse species may help farmers to use tannins as supplementary feed for livestock. But higher concentrations of tannins cause metabolic disorder which in results reduces the animal productivity. Therefore, it is need to investigate the effects of tannin supplementation in animal feeding; mitigation strategies to overcome the toxic effects of tannins on animal health. In this review paper, we have discussed safety and hazard associated with tannins in animal feeding.

Effect of dietary tannins on milk yield and composition, nitrogen partitioning and nitrogen use efficiency of lactating dairy cows: A meta-analysis.

Tannins are secondary plant compounds which have been extensively studied in order to improve the nitrogen use efficiency (NUE) of ruminants. A meta-analysis was performed of 58 in vivo experiments comparing milk yield, composition and nitrogen metabolism of lactating dairy cows fed diets with or without tannins. The meta-analysis shows that tannins have no impact on corrected milk yield, fat and protein content or NUE (p>.05). However, tannins reduce ruminal ammoniacal nitrogen (N) production by 16% (from 10.95 to 8.47mg/dl on average), milk urea by 9% (from 15.82 to 14.03mg/dl) and urinary N excretion (-11%; p<.05). This is compensated for by a lower apparent N digestibility (61.51% with dietary tannins compared to 66.17% without). The effect of tannin on N metabolism parameters increases with tannin dose (p<.05). The shift from urinary to faecal N may be beneficial for environment preservation, as urinary N induces more harmful emissions than faecal N. From a farmer's perspective, tannins seem unable to increase fat- and protein-corrected milk yield or reduce feed protein requirements and thus have no direct economic benefit. Potentially less costly than tannin extracts, forage or by-products naturally rich in tannins could still be useful to reduce the environmental impact of ruminant protein feeding.

Tannin characteristic from Hevea brasiliensis and Durio zibethinus with pressure and hot water extraction

The aim of this study was selected the best bark, temperature and pressure for extraction phenol and tannin with hot water solvent. The extract was characterised into condensed tannin and hydrolysable tannin with spectrophotometer. Tannin are plant secondary compound that influence feed metabolisme in the rumen and pasca-rumen organ. Tannin have ability to bounding feed protein and other nutrient. Tannin classified into condensed and hydrolysable tannin, condensed tannin is a bypass agent to decrease deamination and other nutrient degradation in the rumen organ, furthermore hydrolysable tannin may divide as phenol and sugar group in the rumen. Phenol group form HT may become antioxidant in the blood and influence rumen ecology. The result for this study is Hevea brasiliensis has phenol and tannin content more than Durio zibethinus with P<0.01 if using hot water extraction. Temperature significantly influence concentration of phenol and tannin content, at 120 °C phenol and tannin extract more than 70 °C with P< 0.01. Phenol extract significantly effected by pressure, 1 bar get phenol and tannin more than 2 bar with P<0.01. Treatment in this study have interaction, so generally concluded that to get phenol and tannin extract the highest used Hevea brasiliensis with temperature 120 °C and pressure 1 bar.

Geophagy in the yellow-tailed woolly monkey (Lagothrix flavicauda) at La Esperanza, Peru: site characterization and soil composition.

Geophagy is the intentional consumption of soil and has been observed in various animal taxa including human and nonhuman primates. Among the numerous adaptive hypotheses proposed to explain this behavior, two of them stand out: soil either protects the gastrointestinal tract from secondary plant compounds, parasites and pathogens, and/or supplements micronutrients in the diet. Few studies have characterized the physical and chemical characteristics of soils consumed by nonhuman primates. Here, we describe the composition of soils consumed by yellow-tailed woolly monkeys (Lagothrix flavicauda) in comparison with soils taken from surrounding areas. We also studied the physical aspects of geophagy sites in terms of accessibility, dimensions and vegetation density. This study took place at the La Esperanza field site, in northern Peru, between 2016 and 2018. We conducted focal follows, placed camera traps at geophagy sites and sampled soils. In total, we recorded 77 geophagy events. Our results highlight some aspects of soil and site selection in these arboreal primates, who face an increased predation risk when descending to the ground. Animals preferred smaller sites with denser surrounding vegetation. Composition of consumed soils was similar between geophagy sites. Soils were poor in micronutrients, but contained around 20% clay. High clay content, coupled with the fact that geophagy was performed significantly more in the dry season, when leaf consumption is highest, lends support to geophagy as a mechanism for protection of the gastrointestinal tract in L. flavicauda.

Metabolite profiling of Artemisia carvifolia Buch transgenic plants and estimation of their anticancer and antidiabetic potential

Abstract Diabetes and cancer are common diseases worldwide with terrific effect on human health. In the present study, a high valued medicinal plant Artemisia carvifolia Buch was subjected for evaluation of anticancer and antidiabetic potential. Previously produced rolB and rolC gene transgenic plants of A. carvifolia were also compared with the wild type plant for a differential count of cytotoxicity and antidiabetic activity. Lowest IC50 values were shown by rolB transgenic line TB4 for alpha-glucosidase (838.6 μg/ml), alpha-amylase (742.8 μg/ml) and dipeptidyl peptidase-4 (1300 μg/ml) in contrast to the wild type plant which showed IC50 values of 1608.4 μg/ml for alpha-glucosidase, 1973.8 μg/ml for alpha-amylase and 1800 μg/ml for dipeptidyl peptidase-4. Among rolC transgenic plants, TC1 showed lowest IC50 value i.e. 873 μg/ml for alpha-glucosidase, 747.7 μg/ml for alpha-amylase and 1400 μ/ml for dipeptidyl peptidase-4. Viability of the cancer cells including HeLA, HePG2 and MCF7 decreased to 80% when treated with methanolic extract of the plant and it decreased to 70% when treated with n-hexane extract. Cytotoxic effect was found more enhanced when cells were treated with both the extracts combined, showing synergism between flavonoids and artemisinin. RolB transformants showed slightly better activity than the rolC transformants which were found superior in activity than the wild type plant. Metabolite profiling by ESI/MS-TOF showed the involvement of significant plant secondary compounds in antidiabetic and anticancer potential in the extracts of transgenic lines. Vital amino acids, substantial phenylpropanoids and important phytochemicals were detected at a higher level in rolB and rolC transgenic plants than wild type plants.

Genomic features of the fall armyworm (Spodoptera frugiperda) (J.E. Smith) yield insights into its defense system and flight capability

AbstractThe fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) is an agriculturally important insect pest and causes significant economic loss due to its resistance to insecticide and high dispersal ability (i.e. long‐distance flyer). We performed comparative genomics analysis based on the recently released chromosome‐scale genome of the FAW to investigate the genetic mechanisms of FAWs defense system and flight ability. The gene families encoding receptors for bitter or toxic substances and detoxification enzymes, such as cytochrome P450, carboxylesterase and glutathione‐S‐transferase, were expanded in FAW, enabling its ability to detect and detoxify many plant secondary compounds. The chromosomal locations of five detoxification‐related genes (i.e. ABC, CCE, GST, P450, and UGT) were analyzed, which revealed the density of these genes across the FAW genome. Several genes like Mio, Sik2, CRTC, and Lpin were positively selected in FAW, which were associated with energy metabolism, lipid metabolism, and/or muscle development, and thus possibly contributed to the high flight ability of FAW. We also analyzed the homologs to antimicrobial genes reported in the Drosophila genome, and identified 2 attacins, 6 cecropins, 3 gloverins, and 2 moricins in FAW. The findings of this study will broadly expand our knowledge on the biology of the devastating FAW, and contribute to the development of new pest management strategies for the control of major agricultural pests like FAW.

Neuroactive nectar: compounds in nectar that interact with neurons

As well as sugars to entice pollinators, nectar contains many other chemicals including amino acids and plant secondary compounds such as phenolics, alkaloids, and glycosides. Rather than simply the byproducts of plant metabolism or contamination by compounds meant to deter herbivory, it is clear that these chemicals may have important roles in nectar. Proposed functions of non-sugar components of nectar include pollinator nutrition, reducing nectar robbing, and defense against microbes. Additionally, some of these compounds are able to interact directly with the nervous system via binding to receptor proteins found on the surface of neurons. Thus, these neuroactive components of nectar may be able to manipulate pollinator behavior. To increase our ability to analyze the many functions of nectar, it is important to understand how specific components may interact with neurons. This review examines the neurotransmitter receptors that are targets of some of the chemicals present in nectar. Although these compounds also affect the nervous systems of vertebrates, the focus of this review is on the interactions between nectar and insect pollinators.

Dose-response effects of woody and herbaceous forage plants on in vitro ruminal methane and ammonia formation, and their short-term palatability in lactating cows

Plant secondary compounds (PSC) are prevalent in many woody, temperate-climate plant species and play a crucial role in dietary attempts to mitigate methane emissions in ruminants. However, their application requires sufficient palatability and feeding value. In the present study, leaves from silver birch (Betula pendula), hazel (Corylus avellana), blackcurrant (Ribes nigrum), green grape vine (Vitis vinifera) and the herbs rosebay willow (Epilobium angustifolium) and wood avens (Geum urbanum) were tested in various doses with the Hohenheim gas test method in vitro and their short-term palatability in dairy cows. For the palatability experiment, the plants were pelleted with lucerne in different proportions to obtain the same phenol content, but realised contents differed from expected contents. The pellets were provided separately from a mixed basal ration (0.4 : 0.6) to each cow, in a randomised order, for 3 days per plant. All plants mitigated in vitro methane and ammonia formation, often in a linear dose response. These levels of effects differed among plants. Significant effects were observed at 100 (hazel, rosebay willow) to 400 g/kg of plant material. The test plants had a lower feeding value than the high-quality basal diet. This was indicated by in vitro organic matter digestibility, short-chain fatty acid formation and calculated contents of net energy of lactation. Simultaneously, the linear depression of ammonia formation indicated a dose-dependent increase of utilisable CP. Only blackcurrant and birch were less preferred to lucerne. However, this aversion subsided on day 3 of offer. The rosebay willow pellets had the highest phenol content but were not the least palatable. Accordingly, PSC may not be the main determinants of palatability for the plants tested. Plants did not differ significantly in their short-term effects on milk yield and composition, and all of the plants substantially reduced milk urea content. Overall, the results suggest that hazel and vine leaves, and rosebay willow and wood avens herbs should be tested for their potential to mitigate methane and N emissions in vivo.

Inclusion of a blend of copaiba, cashew nut shell and castor oil in the protein-energy supplement for grazing beef cattle improves rumen fermentation, nutrient intake and fibre digestibility

Context Essential oils are secondary plant compounds extracted from plants, with potential for the modulation of rumen fermentation. Aims Two experiments, namely one in vivo and another in vitro, were conducted to analyse the effects of a commercial blend of essential oils (EO; copaiba (Copaifera langsdorffii), cashew nut shell (Anacardium occidentale) and castor oil (Ricinus communis) and monensin as dietary feed additives in protein–energy supplements (PES) provided to grazing beef cattle, on ruminal fermentation, intake, total nutrient digestibility and protein dietary efficiency. Methods In the in vivo experiment, four entire Nellore bulls cannulated in the rumen (374 ± 15.66 kg; mean ± s.d.) were used in a 4 × 4 Latin-square design to evaluate the effects of EO concentration and monensin on voluntary intake, digestibility, and rumen and metabolic characteristics of grazing beef cattle provided with supplementation during the rainy season. Treatments were as follows: control (CON; PES without additives); monensin (MON; PES with inclusion of monensin at 20 mg/kg DM consumed); EO150 (PES with inclusion of EO at 150 mg/kg DM consumed); EO300 (PES with inclusion of EO at 300 mg/kg DM consumed). In the in vitro experiment, the effects EO150, EO300 and EO450, MON and CON on DM and neutral detergent-fibre (NDF) digestibility, and total gas production, were evaluated in four consecutive runs using a gas-production (GP) system. Key results In the in vivo experiment, DM intake, forage DM intake, crude protein intake and NDF intake were similar (P &amp;gt; 0.05) between EO150 and MON, but both were greater than those in EO300 and CON (P &amp;lt; 0.05). A lower EO concentration (EO150) increased (P &amp;lt; 0.05) NDF digestibility and improved nitrogen utilisation efficiency. In the in vitro experiment, the addition of MON and EO150 did not modify (P &amp;gt; 0.05) GP, DM and NDF digestibility compared with the control, but EO300 and EO450 decreased GP at 12 and 24 h and decreased DM and NDF digestibility at 48 h compared with the control, MON and EO150. Conclusions In vivo and in vitro results suggested that EO (copaiba oil, cashew nut shell and castor) at low doses (150 mg/kg DM) has the potential to improve ruminal fermentation in grazing beef cattle receiving supplements, but medium and high doses of EO can have adverse effects. Implications EO blends could be an alternative to MON for grazing beef cattle with access to supplements.