The effect of heather supplementation on gastrointestinal nematode infections and performance in Cashmere and local Celtiberic goats on pasture

Antiparasitic Tannin-Rich Plants from the South of Europe for Grazing Livestock: A Review

Internal parasites are one of the main causes of health threats in livestock production, especially in extensive livestock farming. Despite the environmental toxic effects (loss of dung beetles, biodiversity, and other issues) and resistance phenomenon derived from their prolonged use, anti-parasitic chemical pharmaceuticals are frequently used, even in organic farming. Such a situation within the context of climate change requires urgent exploration of alternative compounds to solve these problems and apparent conflicts between organic farming objectives regarding the environment, public health, and animal health. This review is focused on some plants (Artemisia spp., Cichorium intybus L., Ericaceae family, Hedysarum coronarium L., Lotus spp., Onobrychis viciifolia Scop.) that are well known for their antiparasitic effect, are voluntarily grazed and ingested, and can be spontaneously found or cultivated in southern Europe and other regions with a Mediterranean climate. The differences found between effectiveness, parasite species affected, in vitro/in vivo experiments, and active compounds are explored. A total of 87 papers where antiparasitic activity of those plants have been studied are included in this review; 75% studied the effect on ruminant parasites, where gastrointestinal nematodes were the parasite group most studied (70%), and these included natural (31%) and experimental (37%) infections.

Toxicity of phenolic compounds to entomopathogenic nematodes: A case study with Heterorhabditis bacteriophora exposed to lentisk (Pistacia lentiscus) extracts and their chemical components

Insects show adaptive plasticity by ingesting plant secondary compounds, such as phenolic compounds, that are noxious to parasites. This work examined whether exposure to phenolic compounds affects the development of insect parasitic nematodes. As a model system for parasitic life cycle, we used Heterorhabditis bacteriophora (Rhabditida; Heterorhabditiade) grown with Photorhabdita luminescens supplemented with different concentrations of plant phenolic extracts (0, 600, 1200, 2400 ppm): a crude ethanol extract of lentisk (Pistacia lentiscus) or lentisk extract fractionated along a scale of hydrophobicity with hexane, chloroform and ethyl acetate; and flavonoids (myricetin, catechin), flavanol-glycoside (rutin) or phenolic acids (chlorogenic and gallic acids). Resilience of the nematode to phenolic compounds was stage-dependent, with younger growth stages exhibiting less resilience than older growth stages (i.e., eggs < young juveniles < young hermaphrodites < infective juveniles < mature hermaphrodites). At high concentrations, all of the phenolic compounds studied were lethal to eggs and young juveniles. The nematodes were able to survive in the presence of medium and low concentrations of all studied compounds, but very few of those treatments allowed for reproduction beyond the infective juvenile stage and, at low concentrations, the crude 70% ethanol extract, chloroform and hexane extracts, and myricetin were associated with some impaired reproduction. The ethyl-acetate fraction and gallic acid were extremely lethal to the young stages and allowed almost no development beyond the infective juvenile stage. We conclude that exposure of infective juveniles to phenolics before they infect insects and post-infection exposure of other nematode developmental stages may affect the initiation of the infection, suggesting that the chemistry of dietary phenolics may limit H. bacteriophora's infection of insects.

Interactions Between Nutrition and Infections With Haemonchus contortus and Related Gastrointestinal Nematodes in Small Ruminants

Interactions between host nutrition and feeding behaviour are central to understanding the pathophysiological consequences of infections of the digestive tract with parasitic nematodes. The manipulation of host nutrition provides useful options to control gastrointestinal nematodes as a component of an integrated strategy. Focussed mainly on the Haemonchus contortus infection model in small ruminants, this chapter (1) illustrates the relationship between quantitative (macro- and micro-nutrients) and qualitative (plant secondary metabolites) aspects of host nutrition and nematode infection, and (2) shows how basic studies aimed at addressing some generic questions can help to provide solutions, despite the considerable diversity of epidemiological situations and breeding systems.

Anthelmintic effect of heather in goats experimentally infected with Trichostrongylus colubriformis

The effects of heather (composed primarily of Calluna vulgaris with a smaller content of Erica umbellata and Erica cinerea) consumption on the establishment of incoming infective larvae (experiment 1, preventive treatment) and an adult worm population (experiment 2, curative treatment) were investigated in Cashmere goats experimentally infected with Trichostrongylus colubriformis. In experiment 1, 12 castrated male goats were divided into two groups: heather-supplemented vs. non-supplemented animals. After 2 weeks of adaptation to the diet, all goats were experimentally infected per os with 6,000 T. colubriformis third-stage larvae. Three weeks post-infection, the goats were slaughtered, and worm counts as well as female worm fecundity and development were determined. Heather consumption was associated with a close to significant (P=0.092) reduction (mean 14 %) in larvae establishment. No effect on fecundity was observed, but the length of female worms in supplemented goats was greater (P<0.001). In experiment 2, 15 non-lactating does were experimentally infected with 6,000 T. colubriformis third-stage larvae. At 6 weeks post-infection, three groups were established: control, heather-supplemented and heather-supplemented with polyethylene glycol. Individual faecal nematode egg output was measured twice weekly to assess gastrointestinal nematode egg excretion. The goats were slaughtered 5 weeks after heather administration (11 weeks post-infection), and worm counts as well as female worm fecundity and development were subsequently determined. Heather administration was associated with a significant (P<0.001) decrease (between 47 and 66 % compared with control group) in egg excretion from 45 to 76 days post-infection. Although worm counts and female fecundity were lower in supplemented goats, no significant differences were observed. Overall, the results showed a reduction in T. colubriformis larvae establishment and a decrease in nematode egg excretion when heather was administered in experimentally infected goats. The heather plus polyethylene glycol treatment reduced nematode egg excretion levels at the same proportion as heather, thereby suggesting that the threshold of tannins required for an anthelmintic effect is most likely quite low.

Control of endoparasitic nematode infections in goats

In 2007, the world goat population was estimated at 831 million, compared with 1.09 billion sheep, but the goat population is expanding more rapidly. More than 90% of goats are found in developing countries, with the primary commodity being its meat. The commonly used description of the goat as the "cow of the poorest" underlines its importance for small farmers. However, in the developed world (eg, the European Union and much of North America), the value of goats relates to its select ability to produce high yields of milk and the increased returns associated with the dairy products, particularly artisanal cheeses. Therefore, the current success of goats seems to be related to 2 characteristics: (1) its ability to efficiently convert low-quality forages into high-quality protein sources, that is, milk and meat, in developing countries and (2) its ability to produce commodities for valuable niche markets in developed countries. In both systems, parasitism with helminths, and particularly nematodes of the gastrointestinal tract is a major threat for health and production.

Anthelmintic activity of some Mediterranean browse plants against parasitic nematodes

The anthelmintic properties of tannin-rich plants are being explored as an alternative to chemical drugs. Most data have been acquired on legume forages, but only few on browse plants. The present study aimed to (i) screen the in vitro effects of extracts from 7 Mediterranean plants on Haemonchus contortus, (ii) verify the role of tannins using an inhibitor, polyvinyl polypyrrolidone (PVPP) and (iii) verify the in vivo effects of extracts from 4 plants. Significant inhibition was shown in vitro using a larval migration inhibition (LMI) assay for all extracts except that from Olea europaea var. koroneiki. After adding PVPP, the LMI values were restored to control levels for all plants except Pistacia lentiscus and Ceratonia siliqua, confirming a role for tannins in the activity. In the in vivo experiment, 48 lambs composed 6 groups, depending on diet. On Day 0, groups G1–G5 received H. contortus and Trichostrongylus colubriformis larvae and G6 remained uninfected. The various diets were distributed from Days 14 to 45: P. lentiscus (G1), Quercus coccifera (G2), C. siliqua (G3), Onobrychis viciifolia (G4), or Medicago sativa for the 2 control groups (G5, G6). Egg excretion, packed cell volumes (PCVs) and inorganic phosphate were measured weekly throughout the entire experimental period. At slaughter, the worms were enumerated and their fecundity assessed. Consumption of the 4 browser plants did not provoke differences in pathophysiological measurements but there were significant decreases in egg excretion, mainly explained by significant decreases in worm fecundity for both species, without any statistical difference in worm numbers.

Anthelmintic and nutritional effects of heather supplementation on Cashmere goats grazing perennial ryegrass-white clover pastures1

To investigate anthelmintic and nutritional effects of heather supplementation in goats grazing perennial ryegrass-white clover pastures, 40 dry Cashmere goats were randomly assigned to 4 treatments in a 2 x 2 factorial arrangement: 2 grazing management treatments (supplementation with heather vs. nonsupplementation) and 2 anthelmintic treatments (treatment vs. nontreatment). Goats grazed continuously from May to September 2004. At the end of the grazing period, the number of dead goats due to gastrointestinal parasitism was 1 in the group supplemented with heather and dosed with anthelmintic, 4 in the group that received neither supplementation nor anthelmintic, and 0 in the other 2 groups. For goats that did not receive anthelmintic treatment, the percentage of heather in the diet was negatively correlated with fecal egg count in August (r = -0.59, P < 0.05) and September (r = -0.49, P < 0.1) and positively correlated (r = 0.54, P < 0.05) with BW changes during the grazing season. Therefore, the correlation coefficient between BW change and fecal egg count was negative (r = -0.62, P < 0.05). Rumen ammonia concentrations were always lower in supplemented goats (P < 0.05). However, VFA concentrations were greater in goats consuming heather (58.9 vs. 50.9 mmol/L), which suggests that ruminal fermentation was not adversely affected by consumption of tannins. Heather availability in the vegetation might represent a valuable opportunity and sustainable method to control gastrointestinal nematode infections in a goat production system based on grazing perennial ryegrass-white clover pastures.