Abstract: Background: The environmental issues related to the presence of phosphorus (P) in poultry excreta have led the researchers to manipulate the diet of poultry in order to decrease the P excretion without having any negative impact on the performance of birds. Presently, added minerals are used as nanoparticles in order to increase absorption and subsequent decreased presence in poultry excreta. Therefore, an experiment was conducted to study the effect of dietary nano-dicalcium phosphate (NDCP) compared to conventional dicalcium phosphate (CDCP) on performance and excreted calcium (Ca) and P in broiler chicken. Materials and Methods: Two hundred and eighty one day-old male broiler chicks were divided into seven treatment groups for a period of 26 days. Seven experimental diets were formulated having three levels of either CDCP or NDCP at 1.75, 1.31 and 0.88% and a lower level of NDCP at 0.44%. Thus, these diets contained 100, 75, 50 and 25% of the recommended non-phytate P i.e., 0.45%. The diet having 1.75% CDCP (100% recommended non-phytate P) served as a control diet. Every dietary treatment had 4 replicates of 10 chicks each. Broiler performance, Ca and P excretion were studied. Results: Birds fed different levels of NDCP gained significant more body weight (p<0.05) and utilized feed more efficiently than the control group (1.75% CDCP). Decreasing levels of CDCP led to decrease in body weight gain and impaired feed conversion ratio compared to the control group. Values of body weight gain and feed intake increased by about 25 and 10%, respectively, feed conversion ratio improved by about 12% for birds fed NDCP compared to those fed CDCP. Level of dietary DCP significantly (p<0.001) affected Ca and P excretion while source of DCP significantly (p<0.001) affected P excretion but had no effect on (p>0.05) Ca excretion. Feeding 0.44% NDCP in the diet decreased the excreted Ca and P by 50.74 and 46.24%, respectively, compared to the control. Conclusion: It could be concluded that using NDCP in broiler diets allow successfully to reduce the dietary DCP by 75%. Diet formulated containing only 25% of the required non phytate P in form of NDCP could be used instead of 100% CDCP. Also, using dicalcium phosphate in nanoparticle size allow to reduce the excreted Ca and P by about 50% which reduce the impact of poultry on environmental pollution.
INTRODUCTION
Calcium (Ca) and phosphorus (P) are required in large quantities by poultry and involved in many biological processes. Calcium requirement is easily satisfied with low price sources such as limestone or oyster shell. However, diets based on plant ingredients contain large amounts of unavailable phosphorus in the form of phytates (60-80% of total P) which cannot be utilized by poultry. Thus, inorganic phosphorus, which is relatively costly, is added to meet dietary P requirements of chicken for optimal growth and production1. This practice results in excess amounts of P excretion that can have negative environmental effects when such litter is applied as a fertilizer to soil2,3. The excretion of P has direct implications for both water and air quality concerns4.
In view of environmental concerns, attempts are being made to manipulate the poultry diets in order to decrease the concentration of P in excreta with no adverse effect on performance or feed utilization. Feeding broiler chicken with P source in accordance with nutrient recommendations can decrease P intake as well as the amount of P excreted5,6. Earlier, addition of phytase to improve P availability and utilization by poultry has been reported to substantially decrease P excretion7-10.
The recent trend has been focused on use of nanoparticles. Supplementation of minerals in nano form reportedly increases the absorption and subsequent reduction in their excretion. Swain et al.11 reported that nano minerals are having a great potential even at very lower doses than the conventional organic and inorganic sources. These results have been proven for nano-Se (selenium)12,13, nano-Zn (zinc)11,14-16 and nano-Cr (chromium)17.
In view of beneficial effects of nano minerals, the present study was taken up with the objectives to examine the different dietary levels of nano dicalcium phosphate (NDCP) on performance and calcium and phosphorus excretion compared to conventional dicalcium phosphate (CDCP) in broiler chicken.
MATERIALS AND METHODS
Preparation of NDCP: Dicalcium phosphate was synthesized in nanoparticle size by Sol-Gel method using two different solvents (deionized water and ethanol). The synthesized NDCP was characterized by means of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Energy Dispersive Analysis by X-ray (EDAX). Using ethanol solvent resulted in 81.8% NDCP and 18.2% calcium carbonate, but deionized water solvent gave 100% NDCP. Crystal sizes of NDCP synthesized using deionized water or ethanol as solvent was 26 and 34 nm, respectively. Crystal size of NDCP synthesized using deionized water was 26 nm, with 100% purity. The proposed method doesn't involve using or production of any toxic or environmentally hazardous solvents, surfactants, or organic chemicals and is economical, time-saving and performed at room temperature18.
Animals and experiment design: A broiler chicken growth trial was designed to examine the NDCP produced using water as a solvent. For this purpose, two hundred and eighty one day-old (Ross 308) male broiler chicks were divided into seven treatment groups. Seven experimental diets were formulated having three levels of either CDCP or NDCP at 1.75, 1.31 and 0.88% and a lower level of NDCP at 0.44%. Thus, these diets contained 100, 75, 50 and 25% of the recommended non-phytate P i.e., 0.45%. The diet having 1.75% CDCP (100% recommended non-phytate P) served as a control diet. Diets were formulated to cover all the nutrient requirements of Ross broiler chicks except that of calcium and phosphorus. The Ca:P ratio was kept 2:1 in all the diets. Formulation and nutrient composition of these diets are shown in Table 1.
Every dietary treatment was fed to 4 replicates of 10 chicks each. The average initial live body weights of all replicates were nearly similar. Replicates were randomly allocated in batteries cages divided into 28 compartments (4 replicates×7 dietary treatments). Birds were raised in a warmed brooder house and fed the dietary treatments from 1-26 days of age. Light was provided 23 h daily throughout the experimental period. Feed and water were provided ad libitum. A vaccination program against avian flu, New Castle, IB and IBD was strictly adopted throughout the experimental period.
Sample preparation and evaluation: At 15 and 26 days of age, after fasting overnight, birds were individually weighed and feed consumption was recorded per replicate. Body Weight Gain (BWG) and Feed Conversion Ratio (FCR) were calculated accordingly. Samples of excreta from all treatments were collected at 24-26 days of age, to determine Ca and P excretion. Feathers and any scattered feed were taken out. The collected excreta were dried in an air-draft oven at 60°C for 24 h and left in room temperature afterwards to equilibrate with atmosphere moisture. The dried excreta from each replicate for the successive 3 days post collection were pooled; finely ground, well mixed and placed in a screw-top glass jar for the determination of Ca and P as per AOAC19.
| Table 1: | Formulation and nutrients composition of experimental diets |
(1)Vitamin: Mineral mixture supplied per kg of diet: Vit A: 12000 IU, Vit D3: 2200 IU, Vit E: 10 mg, Vit K3: 2 mg, Vit B1: 1 mg, Vit B2: 4 mg, Vit B6: 1.5 mg, Vit B12: 10 mg, Niacin: 20 mg, Pantothenic acid: 10 mg, Folic acid: 1 mg, Biotin: 50 mg, Copper: 10 mg, Iodine: 1 mg, Iron: 30 mg, Manganese: 55 mg, Zinc: 50 mg and Selenium: 0.1 mg. (2)According to NRC22 | |
Statistical analysis: Data were statistically analyzed by analysis of variance using the General Liner Model of SAS20. One way analysis of variance was used to detect the treatment effect. Two ways analysis of variance (factorial 2×3) was used to detect main effects of source and level of the tested dicalcium phosphate (DCP). Significant differences among treatment means were determined by Duncan’s multiple range test21 with a 5% level of probability.
RESULTS AND DISCUSSION
Growth performance: Table 2 showed growth performance of birds fed different dietary CDCP and NDCP levels at 15 day of age. The results showed significant (p<0.001) improvements in Body Weight Gain (BWG) from 356-405 g (13.8%), from 356-396 g (11.2%) and from 356-382 g (7.3%) and Feed Conversion Ratio (FCR) from 1.39-1.24 (10.8%), from 139-1.27 (8.6%) and from 1.39-1.30 (6.5%) for treatments fed 1.75, 1.31 and 0.88% NDCP, correspondingly compared to the control group fed 1.75% CDCP. However, there was no significant difference on BWG and FCR among treatments fed 1.75, 1.31 CDCP and 0.44% NDCP. The best values of BWG and FCR were recorded for birds fed 1.75% NDCP. Among NDCP groups, as the level of NDCP was increased in the diet from 0.44-1.75 %, higher was the corresponding improvement in BWG and FCR. The lowest value for BWG and worst value for FCR were recorded for birds fed 0.88% CDCP.
| Table 2: | Growth performance of broiler chicken fed different dietary CDCP and NDCP levels at 15 day of age |
Means designated with the same letter within the same column are not significantly different at 0.05 level of probability. **p<0.01, ***p<0.001, NS: Not Significant (p>0.05), *level of 0.44% NDCP was not including in the two way statistical analysis | |
No significant differences in Feed Intake (FI) were observed among different groups except for the group fed 0.88% CDCP which had significantly (p<0.05) low FI compared to the control group.
| Table 3: | Growth performance of broiler chicken fed different dietary CDCP and NDCP levels during 16-26 days of age |
Means designated with the same letter within the same column are not significantly different at 0.05 level of probability. ***p<0.001, NS: Not significant (p>0.05), *level of 0.44% NDCP was not including in the two way statistical analysis |
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| Table 4: | Growth performance of broiler chicken fed different dietary CDCP and NDCP levels for the entire period (1-26 days of age) |
Means designated with the same letter within the same column are not significantly different at 0.05 level of probability, ***p<0.001, *level of 0.44% NDCP was not including in the two way statistical analysis | |
The main effects (level and source) showed that the highest dietary level of DCP (1.75%) improved (p<0.001) BWG and FCR by about 5.5 and 4%, respectively, compared to 0.88% DCP level. Source of DCP showed that birds fed NDCP diets gained (p<0.001) 12.6% more body weight and consumed (p<0.01) 1.6% more feed than CDCP groups. Values of FCR enhanced (p<0.001) by 10% for birds fed NDCP diets compared to those fed CDCP diets.
The effect of different dietary CDCP and NDCP levels on performance of broiler chicken from 16-26 days of age is shown in Table 3. Birds fed diets containing 1.75, 1.31, 0.88 and 0.44% NDCP showed significant (p<0.05) improvements in BWG and FCR compared to the control group. The best values of BWG (904, 892 and 891 g) and FCR (1.37, 1.38 and 1.38) were recorded for treatments fed 1.75, 1.31 and 0.88% NDCP, respectively. No significant difference in FI was detected among treatments fed different levels of NDCP and the control group. Treatments fed 1.31 or 0.88% CDCP consumed significant less feed (p<0.05) compared to the control group.
The results of the main effects indicated that both level and source of DCP significantly (p<0.001) affected the measured performance parameters (BWG, FI and FCR). Feeding low levels of CDCP or NDCP resulted in low values of BWG and FI. Also, values of FCR were negatively affected by lowering the dietary level of CDCP. The results also showed the superiority of using NDCP over CDCP. Birds fed NDCP diets gained about 32% more weight and consumed about 14% more feed compared to birds fed CDCP. This improved the values of FCR by about 14%.
The results of performance of broiler chicken fed different dietary CDCP and NDCP for the entire period (1-26 days of age) are shown in Table 4. Birds fed different levels of NDCP gained significant (p<0.05) more body weight and utilized feed more efficiently than the control group. Decreasing levels of CDCP led to decrease in BWG and impaired FCR compared to the control group. No significant differences in FI were detected among birds fed different levels of NDCP, but birds fed low CDCP consumed less feed (p<0.05) compared to the control group. Birds fed different levels of NDCP showed close range in values of BWG and FI. Values of FCR impaired with decreasing dietary level of either CDCP or NDCP. Values of BWG, FI and FCR improved by about 25, 10 and 12%, respectively, for birds fed NDCP compared to those fed CDCP. These results proved that using NDCP improved BWG, FI and FCR effectively compared to CDCP.
The results of enhanced performance observed in the present study by inclusion of NCDP in the diet are in accordance with Vijayakumar and Balakrishnan23 who found that using 50% calcium phosphate nanoparticles (hydroxyapatite) instead of the conventional dicalcium phosphate in diet led to increased BWG of broiler chicken over the control.
| Table 5: | Effect of different dietary CDCP and NDCP levels on excreted calcium and phosphorus of broiler chicken at 26 day of age |
Means designated with the same letter within the same column are not significantly different at 0.05 level of probability, **p<0.01, ***p<0.001, NS: Not Significant (p>0.05), *Level of 0.44% NDCP was not including in the two way statistical analysis | |
The same results were reported for other nano menirals; Liao et al.24, Shi et al.25, Zhou and Wang26, Cai et al.27, Mohapatra et al.12 and Huang et al.13 concluded that nano-Se could be utilized more effectively than inorganic or organic Se. Furthermore, Cai et al.28 found that the supplementation of nano-Se in broiler diets could improve meat quality, immune function, oxidation resistance and the selenium content of liver and muscles. Ahmadi et al.14, Mishra et al.15, Sahoo et al.29, Mohammadi et al.16 and Swain et al.11 found that the supplementation of zinc oxide nanoparticles in broiler diets improved growth performance during the starter period. Using chromium in nanoparticle size has been reported to show similar results17.
The improvement in the performance as a result of NCDP could be attributed to the fact that the nano materials are very minute in size, leading to a great improvement in their properties because of higher surface area and increased absorption. Chan et al.30 and Gross et al.31 have reported that calcium phosphate materials in nano-size have higher specific surface area and surface roughness compared to the conventional calcium phosphate. Weiss et al.32 reported that nanoparticle-sized ingredients might increase the functionality or bioavailability of ingredients and nutrients, thereby minimize the concentrations needed in the food product. Calcium phosphate materials in nano-size are expected to have better bioactivity compared to conventional materials because supplementation of minerals in nano form (Se, Cr and Zn) increases the bioavailability and efficiency of utilization by increasing the surface area33. The usefulness of nano form in reducing the mineral quantity to half or more in the diet will reduce the cost of feeding when the actual production of calcium phosphate nano-particles is upscaled to an industrial level.
Calcium and phosphorus excretion: The effect of different dietary levels of NDCP and CDCP on calcium and phosphorus excretion of broiler chicks at 26 days of age is shown in Table 5. The Ca and P excretion significantly (p<0.001) decreased with decreasing DCP levels. Birds fed 0.88% CDCP excreted 34.07% less Ca and 27.17% less P while those fed 0.88% NDCP excreted 39.63% less Ca and 35.84% less P than those fed 1.75% CDCP diet. Level of dietary DCP significantly (p<0.001) affected Ca and P excretion while source of DCP significantly (p<0.001) affected P excretion and did not affect (p>0.05) Ca excretion. Feeding 0.44% NDCP decreased the excreted Ca and P by 50.74 and 46.24%, respectively, compared to the control diet.
Addition of dicalcium phsphate in nano form improves the absorption and subsequent reduction in their excretion. Swain et al.11 reported that nano minerals are having a great potential even at very lower doses than the conventional organic and inorganic sources. Nano form of minerals supplementation increases the surface area which possibly could increase absorption and utilization leading to reduction in the quantity of supplements and ultimately reduction in mineral excretion. The growing concerns with regard to the potential contribution of phosphorus in poultry excreta on eutrophication of surface waters has led to increasing pressure to limit the amount of excess phosphorus in poultry ration and thus reduce output of phosphorus27.
CONCLUSION
Reducing dietary CDCP had a negative effect on BWG and FCR. Meanwhile, using different levels of NDCP did enhance BWG and FCR of broiler chicks compared to CDCP. Birds fed diets contained 0.88 or 0.44% NDCP did perform as well as those fed diet contained 1.75% CDCP. Using NDCP in broiler diets allow successfully to reduce the dietary DCP by 75%. Diet formulated containing only 25% of the required P level in form of NDCP could be used instead of using 100% of the requirements in form of CDCP. Also, using dicalcium phosphate in nanoparticle size allow to reduce the excreted Ca and P by about 50%, which reduce the impact of poultry on environmental pollution.
It could be concluded that nano dicalcium phosphate is having a great potential as performance enhancer in broiler chicken production even at very lower doses than the conventional organic and inorganic sources. Further, using the added minerals to poultry diets in nano-particle size helped in reducing the excretion and subsequent possible environmental issues.
ACKNOWLEDGMENT
This study is a part of the Internal Research Project No. 10120502 of NRC, Egypt.