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© 2019 Conscientia Beam. All Rights Reserved. 

COMPARING POST-PARTUM GROWTH BY BODY WEIGHT BETWEEN SEX AND 
LITTER SIZE OF AGOUTI (Dasyprocta Leporina) OFFSPRING FROM BIRTH TO 360 
DAYS OLD   

 

 

 Riyadh 
Mohammed1+ 
Asad Mohammed2 

 Letetia Addison3 

 Isaac Dialsingh4 

 Kavita Kameela 
Sant5 
Gary Wayne Garcia6 

 

1,2,3,4,5,6University of the West Indies, St. Augustine, Trinidad and Tobago. 

  
(+ Corresponding author) 

 ABSTRACT 
 
Article History 
Received: 13 June 2019 
Revised: 19 July 2019 
Accepted: 22 August 2019 
Published: 10 October 2019 
 
 

Keywords 
Litter size 
Sex 
Growth rate 
Average daily gain 
Offspring  
Growth models.  

 
Thirty (30) offspring were weaned at 7 days old and 12 weights were taken every 30 
days from the date of birth until 360 days old. The objectives of this study were: 1) to 
observe any dimorphism by live weight gain between agouti males and females at each 
30 day interval, 2) to see if there was any difference in growth rate between litter sizes, 
and 3) to observe of there was a point where growth plateaued and to decide on an 
average age and weight for utilization (meat). Results suggested that: 1) Offspring can 
be weaned as early as 7 days, 2) Single born offspring grew faster than double or triple 
born initially in the earlier periods of life (< 6 months old) (18.89 g/d vs.17.61 g/d, 
17.57 g/d) 3) Compensatory growth took place for offspring that came from larger 
litters in the latter stages of life (> 6 months old) (1.25 g/d, 1.21 g/d vs. 0.87 g/d) and 
had no major disadvantage by weight when compared to single born offspring (2750.8g 
2770.0g and 2784.1g,), 4) Male and female offspring grew at the same rate from day 0 
to 360, hence no sexual dimorphism by live weight was seen at day 360, 5) The average 
weight for optimum utilization (harvest) by live weight is no less than 2600g which can 
be achieved by 8 months of age, 6) The Gompertz growth model best describes the 
growth of Agouti offspring as compared to the Logistic and Von Bertalanffy models.   
 

Contribution/Originality: This study is one of very few studies which have investigated the growth and 

development of agouti offspring along a 360 day period and compared the growth rates of sexes and litter sizes to 

the Gompertz , Logistic and Von Bertalanffy growth models. 

 

1. INTRODUCTION 

Brown-Uddenberg [1] reported new born agouti females weighing between 210g-355g while male offspring 

weighed 225g- 308g. At 8 weeks of age, female offspring weighed 1088.9g- 1306.6 g and males at 8 weeks old were 

723.5g- 1298.8g Brown-Uddenberg [1].  Meritt [2] reported Agouti (Dasyprocta sp.) to weigh 3.5 kg (males) and 

4 -5 kg (females) while Nowak [3] reported adults to weigh between 3.4 and 5 kg. There has been no record in the 

literature of how the agouti grows from birth (day old) to juveniles to adulthood or market weight. The three most 

common growth curves used to measure rodents and mammals were the Gompertz, Logistic and Von Bertalanffy. 

Gompertz and Logistic curves both shared the similar “S- shaped” form while the Gompertz function is symmetric 

Current Research in Agricultural Sciences 
2019 Vol. 6, No. 2, pp. 121-134 
ISSN(e): 2312-6418 
ISSN(p): 2313-3716 
DOI: 10.18488/journal.68.2019.62.121.134 
© 2019 Conscientia Beam. All Rights Reserved. 

 
 
 

 
 
 

 

 
 
 
 

https://orcid.org/0000-0002-9639-1397
https://orcid.org/0000-0001-5161-9362
https://orcid.org/0000-0002-6121-6126
https://orcid.org/0000-0002-5055-1965
https://www.doi.org/10.18488/journal.68.2019.62.121.134


Current Research in Agricultural Sciences, 2019, 6(2): 121-134 

 

 
122 

© 2019 Conscientia Beam. All Rights Reserved. 

and the Logistic is asymmetric [4]. The reproduction of wild fauna in ex situ conditions play a critical role in 

animal conservation, production and utilization [5]. Hence this study lends itself to securing food for rural 

communities, creating employment and generating new information for science. The purpose of this study is to 

sustainably produce the Neo tropical agouti in captivity for sustainable utilization by intensive production. This will 

be achieved by adjusting the Gompertz ( ), Logistic (  ) and Von Bertanlaffy 

(  ) nonlinear models to the growth data of male and female agouti of different litter 

sizes for a 360 day period.  

These growth curves were done to observe if: 

1) There is any dimorphism between agouti males and females at day 360.  

2) There is any difference in growth rate in litter sizes throughout the 360 day period. 

3) There is a point where growth plateaued to decide on an average age and weight for utilization (meat).  

 

2. METHODOLOGY  

2.1. Location and Time Frame  

The experiment took place at the University of the West Indies Field Station located at Mt. Hope (Latitude 

10.6468 and Longitude -61.4228), Trinidad. The temperatures within the unit ranged from 22.10C to 33.30C. The 

unit was established on July 31st, 1986. The unit had a total head count of approximately 150 Agouti, of different 

physiological states in 2016. The observations were carried out from May 2016 to December 2017.  

 

2.2. Animals  

Data was collected from 30 offspring (10 single from born, 10 from double, 10 from triple) born within a 6 week 

period in the dry season. Of the 10 single born, there were 6 males and 4 females, of the 10 double born, there were 

5 males and 5 females and of the triple born, there were 6 males and 4 females. Offspring were chosen in a 

systematic way as they were born within the 6 week period.  

 

2.3. Housing and Environment  

The animals were housed in an intensive type system in steel cages (15’’ length, 18’’ width and 15’’ high) and 

supplied with water and food on a daily basis [1]. Pens were cleaned and washed while animals were fed, watered 

and observed daily. Pre-weaned data collection required offspring to stay with their mothers for only 1 week. Post-

weaned data collection required for all young to be separated into different cages with a feeder bowl and water 

container in each. All cages were of the same size (18’’ long, 15’’ width and 15’’high). Weights were collected from 

the day of birth and every 30 days after until they were 360 days old. This meant that each offspring had 13 

weights, their birth weight and 12 (30) day interval weights.  

 

2.4. Feeding and Nutrition  

Offspring were fed 1000g of fresh fruit per day, usually the fruit in season or abundance (farm grown). The 

fruits fed were mangoes (Mangifera indica), pumpkin (Cucurbita), cucumbers (Cucumis sativus) and papaya (Carica 

papaya). Tropical forages such as Trichanthera (Trichanthera gigantea) and Leucaena (Leucaena leucocephala) were 

also fed when fruits were not available. 

 

 

 



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2.5. Analysis 

2.5.1. Non-Linear Curve Fitting of Agouti Data 

 Comparison of growth curves (Gompertz, Logistic, Von Bertanlaffy) for the agouti by sex (male, female) 

and litter size (single, double, triple – born). 

 Fitted polynomial equations of curves for each sex and litter-size for agouti. 

The non-linear growth functions, in mathematical forms described by Gbangboche, et al. [6] are as follows: 

Gompertz:         

Logistic:         

Von Bertalanffy:      

Where  represents the weight (grams) of the animal at age  (days),  represents the asymptotic value of 

the weight (mature weight),  represents the proportion of asymptotic mature weight to be gained post birth 

(using initial values of the weights  and time, ),  provides a function of the ratio of the maximum rate of 

growth to the mature weight (called the maturation rate) and the larger the  value, the earlier the maturation of 

the animal.  

Each model was fitted to the mean body weights of the agouti by sex (male, female) and litter size (single-born, 

double-born, triple-born) respectively using Non-Linear Least Squares curve fitting procedures in MATLAB 

R2017b. Parameter estimates were obtained for each of the curves and a 95% Confidence Interval for each estimate 

was constructed Table 1.  

The models were also evaluated based on the Goodness of Fit. The statistics used were the co-efficient of 

determination ( adjusted co-efficient of determination ( , the root mean square error (RMSE). The 

adjusted R-squared statistic is a good indicator of the quality of the model fit when additional coefficients are added 

to the model.  

The RMSE metric which provides an absolute measure of fit compared to the  values which gives a relative 

measure of fit. Lower values of the RMSE indicate a better fit. Different curves provided the best fit compared to 

the other growth curves based on the highest values of the  and lowest RMSE values in each case, compared 

to the Logistic and Bertalanffy curves see Table 1.  

Sex and Litter size were also fit to polynomial curves respectively. In each case, a non-linear equation was 

obtained with estimates for the regression co-efficients. The form of this equation was: 

 



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© 2019 Conscientia Beam. All Rights Reserved. 

where  represents the fitted model co-efficient of , the variable age (each sex or litter size respectively), for 

. The value of  is based on the highest power in the fitted model polynomial, for instance, a cubic 

polynomial has the value of  

 

3. RESULTS 

 
Table-1. Live weight gains by litter size from day 0 to day 360. 

Time period (Days) Litter size F value p-value 

1 
Mean (SD) 

2 
Mean (SD) 

3 
Mean (SD) 

0 211.2 
(7.48) 

198.4 
(7.71) 

189.0 
(5.25) 

33.597 p < 0.001 

30 1227.2 
(17.57) 

862.3 
(10.58) 

671.7 
(26.21) 

3815.87 p < 0.001 

60 1668.0 
(13.42) 

1275.3 
(10.87) 

1175.0 
(13.43) 

8791.85 p < 0.001 

90 1930.1 
(13.56) 

1673.0 
(16.29) 

1646.1 
(23.41) 

1321.38 p < 0.001 

120 2266.8 
(28.68) 

1954.9 
(15.54) 

1918.4 
(16.28) 

948.21 p < 0.001 

150 2397.6 
(25.80) 

2230.3 
(9.45) 

2170.7 
(14.65) 

423.40 p < 0.001 

180 2516.7 
(21.17) 

2401.6 
(8.64) 

2375.8 
(14.24) 

227.41 p < 0.001 

210 2621.7 
(10.76) 

2547.0 
(9.15) 

2542.2 
(16.94) 

200.78 p < 0.001 

240 2663.7 
(15.03) 

2642.1 
(8.47) 

2635.7 
(10.00) 

19.41 p < 0.001 

270 2701.5 
(12.96) 

2689.9 
(37.31) 

2664.4 
(20.21) 

12.93 p < 0.001 

300 2746.5 
(19.48) 

2717.2 
(43.92) 

2679.7 
(17.43) 

20.58 p < 0.001 

330 2771.1 
(18.14) 

2745.9 
(41.15) 

2697.5 
(20.90) 

22.78 p < 0.001 

360 2784.1 
(14.07) 

2754.4 
(37.23) 

2749.1 
(17.96) 

30.70 p < 0.001 

 

 
Table-2. Percentage weight change by sex from day 0 to day 360. 

Time period intervals (Days) F value p-value 

0-30 1.451 0.239 
31-60 6.416 0.018 
61-90 0.389 0.538 
91-120 1.447 0.240 

121-150 0.550 0.465 
151-180 0.044 0.835 

181-210 4.238 0.050 
211-240 0.587 0.450 
241-270 19.314 p < 0.001 
271-300 0.519 0.478 
301-330 1.173 0.289 
331-360 3.116 0.089 

 

 



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© 2019 Conscientia Beam. All Rights Reserved. 

 
Figure-1. Mean live weights from day 0 to day 360 by sex. 

 

 
Figure-2. Mean live weights from day 0 to day 360 by litter size. 

 

 

 



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© 2019 Conscientia Beam. All Rights Reserved. 

 
Figure-3. Mean live weight of males from day 0 to day 360 using gompertz, logistic and von bertalanffy models. 

 

 
Figure-4. Mean live weight of females from day 0 to day 360 using gompertz, logistic and von bertalanffy models. 

 

 



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© 2019 Conscientia Beam. All Rights Reserved. 

 
Figure-5. Mean live weight of single born offspring from day 0 to day 360 using gompertz, logistic and von bertalanffy models. 

 

 
Figure-6. Mean live weight of double born offspring from day 0 to day 360 using gompertz, logistic and von bertalanffy models. 

 

 



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© 2019 Conscientia Beam. All Rights Reserved. 

 
Figure-7. Mean live weight of triple born offspring from day 0 to day 360 using gompertz, logistic and von bertalanffy models. 

 

 
Figure-8. Gompertz model fitted to curve of mean live weight of male offspring from day 0 to day 360. 

 



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Table-3. Parameter estimates for the growth curves (Gompertz, Logistic, Bertalanffy) fitted to Agouti mean final live weight data by sex and litter-size. 

Model Factor A B K SSE 
 

Adjusted  

 

RMSE 

Gompertz Sex        
 Male 2839  (2411, 3267) 2.149  (1.03, 3.269) 0.01345  (0.00573, 0.02118) 7.9471e+05 0.9155 0.8986 281.9064 

 Female 2755  (2666, 2844) 1.993  (1.697, 2.289)) 0.01642  (0.01391, 0.01892) 5.6876e+04 0.9928 0.9913 75.415 
 Litter size        

 Single - born 2716  (2598, 2834) 1.795  (1.355, 2.236) 0.01997  (0.01499, 0.02496) 1.4319e+05 0.9796 0.9755 119.6613 
 Double-born 2763  (2681, 2846) 2.064  (1.801, 2.328) 0.01553  (0.01348, 0.01758) 4.2557e+04 0.9948 0.9938 65.2356 
 Triple-born 2727  (2674, 2779) 2.329  (2.116, 2.541) 0.01629  (0.0149, 0.01769) 1.8264e+04 0.9979 0.9975 42.7363 

Logistic Sex        
 Male 2760  (2434, 3085) 5.767  (0.5178, 11.02) 0.02024  (0.009703, 0.03078) 7.5836e+05 0.9194 0.9032 275.3840 
 Female 2712  (2592, 2832) 4.579  (2.806, 6.353) 0.02279  (0.01747, 0.0281) 1.3712e+05 0.9827 0.9792 117.0962 
 Litter size        

 Single - born 2690  (2547, 2833) 3.787  (1.77, 5.804) 0.02667  (0.01773, 0.03562) 2.4894e+05 0.9645 0.9574 157.7770 
 Double-born 2713  (2601, 2825) 4.898  (3.196, 6.601) 0.02186  (0.01735, 0.02637) 1.1022e+05 0.9865 0.9938 104.9834 
 Triple-born 2675  (2583, 2767) 6.002  (4.075, 7.93) 0.02331  (0.01929, 0.02733) 7.7768e+04 0.9910 0.9892 88.1862 

Bertalanffy Sex        
 Male 2885  (2392, 3377) 2885  (2392, 3377) 0.01136  (0.004449, 0.01827) 8.1156e+05 0.9137 0.8964 284.8787 

 Female 2780  (2707, 2852) 0.5115  (0.4664, 0.5566) 0.01431  (0.01264, 0.01598) 3.2366e+04 0.9959 0.9951 56.8910 

 Litter size        

 Single - born 2730  (2624, 2835) 0.4732  (0.3944, 0.552) 0.01778  (0.01402, 0.02153) 1.0410e+05 0.9851 0.9822 102.0318 

 Double-born 2793  (2726, 2861) 0.5247  (0.4853, 0.5641) 0.01343  (0.01207, 0.01479) 2.4030e+04 0.9971 0.9965 49.0200 

 Triple-born 2759  (2719, 2798) 0.5754  (0.5472, 0.6036) 0.01393  (0.01309, 0.01477) 8.6871e+03 0.9990 0.9988 29.4739 
                                       Polynomial equations of fitted curves by sex and litter size. 



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Figure-9. Gompertz model fitted to curve of mean live weight of female offspring from day 0 to day 360. 

 

 
Figure-10. Gompertz model fitted to curve of mean live weight of single born offspring from day 0 to day 360. 

 



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Figure-11. Gompertz model fitted to curve of mean live weight of double born offspring from day 0 to day 360. 

 

 
Figure-12. Gompertz model fitted to curve of mean live weight of triple born offspring from day 0 to day 360. 

 

 Percentage Weight Gain (%) =  

 Average Daily Weight Gain =  



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Figure-13. Percentage change of mean live weight gain of offspring from day 0 to day 360 by sex. 

 

 
Figure-14. Mean live weight gain of offspring from day 0 to day 360 by litter size. 

 

 
Figure-15. Average live weight gain of male offspring from day 0 to day 360. 

 



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Figure-16. Average live weight gain of female offspring from day 0 to day 360. 

 

4. DISCUSSION 

Results showed that Agouti offspring can be weaned at day 7 post-partum with a survivability of 100% (30/30). 

This result was also confirmed by the paper written by Mohammed, et al. [7] which indicated the same 

survivability rate from 136 offspring from 80 parturitions regardless of litter size or dams’ body condition. Average 

daily gains (Final weight- Initial weight/ No. of days) for all 3 litter sizes were compared for 4 periods within the 

360 day data collection period. At day 90, offspring grew at an average rate of 18.89 g/d, 17.61 g/d and 17.57 g/d 

for single, double and triple born respectively. At day 180 offspring grew at an average rate of 2.75 g/d, 3.78 g/d 

and 4.17 g/d for single, double and triple born respectively. At day 270 offspring grew at an average rate of 0.87 

g/d, 1.21 g/d and 1.25 g/d for single, double and triple born respectively. At day 360 offspring grew at an average 

rate of 0.41 g/d, 0.41 g/d and 0.38 g/d for single, double and triple born respectively. From the ADG values, single 

born offspring grew fastest in the early quarter (0- 3months) of life while double and triple born offspring showed 

compensatory growth in the second (4-6 months) and third quarters (7-9 months) of life and all 3 litter sizes 

plateaued at day 360 (month 12).  

Table 1 and Figure 14 showed that single, double and triple born offspring weighed significantly different at 

each time point from day 0 to day 360. Table 2 showed the rate of change by live weight gain between sexes were 

similar at every interval except the period of 241-270 days where females were heavier. Figure 1 showed the mean 

weights between sexes, where females were heavier at day 360. Figure 2 showed mean weights for single, double 

and triple born offspring where single born offspring were the heaviest at day 360. Figure 3 and Figure 4 showed 

live weight gain of males and females respectively from day 0 to 360 comparing all 3 curves. Figure 5, Figure 6 and 

Figure 7 show the mean live weight of single, double and triple born offspring from day 0 to 360 comparing all 3 

curves. Figure 8 and Figure 9 show the Gompertz model fitted to the curve of mean live weights of male and female 

offspring from 0 to 360 days old. Figure 10, Figure 11 and Figure 12 shows the Gompertz model fitted to the curve 

of mean live weights of single, double and triple born offspring from 0 – 360 days old. Table 3 summarized the 

comparison of Gompertz, Logistic and Von Bertalanffy equations on offspring by litter size and sex. Here it was 

seen that the Gompertz curve fits closest to the growth of agouti offspring by sex and litter size.  

Figure 13 showed the rate of live weight change by sex and both male and female offspring showed the highest 

growth rate within the period of day 0 to 30, hence early nutrition is very important. Figure 14 illustrated that all 3 

birth types seemed to plateau between days 240 to day 270 and grew differently until day 360. Figure 15 and 16 

showed the live weight gain of all males and females were similar in weight at day 240 to day 270 regardless of 

litter size. Figure 14, 15 and 16 showed that agouti males can be harvested and utilized for meat from 8 to 9 months 

of age, where the average live weight is 2616g and 2685g. 



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5. CONCLUSION 

 Male and female offspring grew at the same rate from day 0 to 360 except the period of 241-270 days, hence 

no sexual dimorphism by live weight was seen at day 360.  

 Single born offspring grow faster than double and triple born offspring in the first 6 months of life, but 

double and triple born offspring exhibited a form of compensatory growth after 6 months of age.  

 The average weight for optimum utilization (harvest) by live weight is no less than 2600g which can be 

achieved as early as 8 months of age.   

 The Gompertz growth model best describes the growth of Agouti offspring as compared to the Logistic and 

Von Bertalanffy models.  

 

6. RECOMMENDATIONS FOR FUTURE WORK  

 How do agouti offspring grow by allometric growth/scaling?  

 What is the age and live weight for female agouti to reach puberty and first estrus?  

 What is the dressing percentage of agouti males harvested at day 240 in an intensive production system?  

 

Funding: This study received no specific financial support.    
Competing Interests: The authors declare that they have no competing interests.  
Contributors/Acknowledgement: All authors contributed equally to the conception and design of the 
study. 

 

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[7] R. Mohammed, L. George, and W. G. Gary, "Towards the determination of a “Weaning Age” for the intensive 

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