Papers by J. Torres-acosta
ABSTRACT The use of rangeland is one of the elements that make possible goat production in many p... more ABSTRACT The use of rangeland is one of the elements that make possible goat production in many parts of Mexico. Goats pose anatomic and physiological adaptations, as well as an adapted ruminal and intestinal flora that allow them to make an efficient use of available plants in the native rangeland. These plants contain a range of secondary compounds that permit them to defend from herbivores. Among the important secondary compounds are the tannins. When animals exceed certain amount of these compounds during herbage intake, negative effects are found on health and animal production. However, tannins consumed in low quantities can encompass positive effects on animal production. In fact, goats are willing to ingest tanniniferous plants even when they have the opportunity to choose other more digestible and nontanniniferous plants. This permit goats to use these plants as a source of basic nutriments for their survival and production, taking advantage from the benefits of tannins (as anti-tympanic or to increase the amount of bypass protein). At present, another beneficial effect of tannins has been found: their direct and indirect anthelmintic (AH) effect. Several researchers have advocated to the study of this AH effect on ruminants´ parasites. However, before proposing its use as AH, its mechanism of action on parasites should be investigated. Furthermore, the effective dose that affects to parasites but not to the intake and digestion of goats, as well as the organoleptic characteristics of the carcass should also be determined.
Small Ruminant Research, 2015
ABSTRACT This study estimated the frequency of anthelmintic (AH) treatments in sheep from commerc... more ABSTRACT This study estimated the frequency of anthelmintic (AH) treatments in sheep from commercial flocks using a targeted selective treatment scheme based on FAMACHA©, body condition score (BCS) and faecal egg counts (FEC) in a hot and humid tropical area. An initial survey of the faecal material of adult hair-sheep ewes (n = 401) from four farms showed a high proportion of ewes with zero eggs per gram of faeces (EPG) (32.7 to 61.0%), an over-dispersed distribution of EPG (skewness from 2.32 to 5.67) and a small proportion of ewes excreting ≥750 EPG (from 9.2 to 25.0%) or ≥1000 EPG (from 5.0 to 19.6%). The TST scheme included 918 ewes inspected individually every two weeks over a six-month period (rainy season). Ewes with FAMACHA© 4,5 and BCS 1,2 scores were faecal sampled to estimate the number of GIN eggs per gram of faeces (EPG). Ewes with EPG ≥750 were dewormed. From the 981 ewes evaluated monthly, 65.5% did not require any AH treatment. The proportion of ewes requiring a single AH treatment was 17.8%. Meanwhile, 8.3% required two, 4.5% three, and 3.9% four or more AH treatments. Variability of sensitivity and specificity suggested that either FAMACHA© 4-5, BCS 1-2 or BCS 1 alone were not good enough to predict which ewes had a GIN egg excretion ≥750 EPG. Faecal examination remained essential to identify animals with significant GIN infections. Thus, the combination of FAMACHA©, BCS and EPG helped to avoid unnecessary AH treatments of anaemic or emaciated ewes with negligible GIN infections. The TST scheme suggested that few ewes require an AH treatment under the warm, humid tropical conditions of Tabasco, Mexico. Thus, current monthly mass AH treatment of all ewes seems unnecessary.
Journal of Applied Animal Research, 2015
Veterinary Parasitology, 2015
This study reports the percentage of cattle farms with ivermectin (IVM) resistant gastrointestina... more This study reports the percentage of cattle farms with ivermectin (IVM) resistant gastrointestinal nematodes (GINs) in Veracruz, Mexico, and identifies the GIN genera involved in the resistances. It also describes management practices of anthelmintic (AH) use on the surveyed farms. Twenty-one farms were assessed by means of the faecal egg count reduction test using the McMaster technique. Only two farms had GIN populations susceptible to IVM (9.5%). The proportion of farms with IVM resistant GIN was 71.4% (15/21). Seven of these farms had less than 80% egg count reductions. Haemonchus and Cooperia were the genera most commonly found in the resistant populations, followed by Oesophagostomum. Inappropriate AH treatment practices were identified from the completed questionnaires. Further management practices such as selective treatment and quarantine treatments are proposed to further reduce the spread of IVM resistance between farms.
Journal of Medical Entomology
Veterinary Parasitology, 2015
Parasitic infections with gastrointestinal nematodes (GINs) still represent a worldwide major pat... more 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.
Physiology & behavior, Jan 2, 2015
Sheep have been suggested to use their senses to perceive plant properties and associate their in... more 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 (23.7 kg±1.43 LW) with eight months of browsing experience in native vegetation were used in this study. Polyethylene glycol (PEG 3600MW) was administered to five...
Journal of Medical Entomology, 2015
Journal of Helminthology, 2014
An in vivo study in goats evaluated the effect of superimposing a single artificial infection wit... more An in vivo study in goats evaluated the effect of superimposing a single artificial infection with a benzimidazole (BZ)-susceptible Haemonchus contortus isolate upon established H. contortus populations of known BZ resistance by measuring the phenotypic BZ resistance of eggs collected from faeces before and after re-infection. Two H. contortus isolates, one benzimidazole resistant (BZR) and the other susceptible (BZS), were used to infect worm-free goats. Eight goats were initially infected with 2000 third-stage larvae (L3). In each case the inoculum contained a predetermined proportion of the two isolates: 100% BZS (one goat), 75% BZS/25% BZR (two goats), 50% BZS/50% BZR (two goats), 25%BZS/75% BZR (two goats) and, finally, 100% BZR (one goat). The phenotypic BZ susceptibility of the H. contortus population formed in each goat after the first infection was determined on days 30 and 36 post-infection using an egg-hatch assay (EHA) that estimated the concentration of thiabendazole (TBZ) required for 95% inhibition of larval hatching (EC 95 ) with a 95% confidence interval (95% CI). On day 49 post-infection, goats were re-infected with 2000 L3 of the BZS isolate alone. A second set of EHA bioassays was performed 28 days and 34 days after re-infection. The first infection protocol produced three populations classified as BZS (EC 95 0.055-0.065 mg TBZ/ml) while four were categorized as BZR (EC 95 0.122-0.344 mg TBZ/ml). The status of one other population could not be determined. After re-infection with BZS L3, the number of susceptible populations increased to six (EC 95 0.043-0.074 mg TBZ/ml) while the remaining two were deemed resistant (EC 95 0.114-119 mg TBZ/ml). Re-infection with BZS L3 thereby reduced the resistance status of most H. contortus populations.
Veterinary Parasitology, 2008
The anthelmintic (AH) effect of Acacia pennatula, Leucaena leucocephala, Lisyloma latisiliquum an... more The anthelmintic (AH) effect of Acacia pennatula, Leucaena leucocephala, Lisyloma latisiliquum and Piscidia piscipula was evaluated in the infective larvae (L 3 ) of Trichostrongylus colubriformis. Different concentrations of lyophilized extracts were tested using the larval migration inhibition (LMI) test. An inhibitor of tannins (the polyvinyl polypyrrolidone [PVPP]) was used to verify whether these compounds were responsible for the AH effects. Then, the effect of extracts on larval exsheathment was examined by observing the exsheathment process at 10-min intervals for 70 min. The LMI test showed a dose-dependant AH effect for A. pennatula, L. leucocephala and L. latisiliquum (P < 0.01), but not for P. piscipula. The restoration of L 3 migration to values similar to those of controls after the addition of PVPP, indicates that tannins are involved in AH effects. Trichostrongylus colubriformis exsheathment was partially or totally blocked by the four plants extracts. Tropical tanniniferous plants evaluated in the current study may have potential as AH for the control of T. colubriformis if in vivo investigations indicate useful effects. #
Veterinary Parasitology, 2011
The objectives of this study were to evaluate the in vitro acaricidal effects of lyophilized extr... more 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 g 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 g 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.
Small Ruminant Research, 2006
This trial determined the effect of a sustained-release intra-ruminal sodic sulfamethazine (SMZ) ... more This trial determined the effect of a sustained-release intra-ruminal sodic sulfamethazine (SMZ) bolus on the Eimeria spp. oocyst output and the cumulative live-weight gain (CLWG) of naturally infected lambs in two different production systems (penned and penned-grazing). Forty male Pelibuey lambs (2-2.5 months old), naturally infected with Eimeria spp., were randomly included in four groups of 10 animals at weaning: (a) penned with SMZ bolus treatment (P-B), (b) penned untreated (P-U), (c) penned-grazing with bolus treatment (PG-B), and (d) penned-grazing untreated (PG-U). Treated lambs (P-B and PG-B) were dosed orally on day 0 with a single SMZ bolus (28.5% of SMZ). Lambs in the PG-U and PG-B groups were allowed to graze 10 h/day. Faecal samples and live-weights were obtained from each lamb on days 0, 8 and every 7 days until day 57 post-treatment (PT). Oocyst per gram of faeces (OPG) were determined for each animal on the same dates. Mean CLWG and log transformed OPG values were compared within production systems using the Student's t-test. Partial budget analysis was used to evaluate the economic impact of bolus treatment. Untreated animals (P-U and PG-U) showed higher OPG excretion than animals treated with bolus (P-B and PG-B). OPG were reduced in the treated groups of both production systems (P < 0.001), especially in the first 29 days post-treatment. PG-B lambs showed higher CLWG than PG-U lambs (P < 0.05). CLWG of P-U and P-B lambs were similar. Bolus treatment was economically feasible in both systems (PG-B: $1.78 USD/animal and P-B: $0.11 USD/animal). Intra-ruminal SMZ boluses reduced excretion of Eimeria OPG in P-B and PG-B groups; however, CLWG was only improved in PG-B lambs.
Veterinary Parasitology, 2014
Please cite this article in press as: Vargas-Magaña, J.J., et al., Anthelmintic activity of aceto... more Please cite this article in press as: Vargas-Magaña, J.J., et al., Anthelmintic activity of acetone-water extracts against Haemonchus contortus eggs: Interactions between tannins and other plant secondary compounds. Vet. Parasitol. (2014), http://dx.
Veterinary Parasitology, 2012
The development of anthelmintic resistance has impacted on the success of conventional anthelmint... more The development of anthelmintic resistance has impacted on the success of conventional anthelmintics (AH) for the control of gastrointestinal nematodes in grazing/browsing sheep and goats. Medicinal plants from the traditional herbolary in Mexico may provide new candidates that can be explored as alternative sources of AHs for ruminants. This study evaluated the leaf extracts derived from Phytolacca icosandra against infective L 3 larvae and eggs from Haemonchus contortus collected from sheep. Three extracts of different polarities were obtained from the leaf plants using ethanol, n-hexane and dichloromethane as the solvents. The effectiveness of the in vitro AH activity of the plant extracts was evaluated using larval migration inhibition (LMI) and egg hatch (EHA) assays. For the LMI assays, the ethanolic extract of P. icosandra showed 55.4% inhibition of larval migration at 2 mg/mL (p < 0.05). The dichloromethane extract of P. icosandra showed 67.1% inhibition of migration at 3 mg/mL (p < 0.05) and a dose-dependent response with an LD 50 of 0.90 mg/mL. The n-hexane extract failed to show inhibition of larval migration at any concentration explored. In the EHA for the ethanol extract, the lowest concentration tested (0.15 mg/mL) resulted in inhibition of egg hatching greater than 72.6%. Therefore, the LD 50 could not be calculated for this extract. The LD 50 of the dichloromethane extract of P. icosandra was 0. 28 mg/mL. An egg hatch inhibition greater than 90% was observed with both the ethanolic and dichloromethane extracts when using a concentration of 0.90 mg/mL or higher. The n-hexane extract failed to show egg hatch inhibition at any concentration tested. The AH activity reported for P. icosandra could be attributable to the flavonoids, steroids, terpenoids, coumarins and/or saponins that were present in the ethanolic and dichloromethane extracts. A combination of more than one component may also explain the observed AH activity against the H. contortus life stages that were evaluated. In conclusion, the ethanolic and dichloromethane extracts of P. icosandra showed clear in vitro AH activity against the H. contortus eggs and the L 3 larvae. However, the hexanic extract of the plant leaves failed to show any in vitro AH activity.
Veterinary Parasitology, 2012
Parasitic infections with gastrointestinal nematodes (GINs) represent a major pathological threat... more 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.
Veterinary Parasitology, 2012
Gastrointestinal helminth parasites impact on livestock production systems throughout the world, ... more Gastrointestinal helminth parasites impact on livestock production systems throughout the world, and the use of anthelmintics to control this problem has lead to the inevitable development of populations of helminths resistant to these treatments. This, coupled with consumer desires for minimal chemical inputs into food and fibre production, has prompted research into non-chemical approaches to helminth control. Scientists of the &amp;amp;quot;Novel Approaches to the Control of Helminth Parasites of Livestock&amp;amp;quot; group met for the 6th time in August 2010 and this paper summarises that meeting. Six scientific sessions addressed current approaches and topics of interest through formal presentations and discussion of issues raised by the contributing authors. Close interaction between researchers and extension specialists during the meeting has contributed to enhanced prospects for field application of research outcomes in the future.
Veterinary Parasitology, 2011
The present trial aimed at comparing the sensitivity of two in vitro methods, i.e. the larval mig... more The present trial aimed at comparing the sensitivity of two in vitro methods, i.e. the larval migration inhibition assay (LMIA) and the larval exsheathment inhibition assay (LEIA), to evaluate the anthelmintic (AH) properties of tannin-rich plant extracts against Haemonchus contortus infective larvae. The two assays were applied on the same batch of H. contortus infective larvae exposed to water/acetonic extracts obtained from four tropical plants with different tannin contents: Acacia gaumeri, Brosimum alicastrum, Havardia albicans and Leucaena leucocephala. Increasing concentrations (0, 75, 150, 300, 600, 1200 μg/ml PBS) of lyophilized extracts were used in both in vitro assays. A general lineal model test was used to determine the dose-effect in the LMIA or the difference in the percentage of exsheathed larvae between the respective control and treated groups. The LMIA showed a dose-dependent AH effect for H. albicans (P&amp;amp;amp;amp;amp;amp;lt;0.001) and A. gaumeri (P&amp;amp;amp;amp;amp;amp;lt;0.05), but not for L. leucocephala and B. alicastrum. In contrast, the exsheathment process was significantly affected by all doses of H. albicans and A. gaumeri extracts and a significant dose-dependent effect was found for B. alicastrum and L. leucocephala. Calculation of lethal dose (LD) was possible with LEIA using B. alicastrum and L. leucocephala but not with H. albicans and A. gaumeri as the lowest tested concentration was achieving more than 50% inhibition. Calculation of LD with the LMIA results was not feasible. These results suggest that tannin-rich plant extracts are more potent inhibitors of the exsheathment of H. contortus L(3) larvae than their motility. This information underlines the difference of sensitivity between methodological procedures to evaluate the AH properties of plant extracts on the same nematode stage.
Veterinary Parasitology, 2011
The aim was to determine the persistent efficacy of copper oxide wire particles (COWP) against Ha... more 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 ± 3.8 kg). 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 (1.7 g 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.
Veterinary Parasitology, 2006
This paper focuses on targeted nutritional supplementation as a means to reduce the requirement f... more This paper focuses on targeted nutritional supplementation as a means to reduce the requirement for chemotherapeutic control of gastrointestinal nematode infection of small ruminants and considers the limitations to practical application. Supplementary feeding, particularly with additional dietary protein, can assist resilience to infection during times when metabolic resources are being directed towards dealing with the pathophysiological effects of infection and away from production of meat, milk and fibre. Substantial experimental evidence from studies of both sheep and goats supports this hypothesis particularly in relation to young lambs and kids after weaning and in ewes around parturition. In addition, nutritional supplementation frequently increases resistance to infection, as indicated by decreased faecal worm egg counts and worm burdens. As a result, supplementation has the potential to reduce the requirement for anthelmintic treatment. Practical application of this knowledge can, however, be quite complex in many small ruminant production systems. In general, strategic supplementation should target those times when nutrient requirements are greatest and provide those nutrients which are deficient whether protein, energy, minerals or trace elements. Complexity arises when we consider that nutrient requirements will differ between localities for different species and breed of host, at different stages of growth and reproduction, with differing seasonal availability of forage, with different species of nematodes and different levels of established infections and exposure to infective stages. As a starting point, the provision of nutrients to optimize rumen function and animal performance in the particular production system should assist in maintaining resilience to nematode infection. Provision of nutrients in excess of this requirement, if economically feasible, may yield further benefits in some situations and reduce the need for alternative control measures for gastrointestinal nematode parasites. #
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Papers by J. Torres-acosta