Indigenous poultry farming is very popular in the sub-Saharan region, sustaining the livelihood of millions of farmers and vulnerable communities [1]. In Cameroon, indigenous poultry farming is predominantly dominated by GallusGallus species [2]-[4]. Most of the research has been oriented towards predominant species of broiler, local chickens, to improve local chicken [5][6]. Within vulnerable communities, poultry farming represents one of the few opportunities for food security, savings and investment [7]. Unfortunately, disease outbreak, climate change and global warming are among factors that decreased productivity of indigenous genetic resources in sub-Saharan countries and in Cameroon, hence, delaying their sustainable management initiatives, making them fragile in face of global changes and unsustainable for food security [4]. There is a need to look for non-conventional animal alternatives. In fact, non-conventional animal species can be justified by the fact that they can be adapted to harsh environmental condition and they can utilize natural resources that conventional species cannot, easy to manage, handle, feed, and thus be raised by smallholder farmers within household in Africa [8][9]. In this regard, indigenous guinea fowl represent an important asset for diversifying animal protein origins but also for reducing pressure towards intensive chicken meat and egg production which is not affordable for many vulnerable families [7][10].

In the Sudano-Guinean zone of Cameroon, the indigenous guinea fowl are considered as a non-conventional poultry species with great production potential and thus is a good candidate to increase availability of protein of animal origin [4]. Dongmo and collaborators have suggested that, based on morphometric analysis, indigenous guinea fowl could constitute a high potential food resource if provided appropriate breeding [11]. However, in Cameroon context, a large amount of guinea fowl eggs and meat are collected from the wild [4]. Henceforth, most of efforts towards production of indigenous guinea fowls remained in the scavenging rearing system with very scanty knowledge regarding their health care, nutrition, reproduction, housing, breeding and selection [2][4][7][12]. Banla and collaborators also emphasized that most of the husbandry techniques adopted in the breeding of indigenous guinea fowls are copied from the common domestic chicken as they are similar [4]. It implies that, indigenous guinea fowl, may inherit most of constraints encountered in scavenging chicken farming. As a result, guinea fowl production has remained undeveloped for a long time.

In Cameroon, several studies have been carried out on breeding practice [2] morphobiometric characterization of guinea fowls [13], production performance [7][14]. Research on eggs characteristics, early growth performance of guinea fowl keet are still very scanty. If properly managed and fed, guinea fowls could make a significant contribution to satisfying animal protein requirements and raising the standard of living of vulnerable population. The nutritional needs of guinea fowl are specific to the Sudano-Sahelian zone, where Moringa oleifera production and use is fairly widespread.

There are many unconventional food resources in the Sudano Guinean zone of Cameroon [15][16], such as Moringa oleifera, reputed for its virtues and richness in nutrients, vitamins, minerals, essential amino acids, etc. Moringa has already been used in animal feed to improve growth performance in guinea pigs [17], quail [3][18][19] and the reproduction of laying hens [17][20], but to our knowledge no work has been done on the use of Moringa oleifera on the production performance of guinea fowl. Henceforth, the present study aims to characterize guinea fowl eggs, evaluate the hatching rate, and to investigate the early growth performances of keets post-hatch fed on experimental diet containing Moringa oleifera leaf meal (MOLM) in the Sudano-Guinean zone of Cameroon.

Egg weights ranged from 27.71 to 45.56 g, with an average of 37.81 ± 3.54 g. This average is similar to the value 37.3 ± 4.1 obtained by Sanfo et al. investigations [25] in the northern Sudanian zone of Burkina Faso and to the value 37 ± 6.2 in dewormed guinea fowl and to the value 36.15 ± 6.5 g in non-dewormed guinea fowl reported by Hien et al. [26] in western part of Burkina Faso; it is lower than the 39.8 ± 0.08 g reported by Yamak et al. works [27] in India and the 40.37 ± 0.32 g recorded by Dzungwe et al. [28] in wetland Nigeria. Overall measurements increased with weight, with averages of 46.73 ± 1.80 mm for height and 37.77 ± 1.19 mm for large diameter. These averages obtained for height and large diameter are similar to 47.6 ± 2.4 mm and 37.3 ± 1.2 mm reported by Sanou trials [29] from the east of Ouagadougou in Burkina Faso, and, 48.6 ± 0.2 mm and 39 ± 0.2 mm noted by Dzungwe et al. [28] in Nigeria; lower than 52.3 ± 0.06 mm and 44.9 ± 0.3 mm according to Elergoglu et al. investigations [30] in Nigeria. The shape index ranged from 0.79 to 0.85 with an average of 0.75 ± 0.02. This value is lower than 0.78 ± 0.54 (common) and 0.78 ± 0.52 (black) two improved guinea fowl breeds recorded by Obike et al. trials [31] in the dense tropical rainforest zone of Nigeria. But higher than 0.73 (French meat guinea fowl) and 0.74 (Polish domestic guinea fowl) found by Dzungwe et al. [28]. Several factors could exert significant effects on the characteristics of local guinea fowl eggs. Indeed, the variation in egg weight observed in this study could be explained by genetic difference, egg collection from layers of heterogeneous age and weight, and related to environmental factors [31]-[34]. The egg measurements and weights observed in this study are justified by the theory of Obike et al. [31] that egg measurements and weights are proportional to the weight of the animal. According to Oke et al. [32] show a high and positive correlation between the weight of the female guinea fowl and the weight of the egg laid. Shape index is an important factor in characterizing avian species and can be used as a selection criterion. It not only provides information on egg shape, but also measures the mechanical strength of eggs. And would suggest that guinea fowl eggs may be more resistant to breakage and environmental stress [31][35][36].

Fertility rates varied with egg weight category from 0.34% to 31.69%, with the majority of fertile eggs weighing between 35 and 40 g. The average rate of fertile eggs is 58.2% for all categories (71.71% in Biou, 67.60% in Figuil and 35.30% in Batao). It is similar to 58.46% reported by Yamak et al. [27]. It is lower than the 70.3% obtained by Sanfo et al. [37] and 97.1% reported by Dzungwe et al. [28]. There are a number of factors affecting the fertility of guinea fowl eggs. A sex ratio of two females to one male has been reported in Benin [38], while this parameter is three females to one male in traditional breeding in Burkina Faso [25][39]. In the work of Boko [40] carried out on local guinea fowl in Nigeria, indicated that problems of sex ratio, with their monogamous sexual behavior [30] and maturity of breeders are considered factors to be taken into account to optimize egg fertility, especially the onset of puberty and the level of hormones (gonadostimulis) [41].

In the present study, the average hatching rate overall was 30.53%. This average is lower than the 82.7% recorded by Sanfo et al. [37], to 58.46% noted by Yamak et al. [27]. The best effective hatching rate of eggs weighing between 35 - 40 g records 17.54% (with 22.92% in Figuil, 19.72% in Biou and 10% in Batao); 9.95% in 40 - 45 g (with 16.67%, 9.86% and 3.33% in Figuil, Biou and Batao respectively); and 0% in 25 - 30 g. These results by weight category are lower than those of 54.1% (25 - 30 g), 87.5% (35 - 40 g) and 90.7% (40 - 45 g) reported by Sanfo et al. [25]; by 20% (<39 g), 69.23% (39 - 42 g) and 58.85% (>42) reported by Moreki and Mothei [42] on local guinea fowl in Botswana; and by 79.89% (35 - 40 g), 86.33% (40 - 45 g), 90.12% (45 - 50 g) and 87.69% (50 - 55 g) recorded by Abudabos et al. [43] on native chickens in Saudi Arabia. This difference in hatchability is thought to be due to certain storage [27][29][44] and egg incubation factors [28]. Weight loss during egg storage is linked to the temperature and relative humidity of the environment, as well as to the length of storage. In the work of Khan et al. [44] on improved breed chickens (Rhode Island Red), at 16˚C and 78% relative humidity, they recorded a loss of hatchability of 2.52% after 9 days’ storage. While Sanou [29] records an average loss of 3.9% per day of storage after laying in local guinea fowl.

Overall, there was more embryonic mortality in the 35 - 40 g egg category than in the other categories, with 23.41% mortality (early and very early), the majority in Batao and Figuil; 8.68% late mortality, with a high rate in Biou; and 7.47% very late mortality, the majority in Batao. These averages are similar to 27% (early mortality) and 7.3% (late mortality) obtained by Sanfo et al. [45], higher than that of Sanfo et al. [25] and Yamak et al. [36] who report 1.65 - 7.9% (early mortality) and 4.6 - 5.71% (late mortality). But lower than the 48.3% early mortality and 17.6% late mortality recorded by Khan et al. [44]. Batao eggs showed low hatchability and high mortality during incubation. In the context of our study, embryonic mortality would be due to poor egg handling and storage conditions, temperature, humidity and/or ventilation. Indeed, a long storage period leads to water loss and albumen degradation [44]. These losses disrupt their physiological equilibrium and hence that of the embryo; similarly, fluctuating incubation temperature is said to be the result of unstable tension [27]-[29] in the work of Nwagu [46] cited by Boko [40] carried out on local guinea fowl in Nigeria, indicated that severe nutritional deficiencies in female guinea fowl, such as biotin, vitamin A and E, pantothenic acid are the cause of delayed development or mortality on the third day of incubation of guinea fowl (keet).

The average hatchling weight for all categories and localities was 22.84 g ± 3.38 g. This is similar to 23.5 ± 2.5 g found by Sanou [29] and 24.85 g obtained by Hien [39]. However, it is lower than the 25.6 ± 2.6 g reported by Sanfo et al. [25]. The significant effect of egg weight on guinea fowl weight is in line with the work of Ayorinde [47]. It confirms the importance of egg weight in improving the weight productivity of guinea fowl, with more nutritional reserves available to the fetus [25]. According to Alkan et al. [48], hatchability and hatch weight of quail, and subsequent growth performance, are closely linked to egg weight. The importance of the egg’s nutrient reserves is thought to favor better embryo development.

From hatching to 12 weeks (end of trial), we recorded a 39% rate of non-viable (dead) guinea fowl. This rate is similar to the 39.6% obtained by Sanou [29]. It is higher than the 18.9% reported by Dzungwe et al. [28] and the 16.5% recorded by Sanfo et al. [37] in guinea fowl, lower than the rates of 63% to 89% quoted by Bessin et al. [49], and those of 22% and 100%, respectively in controlled and real environments, according to Hien et al. [50]. The difference in reported mortality rates could be due to the conditions under which the guinea fowl are kept, such as the measures taken to avoid accidental drowning and the aggregation of the animals. The same applies to drowning, which is often fatal to guinea fowl, especially in cold weather [37]. This situation is compounded by guinea fowl’s inability to thermoregulate and their chilly disposition. With regard to temperature, Bessin et al. [49] recommend 36˚C to 40˚C, with a drop to 32.2˚C after 3 weeks, in brooding houses.

Guinea fowl feed intake showed a non-significant mean difference throughout the experiment from 34 to 318.87 g/week/subject. This is similar to the 44.95 to 46.74 g/day/subject reported by Savadogo [51] on the substitution of cowpea for soybean did not affect the feed intake of local guinea fowl at 03 months of age in Burkina Faso. The finding was that, as the rate of incorporation of Moringa oleifera leaf meal increased, feed intake decreased; such is the case here, which is similar to the results of Olugbemi et al. [52] who incorporated up to 20%, Gadzirayi et al. [53] who incorporated up to 100%, Abasse et al. [54] who incorporated up to 4%, of M. oleifera leaf powder meal on broiler performance. In contrast, studies by Tendonkeng et al. [55] showed that incorporating up to 60% Moringa.oleifera leaf meal into the finishing ration of broilers in substitution for soybean meal, had no negative effect on feed intake. The same is true with the investigations of Kakengi et al. [56], who found that high levels (15% and 20% respectively) significantly improved feed intake in laying hens. These observations of food consumption can be explained by the digestibility produced by the nutrients contained in leafy vegetables. In the case of moringa, it should be noted that its high nutritional quality has already been demonstrated in humans, particularly in sick and malnourished children [57][58]. Moringa leaves are said to contain a very high concentration of vitamins A and C, a complex of B vitamins, iron, calcium, proteins, zinc and selenium [59].

In the present study, moringa leaf powder was used in proportions of 1, 2 and 3% incorporation. But these levels of incorporation did not induce a difference in body weight between these different treatments. At 12 weeks of age, body weights ranged from 447 ± 35.07 to 489.32 ± 23.59 g, which is similar to that reported by Savadogo [51], which ranged from 503.96 to 595.28 g at the same age when cowpea was incorporated in place of soya. A decrease in animal weight was observed with increasing amounts of M. oleifera leaf meal in the experimental diets. These results are similar to those obtained by Tendonkeng et al. [55], Olugbemi et al. [52] in broilers and Kana et al. [6] in laying hens up to 10%; which is contrary to those obtained by Mufwaya and Kiatoko [60] with moringa hay replacing palm kernel meal in broilers up to 10%. These results are lower than those obtained by Farougou et al. [61] in guinea fowl fed Mucunapruniens seed meal as a substitute for palm kernel cake in broilers up to 10%. The weekly weight gain obtained (8.99 to 86.4 g/week) are better than those reported by Sanfo et al. (40.6 g/week) and similar to the Weight gain of 87.5 g/week reported by Halbouche et al. [62]. In addition, the peak of 96.2 g/week recorded in this experiment is better than that reported by Dahouda et al. [63] (61.67 g/week). T1 (basal diet + 1% MOLM) showed the best GMH, which does not corroborate the results of Tendonkeng et al. [55] and Abasse et al. [54], who obtained the best GMH with T0 (only basal diet), but is similar to the results obtained by Bello [64] compared with the control treatment, which recorded the lowest GMH. This drop in body weight and weight gain with increasing moringa content is thought to be due to the anti-nutritional factors contained in moringa leaves, such as tannins and phytates, which are known to reduce the bioavailability of proteins, carbohydrates and minerals in the animal’s intestine, and which can not only reduce the nutritional value of the feed but also zootechnical performance by reducing feed intake, particularly in poultry, and are also responsible for the low palatability of leaves, and consequently a drop in food consumption and growth in monogastric animals [65]-[67]. In their work, Sanfo et al. [25][37] note that heterogeneity in growth is a guinea fowl characteristic, which is also due to the inbreeding observed in free-range farming.

The best feed conversion ratio (FCR) was found at T1 (basal + 1% MOLM), compared with the other treatments. These results are lower than those of Tendonkeng et al. [55], Bello [64] and Kout et al. [18] who incorporated up to 2% moringa leaf powder in laying hens, broilers and Japanese quail respectively. It is higher than that reported at T0 (only basal diet), by Abasse et al., 2017 in broilers. This is thought to be due to adequate utilization of the nutrients consumed in the feed ration [68][69]. Furthermore, Berrama et al. [70] assert that high feed intake coupled with low weight gain for the same period leads to a decrease in the bird’s ability to convert feed at the end of growth.

This study assessed the incubation and growth performance of local guinea fowl (Numida meleagris) in the Sudano-Guinean zone of Cameroon. It is showed that: the 35 - 40 g egg category was the most representative, with the highest values for height and large diameter noted in the 40 - 50 g category. The Biou locality recorded the best egg characteristics. The 35 - 40 g category recorded the highest incubation performance in Figuil and Batao. Guinea fowl eggs collected in village environments appear to have low fecundity and hatchability, and vary greatly from one locality to another. The low hatchability and fecundity rates of guinea fowl eggs from village areas can be attributed to the variation of several interrelated factors, including nutritional deficiencies, management practices and environmental conditions, such as temperature and humidity. The use of 1% Moringa oleifera leaf powder improves the early growth performance (feed intake, body weight, weight gain and feed conversion ratio) of the indigenous guinea fowls keets. Findings from this study provide farmers with the appropriate range of egg weight (35 - 40 g) which is suitable for incubation, hatchability as well as the potential of the locally available resources that can be used in the low inputs system to enhance resilience and sustainability in local poultry farming.

FDK and LFN, performed data curation and formal analysis; ANT, JP, FDK and HMW investigated, methodology, and wrote the original draft; FDK, ANT, JP, HWM, DM, HM, and ME writing reviewed and edited the manuscript. FDK and ME supervised, validated, and visualized the entire study. All the authors have read and approved the final version of the manuscript.