Feed particle size preference and feed wastage in Agouti (Dasyprocta leporina) reared intensively in the Republic of Trinidad and Tobago

Birendra Dookie, Kegan Romelle Jones, Riyadh Mohammed 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

Increasing demands for agouti meat will eventually lead to a shift from small to large scale production where inefficient feed usage by the animal can result in high production costs. There are currently no commercial feeds designed for agouti which take into consideration the animal’s feeding habits and techniques. This study seeks to take the first step by determining whether or not the agouti exhibits a preference for a particular feed particle size. Twelve agoutis (6 male, 6 female) were offered three different particle sizes of varying thickness (6.35 mm ´ 25.4 mm, 9.53 mm ´ 25.4 mm and 12.7 mm ´ 25.4 mm) simultaneously over a period of seven (7) days and quantity selected was used to determine preference. Wastage of each feed particle size was also evaluated. It was observed the agoutis most preferred the 12.7 mm x 25.4 mm particle and that preference was not affected by gender. The particle size resulting in the least wastage and least likely to slip through the cage flooring was determined to be the 12.7 mm x 25.4 mm particle. This suggests that this may be the minimum sized feed pellet suitable for agoutis in this system.

Key words: behaviour, feed design, feeding habits

Introduction

The agouti (Dasyprocta leporina) is a diurnal neo-tropical animal of the order Rodentia ranging from northern Argentina and Chile to southern Mexico and many Caribbean islands (Smythe 1978; Brown-Uddenburg et al 2004). It is an animal favoured for its meat and therefore possesses the potential for domestication (Mollineau et al 2013). A large proportion of agouti production currently exist as small scale intensive “backyard” systems, grown and maintained using locally available plant materials (fruits, vegetable, forages, tubers). The agouti is generally reported to consume a wide range of fruits and vegetables and is therefore commonly classified as a frugivore (Smythe 1978). Lall et al (2018) reviewed the nutrition and feeding habits of the agouti and considered them a frugivorous monogastric rodent which practiced caecotrophy. Garcia et al (2000) found that these animals had large caeca in relation to body weight.

An examination of the stomach contents of wild agouti by Henry (1999) identified five food types fruit pulp, seeds, fibre, leaves and animal matter. It was determined in time of fruit abundance the main constituent of the agouti diet was pulp; however, as food abundance declined there was an observed increase in consumption of both animal matter and seeds. In a later study the annual dietary composition based on the stomach contents of wild agouti was found to be 47.8% pulp, 29.2% seed, 6.2% insects and 4.3% fibre (Dubost and Henry 2006). Brown-Uddenburg et al (2004) found that in captivity agoutis were fed pumpkins (Cucurbita moschata), cassava ( Manihot escuelenta), mangoes (Mangifera indica) and papaya (Carica papaya). It has been observed that whilst they may attempt to eat items as small as 5mm and as large as 100-150 mm in diameter there was a preference for items that measured no greater than 15 mm in the largest dimension (Smythe 1978). In the case of large or heavy items the agouti uses its sharp incisors to tear off a smaller piece.

Due to the seasonal availability and storage issues such as space availability, bulkiness of raw materials, and perishability of organic matter, methods of pelleting and feed storage have to be developed. Formulation of rations for each physiological state will have to be developed using local feed resources to prevent uneven population growth. The use of pelleted feed from local feed resources will allow for a consistent diet reducing selective feeding, improving animal performance and feed bulk density (Ziggers 2012). At present there is a dearth of information on the digestive ecology of the agouti as well as feed formulations for these animals in captivity. Recently Jones and Garcia (2017, 2018) investigated the parasites and parasitic load present in the digestive tract of intensively reared animals which may affect the digestive performance of the animal. The objective of this paper is to identify the suitable size of feed that will be accepted by the agouti with minimal feed wastage.

Methodology

The experiment was conducted at the University Field Station (UFS) of The University of the West Indies (UWI) at Mt. Hope, Trinidad (10º38’16”N and 61º25’41”W. At the time the unit contained approximately 100 agoutis of varying physiological states. The trials were conducted during the months of September and October 2016. Twelve (12) random adult agoutis, six (6) males (M1-M6) and six (6) females (F1-F6), between the ages of two (2) and five (5) years and of similar sizes were selected from the population. They were placed in six (6) compartmentalized cages similar to standard cages throughout the unit. Each cage was 91 cm long, 61cm wide, 51 cm high and split into two equal compartments each 46cm long. Each compartment held one animal. Cages were made using 25mm x 25mm wire mesh with the flooring being 25mm x 13mm wire mesh. Due to the limited space within the unit, three cages housing two males each were placed in one pen while three cages housing two females each were placed in an adjacent pen (Figure 1).

Figure 1. Layout of housing for the experiment

Photo 1. Two agoutis under experimental conditions	Photo 2. Weston French Fry cutter and cutting plates (Williams and Sonoma 2017)

Cages were hung 122 cm from the ground against the walls using iron hooks. To reduce bouncing and swaying the cages were further secured to the wall using metal wire. Each animal was provided with adequate water and a specially designed feed tray labelled with its designation (e.g. M1, M2…F6). Each feed tray was 61 cm long, 10 cm wide, 8 cm high and divided into six (6) equal slots numbered 1 to 6. The numbering was not visible to the animals. The feed trays were placed on opposite ends on the cages to thwart access by the neighbouring animal (Photo 1). A small door was made into the corner of each compartment to allow the feed tray to slide in and out of the compartment easily. The tray door was secured to prevent the tray from moving.

The animals were allowed twenty-one (21) days to adjust to their new environment before trials began. During this adjustment period they were fed a combination of diced pumpkin pulp and rabbit ration similar to their diet for the trials. Their behaviour and eating habits were monitored. Every morning the trays were removed and washed. Cages were washed and the animals given fresh water prior to feeding.

Each day pumpkin (Cucurbita moschata) was peeled and cut into blocks which were passed through a Weston Restaurant Quality French Fry Cutter (see Photo 23) which resulted in strips. Three cutting plates were available which allowed for a varied thickness, 6.35 mm, 9.53 mm and 12.7 mm. The strips were then cut into 25.4 mm long pieces on a cutting board marked with a 25.4 mm grid. Particles were then weighed, packaged and refrigerated for the next day’s feeding. The feed particles were allowed to reach ambient temperature prior to being offered. A total of 600g of pumpkin was fed to each animal daily. Each day after collecting data 200g of rabbit ration was added to the feed tray divided among the slots. All weights were measured using a calibrated OHAUS Navigator® XT (Model: NVT1001/1), maximum capacity = 10,000g, d = 0.5g. Two trials were conducted. Trial 1 was called Feed Particle Size Preference and Trial 2 was called Feed Wastage.

Trial 1.Feed particle size preference

After the twenty-one day adaptation period, over the course of seven days, each animal was fed 200g of each particle size divided equally into two slots per particle size (i.e. 100g per slot). The objective of this trial was to measure the Feed Selected Ratio (FSR) for each particle size and then use the data collected to compare the preference for feed particle size. After one hour the trays were removed and the feed remaining in each slot was weighed. The ratio of feed selected to feed offered was calculated using the following formula:

Feed selected ratio (FSR)= (Feed offered – Feed remaining)/Feed offered

Feed and trays were then returned to the cages. Each day each particle size was rotated so that it was not in the same slot as the previous day (1>2>3>4>5>6>1). Same sizes were not placed next to each other. The sequence of the slots 1-3 was replicated in slots 4-6.

Trial 2. Feed wastage

The objective of this trial was to measure the Feed Wastage Ratio (FWR) and Feed Retention Ratio (FRR) of each particle size to determine the feed wastage of selected feed for each particle size. For seven consecutive days each animal was fed 600g of the 6.35mm particle size (this was repeated for the 12.7 mm and 9.53 mm particle sizes as well). Only one particle size was done at a time to ensure that all feed wastage was derived from the same particle size. The feed was placed in the two middle slots (slots 3 and 4) of the feed tray (i.e. 300g in each slot). A framed nylon net (mesh size 2 mm x 2 mm) measuring 64 cm x 94 cm and partitioned in half, was hung 15 cm below each cage. After one hour all feed particles (whole and shredded) that had fallen through the cage floor and onto the net (i.e. inaccessible to the animal) was collected and weighed. All feed particles retained by the cage floor were collected and weighed. All feed remaining in the feed tray was weighed and used to calculate the mass of feed selected.

Feed Wastage Ratio (FWR) was calculated using the following formula:

Feed Wastage Ratio (FWR) = Feed lost / Feed selected

A Feed Retention Ratio (FRR) was calculated using the following formula:

Feed Retention Ratio (FRR)= Feed retained / (Feed lost + Feed retained)

Three (3) particle sizes were offered: (1) 6.35 mm ´ 25.4 mm, (2) 9.53 mm ´ 25.4 mm, (3) 12.7 mm ´ 25.4 mm. Each particle size was offered for seven (7) consecutive days.

Statistical analyses

Statistical analyses were performed using SPSS Version 16 (IBM, CA, USA). One-way ANOVA was used to compare the means FSR, FWR and CRR when different feed particle sizes were offered. A Two-way ANOVA was used to compare the FSR and FWR of each particle size between male and female agoutis.

Results

Feed particle size preference

The feed particle sizes were identified by the following names: Quarter for 6.35 mm, Three-eighths for 9.53 mm; and Half for 12.7 mm.

The particle size of Half was the most preferred with poorest acceptance for the uarter siz (Table 2; Figure 2).

Figure 2. Feed selected ratio (FSR) for each particle size

There were no differences in the preference for different sizes of feed particle between male and female agouti (Figure 3)

Figure 3. FSR of each article size according to gender

Feed wastage

FWR was less for Half size particles when compared to Quarter and Three-eighths (Table 3; Figure 4).

Figure 4. Feed wastage ratio (FWR) means for each particle size

Feed retention ratio (FRR)

FRR was least for Quarter and highest for Half size particles (Table 4; Figure 5).

Figure 5. Feed retention ratio (FRR) means for each particle size

Discussion

The agoutis preferred the larger sized food particle. The most preferred particle size, 12.7mm, resulted in the least wastage, as it was less likely to slip through the cage flooring. All feed particle retained by the cage floors were consumed by the following morning. It is inferred that the feed pellet should be designed with the dimensions of 12.7 mm x 25.4 mm. The feed particles deposited on the cage floor were usually the result of them being dropped or being dug out of the feed tray and scattered. No comparison was made with commercial feeds for this experiment as the differences in other factors such as smell, taste and texture would have rendered any data unreliable. The feed particles evaluated in this experiment were all of cuboidal form and therefore further studies should be conducted to determine the effect of other forms such as oval and spherical.

What specifically drives the agouti to choose particles of larger size is uncertain but studies have been done which suggest that it may be linked to caching (burying) behaviour rather than nutrient value or energy content. In the wild, smaller seeds were generally consumed while larger seeds, which need longer handling times, are cached (Muñoz and Bonal 2008; Wang and Chen 2009; Jorge et al 2012; Wang and Yang 2014). Since caching behaviour is most common when food is abundant longer handling times can translate into less time spent eating and can also result in increased predatory risk. Pumpkin was chosen for its large size, firm pulp, increased use by farmers as well as its familiarity and acceptability to these animals. Large, evenly shaped pumpkins could be fabricated into the large blocks of solid pulp. These solid blocks could then be easily and efficiently processed into the various sizes allowing for maximum utilization of pulp and reducing financial expenditure. Removal of the pumpkin exocarp eliminated any bias towards it by the animal and all pumpkin used were of similar maturity as possible in the hope of reducing variations in taste, smell and texture. All pumpkins were purchased from the same vendor and are claimed to be grown on the same field under similar conditions. The 25.4 mm x 12.7 mm grid seemed best suited for this but was ineffective in conserving feed particles smaller than the grid size. Using smaller grids have resulted in the increased trapping of faecal matter. Therefore, the most suitable pellet size would have to be ≥ 25.4mm x 12.5mm as proven by the results.

Conclusions

• Agoutis most preferred the 12.7 mm x 25.4 mm particle and that preference was not affected by gender.
  
  
• The particle size resulting in the least wastage and least likely to slip through the cage flooring was also determined to be the 12.7 mm x 25.4 mm particle.
  
  
• It is suggested that 12.7 mm x 25.4 mm should be the minimum sized feed pellet suitable for agoutis in this system.

Acknowledgements

It is with my most heartfelt appreciation that I would like to acknowledge Ms. Natalie Malzar-Khan, Mr. Neil Ramsingh and Mr. Indar Ramroop for their patience and technical support at the UFS during this endeavour.

References

Brown-Uddenberg R, Garcia G W, Baptise Q S, Counand T, Adogwa A O and Sampson T 2004 The Agouti (Dastprocta leporina) Booklet and Producers’ Manual. Trinidad and Tobago: GWG Publications.

Dubost G and Henry O 2006 Comparison of Diets of the Acouchy, Agouti and Paca, the Three Largest Terrestrial Rodents of French Guianan Forests. Journal of Tropical Ecology 22 (6), 641-651.

Garcia G W, Baptiste Q W, Adogwa A O, Kakuni M, Arishima K and Makita T 2000 Digestive System of the Agouti (Dasyprocta leproina) - Gross Anatomy and Histology. Japanese Journal of Zoology and Wildlife Medicine 5(1), 55-66.

Henry O 1999 Frugivory and the Importance of Seeds in the Diet of the Orange-Rumped Agouti (Dasyprocta leporina) in French Guiana. Journal of Tropical Ecology 15 (3), 291-300.

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Lall K R, Jones K R and Garcia G W 2018 Nutrition of Six Selected Neo-tropical Mammals in Trinidad and Tobago with the potential for Domestication. Veterinary Sciences 5, 52.

Mollineau M W, Avril D and Garcia G W 2013 An Evaluation of the Courtship Behaviour of the Male Agouti (Dasyprocta leporina) Towards Introduced Females.Journal of Agricultural Economics and Development 2 (8), 301-304.

Muñoz A, and Bonal R 2008 Are You Strong Enough to Carry that Seed? Seed Size/Body Size Ratios Influence Seed Choices by Rodents. Animal Behaviour 76 (3), 709-715.

Smythe N 1978 The Natural History of the Central American Agouti (Dasyprocta punctata). Smithsonian Contributions to Zoology 257, 1-52.

Wang B and Chen J 2009 Seed Size, More than Nutrient or Tannin Content, Affects Seed Caching Behavior of a Common Genus of Old World Rodents. Ecology 90 (11), 3023-3032.

Wang B and Yang X 2014 Teasing Apart the Effects of Seed Size and Energy Content on Rodent Scatter-Hoarding Behavior. PLOS ONE 9 (10), e111389.

Williams S 2017 Weston French Fry Cutter & Blades. Williams Sonoma. Accessed November 10, 2017. https://www.williams-sonoma.com/products/weston-french-fry-cutter-blades/.

Ziggers D 2012 The Better the Pellet, the Better the Performance.All About Feed. Last modified August 6, 2012.http://www.allaboutfeed.net

Received 5 September 2018; Accepted 17 October 2018; Published 1 November 2018

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