The in vitro rumen exsheathment test for studying the effect of plant extracts on the exsheathment of Haemonchus contortus infective larvae

This study applied the in vitro rumen exsheathment test (IVRET) to evaluate the exsheathment kinetics of Haemonchus contortus infective larvae (L3) incubated in ruminal liquor (RL) containing acetone:water extracts of Acacia pennatula (AP), Gymnopodium floribundum (GF), Havardia albicans (HA) or Lysiloma latisiliquum (LL). The role of polyphenols in the biological activity of the evaluated extracts was also determined. Larvae were incubated in RL either alone or added with a different plant extract (AP, GF, HA, or LL) at 1200 μg/mL. Polyethylene glycol (PEG) was added to block polyphenols in each treatment (RL+PEG, AP+PEG, GF+PEG, HA+PEG, and LL+PEG). After incubation times of 0, 1, 3, 6, 9, and 24 h, the exsheathment process was stopped to count the number of ensheathed and exsheathed L3. A Log-Logistic model was used to determine the L3 exsheathment kinetics in the different RL treatments. The inflection point of the respective kinetic curves, which indicates the time to reach 50 % exsheathed L3 (T50), was the only parameter that differed when comparing the exsheathment models (99 % probability of difference). The T50 values obtained for GF, HA, and LL treatments (T50 = 7.11 - 7.58 h) were higher in comparison to the T50 of RL (5.72 h) (≥ 70 % probability of difference). The L3 incubated in RL added with GF, HA, and LL extracts delayed their exsheathment at 3 and 6 h of incubation (28.71 - 48.06 % exsheathment reduction) compared to the RL treatment. The T50 value for AP, AP+PEG, GF+PEG, HA+PEG, and LL+PEG were similar to RL and RL+PEG (T50 = 5.34 - 6.97 h). In conclusion, the IVRET can be used to identify plants with the potential to delay the exsheathment of H. contortus L3 in the ruminal liquor. The acetone:water extracts of G. floribundum, H. albicans, and L. latisiliquum delayed the T50 of H. contortus exsheathment, which was evident at 3 and 6 h of incubation in ruminal liquor. The observed exsheathment delay was attributed to the polyphenol content of the extracts.

Adapting the in vitro rumen incubation method to evaluate the effect of a plant extract on the exsheathment inhibition of Haemonchus contortus infective larvae

This study adapted the in vitro rumen incubation (IVRI) method to evaluate the biological activity of a Gymnopodium floribundum leaves extract against the exsheathment of Haemonchus contortus infective larvae (L3), and to determine the role of plant polyphenols on the biological activity. The incubation protocol followed the IVRI method, adding polyethylene glycol (PEG) as a polyphenol-blocking agent. The L3 were incubated in ruminal liquor (RL), ruminal liquor with PEG (RL+PEG), ruminal liquor with G. floribundum extract (RLE), and ruminal liquor with G. floribundum extract and PEG (RLE+PEG). Incubation condition controls included phosphate buffered saline (PBS), PBS with PEG (PBS+PEG), incubation medium (without ruminal liquor) (IM), and incubation medium with PEG (IM+PEG). The L3 were recovered after incubation times of 0, 1, 3, 6, 9, and 24 h (39 °C). The respective L3 exsheathment kinetics were estimated for the different treatments (RL, RL+PEG, RLE, and RLE+PEG) using Log-Logistic models. The parameters of the different models were compared to determine the impact of the extract, with or without PEG, on the L3 exsheathment kinetics. The exsheathment in PBS and PBS+PEG remained < 2.71% at each incubation time. The exsheathment in IM and IM+PEG reached 13.58% and 17.18% at 24 h, respectively. The exsheathment percentages for RLE were lower than those for RL at 3, 6 and 9 h of incubation. The inflection point, indicating the time required to reach 50% of the maximal exsheathment (T50), was the only parameter that differed between the ruminal liquor models. The T50 in RLE (7.106 h) was higher than the values obtained for RL (5.385 h) and RL+PEG (4.923 h) (99.99% probability of being different). Such delay resulted in a reduction of exsheathment in RLE of 62% at 3 h, 38% at 6 h, and 12% at 9 h, relative to RL values. When PEG was added with the extract (RLE+PEG), the T50 (5.045 h) was similar to that of RL and RL+PEG. The IVRI method was adapted as an in vitro rumen exsheathment test (IVRET). The IVRET showed that H. contortus L3 exposed to G. floribundum extract delayed their exsheathment kinetics at different time points. The exsheathment delay was attributed to the polyphenol content of the extract.

Relevance of Individual Data When Assessing the Gastrointestinal Nematode Infection Level, Nutritional and Productive Variables in a Tropical Farm Context: The Median Isn't the Message

We evaluated the relationship between individual and herd GIN infection level, nutrition, production performance and anemia parameters in a tropical farm context. Fifty-four female goats were monitored to assess their body condition score (BCS, nutritional status indicator), live weight (LW) and LW gain (LWG, both used as production level indicators), FAMACHA© and hematocrit (HT, both used as anemia indicators). Goats browsed for 4 h in a tropical forest and received balanced feed and chopped grass. The eggs per gram of feces (EPG) indicated the GIN burden, with fecal samples obtained at 7:00 (AM) and 15:00 h (PM.) from each goat at six sampling points during the study. The variables and their relationship with GIN burdens were analyzed using Kruskall-Wallis, ANOVA and Friedman tests and Spearman correlations. The fecal samples obtained in the AM and PM can be equally representative of parasitic burdens (similar and highly correlated). However, the EPG of individual goats from periods of 30 days apart can be considered independent. The BCS and LWG varied between sampling times (p < 0.05), whereas EPG, LW and HT did not (p > 0.05). The GIN burden was negatively correlated with HT and BCS (-0.21, p = 0.01 for each one). The individual pattern of infection demonstrates the true impact of GINs on their hosts. Additionally, feeding and nutritional status may present important variations influencing the performance of the goats more than the impact of GINs under the farm conditions of the present study. However, GIN infection contributed to the variation in goat health and productivity in this tropical farm.

Curcumin-PVP improves the in vitro efficacy of ivermectin against resistant and susceptible Haemonchus contortus

Ivermectin (IVM) resistance in parasitic nematodes such as Haemonchus contortus has spurred a search for substances that help to recover its efficacy. One potential agent is the natural product curcumin (CUR). In this study, CUR was combined with polyvinylpyrrolidone (PVP) (CUR/PVP) to improve its solubility and biological applicability. This study determined the effect of CUR preincubation on the effective concentration 50% (EC50) of IVM in three H. contortus isolates with different susceptibilities to IVM. The IVM EC50 was determined for three H. contortus isolates with different IVM susceptibilities using the larval migration inhibition (LMI) test. The three isolates were (i) PARAISO (IVM resistant), (ii) FMVZ-UADY (IVM susceptible), and (iii) CENID-SAI INIFAP (reference IVM susceptible). The L3 of each isolate were preincubated for 3 h with one of three concentrations of CUR (μg curcumin/mL): CONC-1 (3.67), CONC-2 (5.67), or CONC-3 (8.48). Corresponding controls were performed without CUR. The EC50 of IVM was determined for each isolate after they were exposed to the different CUR concentrations. The EC50 of IVM differed between the isolates PARAISO > FMVZ-UADY > CENID-SAI INIFAP (P < 0.05). The CUR preincubation at CONC-1 did not decrease the EC50 of IVM for any of the three isolates, suggesting a hormetic effect. By contrast, CUR preincubation at CONC-2 or CONC-3 decreased the IVM EC50 for the PARAISO isolate (P < 0.05) compared with the reference isolate and reduced the EC50 of IVM for the FMVZ-UADY and CENID-SAI INIFAP isolates below the EC50 for the CENID-SAI INIFAP isolate without CUR preincubation. In conclusion, preincubation of H. contortus L3 with CUR reduced the EC50 of IVM for field isolates classified as resistant and susceptible to IVM. The CUR preincubation reduced the IVM resistance factor in the different isolates tested.

Selection of Forage Resources by Juvenile Goats in a Cafeteria Trial: Effect of Browsing Experience, Nutrient and Secondary Compound Content

Simple Summary

Grazing/browsing goats ingest a diverse diet selected from the forage resources available in the range/paddock intending to meet their nutritional requirements. Intake and selection of any given forage can be modified by several factors, such as its nutrient content, including secondary compounds, as well as its biomass availability in the environment. The animal’s previous browsing experience can also be an important factor driving intake and selection. Therefore, the present study evaluated all these factors as well as their interaction. The results showed that the goats’ browsing experience guided the selection and intake towards those forage resources of better nutritional quality when there was no restriction in forage supply, as is the case for cafeteria trials. Goats with browsing experience showed their ability to limit secondary compounds and optimize their selection and intake for plants with better digestibility. This cafeteria protocol made it possible to identify the selection and consumption pattern of plant species with limited availability in the natural vegetation. This methodology could help identifying the forage resources that may be useful for small ruminant feeding, versus those resources that are not consumed by goats despite having a suitable chemical composition and in vitro digestibility or a high abundance.

Abstract

We evaluated the effect of browsing experience, nutritional quality and secondary compounds of forage resources, and the interaction between these factors on the selection and intake of goats in a cafeteria trial. Twelve juvenile Criollo goats from 7 to 9 months of age, weighing 22 ± 3 kg, were divided into two groups: (a) browser goats group (n = 6, BG), and (b) naïve goats group (n = 6, NG), formed according to their previous browsing experience (with and without, respectively). Animals were housed in individual pens. The cafeteria experiment lasted 21 days considering pen adaptation, foliage adaptation, and measurements, which included the selection index (SI) of experimental forage resources (Chesson’s alpha) and their dry matter intake (DMI/Kg^0.75), using a multiple Latin square design. Furthermore, correlation and regression analyses were used to assess the relationship between the aforementioned factors. The NG did not show any selection pattern, while the BG selected Piscidia piscipula and Senegalia gaumeri (p = 0.0002). The BG consumed smaller amounts of secondary compounds compared to NG (p = 0.0001). In the BG, the flavonoids affected negatively their selection (R² = 97.51, p = 0.0001), while the DMI was affected by in vitro DM digestibility and flavonoids (R² = 99.85; p = 0.0001). For the NG, the crude protein and organic matter contents were associated with DMI, but none had a significant relationship with SI. The BG selected and consumed forages with suitable nutritional quality avoiding those with high content of secondary compounds such as flavonoids. Conversely, NG did not show a clear pattern for their selection or intake.

Impact of Dietary Condensed Tannins and Haemonchus contortus Infection in Growing Sheep: Effects on Nutrient Intake, Digestibility, and the Retention of Energy and Nitrogen

PURPOSE

A controlled study evaluated the effect of condensed tannins (CT) from Gymnopodium floribundum leaf meal (GF), infection with Haemonchus contortus (I) and their interaction, on feed intake, diet digestibility and retention of N (NR) and energy (ER) in hair sheep lambs.

METHODS

Thirty-six, worm-free hair sheep lambs (14.9 ± 1.56 kg body weight) were housed in metabolic cages. Eighteen animals were infected with 6000 H. contortus L₃, while other 18 lambs were kept non-infected. On day 28th post-infection (PI), infected lambs were assigned to three diet groups: a diet without GF (I-NONGF), a diet with GF (I + GF) and a diet with GF + polyethylene glycol (PEG) (I + GF + PEG). Non-infected (NI) lambs were assigned to similar diet groups: NI-NONGF, NI + GF and NI + GF + PEG. The packed cell volume (% PCV), ante-mortem faecal egg counts and post-mortem worm burdens were also evaluated.

RESULTS

Infection did not affect digestibility, NR and ER. Meanwhile, CT intake from the GF diet reduced the digestibility of dry matter, organic matter and crude protein, as well as NR, compared to lambs consuming the NONGF and GF + PEG diets (P < 0.05). Although, the digestible energy was similar between lambs consuming NONGF and GF + PEG diets, the ER was higher for lambs consuming the control NONGF diet. Diets did not affect the PCV, or the ante-mortem and post-mortem parasitological variables.

CONCLUSION

The costs on N and energy metabolism were mainly associated with the CT content of the GF diet, but other features of the diet such as the high lignin content, seemed to affect animals consuming GF meal. Meanwhile, the H. contortus infection had a non-significant impact.

Variabilidad en el contenido de polifenoles, actividad biológica y antihelmíntica de extractos metanol:agua de las hojas de Gymnopodium floribundum Rolfe

Se determinó el efecto del mes de cosecha y edad de las hojas de Gymnopodium floribundum sobre el contenido de compuestos polifenólicos (fenoles totales (FT), taninos totales (TT) y taninos condensados (TC)) de extractos metanol:agua. Además, se determinó la actividad biológica de los polifenoles medida como la capacidad de precipitar proteína (PP), inhibir la eclosión de huevos (EH), y el desenvaine larval (IDL) de Haemonchus contortus. Se cosecharon hojas de G. floribundum en cuatro meses del año: diciembre, marzo, junio y septiembre. Se obtuvieron 24 extractos metanol:agua (70:30), 12 producidos de hojas de edad variada (EV) y 12 de hojas de 90 días (E90). Todos los extractos ocasionaron similar PP independientemente de edad y mes de cosecha. La inhibición de la EH solo fue significativa para el extracto EV de diciembre (CE50 = 374.4 μg/ml; P<0.05). Los extractos de hojas E90 mostraron una CE50 > 1500 μg/ml en diciembre, junio y septiembre. Aunque todos los extractos inhibieron el desenvaine larval (IDL), la menor CE50 fue la del extracto de hojas EV de junio (CE50 = 80.4 μg/ml; P<0.05). La incubación de extractos con polivinilpolipirrolidona (PVPP) limitó la IDL (P<0.05), pero los polifenoles solo explicaron parte de esa actividad. En conclusión, el contenido de TC de los extractos de hojas de G. floribundum depende de su edad y mes de cosecha. Los polifenoles mostraron actividad de PP y se asociaron parcialmente con la IDL. Sin embargo, los polifenoles no explican la actividad contra huevos de H. contortus.

Scanning electron microscopy of different vulval structures in a Mexican Haemonchus contortus isolate

Haemonchus contortus is a parasite species that affects the health and production of grazing small ruminants in different parts of the world. Scanning electron microscopy (SEM) is an important tool for the study of parasites' morphology and taxonomy as it generates images that appear 3D and are generally easier to interpret than optical microscopy images. This study used the SEM to describe the vulval types of adult H. contortus from a Mexican isolate. A total of 14 adult H. contortus females were obtained from two artificially infected goats. Females were fixed and processed by critical point drying and observed with SEM. A collection of SEM images was obtained from these parasites and those images were used to identify the structures previously described by optical microscopy studies. Two different types of vulval structures were described in this Mexican H. contortus isolate: Type 1 (vulval flap), Type 2 (epiptygma). An unusual vulval structure was reported in a single individual. The Type 1 included vulval flaps of different sizes and spatial dispositions, as well as one or more knobs in different positions around the vulva. The Type 2 shows differences in the epiptygma. The present study suggests that the Mexican H. contortus isolate used in donor animals possess intraspecific polymorphism in vulval structures.

Nitrogen retention in hair sheep lambs with a gradient of Haemonchus contortus infection

The impact of Haemonchus contortus infections on nitrogen retention (NR) of hair sheep lambs is unknown. This study estimated the feed intake, digestibility, NR, haematocrit (HT), and their relationship with the gradient of H. contortus infection in hair sheep lambs. Twenty-four hair sheep lambs, 3-4 months old, reared parasite-free were used (live weight (LW) 16.7 ± 1.7 kg). Six lambs were kept parasite-free, nine lambs received a dose of 300 H. contortus infective larvae (L₃)/kg LW, and the remaining nine lambs received 500 H. contortus L₃/kg LW. Infection doses ranged from 3870 to 9,500 L₃. Lambs were individually fed for an average daily gain (ADG) of 100 g. On days 1 (P < 0.01) and 7 (P < 0.001) post-infection (PI), the L₃ doses were positively associated with HT, possibly due to platelet recruitment. On week 1 PI, the infection (L₃) reduced the crude protein (CP) intake (g/kg metabolic LW) (P < 0.05). A reduction of 1% HT corresponded to 1200 eggs per gram of faeces (EPG) for day 21 PI (P < 0.05), 2300 EPG for day 28 PI (P < 0.001), 2400 EPG for day 35 (P < 0.001), and 1300 EPG for day 41 PI (P < 0.001). However, the HT levels were never lower than 21 %. A lower CP digestibility was associated with EPG only on week 5 PI (P < 0.05). There was no significant association between EPG, Total egg in faeces, or worm burden (WB) with intake, dry matter digestibility (DMD), ADG or NR. The NR of lambs was positive along the different weeks of study irrespective of infection level. The WB was negatively associated only with HT on day 41 PI (P < 0.001), where a 1 % HT reduction was estimated for every 257 worms hosted. In conclusion, no relationship was found between H. contortus infection and DMD, ADG or NR in hair sheep lambs. The cost of H. contortus infection resulted only from the HT reduction and depended on the gradient and stage of the infection.

Small Ruminant Production Based on Rangelands to Optimize Animal Nutrition and Health: Building an Interdisciplinary Approach to Evaluate Nutraceutical Plants

The plant kingdom can influence the productivity and health of herbivores at different levels. However, demonstrating this process in a scientific manner entails substantial endeavors from different disciplines. In the present review, we will describe the features of a native vegetation system traditionally used by small ruminants and use its particularities to build an interdisciplinary approach to evaluate the nutraceutical properties of plants. Initially, we will establish the context of the low deciduous forest (LDF), considering some botanical and nutritional aspects, as well as the presence of plant secondary compounds (PSC) and gastrointestinal nematodes (GIN). Furthermore, we will focus on coevolutionary aspects that undoubtedly shaped the plants-nutrients-PSC-GIN-herbivore relationship. In addition, the concept of nutraceutical will be discussed to provide clarity and aspects to be considered for their evaluation. Then, ethological, agronomical, nutritional, PSC, parasitological and animal species issues are deepened placing emphasis on methodological approaches. Special focus is given to condensed tannins, as they are the fourth largest group of PSCs and the most studied in livestock sciences. Validation of the nutraceutical properties of plants from native vegetation systems should be seen as a process derived from many scientific disciplines that feed into each other in a cyclic manner.

Ultrastructural study of adult Haemonchus contortus exposed to polyphenol-rich materials under in vivo conditions in goats

This study assessed the ultrastructural changes caused in adult Haemonchus contortus obtained from goats fed fodder based on polyphenol-rich plants Lysiloma latisiliquum or Onobrychis viciifolia or from goats drenched with quebracho extract, Schinopsis spp. The H. contortus were obtained from artificially infected goats used as models to investigate the anthelmintic effect of feeding or drenching with the polyphenol-rich materials. Nematode populations were exposed to polyphenol-rich plant materials by feeding host goats for 8 consecutive days (D28 to D35 post-infection) with (a) L. latisiliquum fodder at 800 g fresh basis/day, (b) O. viciifolia fodder offered ad libitum, and (c) drenched with a solution containing quebracho extract (90 g/day). Meanwhile, control H. contortus were obtained from goats fed polyphenol-free diets. The H. contortus specimens were recovered from the goats on D36 post-infection, and transmission electron microscopy (TEM) was used to identify ultrastructural changes. In vivo exposure to different polyphenol-rich plant materials caused vacuolization of the nematodes’ intestinal, muscular and hypodermal cells. These alterations represent the first evidence of cell damage caused in H. contortus when hosts were fed or drenched with polyphenol-rich materials. Ultrastructural changes affecting several types of cells could explain modifications in worm motility and nutrition, eventually affecting H. contortus reproductive success. This study contributes to our understanding of the mechanisms of action of polyphenol-rich plants against H. contortus when given as nutraceuticals to goats.

Cytotoxic Furanoditerpenes from the Sponge Spongia tubulifera Collected in the Mexican Caribbean

Two new spongian furanoditerpenes, 3β-hydroxyspongia-13(16),14-dien-2-one (1) and 19-dehydroxy-spongian diterpene 17 (2), along with five known terpenes, the spongian furanoditerpenes 9-nor-3-hydroxyspongia-3,13(16),14-trien-2-one (3), 3β,19 dihydroxyspongia-13(16),14-dien-2-one (epispongiadiol) (4) and spongian diterpene 17 (5), the furanoditerpene ambliol C (6), and the sesterterpene scalarin (7), were isolated from the methanolic extract of the sponge Spongia tubulifera, collected in the Mexican Caribbean. The planar structures of the new compounds were elucidated by 1D/2D NMR and IR spectroscopic analysis, high resolution electrospray mass spectrometry (HRESIMS), and comparison of their spectral data with those reported in the literature. Absolute configurations were determined by comparison of the experimental electronic circular dichroism (ECD) spectrum with those calculated by time-dependent density functional theory (TDDFT). Compounds 1, 4, and 6 displayed weak cytotoxic activity against different human tumour cell lines.

The worm burden of tracer kids and lambs browsing heterogeneous vegetation is influenced by strata harvested and not total dry matter intake or plant life form

This study assessed the effect of total dry matter intake (DMI), plant life form and strata harvested on the gastrointestinal nematode (GIN) worm burdens of tracer kids and lambs browsing heterogeneous vegetation during the rainy season (August-November). The rainy season was divided into 6 2-week periods (P1-P6), and environmental conditions (rainy days, rainfall, temperature and humidity) were recorded daily. Five pairs each of tracer kids and tracer lambs raised free of GIN infections were used. Every 15 days, different pairs of kids and lambs were introduced to a 2.2-ha plot and co-grazed with a flock of 30 sheep and 70 goats for a period of 3 weeks. Feeding behaviour of each pair of tracers was measured in weeks 2 and 3. The continuous bite monitoring method was used to estimate total DMI, DMI of plant life forms and DMI from plants of different strata. After each 3-week period, the tracer pair was maintained indoors for 28 days and necropsied on day 29 to recover the worm burden. The feeding behaviour of the tracers was compared between periods (P2-P6) and between kids and lambs. The differences in the worm burdens of the tracers between periods were not associated with total DMI or DMI from plant life forms. Worm burdens were highest during P5 and P6 in tracer kids and lambs (P < 0.05), suggesting a build-up of infective larvae in the tropical deciduous forest (TDF). The lower worm burdens of tracer kids compared with lambs (P < 0.05) seemed to be associated with less low- and more medium-stratum ingestion.

Evaluation of cinnamic acid and six analogues against eggs and larvae of Haemonchus contortus

This study evaluated the in vitro anthelmintic (AH) activity of cinnamic acid and six analogues against eggs and larvae of Haemonchus contortus. Stock solutions of each compound (trans-cinnamic acid, p-coumaric acid, caffeic acid, trans-ferulic acid, trans-sinapic acid, 3,4-dimethoxycinnamic acid, and chlorogenic acid) were prepared in PBS:Tween-20 (1%) for use in the egg hatch test (EHT) and larval exsheathment inhibition test (LEIT) at different concentrations (25-400 μg/mL). The respective effective concentration 50% (EC₅₀) values with 95% confidence intervals were estimated. Mixtures made of all cinnamic acid and its analogues as well as some selected individual compounds were also tested in the EHT. Only ferulic and chlorogenic acids showed AH activity in the EHT (EC₅₀: 245.2 μg/mL (1.26 mM) and 520.8 μg/mL (1.47 mM), respectively) (P < 0.05). A higher EC₅₀ (1628.10 μg/mL) of the mixture of cinnamic acid and its analogues was required to observe activity against eggs mostly blocking the larvae hatching. The analogues' mixtures tested were less active than ferulic or chlorogenic acid alone. The activity of ferulic and chlorogenic acids against eggs was associated with larvae failing to hatch, and the two compounds exhibited antagonistic effects when evaluated together. All standards had an EC₅₀ lower than 0.42 mM in the LEIT. Caffeic acid had the best activity in the LEIT (EC₅₀ 0.04 mM), followed by ferulic acid (EC₅₀ 0.11 mM) (P < 0.05). There was no clear, definitive structure-activity relationship for these non-flavonoid polyphenols against eggs or larvae of H. contortus in vitro. This study is the first to directly evaluate cinnamic acid and its derivatives as active compounds against eggs and larvae of H. contortus.

Bio-guided fractionation to identify Senegalia gaumeri leaf extract compounds with anthelmintic activity against Haemonchus contortus eggs and larvae

Small ruminants browsing in tropical forests readily consume the foliage of Senegalia gaumeri. A S. gaumeri methanol:water extract was recently shown to have ovicidal activity against Haemonchus contortus eggs in vitro. In the present study, the fraction of a S. gaumeri methanol:water extract with ovicidal activity against H. contortus eggs and the metabolites potentially involved in this activity were identified. Bio-guided fractionation of the S. gaumeri methanol:water extract identified high ovicidal activity (80.29%, EC₅₀ = 58.9 μg/mL) in the non-polar sub-fraction P1. Gas chromatography-mass spectrometry (GC-MS) identified several fatty acids: pentacosane (18.05%), heneicosane (18.05%), triacontane (30.94%), octacosane (18.05%), and hexanedioic acid bis-(2-ethylhexyl) ester (32.72%). Purification of the polar components of sub-fraction P1 led to the identification of p-coumaric acid as a major constituent. In egg hatch tests, 400 μg/mL p-coumaric acid resulted in an ovicidal effect of 8.7%, a larvae failing eclosion effect of 2.9%, and of the emerged larvae (88.4%), many were damaged. In conclusion, the low AH activity of p-coumaric acid against H. contortus eggs indicates that it is not solely responsible for the ovicidal activity of sub-fraction P1 but might act in synergy with other compounds in this fraction. However, p-coumaric acid showed potential anthelmintic effects against the larval stage of H. contortus.

Impact of gastrointestinal parasitism on dry matter intake and live weight gain of lambs: A meta-analysis to estimate the metabolic cost of gastrointestinal nematodes

This study aimed to estimate the effect of gastrointestinal nematodes (GIN) on the productive performance assessed by the live-weight change (LWC) of lambs, and the metabolic cost associated with parasitism by means of a meta-analysis. Data used in the meta-analyses were obtained from twenty papers selected using the following criteria: (a) lambs with (I) and without (NI) GIN; (b) lambs fed ad libitum; (c) LWC data; (d) feed consumption data; and (e) chemical composition of diets. The effect of diet composition (crude protein [CP] and metabolizable energy [ME]) on dry matter intake (DMI), and the effect of composition and nutrient intake (DMI and CP intake [CPI]) and ME intake (MEI) on LWC was evaluated using respective regression analyses. The metabolic cost of worm burden was determined as the difference in CP and ME requirements between NI and I lambs for each adult parasite. The CP and ME cost were evaluated for lambs at two different levels: maintenance level 0 g LWC and 100 g LWC. The worm burden had an impact on the DMI and LWC of lambs (P < 0.05). The association of CP x infection level was the best predictor of DMI. The association between MEI and infection level were the best predictors of LWC. The metabolic cost of GIN increased to 0.30 mg CP/kg LW^0.75 and 0.0056 kJ ME/kg LW^0.75 for each adult parasite. The metabolic cost was not modified by diet quality (maintenance level 0 g LW/day or 100 g LW/day). In conclusion, GIN has a negative effect on DMI and LWC. The metabolic cost of GIN infection can be covered by supplying the additional requirements for protein and energy in the diet of infected lambs.

Simpler intake estimation using direct observation in small ruminants: grouping bites by plant structure and morphology

Objective

To validate the estimation of dry matter intake (DMI) obtained from bite categories (BC) and weight for every plant species (method 1: M1) vs. an alternative method (method 2: M2) grouping plants based on structure and leaf morphology. A dataset containing 80,813 bites and 33 plant species obtained by M1 for sheep and goats browsing a tropical forest was used. Plant species and their respective bite weight were regrouped according to M2. BC weights within each morphological group were compared using ANOVA and post hoc Tukey’s honest significant difference comparisons. DMI was estimated for sheep, goats and DMI obtained with both approaches was compared using the t-test, Pearson correlation and orthogonal regression analyses.

Results

Dry matter intake estimations were: M1 = 369 ± 153 vs. M2 = 425 ± 161 gDM for sheep and M1 = 567 ± 190 vs. M2 = 681 ± 203 gDM for goats. DMI estimations by M1 and M2 were similar and strongly correlated. Orthogonal regression showed both procedures yielded a similar DMI estimation (P < 0.001). M2 reduces the amount of work required to estimate DMI in heterogeneous vegetation without reducing accuracy. M2 reduced the time required and made simpler to include data from larger number of animals/replicates.

A protocol of human animal interaction to habituate young sheep and goats for behavioural studies

Animal habituation is key to obtain reliable data on behavioural studies but detailed procedures to achieve it are scarce. This study designed a set of actions to habituate sheep and goats to human observers. Pelibuey sheep (n = 15) and Criollo goats (n = 10) were classified as (a) avoider, flight from human interaction, or (b) follower, seek human interaction. Habituation was measured by the reduction of flight distance by avoiders, or number of followers in the presence of observers. The habituation protocol consisted of a gradually increased series of five manoeuvres, either challenge (for avoiders) or evasion (for seekers), performed first inside a pen and subsequently in a grass paddock. Habituation was considered successful when animals could be observed from a 1-m distance without flight or following the observer. In the pen, habituation took 12 and 13 days for sheep and goats, respectively. Meanwhile, in the grass paddock habituation took 10 days, for both species. The number of challenge and evasion series was negatively correlated with the flight distance in sheep and with the number of followers in goats. This protocol is simple and practical to implement and enables animal habituation for behavioural studies.

Salivary tannin-binding proteins are a pervasive strategy used by the folivorous/frugivorous black howler monkey

Dietary tannins can affect protein digestion and absorption, be toxic, and influence food selection by being astringent and bitter tasting. Animals that usually ingest tannins may regularly secrete tannin-binding salivary proteins (TBSPs) to counteract the negative effects of tannins or TBSPs production can be induced by a tannin-rich diet. In the wild, many primates regularly eat a diet that contains tannin-rich leaves and unripe fruit and it has been speculated that they have the physiological ability to cope with dietary tannins; however, details of their strategy remains unclear. Our research details the salivary protein composition of wild and zoo-living black howler monkeys (Alouatta pigra) feeding on natural versus manufactured low-tannin diets, and examines differences in TBSPs, mainly proline-rich proteins (PRPs), to determine whether production of these proteins is dependent on the tannin content of their food. We measured the pH, flow rate, and concentration of total protein and trichloroacetic acid soluble proteins (an index of PRPs) in saliva. Howler monkeys produced slightly alkaline saliva that may aid in the binding interaction between tannin and salivary proteins. We used gel electrophoresis to describe the salivary protein profile and this analysis along with a tannin-binding assay allowed us to detect several TBSPs in all individuals. We found no differences in the characteristics of saliva between wild and zoo-living monkeys. Our results suggest that black howler monkeys always secrete TBSPs even when fed on foods low in tannins. This strategy of constantly using this salivary anti-tannin defense enables them to obtain nutrients from plants that sometimes contain high levels of tannins and may help immediately to overcome the astringent sensation of their food allowing howler monkeys to eat tanniferous plants.

Do condensed tannins from Lysiloma latisiliquum have a role in its anthelmintic activity?

We would like to comment on a recent paper by Hernandez-Bolio et al. (2017, Nat. Prod. Res. DOI: 10.1080/14786419.2017.1317774) where an extract free of condensed tannin (CT) was evaluated and concluded that Lysiloma latisiliquum CT does not have a role in its anthelmintic (AH) activity. This letter discusses the AH potential of L. latisiliquum based on previously published evidence of a partial role of CT using different AH assays and Haemonchus contortus isolates. Because the experimental design employed in the above-mentioned paper did not allow a clear-cut conclusion regarding the role of CT, this suggests that a specific experiment must be designed to confirm or reject the involvement of CT fraction(s) on L. latisiliquum AH activity.

Is there a negative association between the content of condensed tannins, total phenols, and total tannins of tropical plant extracts and in vitro anthelmintic activity against Haemonchus contortus eggs?

In vitro studies using plant extracts suggest a relationship between their polyphenol contents and their anthelmintic (AH) activity against Haemonchus contortus. High polyphenol content appears to increase the efficacy of plant extracts against H. contortus as assessed by the larval exsheathment inhibition assay (LEIA) while appearing to reduce the AH efficacy measured using the egg hatch assay (EHA). In addition, some plants lack AH activity. Therefore, the present study investigated the relationship between the contents of condensed tannins (CT), total phenols (TP), and total tannins (TT) in methanol:water extracts (70:30) obtained from ten tropical plant species consumed by small ruminants as well as their AH activity against H. contortus evaluated by LEIA and EHA. Extracts of Acacia collinsii, Lysiloma latisiliquum, Havardia albicans, Senegalia gaumeri, Mimosa bahamensis, Piscidia piscipula, Acacia pennatula, Gymnopodium floribundum, Leucaena leucocephala, and Bunchosia swartziana were examined. Positive correlations were found between the effective concentration 50% (EC₅₀) (EHA) of extracts and their CT (r = 0.6809, P < 0.05, n = 10) and TP (r = 0.9152, P < 0.05, n = 10) content, suggesting that their concentration negatively affected AH activity against eggs. Based on the LEIA, there was no significant association between the EC₅₀ and the CT, TP, or TT of all extracts evaluated. Thus, if sheep and goats consume a complex feed mixture with high amounts of CT, TP, and TT, it might be difficult to observe an AH effect against H. contortus egg hatching. However, the AH effect upon L₃ establishment might be feasible.

Age of Haemonchus contortus third stage infective larvae is a factor influencing the in vitro assessment of anthelmintic properties of tannin containing plant extracts

The larval exsheathment inhibition assay (LEIA) of infective larvae (L₃) is an in vitro method used to evaluate the anthelmintic (AH) activity of tannin-containing plant extracts against different species of gastrointestinal nematodes, including Haemonchus contortus. Some conditions remain to be defined in order to standardize the LEIA, i.e. the optimal age of larvae produced from donor animals to use in the assays. Therefore, this study aimed at identifying the effect of age and age-related vitality of H. contortus infective larvae produced under tropical conditions, on the in vitro AH activity measured with the LEIA. The same acetone:water (70:30) extract from Acacia pennatula leaves was used to perform respective LEIA tests with H. contortus L₃ of different ages (1-7 weeks). Each week, the L₃ were tested against different concentrations of extract (1200, 600, 400, 200, 100, 40μg/mL of extract) plus a PBS control. Bioassays were performed with a benzimidazole (Bz) resistant H. contortus (Paraíso) strain. In order to identify changes in L₃ vitality on different weeks (1-7), two assays testing larval motility were included only with PBS: the larval migration assay (LMA) and the larval motility observation assay (LMOA). Mean effective concentrations causing 50% and 90% exsheathment inhibition (EC₅₀, EC₉₀) were obtained for every week using respective Probit analyses. On the first week, the larvae had lowest EC₅₀ and EC₉₀ (39.4 and 65.6μg/mL) compared to older larvae (P<0.05). The EC₅₀ and EC₉₀ for weeks 2-5 were similar (P>0.05), while older larvae tended to show higher EC₅₀ and EC₉₀ (P<0.05). Motility showed strong negative correlations with age of larvae (r≥-0.83; P <0.05) and EC₅₀ (r≥-0.80; P<0.05), suggesting that the lower extract efficacy could be associated with decaying vitality of larvae associated with age. More stable efficacy results were found between two to five weeks of age.

Gastrointestinal nematode infection does not affect selection of tropical foliage by goats in a cafeteria trial

It is important to determine whether gastrointestinal nematodes (GINs) affect foliage choice of goats leading to confirm the expression of a self-medication behavior. This study investigated the effect of GIN infection on tropical foliage selection by goats. During experimental stage 1 (10 days), goats had a natural mixed GIN infection, and at stage 2 (10 days), goats were treated with effective anthelmintics to maintain them free of GIN infection. During stage 1 the twelve adult goats (32 ± 2.3 kg live weight [LW]) were assigned to three groups (n = 4) according to their initial GIN infection status: HI group, with fecal egg count (FEC) between 1450 and 2150 eggs per g/feces (EPG); MI group, medium FEC (592-1167 EPG); and the NI group, free from GIN infection. Fresh foliage of four tropical plants were offered to goats ad libitum for 1 h daily: Gymnopodium floribundum (high condensed tannin [CT] content, 37-40 %), Mimosa bahamensis (medium CT content, 16-17 %), Leucaena leucocephala (low CT content, 3-5 %), and Viguiera dentata (negligible CT content, 0.6-0.9 %). Jacobs' selection indexes (JSIs) were estimated for the experimental foliage based on dry matter (DM), CT, or crude protein (CP) intake. During both study stages, individual fecal egg counts were estimated. The JSI patterns of different plant species, based on DM, CT, or CP, were similar irrespective of infection level during stage 1 (HI, MI, and NI) or no GIN infection (stage 2). Thus, irrespective of GIN infection, goats actively selected M. bahamensis (high CT, low CP content) and V. dentata (negligible CT, high CP content) but avoided G. floribundum (high CT, low CP content) and L. leucocephala (medium CT and high CP content). Thus, natural GIN infection did not influence goats' foliage selection.

Anthelmintic activity of acetone-water extracts against Haemonchus contortus eggs: interactions between tannins and other plant secondary compounds

This study aimed at (i) describing the effects of acetone-water extracts obtained from a range of different plant materials, on the hatching process of Haemonchus contortus eggs under in vitro conditions and (ii) identifying the role of tannins and other plant secondary compounds (PSC), on these AH effects by using polyvinylpolypyrrolidone (PVPP), an inhibitor of tannins and other polyphenols. An egg hatch assay (EHA) was used to determine the AH effect. Acetone-water (70:30) extracts from different foliages (Lysiloma latisiliquum, Laguncularia racemosa, Rizophora mangle, Avicennia germinans) and plant by-products (Theobroma cacao seed husk and pulp, and percolated Coffea arabica) were obtained. Fresh H. contortus eggs were incubated in PBS with increasing concentrations of each extract (0, 600, 1200, 2400 and 3600 μg/ml PBS). A general linear model was used to determine the dose effect of each extract. A mild ovicidal activity was only recorded for T. cacao extracts (seed husk and pulp). The main anthelmintic (AH) effect for all the extracts, except for C. arabica, was to block the eclosion of larvated eggs. The use of PVPP at 3600 μg/ml PBS showed that tannins of the L. racemosa extract were responsible for blocking eclosion of larvated eggs. Extracts of L. latisiliquum, A. germinans, T. cacao seed husk and pulp also blocked eclosion of larvated eggs but the addition of PVPP indicated that tannins were not responsible for that activity. In contrast, it suggested unfavorable interactions between polyphenols and other PSC contained in those extracts, limiting the AH effect on the egg hatching process. The present results suggest that the interactions between tannins and other PSC are complex and may reduce the AH effects against H. contortus eggs.

Tannin containing legumes as a model for nutraceuticals against digestive parasites in livestock

Parasitic infections with gastrointestinal nematodes (GINs) still represent a worldwide major pathological threat associated with the outdoor production of various livestock species. Because of the widespread resistance to synthetic chemical anthelmintics, there is a strong impetus to explore novel approaches for a more integrated management of these infections. The use of nutraceuticals in the control of GINs is one of the alternatives which has been widely studied for 20 years. The objectives of this review are: (i) to define and illustrate the concept of 'nutraceutical' in the context of veterinary parasitology based on data obtained on the most studied models to control GINs in small ruminants, the tannin-containing legumes (Fabaceae); (ii) to illustrate how the 'nutraceutical concept' could be expanded to other plants, other livestock production systems and other GI parasitic diseases, and (iii) to explain how this concept is opening up new research fields for better understanding the interactions between the host, the digestive parasites and the environment.

Estimating Apparent Nutrient Digestibility of Diets Containing Leucaena leucocephala or Moringa oleifera Leaf Meals for Growing Rabbits by Two Methods

This study aimed to evaluate the nutrient digestibility of growing rabbits fed diets with different levels of either Leucaena leucocephala (LLM) or Moringa oleifera (MOLM) leaf meals and also to compare total collection and TiO₂ marker methods for estimating digestibility. A total of 30 California growing rabbits (1.81±0.19 kg live weight on average) were randomly distributed into five experimental groups of six rabbits each and were housed in individual cages. The groups were control, 30% LLM, 40% LLM, 30% MOLM, and 40% MOLM. All groups received pelleted diets for two weeks; diets also contained 4 g/kg titanium dioxide as dietary marker. Daily feed intake was recorded during the whole experimental period and total feces were collected daily and weighed individually during four days. The results showed that there were no difference (p>0.05) in feed, dry matter (DM), organic matter (OM), crude protein (CP), digestible energy, and crude fiber (CF) intake between the control group and the other experimental groups. The apparent digestibility values of DM, OM, CP, CF, acid detergent fiber, and gross energy were the highest for control group (p = 0.001), meanwhile MOLM diets had generally higher nutrient digestibility coefficients than LLM diets. Increasing the inclusion level of leaf meal in the diet from 30% to 40% improved the digestibility of CF from 45.02% to 51.69% for LLM and from 48.11% to 55.89% for MOLM. Similar results for apparent nutrient digestibility coefficients were obtained when either total collection or indigestible marker method was used. In conclusion, the digestibility of MOLM containing diets were better than LLM diets, furthermore TiO₂ as an external marker could be used as a simple, practical and reliable method to estimate nutrients digestibility in rabbit diets.

Comparing different maize supplementation strategies to improve resilience and resistance against gastrointestinal nematode infections in browsing goats

The effect of maize grain supplementation on the resilience and resistance of browsing Criollo goat kids against gastrointestinal nematodes was evaluated. Five-month-old kids (n = 42), raised worm-free, were allocated to five groups: infected + not supplemented (I-NS; n = 10), infected + maize supplement at 108 g/d (I-S108; n = 8), maize supplement at 1% of body weight (BW) (I-S1%; n = 8), maize supplement at 1.5% BW (I-S1.5%; n = 8), or infected + supplemented (maize supplement 1.5% BW) + moxidectin (0.2 mg/kg BW subcutaneously every 28 d) (T-S1.5%; n = 8). Kids browsed daily (7 h) in a tropical forest for 112 days during the rainy season. Kids were weighed weekly to adjust supplementary feeding. Hematocrit (Ht), hemoglobin (Hb), and eggs per gram of feces were determined fortnightly. On day 112, five goat kids were slaughtered per group to determine worm burdens. Kids of the I-S1.5% group showed similar body-weight change, Ht and Hb, compared to kids without gastrointestinal nematodes (T-S1.5%), as well as lower eggs per gram of feces and Trichostrongylus colubriformis worm burden compared to the I-NS group (P > 0.05). Thus, among the supplement levels tested, increasing maize supplementation at 1.5% BW of kids was the best strategy to improve their resilience and resistance against natural gastrointestinal nematode infections under the conditions of forage from the tropical forest.

A tannin-blocking agent does not modify the preference of sheep towards tannin-containing plants

Sheep have been suggested to use their senses to perceive plant properties and associate their intake with consequences after ingestion. However, sheep with browsing experience do not seem to select against tannin-rich browsing materials in cafeteria trials. Thus, the objective of the present study was to evaluate the relationship between the chemical composition, selectivity index (SI), preference and intake rate (IR) of tannin-containing forage trees offered to sheep in cafeteria experiments. Four trees were selected for their condensed tannin content and their varying biological activities. Havardia albicans (high biological activity), Leucaena leucocephala (medium biological activity), Acacia gaumeri (low biological activity) and Brosimum alicastrum (very low biological activity) were used in this study. Ten hair sheep (23.7kg±1.43LW) with eight months of browsing experience in native vegetation were used in this study. Polyethylene glycol (PEG 3600MW) was administered to five sheep during all experiments. In experiment 1, fresh foliage from all trees was offered ad libitum for 4h. In experiment 2, B. alicastrum was withdrawn and the preference was determined again. The forage preference in experiment 1 was A. gaumeri (14.77gDM/kgLW)>B. alicastrum (11.77gDM/kgLW)>H. albicans (3.71gDM/kgLW)=L. leucocephala (1.87gDM/kgLW) (P<0.05). The preference in experiment 2 was A. gaumeri>H. albicans=L. leucocephala. PEG administration had no effect on the preference or IR. The intake rate seemed to have been affected by the plant density. Moreover, fiber compounds were found to be better predictors of DM intake than polyphenolic compounds at levels typically found in the evaluated forages. It was concluded that tannins and PEG did not modify the preferences of sheep in cafeteria trials. Thus, tannins are not involved in the preference regulation of animals with browsing experience.

Nutrient Digestibility and Metabolizable Energy Content of Mucuna pruriens Whole Pods Fed to Growing Pelibuey Lambs

The nutrient digestibility, nitrogen balance and in vivo metabolizable energy supply of Mucuna pruriens whole pods fed to growing Pelibuey lambs was investigated. Eight Pelibuey sheep housed in metabolic crates were fed increasing levels of Mucuna pruriens pods: 0 (control), 100 (Mucuna100), 200 (Mucuna200) and 300 (Mucuna300) g/kg dry matter. A quadratic (p<0.002) effect was observed for dry matter (DM), neutral detergent fibre (aNDF), nitrogen (N) and gross energy (GE) intakes with higher intakes in the Mucuna100 and Mucuna200 treatments. Increasing M. pruriens in the diets had no effect (p>0.05) on DM and GE apparent digestibility (p<0.05). A linear reduction in N digestibility and N retention was observed with increasing mucuna pod level. This effect was accompanied by a quadratic effect (p<0.05) on fecal-N and N-balance which were higher in the Mucuna100 and Mucuna200 treatments. Urine-N excretion, GE retention and dietary estimated nutrient supply (metabolizable protein and metabolizable energy) were not affected (p>0.05). DM, N and GE apparent digestibility coefficient of M. pruriens whole pods obtained through multiple regression equations were 0.692, 0.457, 0.654 respectively. In vivo DE and ME content of mucuna whole pod were estimated in 11.0 and 9.7 MJ/kg DM. It was concluded that whole pods from M. pruriens did not affect nutrient utilization when included in an mixed diet up to 200 g/kg DM. This is the first in vivo estimation of mucuna whole pod ME value for ruminants.

Scanning electron microscopy of Haemonchus contortus exposed to tannin-rich plants under in vivo and in vitro conditions

The structural changes induced in adult Haemonchus contortus after in vitro and in vivo contact with a tannin-rich (TR) plant, either tzalam (Lysiloma latisiliquum) or sainfoin (Onobrychis viciifolia), were assessed using scanning electron microscopy (SEM). All the worms used in the study were adult females. The Haemonchus adult worms were obtained from the abomasum of infected donor goats. Adult H. contortus were kept in contact with the extracts of TR plants for 24h for the in vitro assays and were compared to worms maintained in PBS (control). For the in vivo studies, the adult H. contortus parasites were obtained from artificially infected goats. All the goats were fed a tannin-free diet until D27 post-infection when infection was patent. On D28 some goats were fed fodder of one of the TR plants for seven consecutive days. Thus, their H. contortus were in contact with TR fodder within the gastrointestinal tract. The control worms were obtained from goats fed only a tannin-free diet. In the in vitro assays and in vivo studies, the SEM observations revealed structural alterations in the worms after contact with TR plants when compared to the control worms (i.e.: longitudinal and transversal folds and thicker cuticular ridges, material aggregates around the buccal capsule and/or vulva or anus). The main changes concerned the cuticle and the buccal area. The structural changes found in the worms exposed to TR plants might affect their motility and nutrition with possible consequences on their reproduction, as suggested by previous in vivo trials.

Direct and indirect effects of bioactive tannin-rich tropical and temperate legumes against nematode infections

Parasitic infections with gastrointestinal nematodes (GINs) represent a major pathological threat associated with the outdoor production of various livestock species. Up to now, the control of these parasitic diseases essentially relied on the use of commercial anthelmintic drugs. However, resistance to anthelmintics is nowadays widespread in worm populations. Recent results indicate that bioactive tanniniferous plants represent a valuable option as an alternative to commercial drugs for the control of GINs. The pertinent use of tannin-containing fodders as nutraceuticals supposes a clear understanding of the mode of action against the worms. The objectives of this paper are: (1) to discuss the nature and quantity of the active molecules involved in the anthelmintic activity; and (2) to review and analyze the changes provoked to the various parasitic stages. The possible involvement of some main polyphenols to explain the bioactivity of some tannin-rich plants will be discussed as well as the possible effects on the various nematode stages, relying on data obtained either with the temperate forage, sainfoin (Onobrychis viciifoliae) or with the tropical legume tree (Lysiloma latisiliquum). The information on the mode of action will be related to the potential consequences for better field applications under entirely different environmental and ecological conditions of productions.

Persistence of the efficacy of copper oxide wire particles against Haemonchus contortus in sheep

The aim was to determine the persistent efficacy of copper oxide wire particles (COWP) against Haemonchus contortus in sheep, using the harmonization guidelines protocol. Thirty-six male lambs (2 months old) reared free of gastrointestinal nematodes were used (average body weight of 10.8±3.8kg). Before and for the duration of the study, lambs were kept in raised cages with slatted floors and were offered ad libitum a complete mixed diet. Animals were divided into six groups (n=6): one non-treated control group (G0) and five groups treated with one COWP capsule (1.7g of copper oxide; Copinox(®)). Animals in each group were treated on pre-defined dates before the artificial infection was applied: days -35 (G1), -28 (G2), -21 (G3), -14 (G4) and -7 (G5). On day 0 animals were infected with 3700 H. contortus infective larvae per animal. Animals were humanely slaughtered between days 22 and 23 post-infection. The abomasums were individually washed to obtain the contents. These organs were subjected to separate artificial digestions. Adult parasites were counted from the abomasum contents and the larvae from the digested material. Worm burden geometric means were calculated for each group. A significant worm burden reduction in either of the treated groups (G1, G2, G3, G4, and G5) compared to the control (G0) was considered as persistence of the anthelmintic effect. Copper levels were determined from individual liver samples of each animal. The geometric mean worm burden of the control group (G0) was 1959. Compared to the control, worm burdens geometric means were significantly reduced in groups G1 (1108), G4 (528) and G5 (1063) (P<0.03). Efficacies in G1, G4 and G5 were 43.4%, 73.0% and 45.7% respectively. No significant reduction was found for G2 (1342) and G3 (1430). A larger quantity of Cu was found in the livers of treated animals compared to the control group (P<0.05) except for G3 (P=0.06). A negative association between Cu liver content and worm burdens was found (r=-0.42, P<0.05). Live weight gain was similar in all groups and no clinical or post-mortem manifestations of Cu toxicity were recorded in treated animals.

In vitro acaricidal effect of tannin-rich plants against the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The objectives of this study were to evaluate the in vitro acaricidal effects of lyophilized extracts of four tannin rich plants (Acacia pennatula, Piscidia piscipula, Leucaena leucocephala and Lysiloma latisiliquum) against diverse stages of Rhipicephalus (Boophilus) microplus, and to asses whether tannins were involved in the acaricidal effect using polyethylene glycol (PEG) to block tannins. Larval immersion (LIT) and adult immersion (AIT) tests were used to evaluate the acaricidal effect of each of the lyophilized extracts against larval and adult stages of R. microplus respectively. Larvae and adult ticks were exposed to increasing concentrations of each plant extract (0, 1200, 2400, 4800, 9600 and 19,200 μg ml(-1)) for 10 min. Larval mortality was recorded at 48 h post-incubation. Adult mortality was recorded daily over 14 days, at which point their reproductive efficiency was evaluated. PEG was added to the extracts to verify whether tannins were involved in the acaricidal effect. The effect on egg laying inhibition and larval mortality was analyzed using the GLM procedure in SAS. A Kruskal-Wallis test was used to assess the effect of PEG on LIT results. Calculation of the lethal concentration 50 (LC50) was performed using a probit analysis. All extracts reduced the viability of R. microplus larval stages (P<0.001), and viability was restored with the addition of PEG suggesting an important role of tannins in the acaricidal effect (P<0.001). The LC50 values of L. latisiliquum and P. piscipula plant extracts were 6.402 and 2.466 μg ml(-1). None of the tannin-rich plant extracts affected adult mortality (P>0.05). Lysiloma latisiliquum extract inhibited egg hatching of R. microplus (P<0.01). Tannin-rich plant extracts from A. pennatula, P. piscipula, L. leucocephala and L. latisiliquum showed potential acaricidal activity. Further in vivo studies are needed to confirm this finding.

Effect of a tropical tannin-rich plant Lysiloma latisiliquum on adult populations of Haemonchus contortus in sheep

Bioactive plants with anthelmintic (AH) properties represent a promising alternative solution to chemical treatments. The AH effect of several Mexican tannin-rich (TR) plants has been screened in vitro. The in vivo AH effect of one TR legume, Lysiloma latisiliquum (Tzalam) on nematode larval establishment was confirmed. The present trial aimed at evaluating the direct and indirect effects of L. latisiliquum fodder consumption on adult Haemonchus contortus. Twenty-two parasite-naïve hair sheep lambs were allocated to an infected group (I) (400H. contortus L(3)/kg BW on D0) and a non-infected group (NI). From D0 to D28 post infection (PI), all the lambs were fed a complete diet. On D28, the two groups were sub-divided into four groups. Two control (C) groups maintained on the original basal diet (CI: 6 infected lambs and CNI: 5 non-infected lambs). The two treatment groups (T) received L. latisiliquum fodder ad libitum up to D36 when lambs were humanely slaughtered (TI: 6 infected lambs and TNI: 5 non-infected lambs). From D28 to D36 PI, individual fodder consumption and nematode egg excretion were measured daily. At necropsy, abomasal contents were recovered to obtain worm burdens and measure the female worm length and fecundity. Histological samples were taken from the respective abomasums and small intestines to count mucosal inflammatory cells. An increased consumption of TR fodder was observed in the TI vs. the TNI group (P<0.01). Before L. latisiliquum distribution, faecal egg excretion was similar in TI and CI groups. From D29 PI the TI group showed lower faecal egg counts compared to CI group (P<0.02). Although no differences in worm burdens were observed, worms of the TI group were smaller and, according to their size, contained fewer eggs in utero than worms from the CI group (P<0.05). Only minor differences in mucosal inflammatory cells were observed between groups, indicating that the indirect effect was not evident. Thus, a short-term consumption of L. latisiliquum can modulate directly the biology of adult H. contortus affecting the worm size and female fecundity while the worm burdens were not affected. Infected animals ate more L. latisiliquum fodder than non-infected animals.

Effect of the consumption of Lysiloma latisiliquum on the larval establishment of gastrointestinal nematodes in goats

The consumption of tannin-rich (TR) forages has been associated with negative effects against gastrointestinal nematodes and with an improved host resilience. It has been hypothesized that tannins affect the capacity of infective larvae to establish in the mucosae of the host. In this study, we aimed at testing this hypothesis using Lysiloma latisiliquum, a tropical TR tree. The objectives were: (i) to evaluate the effect of the consumption of L. latisiliquum on the establishment of nematode third-stage larvae (L3) in goats; (ii) to define the role of tannins in these effects in vivo by using an inhibitor (polyethylene glycol, PEG); and (iii) to examine a possible indirect effect of tannins on the inflammatory response in the digestive mucosa. Eighteen Criollo goats composed three experimental groups. The control group received fresh leaves of Brosimum alicastrum, a plant with a low level of tannins. Two groups received L. latisiliquum leaves either with (L.L.+PEG) or without (L.L.) daily addition of 25 g PEG. After a 7-day adaptation period, each goat was infected with both Haemonchus contortus and Trichostrongylus colubriformis (3000 L3 per species). The goats were slaughtered 5 days after infection and worm counts and histological analyses were performed. No difference in the voluntary feed intake of foliage was observed between the 3 groups. The consumption of L. latisiliquum significantly reduced the larval establishment of both nematode species compared to the control (P<0.01). For both worm species, the effects were totally alleviated with PEG (L.L.+PEG group), suggesting a major role of tannins in the observed effects. Only minor differences in the mucosal cellular response were observed between the 3 groups. These results confirm that the consumption of TR plants reduces the establishment of nematode larvae in the host and that a direct effect is principally involved.

Combining the effects of supplementary feeding and copper oxide needles for the control of gastrointestinal nematodes in browsing goats

The aim was to assess the benefits obtained from combining supplementary feeding and copper needles (COWP), compared to the use of both approaches independently, for the control of gastrointestinal nematode (GIN) infections in browsing kids. Forty-four nematode free Criollo kids were exposed to natural parasite infection. The kids were divided into six experimental groups: not treated, supplemented (NT-S), not treated, not supplemented (NT-NS), moxidectin treated, supplemented (M-S), moxidectin treated not supplemented (M-NS), copper treated, supplemented (COWP-S) and copper treated, non-supplemented (COWP-NS). Copper treated groups received Copinox (2 g capsules) on day 0 and on day 60 of the trial. Moxidectin treated groups received Cydectin (0.2 mg/kg of body weight s.c.) every 28 days. Three of the groups received individual supplementation (100 g of feed/day fresh basis; 74% sorghum: 26% soybean meal; NT-S, M-S and COWP-S) and the other three groups were not supplemented (NT-NS, M-NS and COWP-NS). Animals browsed native vegetation (6.5 h/day) during the wet season (154 days). Kids were weighed every 14 days to determine live weight gain (LWG) and blood and faecal samples were obtained to determine packed cell volume (PCV), haemoglobin (Hb), peripheral eosinophil counts (PEC) and faecal egg counts (FEC). At the end of the trial, four kids of each group were euthanatized (six kids in each COWP treated group). Worm burdens, female worm lengths and prolificacy were determined. Liver samples were used to determine copper concentration and were stained with haematoxylin-eosin to determine microscopic lesions. Animals receiving the combination of supplementary feeding and COWP improved their LWG, PCV and Hb to similar levels of animals with suppressive AH treatment. This was not the case when COWP was used without supplementation. Liver copper concentration in COWP treated groups increased significantly especially in the COWP-NS kids but this was not associated with liver lesions or clinical signs. Post-mortem Haemonchus contortus and Trichostrongylus colubriformis worm counts had a tendency to be reduced in the different groups (66-35% reduction) compared to NT-NS group at the end of the trial (P>0.05). Also, COWP treatment and/or supplementation reduced female worm length of T. colubriformis and prolificacy of H. contortus and T. colubriformis. This study, confirmed the value of nutritional supplementation in the control of GIN in growing kids. The use of COWP in addition to supplementation had a limited contribution on the kids' resilience against GIN. This may be due to the reduced infection of H. contortus during this trial.

Technical note: Calibration of a simple udder volume measurement technique

A simple technique to measure udder volume in dairy cows using aluminum foil was developed and used to characterize empty udder volume (EUV) in a dual purpose herd (Bos taurus x B. indicus). The technique was calibrated by comparing cows' actual milk yield with the difference between its EUV and full udder volume (FUV). The resulting relationship was: Actual milk volume = 0.718(+/-0.9568) + 0.954(+/-0.0775) * (Calculated milk volume), R2 = 0.949. In 24 lactating cows, EUV was correlated with calving number and milk yield. Estimated mammary parenchyma productivity was 1.85 +/- 0.117 ml/L of EUV. The technique developed is a quick, cheap and yet precise alternative to measure udder volume.