Evaluating the Efficacy of Moringa oleifera Seed Extract on Nutrient Digestibility and Physiological Parameters of Broiler Chickens

Abstract

Moringa oleifera seed extract (MSE) contains phytochemicals that can improve chicken production and health. However, the amount that can be orally administered to the birds is unknown. Thus, this study investigated the optimum level of MSE, administered through drinking water, on nutrient digestibility, growth performance, and haematological and serum biochemical parameters in broilers. A total of 250, one-day-old Cobb 500 male broilers (58.11 ± 0.23 g live-weight) were randomly allocated into five treatments with five replicates of 10 birds each. The treatments were: a negative control involving drinking water only (T1) and positive controls with 5 g multi-strain probiotic/L water (T2), 60 mL MSE/L water (T3), 90 mL MSE/L water (T4), and 120 mL MSE/L water (T5). Crude protein and neutral detergent fibre digestibility linearly decreased, whereas overall water intake and weight gain in one-week-old birds increased linearly (p < 0.05) as MSE levels increased. T1 promoted higher (p < 0.05) overall feed intake and feed conversion ratio than the other treatment groups. All haemato-biochemical parameters were within the range for healthy birds, from which a maximum MSE dosage was determined to be 94.75 mL/L. It can be concluded that oral administration of MSE improved overall feed utilisation efficiency of the chickens.

1. Introduction

Sustainable intensification of broiler chickens as a major source of animal protein is currently restricted by many factors, including high feed cost [1,2]. The increase in feeding cost is caused by the over-reliance on maize and soybean, two major ingredients whose market prices are very high due to high demand by the food, feed, and biofuel sectors [3,4]. Furthermore, the use of conventional antibiotics to promote growth and feed utilisation efficiency in broiler chickens increases production costs because antibiotics are expensive [5,6]. This is not withstanding the fact that their usage has been outlawed in many countries due to traces of antibiotic residues in meat products and the risk of transmitting drug-resistant pathogenic bacteria to humans [1,7]. This has led to the use of probiotics as safe alternatives to conventional antibiotics [8,9]. Indeed, the supplementation of broilers with probiotics has been reported to improve weight gain and feed utilisation efficiency [10]. Unfortunately, the utility of probiotics for large-scale poultry production can be prohibitive because they are also expensive.

The use of locally available phytogenic plant products as sources of nutrients and pharmaceuticals in place of conventional antibiotics and probiotics can deliver sustainable broiler production systems that can contribute to food and nutrition security in South Africa. Moringa oleifera seeds contain a variety of nutrients (calcium, phosphorus, protein, carbohydrates, and vitamins A, C, and E) and bioactive compounds (alkaloids, flavonoids, phenols, saponins, and tannins) with antimicrobial and antioxidant properties [11]. The seed bioactive substances are reported to elicit probiotic effects, growth-stimulating and health-promoting properties, and immuno-modulatory actions, which result in improved broiler performance [12]. However, there are limited and conflicting studies on the effects of including M. oleifera seed meal in the diets of broiler chickens. Ochi et al. [13] reported that the inclusion of 5 g/kg M. oleifera seed powder in broiler diets reduced feed intake (FI) but had no effect on the feed conversion ratio (FCR) and body weight gain (BWG) of the birds. However, the supplementation of diets with 20 g/kg of M. oleifera seed meal reduced FCR and BWG [14]. This could be because the seed meal has high levels of fibre and condensed tannins [15], which can be eliminated through the use of moringa seed extracts (MSE) [16]. Alabi et al. [17] noted that the administration of 120 mL of moringa leaf extract increased weight gain and enhanced feed efficiency in broilers.

Thus, the use of the extracts instead of the meal would reduce the antinutritional effects of dietary fibre and tannins and ensure that the birds have full access to moringa’s beneficial bioactive compounds. In addition, water extraction of phytogenic substances does not require expensive and sophisticated equipment and, as such, could easily resonate with resource-limited poultry farmers. However, the optimum level of Moringa oleifera seed extract (MSE) that can be orally administered to broiler chickens is unknown. This study, therefore, evaluated the effect of oral administration of MSE on nutrient digestibility, growth performance, and blood parameters of Cobb 500 broiler chickens.

2. Materials and Methods

2.1. Study Site

The feeding trial was conducted during summer at Rooigrond Farm (25°55′0″ S; 25°48′0″ E), which is located 16 km southeast of the capital city, Mafikeng (North West, South Africa). The temperatures ranged from 19 °C to 37 °C, with an annual average rainfall of 450 mm at an elevation of 1224 m above sea level.

2.2. Sources of Treatments and Preparation of the Moringa Extract

The M. oleifera seed powder used to prepare the experimental extracts was supplied by Supa Nutri (Johannesburg, South Africa). The seed powder was soaked in distilled water at a ratio of 1:10 for 24 h. The extracts were then kept in clean containers in a cold room at 4 °C after being filtered with a muslin cloth to remove the debris from the filtrate. The extracts were then diluted with fresh drinking water that was offered to the birds daily, as follows: negative control with drinking water only (T1) and positive controls with 5 g probiotic per litre of drinking water (T2), 60 mL of MSE per litre of drinking water (T3), 90 mL of MSE per litre of drinking water (T4), and 120 mL of MSE per litre of drinking water (T5). The probiotic (5 × 10⁸ CFU/g) was acquired from QBLabs (Saint Louis, MO, USA) and contained beneficial bacteria (Aspergillus oryzae, Bacillus subtilis, Lactobacillus acidophilus, and Enterococcus faecium), which were identified via 16S rRNA gene sequencing. Commercial starter (1–21 days) and finisher (22–42 days) diets from De Heus (Pty) Ltd. (Pietermaritzburg, South Africa) were used during the feeding trial. Dry matter, crude protein, crude fibre, and ash were analysed according to the methods of the Association of Official Analytical Chemists [18]. Minerals were analysed using the guidelines from AgriLASA [19]. Metabolizable energy (ME) was calculated using the following equation, ME = 0.821 × DE (MJ), by Khalil et al. [20]. The nutritional composition of the diets is shown in

Table 1. Nutritional composition (g/kg as fed basis, unless stated otherwise) of the starter and finisher diets.

Nutritional Composition	Starter (1–21 Days)	Finisher (22–42 Days)
Dry matter	884.6	885.1
Calculated ME 1 (MJ/Kg)	12.87	13.12
Crude protein	205.7	181.8
Crude fat	33.69	46.64
Crude fibre	44.68	50.35
Ash	35.34	34.85
Available phosphorus	3.80	3.10
Calcium	9.00	7.40
Chloride	2.00	2.00
Sodium	1.70	1.70
Potassium	6.80	5.40
Total phosphorus	5.89	5.21

¹ ME = Metabolisable energy.

.

2.3. Experimental Design and Birds Management

A total of 250, one-day-old Cobb 500 male chicks were purchased from Poultry Ranch (Pty) Ltd. (Pretoria, South Africa). In a completely randomized design, the chicks were allocated to 25 pens (experimental units) to which the five experimental treatments were randomly assigned. The treatments were replicated five times, and each pen (experimental unit) carried 10 birds. The birds were housed in floor pens measuring 2.55 mL × 1.0 mW × 5.0 mH and were partitioned using the galvanized wire net. The pens were covered with dried sunflower husks as bedding. For the first two weeks, infrared electric lights were used to maintain the temperature at 34 °C; it was subsequently reduced by 2 °C every other week. The poultry house was cleaned two weeks before the birds arrived by washing all equipment with a biogel (detergent), while a disinfectant (Verocid) was used to disinfect the ceiling, walls, and floor. Finally, a formalin and salt mixed solution was applied to the floors, wall junctions, and base posts to ensure that the house was free from infectious pathogens [21]. The disinfectant was regularly added to the foot dip to enforce strict biosecurity measures. For the entire duration of the feeding trial, the birds were given free access to fresh water and feed daily.

2.4. Chemical Analysis of Moringa Seed Extract Treatments

The MSE treatments (T3, T4, and T5) were analysed for alkaloids, carbohydrates, flavonoids, glycosides, phenols, proteins, saponins, steroids, tannins, and terpenoids using the standard method by Ijarotimi et al. [22] and Nathaniel et al. [23], as shown in

Table 2. Phytochemical content (mg/L) of moringa seed extract (MSE) treatments.

Phytochemicals	T3	T4	T5
Alkaloids	8.42	8.84	9.30
Carbohydrates	2.77	3.21	3.45
Flavonoids	3.70	4.20	4.66
Phenols	17.84	18.34	19.52
Protein	32.36	33.28	34.52
Saponins	5.90	6.20	6.60
Steroids	4.30	4.80	5.30
Tannins	48.56	52.0	55.60
Terpenoids	18.34	18.90	19.40

.

The calcium, magnesium, phosphorus, potassium, zinc, iron, and sodium content of MSE treatments was determined according to the methods described by Liang et al. [24]. The MSE treatments (T3, T4, and T5) were analysed for vitamin A, B1, B2, B3, B6, B12, C, D3, E, K3, and β-carotene (

Table 3. Mineral and vitamin composition (mg/L) of moringa seed extract (MSE) treatments.

Micronutrients	T3	T4	T5
Calcium	606.8	618.2	630.4
Magnesium	37.40	40.80	43.60
Phosphorus	376.0	395.4	407.0
Potassium	68.00	73.00	76.20
Zinc	1.070	1.160	1.253
Iron	6.160	6.470	6.730
Sodium	253.8	263.6	272.2
Vitamin A	4.030	4.490	4.650
Vitamin B1	0.150	0.180	0.240
Vitamin B2	0.240	0.320	0.360
Vitamin B3	0.220	0.330	0.380
Vitamin B6	0.270	0.320	0.360
Vitamin B12	0.100	0.130	0.180
Vitamin C	4.680	4.800	4.960
Vitamin D3	ND	ND	ND
Vitamin E	548.0	598.0	620.0
Vitamin K3	ND	ND	ND
β-carotene	ND	ND	ND

ND = not detected.

) using the methods described by Sami et al. [25].

2.5. Growth Performance

The initial weights (58.11 ± 0.23 g) of the chicks were taken on the day of arrival, and they were subsequently weighed weekly using digital weighing scales (VidaXL^® Frugo Cumbria, Ulverston, UK) to determine weekly body weight gain. Before feeding, the provided feed was weighed, and refusals were collected and weighed before the next feed. The difference was computed as feed intake (FI). Drinking water was measured before being offered to the birds, and the remaining water was withdrawn and measured before the next drinking. The difference was calculated as water intake (WI). The feed conversion ratio (FCR) was calculated as FI divided by body weight gain.

2.6. Apparent Nutrient Digestibility

At 34 days of age, 5 birds per replicate pen were randomly selected from the growth trial and placed into clean and disinfected metabolic cages (0.50 mL × 0.5 mW × 0.34 mH) for measurement of nutrient digestibility. The cages were fitted with feed troughs, water nipples, and perches for excreta collection. The exact treatments were given to the birds as in the growth study. The birds were acclimatized for three days before measurements began for five days. The excreta obtained per day starting from the fourth day were carefully screened for spilled feed and feathers, then air-dried at room temperature, ground finely, and thereafter used for the proximate analysis. The samples were analysed for crude protein (CP) and ether extract (EE) according to the methods of the Association of Official Analytical Chemists [18]. Minerals (calcium and phosphorus) were analysed following guidelines from the AgriLASA [19]. The acid detergent fibre (ADF) and neutral detergent fibre (NDF) were determined using the detergent methods described by Van Soest et al. [26]. The apparent CP, EE, ADF, NDF, calcium, and phosphorus digestibility values were then calculated as:

$$Apparentnutrientdigestibility (\%)=\frac{nutrientintake-excretanutrient}{nutrientintake}\times 100$$

2.7. Blood Collection and Analysis

On day 42 of age, blood samples were randomly collected from five birds per replicate pen. The branchial veins of the birds were punctured with a set of sterilized needles and 5 mL syringes to draw out 4 mL of blood into two sets of sterilized tubes for haematological and serum biochemical analysis. The collected blood samples for haematology were placed in a cooler box with ice and determined within 48 h after collection [27]. Samples for serum biochemical analyses were centrifuged at room temperature for 10 min at 3000 rpm to obtain serum [28]. The haematological parameters (basophils, eosinophils, haematocrits, haemoglobin, lymphocytes, mean corpuscular haemoglobin (MCH), mean cell haemoglobin concentration (MCHC), mean corpuscular volume (MCV), monocytes, neutrophils, platelets, reticulocytes, and red cell distribution width (RDW)) were determined using an automated IDEXX LaserCyte Hematology Analyzer (IDEXX Laboratories, Johannesburg, South Africa). The serum biochemical indices (albumin/globulin (ALB/GLOB), alkaline phosphatase (ALKP), alanine transaminase (ALT), albumin, amylase, cholesterol, calcium, creatine, gamma-glutamyl transferase (GGT), globulin, glucose, lipase, phosphorus, symmetric dimethylarginine (SDMA), total bilirubin, total protein, and urea) were analysed using the automated IDEXX Vet Test Chemistry Analyzer (IDEXX Laboratories, Johannesburg, South Africa).

2.8. Statistical Analysis

Polynomial contrasts were applied to determine nutrient digestibility and physiology data (apart from the T2 data) for linear and quadratic effects. The following quadratic model was used to predict the optimum MSE level using response surface regression analysis:

$$y=a{x}^2+bx+c$$

(1)

where y = response variable, a and b = coefficients of the equation, c = intercept, x = MSE levels (mL), and −b/2a = x value for optimal response.

Weekly measured data were analysed using the repeated measures analysis option in the general linear model procedure (GLM PROC) of SAS [29] to determine the interaction effect between treatments and week (bird age). Nutrient digestibility, growth performance, and blood parameters data were analysed using a one-way analysis of variance in GLM PROC of SAS [30], where treatment was the main factor. For all the measured parameters, significance was considered at p < 0.05 and the least-squares means were separated using the probability of difference options in SAS.

3. Results

3.1. Nutrient Digestibility

Table 4. Nutrient digestibility (%) in Cobb 500 broilers orally administered moringa seed extract (MSE) through drinking water.

2 Parameters	1 Treatment					p Value
	T1	T2	T3	T4	T5	3 SEM	GLM	Linear	Quadratic
Dry matter	66.62	67.18	67.74	68.48	68.32	0.580	0.487	0.450	0.387
Crude protein	71.83	71.89	73.06	73.68	73.75	2.483	0.254	<0.001	0.088
Ether extract	62.70	62.94	66.66	65.97	66.70	1.762	0.548	0.001	0.003
NDF	64.86	63.60	65.67	62.50	62.24	1.061	0.684	0.009	0.407
ADF	62.73	62.71	64.38	64.16	62.98	1.002	0.187	0.712	0.220
Calcium	57.48 c	55.49 d	62.47 b	64.20 a	63.81 a	0.401	0.031	0.706	0.956
Phosphorus	57.30 b	55.46 c	62.39 a	63.85 a	63.55 a	0.512	0.015	0.884	0.914

^a,b,c,d Means in the same row with different superscripts are significantly different (p < 0.05). ¹ Treatments: T1 = drinking water only; T2 = 5 g probiotic/L of drinking water; T3 = 60 mL of moringa seed extract/L of drinking water; T4 = 90 mL of moringa seed extract/L of drinking water; T5 = 120 mL of moringa seed extract/L of drinking water. ² Parameters: NDF = neutral detergent fibre; ADF = acid detergent fibre. ³ SEM = standard error of the mean.

shows that there were linear and quadratic responses (p < 0.05) for EE digestibility (R² = 0.686; p = 0.003), while linear decreases were observed for CP digestibility (R² = 0.727; p = 0.0001) and NDF digestibility (R² = 0.328; p = 0.0091) as MSE levels increased. There were treatment effects (p < 0.05) on the digestibility of calcium and phosphorus. Calcium digestibility was highest (p < 0.05) with the administration of T4 and T5 and lowest in the T2 group. Birds reared on the T3, T4, and T5 groups had the highest (p < 0.05) phosphorus digestibility, followed by those in T1, and the lowest phosphorus digestibility was in the T2 group.

3.2. Growth Performance

Repeated measures analysis showed significant treatment × week (chicken age) interaction effects on average weekly BWG (p < 0.0001) but not on FI (p = 0.3762), WI (p = 0.4474), and FCR (p = 0.3657).

Table 5. Average weekly body weight gain (g/bird) and overall growth performance in Cobb 500 broilers orally administered moringa seed extract (MSE) through drinking water.

	1 Treatment					p Value
	T1	T2	T3	T4	T5	2 SEM	GLM	Linear	Quadratic
Week 1	234.2 b	236.0 b	256.7 a	262.5 a	266.0 a	11.98	0.008	0.002	0.276
Week 2	266.0	266.0	289.3	294.0	294.0	11.93	0.457	0.051	0.810
Week 3	307.1	301.3	326.4	335.2	326.8	17.16	0.458	0.161	0.919
Week 4	355.0	336.0	331.3	332.5	311.5	18.40	0.098	0.100	0.681
Week 5	371.7	416.0	393.3	391.5	358.3	27.05	0.064	0.819	0.577
Week 6	310.4	310.0	278.1	288.0	277.0	23.10	0.074	0.137	0.440
3 Parameters	Overall growth performance
Overall FI (g)	3547 a	3486 b	3404 d	3397 d	3425 c	19.96	0.012	0.212	0.148
Overall WI (mL)	6264	6178	6202	6113	6099	77.58	0.154	0.019	0.279
Overall FCR	1.91 a	1.86 b	1.81 c	1.80 c	1.84 b	0.030	0.022	0.437	0.689

^a,b,c,d Means in the same row with different superscripts are significantly different (p < 0.05). ¹ Treatments: T1 = drinking water only; T2 = 5 g probiotic/L of drinking water; T3 = 60 mL of moringa seed extract/L of drinking water; T4 = 90 mL of moringa seed extract/L of drinking water; T5 = 120 mL of moringa seed extract/L of drinking water. ² SEM = standard error of the mean. ³ Parameters: FI = feed intake; WI = water intake; FCR = feed conversion ratio.

shows that BWG linearly increased in week 1 only (R² = 0.7406; p = 0.0018) as MSE dosage levels increased. For the entire duration of the study, no significant quadratic effects were observed for BWG in response to the oral administration of MSE levels. Furthermore, overall WI linearly increased (R² = 0.525; p = 0.019) as the administration of MSE through drinking water increased. No linear or quadratic responses (p > 0.05) were recorded for overall FI and FCR as MSE levels increased. The GLM results show that one-week-old birds reared on T1 and T2 had lower BWG than those on T3, T4, and T5, whose weight gain did not differ (p > 0.05). The birds administered T3 and T4 had lower overall FI than those on T1, T2, and T5, whose overall FI differed (p > 0.05). Birds reared on T1 had the highest overall FCR followed by those reared on T3 and T4, and the lowest overall FCR was observed on those reared on T2 and T5, which were statistically similar (p > 0.05).

3.3. Haematology and Serum Biochemistry

Table 6. Haematological parameters of Cobb 500 broilers orally administered moringa seed extract (MSE) through drinking water.

2 Parameters	1 Treatment					p Value
	T1	T2	T3	T4	T5	3 SEM	GLM	Linear	Quadratic
Basophils (×109/L)	0.14	0.15	0.14	0.16	0.15	0.022	0.512	0.559	0.944
Eosinophils (×109/L)	0.33	0.42	0.33	0.36	0.32	0.063	0.478	0.990	0.788
Haematocrits (%)	24.20 a,b	19.84 b	27.16 a	26.38 a	26.72 a	1.912	0.014	0.349	0.532
Haemoglobin (g/dL)	8.50	7.08	9.30	8.42	9.10	0.686	0.247	0.705	0.830
Lymphocytes (×109/L)	68.12	61.50	64.59	60.16	60.04	5.474	0.741	0.258	0.960
MCH (pg)	36.88	29.35	31.05	29.83	29.10	3.202	0.941	0.077	0.607
MCHC (%)	34.80	35.80	35.40	32.00	34.50	0.231	0.084	0.707	0.906
MCV (fL)	104.7	82.21	90.66	93.41	86.54	9.101	0.857	0.183	0.787
Monocytes (×109/L)	9.88	9.05	9.91	9.13	9.84	1.462	0.764	0.884	0.891
Neutrophils (×109/L)	2.97	2.75	2.87	2.71	2.89	0.090	0.365	0.288	0.282
Platelets (K/µL)	1841	2070	2037	1905	1844	72.72	0.653	0.983	0.049
Reticulocytes (×1012/L)	2.350 b	2.420 b	3.000 a	2.830 a	3.192 a	0.122	0.003	0.001	0.507
RDW (%)	24.22	26.28	27.28	26.58	26.88	1.463	0.235	0.209	0.411

^a,b Means in the same row with different superscripts are significantly different (p < 0.05). ¹ Treatments: T1 = drinking water only; T2 = 5 g probiotic/L of drinking water; T3 = 60 mL of moringa seed extract/L of drinking water; T4 = 90 mL of moringa seed extract/L of drinking water; T5 = 120 mL of moringa seed extract/L of drinking water. ² Parameters: MCH = mean corpuscular haemoglobin; MCHC = mean cell haemoglobin concentration; MCV = mean corpuscular volume; RDW = red cell distribution width. ³ SEM = standard error of the mean.

demonstrates that, with the exception of platelets and reticulocytes, there were no linear or quadratic responses (p > 0.05). Platelets showed a positive quadratic response (R² = 0.210; p = 0.049) as MSE levels increased. Reticulocytes linearly increased (R² = 0.459; p = 0.001) in response to incremental MSE dosage levels. There were treatment effects (p < 0.05) on haematocrits and reticulocytes of the birds. The birds that were administered with MSE (T3, T4, and T5) had higher (p < 0.05) haematocrit counts than the birds in T2, but did not vary (p > 0.05) with the birds in T1. The T1 and T2 groups had lower reticulocyte levels compared to all the MSE treatment groups (T3, T4 and T5), whose reticulocyte levels did not differ (p > 0.05).

Table 7. Serum biochemical parameters of Cobb 500 broilers orally administered moringa seed extract (MSE) through drinking water.

2 Parameters	1 Treatment					p Value
	T1	T2	T3	T4	T5	3 SEM	GLM	Linear	Quadratic
ALB/GLOB	0.60	0.62	0.63	0.63	0.61	0.033	0.355	0.244	0.699
ALKP (U/L)	191.2	166.6	148.0	110.6	172.8	30.30	0.604	0.266	0.640
ALT (U/L)	11.00	9.40	11.20	12.00	10.20	1.400	0.685	<0.001	0.058
Albumin (g/L)	20.08	21.48	21.96	21.95	20.37	0.992	0.587	0.001	<0.001
Amylase (U/L)	464.8	495.4	493.0	491.2	486.8	13.09	0.728	0.290	0.245
Cholesterol (mmol/L)	3.75	3.68	3.53	3.49	3.38	0.211	0.854	0.006	<0.001
Calcium (mmol/L)	1.83 b	1.80 b	2.39 a	2.69 a	2.60 a	0.109	0.015	0.734	0.857
Creatine (μmol/L)	11.23	11.55	11.13	11.39	11.30	0.302	0.184	0.934	0.103
GGT (U/L)	13.60	14.40	14.80	14.00	13.60	0.967	0.285	0.001	<0.001
Globulin (g/L)	33.42	34.64	34.71	34.63	33.60	0.618	0.541	0.833	0.831
Glucose (mmol/L)	5.72	7.35	6.37	5.75	7.19	0.749	0.845	0.289	0.016
Lipase (U/L)	130.0	124.0	118.0	126.0	121.2	6.577	0.432	0.290	0.245
Phosphorus (mmol/L)	3.10	3.07	2.96	3.07	2.92	0.276	0.087	0.147	0.182
SDMA (μg/L)	9.20	8.00	10.00	10.00	8.60	1.219	0.072	0.001	0.007
Total bilirubin (μmol/L)	5.00	3.20	3.80	4.60	3.80	1.038	0.598	0.001	<0.001
Total protein (g/L)	53.49	56.12	56.67	56.58	53.97	1.144	0.415	0.288	0.667
Urea (mmol/L)	0.62	0.62	0.67	0.64	0.62	0.038	0.847	0.209	0.896

^a,b Means in the same row with different superscripts are significantly different (p < 0.05). ¹ Treatments: T1 = drinking water only; T2 = 5 g probiotic/L of drinking water; T3 = 60 mL of moringa seed extract/L of drinking water; T4 = 90 mL of moringa seed extract/L of drinking water; T5 = 120 mL of moringa seed extract/L of drinking water. ² Parameters: ALB/GLOB = albumin/globulin ratio; ALKP = alkaline phosphatase; ALT = alanine transaminase; GGT = gamma-glutamyl transferase; SDMA = symmetric dimethylarginine. ³ SEM = standard error of the mean.

shows that alanine transaminase (ALT) linearly increased (R² = 0.673; p = 0.0001) in response to MSE levels. The oral administration of MSE levels resulted in positive quadratic responses for albumin (R² = 0.908; p = 0.001), gamma-glutamyl transferase (GGT) (R² = 0.867; p = 0.001), glucose [R² = 0.350; p = 0.016), symmetric dimethylarginine (SDMA) (R² = 0.913; p = 0.001), and total bilirubin [R² = 0.923; p = 0.001), while cholesterol showed a negative quadratic response (R² = 0.804; p = 0.001). The quadratic responses were used to calculate the optimum dosage level of 94.75 mL/L. The GLM results show that there was a significant treatment effect on serum calcium concentrations only. The birds that were administered with the MSE treatments (T3, T4, and T5) had higher (p < 0.05) serum calcium concentrations than the T2 group, which did not differ (p > 0.05) with the birds reared on the T1 treatment.

4. Discussion

4.1. Nutrient Digestibility and Growth Performance

The MSE showed a rich composition of minerals, vitamins, and bioactive compounds, and these concentrations increased with increasing levels of the dosage per litre of drinking water. The nutraceutical composition of MSE shows its potential as a feed additive. Nutrient digestibility is the portion of feedstuff that is absorbed into the body of an animal upon consumption. In this study, the administration of MSE in the drinking water of Cobb 500 broiler chickens reduced CP digestibility. This corroborates the reports of Rezvani et al. [31], who noted a decline in CP digestibility in broiler chickens reared on pomegranate seed extract diets. The polarity of water might have enhanced the utilization of MSE polyphenolic compounds and, as such, reduced protein utilisation. Indeed, there is a negative relationship that exists between polyphenols and dietary protein [32]. Polyphenols bind to proteins via the interaction of their reactive hydroxyl groups with the protein’s carbonyl group, which can reduce the digestibility of the protein content in MSE. The plausible reason for the observed linear and quadratic increases in ether extract digestibility in response to increasing MSE dosage can be credited to the modification of intestinal microflora [33]. The negative linear response observed for NDF digestibility to increasing MSE dosage levels is understandable due to NDF containing some damaged protein and carbohydrates that may be bound by condensed tannins (NDF + Tannin complex = low NDF digestibility); similar effects were not observed for ADF digestibility. In this study, oral administration of MSE improved calcium and phosphorus digestibility, which could be due to the stimulation of bile secretion, increased pancreatic and intestinal enzyme output, and/or reduction of pathogenic microorganisms in the digestive tract, thereby increasing the efficiency of absorption because of the presence of bioactive compounds [34,35]. These phenols reduce the microbial load in the gut, hence decreasing the host–microbial competition for nutrients [32]. Thus, oral administration of MSE could improve the birds’ development because it increases calcium and phosphorus utilisation.

The MSE can potentially be administered as a beneficial additive in poultry nutrition due to its high levels of minerals, vitamins, alkaloids, glycosides, flavonoids, phenols, saponins, steroids, tannins, and terpenoids (Table 2 and Table 3), which have nutritional, antioxidant, and antimicrobial properties [36,37]. In this study, repeated measures analysis revealed a significant week and treatment interaction effect on weight gain, suggesting that the ability of the birds to assimilate the MSE into body tissues depended on their age. At one week of age, weight gain showed a linear increase, suggesting that the young birds benefitted mostly from the oral administration of MSE. This could be because young birds have lower absolute and relative gastrointestinal tract volumes compared to older birds [38], which allows efficient absorption of nutrients. These results varied with the findings of Mahlake et al. [39], who reported a linear decrease in weight gain of young Jumbo quail at two weeks of age when green tea leaf powder was supplemented at a rate of up to 50 g/kg in their diets. Similarly, Khalaji et al. [40] reported reduced body weight in one-week-old broilers fed with 500 mg/kg of black cumin seed extract–containing feed. The variation in results can also be due to the differences in the processing of the phytogenic products, their nutraceutical composition, and the route of administration. The administration of MSE in the drinking water of birds lowered overall feed intake, with birds in the T3 and T4 treatment groups recording the lowest overall feed intake. This decrease in feed consumption could be because the birds received extra nutrients from the MSE and thus tended to reduce the feed intake since their nutritional requirements were met. This could be the reason why the birds on T3 and T4 had lower FCR values, which suggests that the birds benefited from the nutraceutical properties of the MSE; hence, they had high feed utilisation efficiency. This further demonstrates that higher levels (e.g., 120 mL of MSE per litre of drinking water) could compromise the performance of the birds due to high levels of low molecular weight phenolic acids.

4.2. Haematological and Serum Biochemical Parameters

The pathophysiological responses of chickens to the environment (feed, disease, temperature, etc.) are reflected by their blood profile [41]. Thus, due to the presence of nutraceuticals in MSE, its oral administration was hypothesized to improve haematological and serum biochemical parameters of the birds. However, no treatment-induced changes were noted for all haematological parameters, except for haematocrits, platelets, and reticulocytes. Haematocrit counts, a measure of total erythrocytes per total volume of blood [42], were increased in response to MSE. Nevertheless, the negative control (T1) treatment promoted similar haematocrit counts, suggesting that the increase was not induced by MSE administration. Reticulocytes, which are slightly immature erythrocytes indicating the ability of bone marrow to release erythrocytes [43], linearly increased in response to MSE. This indicates that MSE has the ability to increase the quantity of haemoglobin per red blood cell and thus improve oxygen diffusion in chicken tissues. Platelets, which are colourless blood cells that aid in blood clotting [44], had a positive quadratic response to MSE administration. This suggests a lower risk of haemorrhage in reaction to MSE’s secondary metabolites. In this study, the increased serum calcium and observed quadratic trends for albumin, cholesterol, GGT, glucose, SDMA, and total bilirubin might be attributed to MSE bioactive compounds, which are known to cause different physiological activities in the body. This shows that administration levels beyond 94.75 mL per litre of drinking water can compromise the health status of the birds. However, all the observed values were within the normal blood range for clinically healthy chickens as reported by researchers [44,45].

5. Conclusions

The administration of moringa seed extract via drinking water enhanced ether extract, calcium, and phosphorus digestibility but reduced the digestibility of crude protein and neutral detergent fibre. Furthermore, it improved feed utilisation efficiency and altered the haemato-biochemical parameters of the birds. An optimum dosage level of 94.75 mL per litre was determined using the quadratic equations derived from serum biochemical parameters.