Introduction
Valorisation of agro-industrial by-products as a replacement for conventional feed ingredients in animal nutrition could be a possible solution to the major problems of the feed industry: seasonality and price fluctuations of popular feedstuffs, one of which is maize (Šarac et al., Reference Šarac, Tekić, Mutavdžić, Vukelić, Novaković, Milić and Miljatović2023). Poultry nutritionists have been encouraged to incorporate these by-products as alternatives to conventional feedstuffs in poultry diets, because of their availability and low cost (Abbasi et al., Reference Abbasi, Seidavi, Liu and Asadpour2015). Maximising these products as feed resources offers significant environmental and economic benefits (El-deek et al., Reference El-Deek, Abdel-Wareth, Osman, El-Shafey, Khalifah, Elkomy and Lohakare2020).
Date residue obtained from date (Phoenix dactylifera) fruits after syrup extraction represents a significant quantity of waste, constituting environmental pollution and economic loss (Gourchala et al., Reference Gourchala, Mihoub, Lakhdar-Toumi and Taïbi2022). Many communities cherish their fruit during ceremonies and festivals. It also holds deep historical significance and is referenced across cultures as a vital component of global food security (Al-Karmadi and Okoh, Reference Al-Karmadi and Koh2024). They are rich in sugar, dietary fibre, bioactive compounds and antioxidants but have low-fat content (Chaira et al., Reference Chaira, Ferchichi, Mrabet and Sghairoun2007; Sirisena et al., Reference Sirisena, Ng and Ajlouni2015). Dates are rich sources of carbohydrates, including sucrose, maltose, glucose and fructose, which constitute >80% of the dry matter and can serve as an excellent energy source, providing approximately 1.31 MJ per 100 g dry matter (DM) (Idowu et al., Reference Idowu, Igiehon, Adekoya and Idowu2020; Attia et al., Reference Attia, Reda, Patra, Elnesr, Attia and Alagawany2021).
Wastes/residues, which consist of seeds (pits) and pulp, were reported by Al-Homidan (Reference Al–Homidan2003) to contain sufficient nutrients, implying that these wastes could be alternative sources of feedstuffs. Al-Farsi and Lee (Reference Al-Farsi and Lee2008) reported that its seeds (date pit) contain: 60–80% fibre, 4–14% oil, 4–5% crude protein, essential minerals, 81.92% total carbohydrates and a wide range of phytochemicals. Previous studies have documented the use of date pits as maize replacement in broilers (El-Deek et al., Reference El-Deek, El-Deen, Hamdy, Asar, Yakout and Attia2010), laying hens (Al-Harthi et al., Reference Al-Harthi, El-Deek, Yakout and Al-Refaee2009) and ostriches (Najafi et al., Reference Najafi, Ghasemi, Hajkhodadadi and Khodaei-Motlagh2021). However, reports on the nutrient utilisation of pulp are limited.
Although the bulk of nutrients contained in agro-industrial by-products makes them potential sources of feed for animals, they are limited by the varying concentrations of anti-nutritional factors embedded in them, particularly non-starch polysaccharides, which prevent the utilisation of other nutrients in poultry (Nguyen et al., Reference Nguyen, Bedford, Wu and Morgan2022). This was corroborated by Masoudi et al. Reference Masoudi, Chaji, Bojarpour and Mirzadeh2011, who reported depressed growth and feed efficiency when broiler chickens were fed date pit meal as a replacement for maize at 300 g/kg. Hence, there is a need for some form of physical treatment to harness the nutritional value of date residues completely.
Supplementing poultry diets with exogenous enzymes, either in a single or complex form, can enhance the nutritional value of feed materials that contain anti-nutritional factors (Alagawany et al., Reference Alagawany, Elnesr and Farag2018). Complex exogenous enzymes are more effective because the wide range of enzymes present in this type of product allows for greater action on different types of substrates (Dalólio et al., Reference Dalólio, Moreira, Vaz, Albino, Valadares, Pires and Pinheiro2016). The use of complex enzymes to improve the nutritional value and utilisation of non-conventional feedstuffs in poultry diets has been previously documented (Fafiolu et al., Reference Fafiolu, Oduguwa, Bamgbose, Fanimo, Jegede and Idowu2009; Alagawany et al., Reference Alagawany, Elnesr and Farag2018). The current study, therefore, aimed to evaluate the effects of replacing maize with enzyme-supplemented Dried Date (Phoenix dactylifera) Fruit Pulp in the diet of broiler chickens.
Materials and methods
Experimental site
The study was conducted at the Poultry Unit, Directorate of the University Farms (DUFARMS) of the Federal University of Agriculture, Abeokuta, Ogun State, Nigeria.
Test ingredients
The date residues obtained from date fruits after syrup extraction were collected from a date syrup processing company in Lagos, Nigeria. The variety used was Medjoul (also known as Medjool, Majhul or Majhool). The residue contained both the fruit pulp and seeds (pits). The seeds were separated from the pulp manually and the pulp was oven-dried at 55°C until a uniform weight was obtained. Dried Date Fruit Pulp (DDFP) was milled into fine particles (1 mm). A representative sample of DDFP was used for detailed chemical analyses (Table 1) by high-performance liquid chromatography (HPLC) at the International Livestock Research Institute, Ibadan.
Table 1. Nutrient composition of dried date fruit pulp included in the diets
DM, dry matter.
1 Calculated using Pauzenga (Reference Pauzenga1985) as cited by Edmew et al. (Reference Edmew, Muleta and Tesfaye2024)
Birds and management
The feeding trial was conducted with a total number of 576-day-old commercial broiler chicks (Arbor Acre Plus) with an average weight of 43.56 g ± 1.4 which were sourced from a commercial hatchery. After weighing, the birds were randomly divided into eight dietary treatment groups of 72 birds each. The birds were managed intensively in a deep-litter system in two phases: starter (0–3 weeks) and finisher (3–6 weeks). All routine management practices specified for the Arbor Acre plus strain of chickens were strictly adhered to. Food and water were provided ad libitum. The experimental birds were maintained under standard management conditions for rearing broiler chickens in the tropics.
Experimental diets and layout
Eight experimental diets were formulated (Tables 2 and 3) to meet the specific nutrient requirements of broiler chickens, with DDFP replacing maize at four different levels in a 4 × 2 factorial arrangement: four levels of DDFP (g/kg) (0, 100, 200 and 300) with two levels of enzyme (0 or 0.1 g/kg) at both starter and finisher phases. The enzyme used (Ronozyme®) multigrain contains endo-1,4-beta-xylanase (EC 3.2.1.8; 2,700 U/g), endo-1,4-beta-glucanase (EC 3.2.1.4; 700 U/g) and endo-1,3(4)-beta-glucanase (EC 3.2.1.6; 800 U/g). Each treatment was replicated six times to obtain 12 chicks per replicate group on a weight equalisation basis. After the expiration of the starter phase, the birds were re-assigned on a weight equalisation basis to the same number of treatment groups and replicates. This was performed to eliminate any carryover effects from the starter phase to the finisher phase. Daily and weekly records were recorded as and when appropriate. The average minimum and maximum temperature during the trial was 26 and 35°C, respectively.
Table 2. Gross composition of experimental diet at starter phase
DM, dry matter; DDFP, dried date fruit pulp; ME, metabolisable energy.
1 Vitamin A, 12,000,00 i.u; vitamin D3, 2,500,000 i.u; vitamin E, 30,000 i.u; vitamin k, 2000 mg; vitamin B1, 2,250 mg; vitamin B2, 6000 mg; vitamin B6, 4,500 mg, vitamin B12, 15 mcg; niacin, 40,000; Pantothenic Acid, 15,000 mg; Folic Acid, 1,500; Biotin, 50 mcg; choline chloride, 300,000 mg; Manganese, 80,000 mg; Zinc, 50,000 mg; iron, 20,000 mg; copper, 5000 mg; iodine, 1,000 mg; Selenium, 200 mg; cobalt, 500 mg; antioxidant, 125,000 mg.
2 Calculated according to Pauzenga, (Reference Pauzenga1985) as cited by Edmew et al. (Reference Edmew, Muleta and Tesfaye2024)
Table 3. Gross composition of experimental diet at finisher phase
DM, dry matter; DDFP, dried date fruit pulp; ME, metabolisable energy.
1 Vitamin A, 12,000,00 i.u; vitamin D3, 2,500,000 i.u; vitamin E, 30,000 i.u; vitamin k, 2000 mg; vitamin B1, 2,250 mg; vitamin B2, 6000 mg; vitamin B6, 4,500 mg, vitamin B12, 15 mcg; niacin, 40,000; Pantothenic Acid, 15,000 mg; Folic Acid, 1,500; Biotin, 50 mcg; choline chloride, 300,000 mg; Manganese, 80,000 mg; Zinc, 50,000 mg; iron, 20,000 mg; copper, 5000 mg; iodine, 1,000 mg; Selenium, 200 mg; cobalt, 500 mg; antioxidant, 125,000 mg.
2 Calculated according to Pauzenga, (Reference Pauzenga1985) as cited by Edmew et al. (Reference Edmew, Muleta and Tesfaye2024)
Data collection
Chemical analyses
The proximate, mineral and amino acid compositions were analysed using high-performance liquid chromatography (HPLC).
Growth performance
Body weight was measured initially upon arrival and weekly thereafter, using an electronic weighing scale. Data were recorded daily for feed intake, and the feed conversion ratio (FCR) and weight gain were computed weekly.
$$\begin{align}{\rm{Total\;feed\;intake}}\left( {\rm{g}} \right){\rm{\;}} &= {\rm{\;Total\;feed\;supplied\;}}\left( {\rm{g}} \right){\rm{\;}} \\&\,\,\,\,\,\,- {\rm{\;Left\;over\;feed\;}}\left( {\rm{g}} \right)\end{align}$$
$${\rm{Average}}\;{\rm{feed}}\;{\rm{intake}}\;\left( {\rm{g}} \right) = {{{\rm{Total}}\;{\rm{feed}}\;{\rm{intake}}\;\left( {\rm{g}} \right)} \over {{\rm{Total}}\;{\rm{number}}\;{\rm{of}}\;{\rm{birds}}}}$$
$${\rm{Total}}\;{\rm{weight}}\;{\rm{gain}}\;\left( {\rm{g}} \right)\; = \;{\rm{Final}}\;{\rm{weight}}\;\left( {\rm{g}} \right)\; - \;{\rm{initial}}\;{\rm{weight}}\;\left( {\rm{g}} \right)$$
$${\rm{Average}}\;{\rm{weight}}\;{\rm{gain}}\;\left( {\rm{g}} \right) = {{{\rm{Total}}\;{\rm{weight}}\;{\rm{gain}}\;\;\left( {\rm{g}} \right)} \over {{\rm{Total}}\;{\rm{number}}\;{\rm{of}}\;{\rm{birds}}}}$$
$${\rm{Feed}}\;{\rm{conversion}}\;{\rm{ratio}} = {{{\rm{Feed}}\;{\rm{intake}}\;\;\left( {\rm{g}} \right)} \over {{\rm{Weight}}\;{\rm{gain}}\;\left( {\rm{g}} \right)}}$$
$$\begin{align}{\rm{Feed}}\;{\rm{cost}}/\;{\rm{kg}}\;{\rm{weight}}\;{\rm{gain}}\;\left( {{\rm{NGN}}/{\rm{kgWG}}} \right) \\= {\rm{feed}}\;{\rm{cost}}\;\left( {{\rm{kg}}} \right) \times \;{\rm{feed}}\;{\rm{conversion}}\;{\rm{ratio}}\end{align}$$
Blood indices
On days 21st and 42nd days of the experiment, blood samples were collected from three birds per replicate, making 18 samples per treatment through the brachial vein with a 5 ml scalp vein needle set. Two (2) ml of blood samples were collected from each bird into tubes containing ethylene-diamine-tetra-acetic acid (EDTA) as the anti-coagulant for determination of haematological indices. Another 2 ml were collected into plain tube without anti-coagulant which were centrifuged at 503.1 × g to obtain the serum for biochemical indices. Haemoglobin concentration (Hb) was determined using the Sahli method, and the value was recorded in g/100 ml (Albutt et al., Reference Albutt, Nattrass and Northam1985), Red Blood Cells (RBC) and White Blood Cells (WBC) using an improved Neubauer haemocytometer, as described by Bain et al. (Reference Bain, Bates, Laffan and Lewis2016). Packed Cell Volume was determined using the microhematocrit method, and neutrophil, eosinophil, lymphocyte and monocyte counts were determined using protocols described by Bergmeyer (Reference Bergmeyer2012). The other set of bottles without EDTA was centrifuged in a macro centrifuge to obtain the serum for biochemical analysis. Serum metabolites (total protein, albumin and globulin) were estimated using commercial kits (Span Diagnostics; Surat, India). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (Bergmeyer, Reference Bergmeyer2012) were measured using a spectrophotometer (Uniscope SM7504, England, United Kingdom). Triglyceride and glucose levels were determined by enzymatic colorimetric assay using commercially available kits (Randox Laboratories, United Kingdom) through the GPO-PAP and GOD-PAP methods as described in the manual).
Nutrient digestibility
Nutrient digestibility protocols of Ojewola and Longe (Reference Ojewola and Longe2003) modified by Ndelekwute et al. (Reference Ndelekwute, Afolabi, Uzegbu, Unah and Amaefule2015) were adopted. Three birds with weights close to the average weight of the replicate were selected for digestibility studies between Days 37 and 42. They were placed in cleaned and disinfected metabolic cages for two days of acclimatisation, followed by one day of fasting to clear their digestive tracts. Fresh excreta samples were collected every 24 h for the next three days from the pans placed underneath the metabolic cages. Daily excreta collections were pooled on a replicate-cage basis and representative 100 g samples were taken and oven-dried at 65°C until a constant weight was obtained, and then ground to pass through a 0.5 mm sieve for subsequent analyses of dry matter (DM), ether extract (EE), crude protein (CP), crude fibre (CF) and ash of the feed and faecal samples according to the methods described by AOAC (2005). After evaluating the chemical composition, the Apparent digestibility of the nutrients was calculated as follows:
$$\small {{\rm{Apparent}}\;{\rm{nutrient}}\;{\rm{digestibility}} = \;{{{\rm{Nutrients}}\;{\rm{intake}}\;\left( {\rm{g}} \right)\; - \;\;{\rm{Nutrients}}\;{\rm{voided}}\;\left( {\rm{g}} \right)\;} \over {\;{\rm{Nutrients}}\;{\rm{intake}}\;\left( {\rm{g}} \right)}}}$$
Ileal viscosity and caecal microbiota
On the 42nd day of the experiment, three birds per replicate with weights close to the average were slaughtered to determine the viscosity of the ileal digesta. After slaughter, birds were dissected to expose their intestines. The ileal digesta were collected from the Meckel’s diverticulum to the ileocecal junction. A uniform weight of the content was taken from each bird using a sensitive scale and diluted with a volume of 200 ml distilled water. The viscosity of the supernatant from digesta was measured at 29.1ºC and a shear rate of 60 rpm using a viscometer with coaxial cylinders and a mobile rotor (NDJ-8S, Guangdong Kejian Instruments, Guangdong city, South China) as described by Omidiwura and Agboola (Reference Omidiwura and Agboola2016). To determine the caecal microbiota, fresh caecal content was poured into sterile bottles. The collected samples were used to estimate the composition of gut microbiota (Xia et al., Reference Xia, Sun, Gurr, Vasseur, Xue and You2018). A gram sample was dispersed in 9 ml phosphate-buffered saline solution supplemented with 0.5 g/l cysteine-hydrochloride and further diluted to a factor of 10–8. Exactly 0.1 ml was spread on sterile Petri dishes containing selective media and incubated for the analysis of microbial colony count using plate count agar incubated at 30°C for 72 h. Microbial counts were expressed as colony-forming units (cfu) per gram of fresh sample.
Carcass determination
Three birds with weights close to the group average were selected per replicate, labelled, and fasted for 12 h. They were supplied with water to clear their gastrointestinal tract (GIT). On the 42nd day of the experiment, the birds were weighed individually to obtain their live weight, slaughtered, hoisted to drain blood, de-feathered, eviscerated, cut into different retail parts and weighed. The cut parts (head, neck, back, wings, breast, thighs, drumsticks and shanks) and organs (liver, gizzard, proventriculus, whole intestine, spleen, lungs and heart) are expressed as percentages relative to their live weights.
Statistical analyses
All data generated from the current study were checked for normality and homoscedasticity of error using the Cramer-Von Mises and Brown and Forsythe tests at 5%. The outliers were removed only after checking for plausibility. The unequal growth performance indices were subjected to covariate analysis, with the initial weight as the covariate variable, and were subsequently analysed using a one-way Analysis of Variance in a 4 × 2 experimental arrangement using SAS ODA Software (SAS Institute Inc., Cary, NC, USA). Other variables were analysed using SPSS 20 (IBM Corp, 2011). The means were compared using Tukey’s honestly significant difference test at a probability level of 5%.
Results
Nutritional composition of DDFP
The nutritional composition of Dried Dates Fruit pulp (DDFP) presented in Table 3 revealed that DDFP has a considerable amount of ME (3238 kcal/kg), CP (195 g/kg) and other macro and micronutrients.
Performance characteristics at 3 and 6 weeks
The inclusion of DDFP in the diets of broiler chickens at 3 weeks (Table 4) influenced (P < 0.05) the growth performance indices examined: final weight, weight gain, feed cost/kg and feed cost/kg weight gain. Birds fed 300 g/kg DDFP recorded the least (971 g; P = 0.026) weight gain and final weight (1013 g; P = 0.023) across the treatments. Least feed cost (NGN/kg) (170, 160, 150; P = 0.042 and feed cost/kg weight gain (244, 231, 219; P = 0.033) were observed in birds fed DDFP diets compared with those in the maize-fed diet groups (feed cost = 182; feed cost/kg WG = 257). Similar (P>0.05) feed intake and FCR were however observed in all treatment groups. Inclusion of up to 300 g/kg DDFP at 6 weeks (Table 5) had no significant effect (P > 0.05) on the final weight (0 g/kg; 2520 g, 100 g/kg; 2529 g, 200 g/kg; 2561 g, 300 g/kg; 2521 g: P = 0.665), weight gain (0 g/kg; 1497 g, 100 g/kg; 1499 g, 200 g/kg; 1537 g, 300 g/kg; 1508 g: P = 0.660), FCR (0 g/kg; 2.0, 100 g/kg; 2.0, 200 g/kg; 2.1, 300 g/kg; 2.1: P = 0.396) and feed intake (0 g/kg; 2964 g, 100 g/kg; 3027 g, 200 g/kg; 3158 g, 300 g/kg; 3196 g: P = 0.444) of all experimental groups including the control. Similar to what was observed in the starter phase, an increase in DDFP reduced (P < 0.05) the feed cost (NGN/kg feed) (190, 180 and 170) and feed cost/kg weight gain (385, 370 and 362 NGN/kg WG) in finisher broiler chickens at 6 weeks when compared with those of maize (feed cost (NGN/kg feed) = 205, feed cost/kg WG= 405 NGN/kg WG). The interaction between enzyme supplementation and DDFP inclusion did not influence (P > 0.05) any of the growth performance indices assayed (Tables 4 and 5).
Table 4. Effects of dried date fruit pulp (DDFP) inclusion and enzyme supplementation on performance characteristics of broiler chickens at 3 weeks
FCR, Feed conversion ratio; FC/WG, Feed cost/weight gain.
a–dMeans with different superscripts within the same column are significantly (P < 0.05) different.
Table 5. Effects of dried date fruit pulp (DDFP) inclusion and enzyme supplementation on performance characteristics of broiler chickens at 6 weeks
FCR, Feed conversion ratio; FC/WG, Feed cost/weight gain.
a–dMeans with different superscripts within the same column are significantly (P < 0.05) different.
Haematological and serum indices at 3 and 6 weeks
The inclusion of DDFP in the diets of starter broiler chicks at 3 weeks (Table 6) significantly influenced WBC (0 g/kg = 10.5, 100 g/kg = 10.7, 200 g/kg = 10.6, 300 g/kg = 11.8; P = 0.050), among other haematological indices examined both at the main and interactive stages. There was an interaction between DDFP inclusion and enzyme supplementation (Table 7), which significantly influenced the serum protein concentrations of broiler chickens at three weeks (without enzyme: 0 g/kg = 2.7, 100 g/kg = 2.6, 200 g/kg = 2.8, 300 g/kg = 2.78; with enzyme: 0 g/kg = 2.8, 100 g/kg = 2.7, 200 g/kg = 2.9, 300 g/kg = 2.9; P = 0.031). Birds fed enzyme-supplemented DDFP showed improved (P < 0.05) serum protein values compared with the other treatment groups (Table 7). The other serum indices assayed were not significantly affected (P > 0.05). Dietary inclusion of DDFP significantly influenced (P < 0.05) monocyte concentration, with birds fed 100 g/kg having the lowest monocyte concentration (0.9, P = 0.029) compared to the others (0 g/kg = 1.6, 200 g/kg = 2.1, 300 g/kg = 2.0; P = 0.029) (Table 8). Experimental birds fed enzyme-supplemented DDFP-based diets (Table 9) had higher (4.7, 4.9, 4.9, 5.0, P = 0.03) serum protein levels than those fed diets that were not supplemented (4.5, 4.6, 4.7, 4.8; P = 0.03). Enzyme supplementation also improved (P < 0.05) serum glucose concentrations both in the main (157; P = 0.011) and interaction (with enzyme: 100 g/kg = 153, 200 g/kg = 152 and 300 g/kg = 173, P = 0.02) (Table 9).
Table 6. Effects of dried date fruit pulp inclusion and enzyme supplementation on haematological indices of broiler chickens at 3 weeks
SEM, standard error of means.
a,b,cMeans with different superscripts within the same row are significantly (P < 0.05) different.
1 Amos et al. (Reference Amos, Kareem, Olukowi, Odeyemi, Ajayi, Adekola and Idowu2021)*; Miesle (Reference Miesle2021)**; Kareem et al. (Reference Kareem, Amos, Idowu, Bonagurio and Idowu2024)***.
Table 7. Effects of dried date fruit pulp inclusion and enzyme supplementation on serum indices of broiler chickens at 3 weeks
SEM, standard error of means; AST, aspartate aminotransferase; ALT, alanine transaminase; ALP, alkaline phosphatase.
a,b,cMeans with different superscripts within the same row are significantly (P < 0.05) different.
1 Meluzzi et al. (Reference Meluzzi, Primiceri, Giordani and Fabris1992)*; Nanbol et al. (Reference Nanbol, Duru, Nanbol, Abiliu, Anueyegu, Kumbish and Solomon2016)**; Regar et al. (Reference Regar, Tulung, Londok, Moningkey and Tulung2019)***; Bagno et al. (Reference Bagno, Shevchenko, Shevchenko, Prokhorov, Shentseva, Vavin and Ulrich2021)****; Miesle (Reference Miesle2021)*****.
Table 8. Effects of dried date fruit pulp inclusion and enzyme supplementation on haematological indices of broiler chickens at 6 weeks
SEM, standard error of means.
a,b,cMeans with different superscripts within the same row are significantly (P < 0.05) different.
1 Swenson (Reference Swenson1970)*; Nanbol et al. (Reference Nanbol, Duru, Nanbol, Abiliu, Anueyegu, Kumbish and Solomon2016)**; Miesle (Reference Miesle2021)***
Table 9. Effects of dried date fruit pulp inclusion and enzyme supplementation on serum indices of broiler chickens at 6 weeks
SEM, standard error of means; AST, aspartate aminotransferase; ALT, alanine transaminase; ALP, alkaline phosphatase.
a,b,c Means with different superscripts within the same row are significantly (P < 0.05) different.
1 Meluzzi et al. (Reference Meluzzi, Primiceri, Giordani and Fabris1992) *; Nanbol et al. (Reference Nanbol, Duru, Nanbol, Abiliu, Anueyegu, Kumbish and Solomon2016)**; Regar et al. (Reference Regar, Tulung, Londok, Moningkey and Tulung2019)***; Amos et al. (Reference Amos, Kareem, Olukowi, Odeyemi, Ajayi, Adekola and Idowu2021)****; Miesle (Reference Miesle2021)*****.
Nutrient digestibility coefficients
Nutrient digestibility coefficients of finisher broiler chickens at six weeks (Table 10) revealed that neither DDFP inclusion nor enzyme supplementation had any effect (P > 0.05) on the dry matter digestibility of the birds at either the main or interactive stages. Other variables examined (crude protein digestibility coefficient, ether extract digestibility coefficient, crude fibre digestibility coefficient and ash digestibility coefficient) were significantly influenced (P < 0.05) across the treatments. Birds fed 300 g/kg DDFP had the least (P < 0.05) digestibilities (0.8, P = 0.002) of ether extract and (0.7, P ≤ 0.001) of crude fibre at the main level and (0.8;0.9, P ≤ 0.001) of ether extract and (0.7;0.7, P ≤ 0.001) of crude fibre at the interactive levels.
Table 10. Effects of dried date fruit pulp (DDFP) inclusion and enzyme supplementation on coefficient of nutrient digestibility of broiler chickens at 6 weeks
DMDC, Dry matter digestibility coefficient; CPDC, Crude protein digestibility coefficient; EEDC, Ether extract digestibility coefficient; CFDC, Crude fibre digestibility coefficient; ASHDC, Ash digestibility coefficient.
a–dMeans with different superscripts within the same column are significantly different (P < 0.05).
Ileal viscosity and caecum total bacteria
The ileal viscosity and total cecum bacterial count of broilers fed diets containing DDFP supplemented with or without enzymes (Table 11) were not significantly affected (P > 0.05) by the treatments at either the main or interaction stages.
Table 11. Effects of dried date fruit pulp (DDFP) inclusion and enzyme supplementation on Ileal viscosity and caecal total bacterial count of broiler chickens at 6 weeks
cfu: colony forming unit.
Pa.s: pascal-seconds.
Carcass indices
There was no significant interaction (P > 0.05) between DDFP inclusion and enzyme supplementation for any of the carcass indices (Table 12). However, there were variations (P < 0.05) in the back (211, 193, 204, 210; P = 0.030), shank (45, 48, 46 and 46 g/kg; P = 0.041) and lung (5.40, 5.20, 4.90 and 4.60, P = 0.026) g/kg dressed weight recorded for birds fed varying concentrations of DDFP, as shown in Table 13.
Table 12. Interaction effect of dried date fruit pulp (DDFP) inclusion and enzyme supplementation on carcass characteristics of broiler chickens at 6 weeks
SEM, standard error of means.
1 g/kg of live weight.
2 g/kg of dressed weight.
Table 13. Main effects of dried date fruit pulp (DDFP) inclusion and enzyme supplementation on carcass characteristics of broiler chickens
SEM, Standard error of means.
a,b,c Means with different superscripts within the same row are significantly (P < 0.05) different.
1 g/kg of live weight.
2 g/kg of dressed weight.
Discussion
The metabolisable energy of DDFP examined in the current study is similar to that of maize (Nigerian Institute of Animal Science, 2024) and thus could be a potential maize replacement in broiler chicken diets, which affirms the earlier claims of Oladzad et al. (Reference Oladzad, Fallah, Mahboubi, Afsham and Taherzadeh2021) that date waste (Phoenix dactilifera) is a potential feedstuff in animal nutrition. Similar weight gain, final weight and FCR were observed in the starter phase in birds fed diets containing 100 and 200 g/kg DDFP and those fed maize-based diets, indicating that the birds were able to utilise DDFP up to 200 g/kg (of maize replacement) in a similar pattern with maize-based diets for growth and feed efficiency at the starter phase. The depressed growth in birds fed 300 g/kg DDFP together with the numerically higher FCR may be attributed to the higher fibre concentration and non-digestibility of some nutrients in the nutrient digestibility coefficients of the current study which could not be utilised by the birds for growth and tissue accretion. This corroborates the studies of Walugembe et al. (Reference Walugembe, Rothschild and Persia2014) and Saadatmand et al. (Reference Saadatmand, Toghyani and Gheisari2019) who reported an impaired growth performance of young broiler chickens fed high-fibrous diets. While previous report of Attia et al. (Reference Attia, Reda, Patra, Elnesr, Attia and Alagawany2021) suggested that date waste is more beneficial for older broiler chickens, the current study found that younger birds can effectively utilize DDFP up to 200 g/kg without negative growth impacts.
The reduced cost per kilogram weight gain exhibited by birds fed DDFP diets compared to those fed maize-based diets, both at the starter and finisher phases, implies that DDFP showed a better economic value and cheaper to produce a kg weight gain of meat than those fed the control diet. Therefore, DDFP is expected to reduce the production costs of broiler chickens. The similar pattern of growth indices observed with birds fed DDFP diets and those fed maize diets at the finisher phase indicates that the birds were able to utilise greater percentage of DDFP at the finisher phase compared to the starter phase seeing that 300 g/kg DDFP did not depress growth at the finisher phase. This report corroborates those of Attia and Al-Harti (Reference Attia and Al-Harthi2015) and Attia et al. (Reference Attia, Reda, Patra, Elnesr, Attia and Alagawany2021) who claimed that older birds benefit more from the fibre content of date waste than the younger ones which may be attributed to a more mature and adapted digestive system (Sklan, Reference Sklan2001). Although the feed intake was not influenced statistically by the inclusion levels of DDFP, the linear increase in feed intake as the level of DDFP increased may be linked to the linear decrease in the metabolisable energy content of the feed as birds demonstrate an exceptional ability to control their feed intake to ensure a constant energy intake across different diets, including those with lower energy level (Lopez and Leeson, Reference Lopez and Leeson2008).
The report of the current study revealed that enzyme supplementation did not significantly impact performance, carcass characteristics, nutrient digestibility, ileal viscosity or caecal microbes. This contradicts the findings of Al-Saffar et al. (Reference Al-Saffar, Attia, Mahmoud, Zewell and Bovera2012), who demonstrated the effectiveness of enzyme supplementation in utilising date waste in laying hens. However, other studies on date wastes (Hussien and Alhadrami, Reference Hussein and Alhadrami2003; Jassim, Reference Jassim2010) and other feedstuffs (Kaczmarek et al., Reference Kaczmarek, Rogiewicz, Mogielnicka, Rutkowski, Jones and Slominski2014; Wang et al., Reference Wang, Wang, Lin, Gou, Fan, Ye and Jiang2020; Radhi et al., Reference Radhi, Arif, Rehman, Faizan, Almohmadi, Youssef, Swelum, Suliman, Tharwat, Ebrahim, Abd El-Hack and Mahrose2023) reported non-significant effects of enzyme supplementation on growth indices in broilers. The variations in the findings might be attributed to several factors, including the type of enzymes used, the composition of the diet, the methods of heat processing, conditioning time, moisture content, temperature, the species and age of the birds, as suggested by Amerah et al. (Reference Amerah, Gilbert, Simmins and Ravindran2011).
Nutritional studies that include blood analysis can be used to monitor animals’ health because dietary components have measurable effects on the blood composition (Etim et al., Reference Etim, Akpabio, Okpongete and Offiong2014). Variations in WBC observed during the starter phase could not be attributed to the experimental diet. The WBC concentrations in the current study are an indication of reduced or non-occurrence of immune challenge as a result of the diets and fall within the lower limits of values reported by others (Amos et al., Reference Amos, Kareem, Olukowi, Odeyemi, Ajayi, Adekola and Idowu2021; Kareem et al., Reference Kareem, Amos, Idowu, Bonagurio and Idowu2024). Eosinophils are known for their phagocytic activity and ability to destroy parasites and stimulate immune responses (Akuthota and Weller, Reference Akuthota and Weller2012) whereas monocytes defend against pathogens and mediate antimicrobial activities at infected sites (Serbina et al., Reference Serbina, Jia, Hohl and Pamer2008). The variations in monocyte concentration in broiler chickens at 6 weeks of age observed in the current study were not of any order and could not be attributed to the test diets. Total serum protein has been reported as an indication of protein retention in the animal body (Akinola and Abiola, Reference Akinola and Abiola1999). Improved serum proteins observed in birds fed DDFP-containing diets with or without enzymes compared to those fed the maize-based diets at 3 and 6 weeks could be attributed to the higher crude protein concentration of DDFP, which affirms the adequacy of the diets in supporting normal protein reserves in birds, resulting from efficient protein utilisation and performance of the birds. This report agrees with that of Jassim (Reference Jassim2010), who found that date waste at 50, 100 and 150 g/kg significantly affected total serum protein. The effect of enzyme supplementation on serum protein indices observed in the current study was consistent with previous findings (Lima et al., Reference Lima, Costa, Goulart, Pinheiro, Souza, Morais and Lima2012; Kilany and Mahmoud Reference Kilany and Mahmoud2014). Comparable values of marker enzymes in birds fed DDFP and those fed maize-based diets in the current study indicate the absence of damage to the liver and myocardial tissues. Serum triglyceride and glucose levels indicate the efficiency of metabolisable energy utilisation in each diet. The values obtained in the current study were within the recommended range (Nanbol et al., Reference Nanbol, Duru, Nanbol, Abiliu, Anueyegu, Kumbish and Solomon2016; Regar et al., Reference Regar, Tulung, Londok, Moningkey and Tulung2019) and implying that the energy content of DDFP is usable and can be used to replace maize in poultry diets.
The nutrient digestibility report of the current study revealed that birds fed 30% DDFP had a reduced digestibility of crude protein, ether extract and crude fibre at the main level and a reduced digestibility of ether extract and crude fibre at the interactive level. However, birds fed 10 and 20% DDFP had similar digestibility with those fed the maize-based diets. Although the growth performance of birds fed 30% DDFP at the finisher phase was at par with other treatment groups, the digestibility report reveals that not all the nutrients were utilised in a similar pattern. This report corroborates that of Al-Harti (Reference Al-Harthi2006) who asserted that replacing maize with date waste in broiler chickens’ diet significantly decreases crude fibre digestibility.
The non-significant ileal viscosity values obtained in the current study indicate that the non-starch polysaccharides (NSP) content of DDFP did not impair the ileal viscosity of the experimental animals. Diets of broiler chickens high in NSPs have been documented (Bederska-Kojewska et al., Reference Bederska-Kojewska, Świątkiewicz, Arczewska-Włosek and Schwarz2017) to increase ileal viscosity, which leads to less interaction between endogenous enzymes and nutrients and, consequently, reduced nutrient digestibility. It has also been reported (Bedford, Reference Bedford2006) that chickens consuming diets high in NSPs have increased feed intake to maintain nutrient intake, which increases the transit rate and intestinal viscosity. However, this was not the case in the present study. The similar total caecal bacterial counts of birds fed maize-based diets and those fed DDFP-based diets reported in the current study indicate that DDFP did not compromise the total caecal bacterial population of the experimental birds. The importance of the caecal microbiota in improving feed digestion, nutrient absorption and growth performance is well documented (Stanley et al., Reference Stanley, Hughes and Moore2014; Yan et al., Reference Yan, Sun, Zheng, Wen, Ji, Zhang, Chen, Hou and Yang2019). They also play a role in producing essential substances, such as vitamins, lactic acid and short-chain fatty acids (Vandepopuliere et al., Reference Vandepopuliere, Al-Yousef and Lyons1995). Any diet that interferes with the microbial population would affect nutrient digestion and absorption.
The report of the carcass indices observed in the current study agrees with the previous findings of (El-Deek et al., Reference El-Deek, El-Deen, Hamdy, Asar, Yakout and Attia2010; Zangiabadi and Torki, Reference Zangiabadi and Torki2010) who reported that whole dates at 175 and 350 g/kg did not significantly influence carcass indices at 49 d of age. The similar values observed with the economic parts (drumstick, breast, thigh and gizzard) of birds fed the control diets and those fed DDFP-containing diets confirm the suitability of DDFP in replacing maize on the carcass indices of broiler chickens, as suggested by Attia and Al-Harti (Reference Attia and Al-Harthi2015). Carcass indices represent a significant economic factor for broiler production. The variations observed earlier in the shank and back could not be attributed to any factor related to the diet.
Conclusions
Similar metabolisable energy, higher crude protein and an array of other nutrients embedded in DDFP compared to maize present it as a potential replacement for maize in broiler chickens’ diets. A replacement level of up to 200 g/kg DDFP did not impair growth indices at the starter phase, but 300g/kg depressed the birds’ growth rate and weight gain. At the finisher phase, 300 g/kg DDFP led to reduced feed costs without negatively impacting other variables examined. Enzyme supplementation improved glucose and serum protein concentrations at the starter phase and serum protein at the finisher phase but did not impact the growth performance, carcass characteristics, nutrient digestibility, ileal viscosity and caecal microbes of the broiler chickens.
Author contributions
ATA, AOF, AOO and OMOI conceived the study. ATA, EAA, OPAI and JAA conducted the experiments and collected data for the study. DUK conducted statistical analyses. AAA and BGA interpreted data. ATA and DUK wrote the first draft of this manuscript. All the authors approved the final version of the manuscript.
Funding statement
The current work was supported by the Tertiary Education Trust Fund of Nigeria (grant number: TETFUND/IBR/UNI/ FUNAAB/2022/vol 1/000170.
Competing interests
The authors declare there are no conflicts of interest.
Ethical standards
All procedures used in the current research complied with the research ethics and guidelines of the Animal Care Committee of the Federal University of Agriculture, Abeokuta, Ogun State, Nigeria (FUNAAB/COLANIM/ANN/22-022).
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