Observations on endoparasitic load in captive reared agoutis (Dasyprocta leporina) without anthelmintic exposure in Trinidad, Republic of Trinidad and Tobago

Kegan Romelle Jones and Gary Wayne Garcia

The Open Tropical Forage-Animal Production Laboratory [OTF-APL], Department of Food Production [DFP], Faculty of Food and Agriculture [FFA],
The University of the West Indies [UWI], St Augustine, Trinidad and Tobago.
keganjones11@gmail.com

Abstract

This study was conducted on Agouti animals reared in captivity at the Sugarcane Feed Centre in Trinidad. The agouti is a neo-tropical rodent that has been reared intensively in Trinidad and Tobago by farmers. Gastrointestinal contents were taken from ten (10) male agoutis approximately four years of age. The contents were examined for gastrointestinal parasites using faecal floatation techniques. In the study two helminths and one protozoon were found in the digestive tract; these were Trichuris spp., Strongyloides spp. and Eimeria spp.

The average faecal egg counts of the infected agoutis were Trichuris spp. 220 (± 130) egg per gram, Strongyloides spp. 428 (±558) egg per gram and Eimeria spp. 2150 (±2358) oocysts per gram. Of the animals sampled 40% were positive for gastrointestinal parasites. The animals in this study had an average live weight of 2.34 (±0.25) kg and an average body condition score of 3 out of 5. To the authors’ knowledge this is the first time that work has been done on the parasitic load of gastrointestinal parasites in the Agouti (Dasyprocta leorina). The findings of this study showed that even at the parasitic loads recorded no effects on the animals’ body condition score or live weight were observed.

Key words: Eimeria spp, faecal egg count, Strongyloides spp, Trichuris spp

Introduction

The agouti (Dasyprocta leporina) is one of several neo-tropical animals which have not been domesticated but which possess the potential for domestication (Brown-Uddenburg et al 2004). The production of this animal can aid in the conservation and utilization of this species. At present there is a dearth of information on the biology of this animal. Recently, Lall et al (2018) reviewed the feeding habits of the agouti and they were classified as frugivores. The majority of their diet consisted of fruits and seeds with the minor components found to be fibre, leaves and animal matter (Henry 1999). Further work done by Garcia et al (2000) noted that these animals had a large caecum with the majority of its gastrointestinal tract consisting of its small intestines. A recent publication by Figueira et al (2014) indicated that this animal ate carrion which suggested that this animal also had omnivorous eating habits. Recent personal observations by the authors of this paper have indicated that the agouti if put under dietary stress in captivity would become cannibalistic and eat each other from the ventral side of the body. Most of the research work done on the agouti in the Caribbean and South America investigated its reproductive aspects. Mollineu et al (2012) investigated the male reproductive system while the female reproductive system has been investigated in Trinidad and Tobago by Singh et al (2014) and in Brazil by Guimares et al (2011).

With the recent knowledge of the parasites found in the gastrointestinal tract of this agouti, little is still known about the effects of these organisms on the animals and level of infestation present in these animals. Therefore, the objectives of this study were to (1) identify what parasites were present in a captive reared agoutis colony which were never exposed to anthelmintic drugs and (2) to quantify the level of infestation of these gastrointestinal parasites within these animals.

Methodology

Ten (10) physically healthy adult male animals approximately four years of age were collected from the floor pens at the Sugarcane Feed Centre, Longdenville, Trinidad and Tobago in April 2018. Animal were weighed and had weights ranging from 2.05 kg to 2.77 kg. All animals were examined and a body condition score was given and recorded. The body condition score of each agouti was done using similar methods as used in mice (Ullmann and Foltz 1999). Animals were sacrificed humanely according to Veterinary standards in Trinidad and Tobago.

The digestive tracts of the animals were removed and each segment of the digestive tracts was tied off (stomach, small intestine, colon, rectum and caecum). Each segment of digestive contents were placed in ice and stored at 4⁰C before analysis. Intestinal contents were analysed at the open school of forage and production lab in Barataria, Trinidad. The intestinal mucosa and digestive contents were examined to identify adult helminths and the contents were sieved for identification of adult helminths. Floatation solution (Saturated Sodium Chloride) with a specific gravity of 1.21 was added to the gastrointestinal contents. This mixture was then allowed to settle in a faecalyser^® for 15 minutes before being placed in McMaster Slides for quantification and identification (Hendrix and Robinson 2017).

Animals’ diet consisted of local feedstuff including pumpkin (Cucurbita pepo), mangoes (Mangifera indica), cassavas (Manihot esculenta) and papaya (Asimina triloba). These animals were never given anthelmintic drugs during their life time. Statistical analysis was done using Microsoft Excel ^® 2007 for calculations of Means and Standard deviation of faecal egg count.

Results

This investigation showed that two helminths and one protozoon parasite were found in the digestive tract of the agouti. Trichuris spp., Strongyloides spp and Eimeria spp. eggs were observed in the digestive contents of the agouti. Of the ten (10) animals sampled, four (4) were positive for parasitic eggs giving a prevalence of 40%. No adult helminths were seen in the digestive contents or attached to intestinal mucosa. The prevalence for Trichuris spp., Eimeria spp. and Strongyloides spp. at the Sugarcane Feed Centre was found to be 30% (3/10), 40% (4/10) and 40% (4/10) respectively (Table 1).

Of the three (3) infected agoutis with Trichuris spp. the mean faecal egg count was 220 eggs per gram (epg) and ranged from 50-400 epg. Eimeria spp. was found in 40% of samples, had an average faecal egg count of 2150 oocyst per gram (opg) and ranged from 350 – 7770 opg. Strongyloides spp. was found in 40% of the samples, had an average faecal egg count of 428 epg and ranged from 50-1500 epg (Table 2).

No eggs were found in stomach or small intestines and no adult worms were observed in the gastrointestinal contents. However in the caecum, colon and rectum parasitic eggs were present. Three (3) of the four (4) infected animals (75% of infected samples) were infected with the three (3) parasites found (Eimeria spp., Trichuris spp. and Strongyloides spp.). The ten (10) animals sampled had live weights that ranged from 2.05 kg to 2.77 kg and were in good body condition (BCS 3 of 5) (Table 3). Animals had no clinical signs of illness and no history of gastrointestinal disease.

Discussion

In the animals sampled at the Sugarcane Feed Centre the prevalence of gastrointestinal parasites was found to be 40% (4/10). In a similar survey done in Trinidad, the island’s prevalence (of 65 animals sampled) was found to be 44.6% (Jones and Garcia 2017). Jones and Garcia (2018) suggested that a parasite was defined as “an organism which is present in the host and is metabolically dependent causing decreased production which may manifest clinically or sub-clinically” . Gastrointestinal parasites in the agouti were found in Rio Gande do Sol, Brazil (da Silva et al 2008), Piaui, Brazil (de Mendonca et al 2006), Para, Brazil (Lainson et al 2010) and in the State of Amazonas Brazil (Goncalves et al 2006). In Trinidad and Tobago parasites in wild agoutis have been identified by Suepaul et al (2016) and Cameron and Reesal (1951) and in captive reared animals (Jones and Garcia 2017). In rabbits Eimeria spp. was reported to be a parasite of high economic importance (Aubert et al 2003). However, Eimeria spp. was found in this study but had no negative effect on the agouti with respect the animals’ body condition. The rabbit was reported to be a similar animal to the agouti with respect to its size, digestive anatomy and caecotrophic behaviour. The publication herein was the first document that recorded quantitative data of gastrointestinal parasites of the Agouti ( Dasyprocta leporina). Of the agoutis’ sacrificed in this study none showed clinical sign of gastrointestinal illnesses and had an average body condition score of three (3). This showed that the parasites present in the gastrointestinal tract had no effect on the agouti’s digestive health and body condition. Rabbits with high infestation of endoparasites were reported to have poor body conditions, diarrhoea and ruffled hair coats (Eira et al 2007; Molina et al 1999). Aubert et al (2003) further stated that coccidia accounted for the majority of the parasitic disorders in rabbits causing diarrhoea, decreased feed conversion and mortality. Gastrointestinal parasites in rabbits were reported to be responsible for significant morbidity characterized by a decrease in weight gain and poor feed conversion (Licois 2004). Rabbits treated with anthelminthic and coccidiostats produced more off-springs per female as compared to the untreated group (Yuill 1864).

Similar work was done on lappe (Agouti paca) reared semi-intensively and Trichuris spp., Strongyloides spp. and Eimeria spp. were identified in faeces. These parasites were quantified and the faecal egg counts were; Eimeria spp. 6 x10⁴ opg, Trichuris spp. 4.15 x 10² epg and Strongyloides spp. 2.6x 10³ epg (Ribiero et al 2015). The faecal egg load in the lappe was greater than what was found in this study for the agouti but there were no records of the lappes’ body condition. In rabbits Eimeria spp. caused clinical signs such as melena at a faceal egg count of greater than 2.2 x 10⁶ epg (Li and Ooi 2009). Further experiments carried out in rabbits found that at a range of 1.05-4.5 x 10⁴ oocyst per gram produced per day of Eimeria magna will cause weight loss and diarrhoea in the patent period (Bhat and Jithendran 1995). Our data showed that the animals were infected with different parasites (Trichuris spp., Strongyloides spp., and Eimeria spp.). It also showed a different faecal egg count or faecal oocyte count for the above species (Eimeria spp. 2.15x 10³ opg , Trichuris spp. 2.20x 10² epg and Strongyloides spp. 4.28 x10 ² epg) without causing any overt clinical signs of gastrointestinal illness (Table 2). The levels of Eimeria noted in the agouti were less when compared to the rabbit which causes clinical disease (melena). The average live weight of the animals sacrificed was 2.34 kg. According to Costa et al (2004) the average adult male live weight was 2 .5 kg. Therefore animals in this study were in the normal range of adult live weight. However our study showed that the level of Eimeria recorded did not have any negative effect on the animals' body condition as all animals had an average body condition of three out of five. According to Ullman-Cullere and Foltz (1999), mice with a body condition of 3 out of of 5 would have non-prominent vertebral and dorsal pelvic bones but palpable under slight pressure. At the body condition observed the agoutis were well fleshed with lack of bony prominences. This body condition was normal for adult animals as the animals were not emaciated (underweight) or obese (overweight).

In other domesticated species the removal of parasites by anthelmintics has resulted in better animal performance. Cattle which were dewormed had higher weight gain as compared to cattle that were not dewormed in North America (Baltzell et al 2015). Parasite-free pastures cannot be attained but a low level of endoparasitism may be tolerated to allow positive response of the immune system. Economic parasitism was suggested to be subclinical and depressed weight gain, feed consumption, reproductive potential and lactation (Corwin 1997). In sheep treated with anthelmintics higher live weight, greasy wool and lower faecal eggs count were reported (Waruiru et al 2017).

In this study at the Sugarcane Feed Centre there were no adult helminths found but similar work done by Suepaul et al (2016) and past work done by Cameron and Reesal (1951) found adult helminths in wild caught agoutis. Cameron and Reesal (1951) made  an in depth recording of adult parasites found in the gastrointestinal tract of the agouti. The absence of adult helminths in samples may be due to the analysis and handling of the specimens. In this study one can suggest that the predilection sites for Eimeria spp., Trichuris spp. and Strongyloides spp. were the caecum, colon and rectum (large intestines). No eggs were found in the stomach or small intestines in this study and this may suggest that these were not predilection sites for the above parasites in the agouti.

Recent studies have shown that probiotics can be used for the treatment of gastrointestinal parasites. The mechanism of the probiotic was suggested to be similar to that used in the treatment of bacterial diseases (Travers et al 2011). These probiotics have been reported to be beneficial in that they stimulate the host’s immune system, attach to the sites on the gastrointestinal tract leaving limited sites for the attachment of pathogenic organisms and secrete chemicals to inhibit growth of pathogenic bacteria (Travers et al 2011). At this time one is unaware of the relationship of which these organisms (which are classified as parasites in domestic animals such as rabbits) have on the agouti. If one considers that some quantity of these organisms (parasites) are present and play a role in the immune system of the agouti’s gastrointestinal tract, then these organisms may also be binding to sites which will control the proliferation of the more pathogenic organisms. This study showed that the agouti doesn’t require any treatment with anhelmintic to be in good health or in good body condition.

Further studies on the effect of gastrointestinal parasitism in the agouti should be done. It should be directed to the removal of these organisms which are termed parasites and recording the effects on health and production of the animal. Work must also be done to infect the agouti with a known quantity of virulent parasite and note its effects.

Conclusions

• In this study three parasites were found in the gastrointestinal tract of the agouti: Eimeria spp., Trichuris spp. and Strongyloides spp.
  
  
• At the Sugarcane Feeds Centre, Trinidad, Republic of Trinidad and Tobago, the prevalence of gastrointestinal parasites in agouti was found to be 40% (4/10).
  
  
• The parasitic load seemed to have had no effect on the agoutis’ digestive health and body condition.

Acknowledgements

Special thanks go out to Mr. Rajesh Bhajan at the Sugarcane Feed Centre for providing the animals. Without the animals and help this research would not have been possible. Special thanks is also be given to Dr. Kavita Ranjeeta Lall for her moral support and advice during the construction of this manuscript.

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Received 13 September 2018; Accepted 17 September 2018; Published 1 October 2018

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