Key findings:

The study found that including 15% discarded cocoa seed meal (DCSM) in rabbit diets improved reproductive performance, including litter size at birth and weaning, kit weight at birth and weaning, and reduced mortality rates. Diets with 15-30% DCSM showed no adverse effects, indicating its potential as a cost-effective alternative feedstuff for rabbit farming.

What is known and what is new?

Prior to this study, the use of discarded cocoa seed meal (DCSM) in rabbit diets and its impact on reproductive performance were not extensively researched. This study demonstrates that DCSM can be a beneficial feed ingredient, improving reproductive indices in rabbits without adverse effects. It fills a gap in knowledge regarding alternative feedstuffs for rabbits, particularly in developing countries facing food security challenges.

What is the implication, and what should change now?

The implication of this study is significant for the food security challenge in developing countries. It suggests that utilizing discarded cocoa seed meal as a feed ingredient for rabbits can improve reproductive performance, potentially leading to increased rabbit production and food availability. Farmers and policymakers should consider incorporating DCSM into rabbit diets to enhance food security and reduce production costs.

Rabbit production as a livestock will be heavily reliant on their capacity to utilize foods that have no nutritional value for humans [1]. Because the human population is rapidly outpacing available food supply, surplus or readily available food is rarely addressed [2]. Rabbits as well as other micro livestock are emerging as possible animal protein sources in several poor nations, including Nigeria, according to Ozung et al., (2019) [3]. The scarcity of animal protein, combined with fierce rivalry between humans and animals for agricultural products, necessitates increasing livestock diversification and productivity, which has resulted in a renewed interest in rabbit farming [4].

Increased development rate, small body size, short generation cycle, strong reproductive potentials, and genetic variety are qualities that make rabbits appropriate as meat producing micro livestock in a small-holder integrated subsistence farming type [5]. Even though rabbits may survive on almost any forage diet, optimum performance can only be achieved by combining forage and compounded rations in a combined feeding regimen [6,5].

Poor reproductive performance has been attributed to factors like inadequate nutrition, genetic differences, diseases, heat stress, improper management, etc. [7]. Generally, Machebe et al., (2014) [8] opined that nutrition is important for the development, growth, and proper functioning of reproductive systems in animals, and farm animals' reproductive well-being and performance are highly dependent on their nutrient intake.  However, Ozung et al., (2011) [9] has opined that, the present issues facing animal scientists and researchers are on how to promote the use of low-cost, high-nutrient alternative feed alternatives that are also adaptable to tropical climates. Discarded cocoa seed meal is one of the promising agricultural by-products that could be used in rabbit diet. Cocoa and its by-product has been used as a component of concentrate diets for many farm animals including the rabbits. Cocoa powder is a product from the seed of the tropical tree plant; Theobroma cacao mostly found around tropical areas of Asia, West Africa and Central and South America [10]. Cocoa and its products are known to be therapeutic because of their content of important substances as antioxidants (mainly flavonoids, epicatechin, catechin, and procyanids), nitrogenous compounds, minerals and methylxanthine (caffeine and theobromine which are anti-nutritional factors but its dependent on the quantity fed and means of processing) [11-14].

According to the United State Department of Agriculture (1999) [15], cocoa powder on a dry powder per 100g contains 225-325kcal of food energy, 18g of protein, 22g of fat, 50g of carbohydrates, 30g of fiber and 5g of minerals such as calcium, phosphorus, iron, magnesium, potassium and so on. It also contains vitamins A, E, K and B’s but in small quantities not exceeding 4mg. The use of DCSM will attempt to reduce the cost of feed formulation and also help to ameliorate the adverse effect of climate change due to environmental pollution caused by its inappropriate disposal. Potential impacts of climate change on animal production includes water availability (Henry et al., 2012) [16], diseases (Thornton et al., 2009) [17], reproduction (Nardone et al., 2010) [18], growth and milk production (Henry et al., 2012) [16]. Interest has been channeled on how to make use of this high volume of discarded cocoa bean in animal feeding (Nwanna et al., 2008) [19]; and nevertheless, recommend appropriate level of inclusions towards rabbit breeding improvements.

The main objective of this paper is to evaluate the effect of discarded cocoa seed bean (DCSM) on the reproductive performance of rabbit does using the following parameters; gestation length, litter size at birth, litter size at weaning, kit weight at birth, kit weight at weaning, kit weight gain and mortality rate of kits.

2.1 Site and Duration of the Experiment

This research was carried out at the Rabbit Unit of the Animal Science Teaching and Research Farm, University of Nigeria, Nsukka in Enugu State, Nigeria.

2.2 Management of Experimental Animal

A total number of thirty six (36) rabbits comprising twenty four (24) does and twelve (12) bucks of an average weight of 1384.34 ± 283.34g were used for this research. The rabbits were grouped according to sex (male and female groups). Each group were randomly assigned to 4 treatments diets according to the level of inclusion of DCSM content of the ration. Treatments for bucks contained 3 rabbits each into three different replicates of 1 bucks each. Treatments for does contained 6 rabbits each into three different replicates of 2 does each, respectively. Rabbits were held in individually washed and disinfected hutches with a dimension of 4feet x 2feet x 2feet and a wire-screened floor that allowed faeces and urine to pass through. The formulated rations and water were made available ad-libitum to the rabbits. The DCSM used in the diet formulation was collected in and around cocoa powder manufacturing factories in the Southern part of Nigeria. The percentage and proximate composition of the experimental ration is presented in Table 1.

Table 1: Percentage and proximate composition of the experimental diets containing DCSM at different levels

2.3 Mating of Does

Does were taken to the buck’s hutches for mating after 8 weeks of feeding the test ingredients and were carefully monitored to ensure successful mating. Abdominal palpation to detect pregnancy was carried out at day 14 after mating, non-pregnant does were returned for another mating in order to achieve conception.

2.4 Statistical Analysis

All data collected were analyzed by a one-way analysis of variance (ANOVA) in a randomized complete block design (RCBD) and statistically different means were separated according to the procedures of Duncan’s New Multiple Range Test [20].

3. Results

The results of the effect of varying dietary levels of discarded cocoa seed meal (DCSM) on the reproductive traits of Rabbit does are presented in Table 2.

From the results, gestation length was not significant (P>0.05) among the treatment means. However, litter size at birth, litter size at weaning, mortality rate, kit weight at birth, kit weight at weaning and kit weight gain significantly (P<0.05) differed among the treatment means. The rabbit does in T₂ (15% DCSM) produced the highest significant value for litter size at birth and at weaning compared to T₁, T₃ and T₄ which are significantly (P<0.05) similar, although T₃ for litter size at weaning is similar to T₂. The percentage values for mortality showed the best value in T₃ which is significantly (P<0.05) different from T₁, T₂ and T₄ which are all statistically the same. For kit weight at birth, T₂ and T₃ showed the highest significant (P<0.05) values which are similar to T₄ but different from T₁. T₄ also is similar to T₁. T₁ for kit weight at weaning showed the lowest value whereas T₃ showed the highest value and both values are significantly similar to both T₂ and T₄. For kit weight gain, T₃ showed the highest value that is statistically (P<0.05) different from other treatments. T₂ and T₄ are significantly similar although they differ from T₁ with the lowest value.

Table 2: Reproductive Traits of Rabbit Does and Kits fed discarded cocoa seed meal based diets.

^abc: Means ± SEM on the same row with different superscripts are significantly different (P ≤ 0.05 or P ≤ 0.01).

The obtained results of the reproductive traits of rabbit does in this study are similar to those reported by Apori et al., (2015); Fadare and Fatoba (2018); Nwakpu and Ucheji (2018) [21-23]. The average litter size at birth obtained in this study ranges from 4.50 - 7.50 across dietary treatments which is higher than the range of values (3.10 - 4.65) reported by Nwakpu and Ucheji (2018) [23] when they studied the reproductive performance and survivability of kits from 3 popular breeds of rabbits (OryctolagusCuniculus) in Abakaliki, Nigeria. The significant (P<0.05) results on litter size at birth and weaning are also similar to those reported by Abdel-Khalek et al., (2008) [24] when rabbit does were fed dietary antioxidant vitamin E and C. The result of this study on kit weight at weaning showed higher values than those reported by Hasanat et al., (2006) [25] with values of 310.62 and 408.12g. However, values on kit mortality (26.92 and 45.00%) and kit weight at birth (54.87 and 55.50g) was higher than those obtained in this study. Polyphenols (flavonoids, catechins and epicatechins) bound in DCSM has been exposed as antioxidants by Greer et al., (2001) and Rios et al., (2003). Ismail et al., (1992) [13,14,26] reported an antioxidant (vitamin C) at an inclusion level of 50mg/kg ration resulted in an improved litter size at birth. Antioxidants protective action against lipid oxidation in the cell membrane could explain the positive increase in performance in the treated groups [27]. Furthermore, it is also crucial for the growth of the immune system in young animals, as offsprings are more sensitive to oxidative damage than mature ones [28]. The reduced mortality percentage with 15 and 30% DCSM inclusion could be probably due to what Perez-Cano et al., (2013) [29] reported that cocoa is capable of influencing the immune system especially the inflammatory innate response, systemic and intestinal adaptative immune response. Thus, with an improvement in the immune system, there is expectation on reduced mortality of the rabbit kits. 

Similarly, Ozung et al., (2019) [3] reported a fairly improved reproductive tract morphometry of rabbit does when fed fermented or hot-water treated cocoa pod husk meal up to 25% inclusion levels compared to the raw cocoa pod husk meal (due to inherent theobromine content). Furthermore, similar results were reported by Attia et al., (2009) [30] for using glucose administration in rabbit does, which resulted in a significant increase in litter size at birth and litter size at weaning on 5g glucose per liter of drinking water under tropical condition. Uzochukwu (2016) [31] also reported a better ovarian development (ovarian weight and gonadosomatic index) of Clarias gariepinus female catfish under the influence of cocoa bean meal at 10% and 40% inclusion levels respectively. Tarka et al., (1986) [32] evaluated the effect of dietary cocoa powder on gestation, parturition, lactation and postnatal growth in female CD-rats. Gestation length, litter size at birth and sex ratio were unaffected from gestation up to 21 day of lactation with no clinical signs observed in the dams.

It will be ideal to conclude that DCSM diet tends to improve reproductive indices in female rabbits up to 15 - 30% inclusion level without detrimental effect on kits performance. With an improvement on litter size at birth, litter size at weaning, kit weight gain and mortality rate; the farmer is bound to produce more available animal protein at a lower cost due to incorporation of the DCSM to the compounded diets.

Conflict of Interest

The authors declare that they have no conflict of interest.

Funding: No funding sources 

Ethical approval: The study was approved by the Institutional Ethics Committee of University of Nigeria

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