Effects of graded levels of Curcuma longa Powder on in vivo digestibility in Guinea pigs (Cavia porcellus)

L’effet de l’incorporation de la poudre du Curcuma longa comme phytobiotique sur l’ingestion et la digestibilité in vivo des nutriments a été mesuré sur un total de 40 cobayes de race anglaise ayant un poids moyen de 452±75 g. La poudre de racines de Curcuma longa a été incorporée dans l’aliment composé à des niveaux croissants (0 ; 0,25 ; 0,5 et 1%). Chaque ration a été granulée. Pendant l’essai de digestibilité qui a duré 17 jours (10 jours d’adaptation et 07 jours de collecte des données), chaque ration était répétée sur 10 cobayes (5 mâles et 5 femelles). L’inclusion de la poudre de Curcuma longa a amélioré de manière significative (p<0,05) l’ingestion alimentaire des cochons d’inde quel que soit le niveau d’inclusion considéré dans les rations. La digestibilité de la matière sèche de la ration contenant 0,25% de Curcuma longa a été comparable à celle de la ration R0% et R1%. En outre, la digestibilité de la cellulose brute de la ration R0,25% a été comparable à celle des rations R0,5% et R1%, mais significativement plus élevée que celle des rations R0%. L’inclusion de la poudre de Curcuma longa dans les rations a Tropicultura 2295-8010 Volume 39 (2021) Numéro 3, 1847


Introduction
Malnutrition affects approximately 20% of the Cameroonian population [25]. To fight against this scourge, the development of small scale breeding offers an alternative source of proteins as much as it contributes in a global way to the economy of the country through the promotion of employment, exchanges and the preservation of biodiversity [16]. Among the species concerned, caviaculture offers the guarantee of food security for vulnerable populations, especially in rural areas Fokom et al. [12].
Indeed, Guinea pig is a monogastric herbivore whose main interest lies in a high speed of relative growth, lean meat, an inexpensive natural diet, low capital and labor requirements [17]. Its optimal use as a source of protein and income [16], therefore requires an increase in its productivity which necessarily involves improving breeding strategies on the one hand and better rational management methods of production on the other hand.
In fact, poor breeding strategies lead to low productivity (stunting, low fertility, abortions, low birth weights and high mortality due to poor health) [13].
The use of growth promoters (phytobiotics, prebiotics and symbiotics) has been reported to enhance growth performance, prevent pathogens and promote the growth of beneficial microorganisms in the intestinal flora of animals [3]. Among these compounds, phytobiotics have many properties (antioxidant, antimicrobial, improving digestion and stimulating the immune system).
Effects of graded levels of Curcuma longa Powder on in vivo digestibility in ... Curcuma longa is a plant famous for its culinary and medical uses. It contains non-volatile curcuminoids that are the main constituents responsible for its yellow color [8]. It has a very wide variety of pharmacological properties [15]. According to Brahimi and Terrai [9] it contains active ingredients such as tetrahydro-curcuminoids, curcumin, demethoxy-curcumin and bisdemethoxycurcumin which are non-toxic polyphenolic derivatives of curcumin which possess a wide range of biological activities. Other studies have shown that curcumin has toxic effects on both Enterococcus faecalis and Streptococcus intermedius and on Escherichia coli [14].
In addition, Abdel et al [3] also revealed that supplementation of 0.2 and 0.4g/kg of C. longa powder in rabbit diet increased weight gain. Basavaraj et al [5] recorded an increased in live weight and broiler weight gain with the use of C. longa as feed additive at a level of 0.5%. However, Basavaraj et al. [5] recorded no effect following the inclusion of Curcuma longa rhizome powder at 0; 0.15 and 0.30% on the biochemical characteristics of rabbit blood and meat. Based on these advantages, C. longa has value in animal husbandry and the existing work shows a lot of disparities depending on the animal species used. It is in this perspective that the present work was aimed to evaluate the effect of C. longa on feed intake and digestibility in Guinea pigs.

Experimental site
This study was carried out at the Cavia porcellus Unit of the Teaching and Research Farm of the

Plant material
Curcuma longa was harvested in the district of Santchou (West region of Cameroon), sun dried, then ground into powder using a hammer mill of sieve size 2 mm. The powdered spice was then stored in air-tired polythene bags prior to use in the experimental rations. Sample of the test spice was stored in a refrigerator at a temperature of 4˚C. The phytochemical analyses of Curcuma longa was carried out as described by Talukdar et al. [22] revealed that alkaloids, flavonoids, terpenoids, phenols, steroids and tannins were presents.

Animal material and housing
A total of forty (40) animals (20 males and 20 females) with an average weight of 452 ± 75 g were used and housed in four pens. These pens were made of plywood, measuring 1 × 0.8 × 0.6 m, equipped with light facilities. Each compartment or lodge was equipped with a wooden trough for feed, a concrete water trough and a device for collecting left over feed and feces. The various boxes were fitted with a fine-mesh cover to protect the animals from mice and other predators that could enter the barn.

Animal Experimental Diet
The animals were distributed into four treatments in a completely randomized design (R 0% , R 0.25 , R 0.5% and R 1% C. longa). Each treatment contains 10 Guinea pigs (5 males and 5 females). From the basal diet, (R 0% ) three experimental rations were formulated by adding C. longa powder (Table   1) as follow:

Evaluation of the chemical composition of the rations
The chemical composition of the rations were performed to determine dry matter, ash, organic matter, crude fibre, crude protein, and crude fat contents, as described by AOAC [1]. It was determined at the Animal Nutrition Laboratory of the Faculty of Agronomy and Agricultural Sciences of the University of Dschang.
Effects of graded levels of Curcuma longa Powder on in vivo digestibility in ...

Feed intake and digestibility assessment of rations
Feeds was served every morning at 8:00 am. The quantity of feed served was registered, and the left over was collected daily and weighed. Feed intake was obtained by subtracting the left over feed from the total quantity of feed served to the animals.
The digestibility test followed a 10-day adaptation period of the animals in digestibility cages and pelleted rations. During this period, the amounts of feed served was adjusted to the estimated consumption of 60 g / animal / day. Data was collected each morning within a period of seven days. Where significant differences existed between treatments, the means were separated by the Waller Duncan test at 5% significance level [21].

Phytochemical composition of C. longa and chemical composition rations
Phytochemical analysis shows that C. longa contains the following bioactive compounds such as alkaloids, flavonoids, phenols, steroids, tannins, terpenoids and saponins (Table 2).

Effects of the rate of incorporation of Curcuma longa powder on feed intake in Guinea pigs
The inclusion of Curcuma longa powder in the different diets significantly improved (p <0.05) feed intake in Guinea pigs regardless of the inclusion level ( Figure 1). The crude fiber intake by animals fed on R 0.5% ration was comparable (p> 0.05) to animals fed with R 0.25% and R 1% rations, but significantly higher (p <0.05) to the control ration (R 0% ). However, ingestion of crude fiber from the control diet was significantly (p <0.05) lower compared to the rations containing Curcuma longa. Crude fiber ingested by animals fed on R 0.25% and R 1% rations were comparable (p> 0.05) and significantly lower (p <0.05) than those fed with R 0.5% ration.
The regression value (p <0.05) derived (R 2 = 0.94 for DM, R 2 = 0.95 for OM, R 2 = 0.95 for CP and R 2 = 0.97 for CF) suggest that, the variation of DM, OM, CP and CF are 94%, 95%, 95% and 97% respectively dependent on the rate of inclusion of C. longa in the rations.

Discussion
Qualitative phytochemical analysis revealed that C. longa contain bioactive compounds such as alkaloids, flavonoids, phenols, steroids, tannins, terpenoids and saponins that can affect feed intake and digestibity of nutriments. Attou and Boukhari [2] also revealed the presence of flavonoids, alkaloids, tannins, phenols and steroids in C. longa powder and their in vitro antimicrobien activity.
Feed intake increased with the incorporation of Curcuma longa powder compared to the ration without additive. This increase could be due to the odour and flavour produced by the additive.
According to Bertin et al [6], olfactory stimuli have a considerable influence on the feeding preferences and behaviour of animals. This result corroborates that of Vivian et al. [24] who reported a significant increase in feed intake of broilers fed on garlic and ginger powder. However, a decrease in feed intake was observed with 1% incorporation rate of C. longa. This could be due to the presence of alkaloids in the spices which could have induced a bitter taste to the feed.
According to Bouvarel et al [8], animals consume less feed with a bitter flavour, followed by salty, This ability to bind to proteins, under certain conditions especially at high doses, anti-nutritional agents that can inhibit enzymes in the digestive tract and reduce the availability of certain dietary proteins to the host [20]. This result is consistent with that of Vivian et al. [24] who reported an increase in digestibility in broilers receiving 50ml/L of garlic and ginger infusion through drinking water. In contrast, Nweze et al [18] reported that administration of Tetrapleura tetraptera powder through feed had no significant effect on live weight of broilers. Similarly, Ebile et al [11] reported that, administration of Dichrostachys glomerata powder via feed and drinking water had no significant effect on nutrients utilization (feed conversion ratio) of quails.
The increased digestibility in this study could be due to the presence of active ingredients such as phenols, terpenes and flavonoids present in C. longa, which have antibacterial, anti-inflammatory and antioxidant properties on one hand and, above all, minerals important for metabolic processes that could have favoured the growth of the animals. According to Burt [12], phenolic compounds are capable of crossing the phospholipid bilayer of the bacterial membrane, causing degradation of the membrane, ion leakage and possibly killing the cells. The reduction of pathogenic bacteria, illustrated by the decreased in bacterial load of Escherichia coli and Salmonella in our study, thus maintained the animal in good health, increased the availability of nutrients and thus improved digestibility.

Conclusion and Recommendation
C. longa powder can be used in Guinea-pig diet as phytobiotic. At moderated levels of inclusion, it improves dietary intake and nutrient digestibility in this species.