The use of antibiotics as growth promoters has been used for decades, with great effect on production costs and animal welfare. However, its indiscriminate use caused microbial resistance problems and exacerbated the appearance of residual effects on food for human intake (Ahmed and Gareib 2016 and Muaz et al. 2018). For these reasons, in 2006, the European Community prohibits its inclusion in the diet for prophylactic purposes. In this context, nutritionists and specialists began researches to search for additives that are harmless to animals and humans, with effects similar to these drugs (Linares 2015).
One of the possible alternatives reported in poultry production to replace antibiotics is the use of plants, which are incorporated into the diet to improve the yield and immune response of broilers (Gadde et al. 2017). Moringa oleifera is in great demand due to its high nutritional and medicinal value. Numerous researches were carried out to isolate, identify and characterize bioactive compounds from different parts of this plant. These studies showed that the biologically active components in Moringa oleifera are compounds called glucosinolates and isothiocyanates, including 4- (4'-O-acetyl-α-L-ramnopyranosyloxy) benzyl isothiocyanate, niazimycin, pteriospermine, benzyl isothiocyanate, and 4- ( α-L-ramnanosaniloxy) benzyl glucosinolate, niaziridine, niazirine, as well as carotenoids (Bennett et al. 2003 and Shanker et al. 2007), which give the plant antiparasitic, antibacterial and digestion modifying properties, among others (Dilawar et al. 2018). Due to these properties, it is suggested that their inclusion in the diet in small amounts improves the health and immune response of broilers (Hassan et al. 2016 and Mousa et al. 2017).
According to Padilla et al. (2014), this plant is also of great importance as forage plant, due to its nutritional characteristics and its high yield in the production of fresh biomass. It would be interesting to know if the use of Moringa oleifera forage meal in small amounts can improve broilers health. Therefore, the objective of this study was to evaluate the inclusion of Moringa oleifera forage meal as an additive and its effect on health indicators of broilers.
Materials and Methods
Elaboration of forage meal. The sowing of moringa was carried out in the Unidad Experimental de Pastos y Forrajes "Miguel Sistach Naya" of the Instituto de Ciencia Animal (ICA), Cuba. Leaves and stems of the plant were used, with a cutting age of 60 d and 30 cm height. The forage was milled in a hammer mill and subsequently dried in the sun for 96 h. In the drying period, the material was spread on the plate at bed height, which did not exceed 30 cm. It was turned several times a day with a rake to achieve uniformity of the material. Then, it was passed through a hammer mill until obtaining a particle size of 3 mm. The material was packed in 50 kg jute bags and kept indoors and aired until their use.
Animals and experimental diets. A total of 28 male broilers from the hybrid EB34, of 1 to 42 d of age were used. The birds came from a productive performance experiment (with 700 chickens) and were distributed in a completely randomized design in four treatments: a control diet (corn-soybean) and three diets, with inclusion of 0.5, 1.0 and 1.5 % of Moringa oleifera forage meal. Throughout the experimentation period, the animals had free access to food and water.
Three-phase feeding system was applied: starter (1-14 d), growing (15 to 28 d) and finishing (29 to 42 d). Meal diets were used and formulated according to Rostagno et al. (2017) recommendations. Table 1 shows the base diets for each feeding period. To each base diet (without moringa inclusion) 0.5, 1.0 and 1.5 % of Moringa oleifera forage meal were added.
Table 1.
Base diets of broilers in the different feeding stages.
1 Mineral premixture per kg of food: selenium (0.1 mg), iron (40 mg), copper (12 mg), zinc (120 mg), magnesium (100 mg), iodine (2.5 mg) and cobalt (0.75 mg) and Vitaminic premixture per kg of food: vitamin A (10 000 UI), vitamin D 3 (2 000 UI), vitamin E (10 mg), vitamin K 3 (2 mg), vitamin B 1 (thiamine, 1 mg), vitamin B 2 (riboflavin, 5 mg), vitamin B 6 (pyridoxine, 2 mg), vitamin B 12 (15.4 mg), nicotinic acid (125 mg), calcium pantothenate (10 mg), folic acid (0.25 mg) and biotin (0.02 mg)
At 42 d, seven birds were selected and weighed per treatment. For this, the average weight of the birds of each treatment was taken into account and the immunological and health indicators described below were determined.
Immunological indicators. The birds were slaughtered two hours and thirty minutes after ingestion of food by the method of bleeding the jugular vein, described by Sánchez (1990). Subsequently, the abdominal cavity was opened and the spleen, thymus, and the bursa of Fabricius were removed. These organs were weighed on a SARTORIUS technical balance, with precision ± 0.1 g. The organ weights were expressed as relative weight to live weight (g gLW-1 x100). Live weight was established at the slaughter time.
Health indicators. As health indicators, bird mortality was taken into account, as well as hematocrit (Hto) and hemoglobin (Hb).
Mortality: To calculate this indicator, the number of dead birds during the stage was used and it was divided among those that were housed at the beginning of the experiment.
The determination of the hematocrit was carried out on Hawkley microhematocrit equipment with a sliding scale reader that allowed it to be placed at the level of the hematic sediments to perform the reading.
For hemoglobin, the cyanometahemoglobin method, described by Crosby et al. (1954) was used.
Statistial analysis. A completely randomized design was used for health indicators, with four treatments and seven repetitions. The mortality was analyzed by the Chi-square test, using the CompraPro statistical package de Font et al. (2007), version 1. The health indicators were analyzed by the statistical package INFOSTAT 2012 (Di Rienzo et al. 2012). For the comparison of means, Duncan (1955) mean range test P <0.05 was used.
Results and Discussion
The Hb and Hto indicators did not differ between the studied treatments (table 2). They were found in the established range (7.0-18.6 g dL-1 of Hb and 23-55 % of Hto) for broilers, according to Morton et al. (1993). However, it is suggested that when blood is extracted from the brachial vessels, the stress increases, due to the increase in plasma cortisol. This causes the mobilization of erythrocytes, so there may be a slight increase in hemoglobin (Gutiérrez and Corredor 2017). However, this one did not show significant changes between treatments.
Table 2.
Hematological indicators of broilers with the inclusion of Moringa oleifera forage meal as an additive
| Indicator | Levels of Moringa oleifera forage meal , % | SE (±) | Value of probability | |||
|---|---|---|---|---|---|---|
| 0 | 0.5 | 1.0 | 1.5 | |||
| Hb (g dL-1) | 10.19 | 10.57 | 10.76 | 10.56 | 0.20 | P=0.2658 |
| Hto (%) | 30.57 | 31.71 | 32.29 | 31.71 | 0.61 | P=0.2668 |
Oghenebrorhie and Oghenesuvwe (2016) and Sánchez et al. (2016), when using moringa leaf meal in growing chickens, they do not found differences in Hb and Hto levels. On the contrary, Hassan et al. (2016) when evaluating three levels of moringa leaf meal inclusion (0.1, 0.2 and 0.3 %) in broilers, found an increase in the concentration of Hb (9.16, 9.33 and 9.46 mg/100 mL, respectively) with respect to the control (8.93 mg/100 mL). It is probable that the type of diet, age, sex and physiological state of the animals could influence on these results (Ogbe and Affiku 2012).
Table 3 shows the weight of the lymphoid organs, which according to Perozo et al. (2004) are used as an indicator of birds health. With the inclusion of meal, there was an increase in the relative weight of the thymus and the bursa of Fabricius with respect to the control.
Table 3.
Relative weight (g gLW-1 x100) of lymphoid organs of broilers receiving Moringa oleifera forage meal as additive in the diet
a,b Different letters in the same row differ at P < 0.05 (Duncan 1955).
According to Suárez et al. (2010), the immune system in chickens depends on primary lymphoid organs, such as the bursa of Fabricius and thymus, as well as secondary ones, such as the spleen, among others. B cells are formed in the bursa of Fabricius and T lymphocytes are formed in the thymus from primordial cells that come from the bone marrow or yolk sac during the embryonic phase. For this reason, the development of these lymphatic organs is important to understand the protective functionality of the immune system of chickens. Increasing its size increases the population of cells involved in the immune response, especially B cells. This same process occurs in the thymus, in which the differentiation of T lymphocytes is generated, by which a better immune response is allowed (Cortes and Villamarín 2013).
In a previous study, Perozo et al. (2004) reported that as more developed these lymphatic organs are (except in muscular hypertrophy), there is more immune protection in the birds organism. According to this criterion, the chickens under study did not show immunosuppression. On the contrary, with the inclusion of Moringa oleifera forage meal favors the increase in the function of the birds' immune system and there is a better immunostimulatory response. These results may be due to the chemical compounds present in moringa, and to the ability of plant polysaccharides to modulate the immune system (Dong et al. 2007). In this regard, Cabrera et al. (2017) and Kshirsagar et al. (2017) reported secondary metabolites, mainly polyphenols, flavonoids, and tannins. In this sense, tannins, although considered anti-nutritional factors, small proportions in diets can be efficient bactericides, fungicides, antioxidants and astringents, thus improving the immune system and with it, the of animals health (Savón et al. 2007).
Nkukwana et al. (2014) fed broilers with different levels of Moringa oleifera leaf meal and found no difference between treatment and control group for spleen weight, but not for the bursa of Fabricius. However, Teteh et al. (2013) found higher weight of the spleen, thymus, and the bursa of Fabricius in chickens with 1 and 2 % moringa leaf meal compared to those in the control group. Studies with other plants show higher weight of thymus and the bursa of Fabricius in chickens that intake 2.0 and 5.0% of Morinda citrifolia compared to those that intake the control diet (Renteria 2018).
The bird mortality was not affected by moringa levels (figure 1). This shows that the inclusion up to 1.5 % of moringa forage meal in broilers diets does not cause lethality. In this regard, Mona et al. (2016) neither did they found effect on the mortality of chickens, reporting values of 1.13 and 0.88 % when including 2 and 3 % of moringa forage meal , respectively.
Figure 1.
Effect of the level of Moringa oleifera on the mortality of broilers
Similar results were observed when chickens were fed different levels of leaf meal from Morus alba (Leyva et al. 2012) and Tithonia diversifolia (Buragohain 2016).
Although statistically there are no differences between treatments for animal mortality, figure 1 shows that with 1.0 % moringa there are fewer deaths. During the entire experimental period (from 1 to 42 d), 17, 8, 4 and 12 dead animals were recorded for the control treatments, 0.5, 1.0 and 1.5% of Moringa oleifera forage meal, respectively. This result corresponds to the immune response of the animals, since despite the fact that there were no differences in the relative weight of the thymus and the bursa of Fabricius in the chickens that intake moringa (table 3), numerically the birds with 1.0 % of inclusion, showed the highest values, which shows higher immunity.
The results showed the possibility of including up to 1.5 % of Moringa oleifera forage meal in feed rations for broilers, without affecting the animals health. Future researches are recommended to complement this information and to measure other indicators to be able to recommend Moringa oleifera forage meal as an additive for broilers.