The effect of partial replacement of maize by alkali-treated date pits on broiler growth, survival rate and economic returns

M Al-Bowait and S I Al-Sultan*

Central Animal Production and veterinary Training in AL-Ahsa, Saudi Arabia
* Department of Public Health and Animal Husbandry . College of Veterinary Medicine and Animal Resources, King Faisal University,
PO Box 11647, Al-Ahsa 31982, Saudi Arabia
Alsultan87@hotmail.com

Abstract

The study fell into two parts .In the first part date pits were treated with 3, 6, 9 or 12% NaOH solution to improve its digestibility. Both treated date pits (TDP) and untreated date pits (UDP) contained low crude protein (51-57 g/kg) and high crude fiber (188.2-149.7 g/kg). NaOH treatment improved dry matter digestibility (DMD). DMD coefficient of UDP was 0.137 and that of TDP varied between 0.187-0.198.DMD increased progressively with the increase in the strength of NaOH solution used to treat date pits.

 In the second part of the study 3% and 6% NaOH treated date pits partially replaced maize in broiler’s diet and were included at the rate of 10, 20, 30 or 40% of the diet. The eight experimental diets and the control diet that contained 40% maize and no date pits were assigned at random to nine groups of 44 day-old chicks each. Each group contained four replicates of 11 chicks. The diets were fed for six weeks. Overall mean feed consumption  on the control diet was 3042 g , feed conversion ratio was 1.807 units , survival rate was 95.46 % and  mean final weight was the were the heaviest . The corresponding values for chicks raised on diets containing treated date pits were 3151 g, 2.582 units and 85.5%, respectively. Carcass composition and eating quality of the meat was not affected by the treatment. The highest financial return was obtained on the control diet whereas the best financial return of date pits containing diet represented 0.77 of the returns displayed by the control group.

Keywords: alkali-treated date pits, broiler growth, economic returns, replacement of maize, survival rate

Introduction

Poultry feeding is a great bother to poultry industry in Saudi Arabia. A raw material feeding import amounted to 399,000 tones in 1999 and is anticipated to go up 9.2 million tones by year 2010.  So the production of energy rich cereal grains in the kingdom for incorporation in poultry feeds is lacking and the industry relies on costly, irregular unguaranteed raw material important. The kingdom is the largest producer of dates in the world with 14 million date palm trees producing 17.6% of the world date, 568,000 tones in the year 2002 mostly at Al-Ahsa, the largest world oasis and the site of this study. Date pits stones, kernels or seeds constitute 12-16% of the date fruit of the have no economic value at present. Date pits are cheep by –products with high energy content that can provide a potential alternative for conventional energy feed ingredients in the poultry industry. This will help reduction of reliance on foreign imports of raw materials, will cope with international policies of relying on agro-industrial by –products for animal feed to reduce competition with man for cereals and to help reducing environmental pollution. 

Alternative feed energy sources for cereal grains specially maize have been investigated by many research workers, fibrous feeds being a potential substitute for convential energy feeds could be used provided that measures are taken to improve quality and utilization and date pits were investigated in Gabrial et al (1981)  studied that seeds as an unconventional protein source. However, Harry et al (1936) stated that date pits contain 8% moisture and 7.5% fat and Al-Hiti and Rous (1978) recorded 5.8% protein content. Kamel et al (1981) were reported when comparing amino-acid profile percent of Zabadi date pits and maize stated that date pits contained 0.17 methionine, 0.31 lysine and 0.36 % theronine compared to 0.15, 0.27 and 0.31%, respectively, for maize. Thus the limiting amino-acids are almost similar through the total protein of date pits is lower than maize, the same worker incorporated date pits in broiler diets at 5,10 and 15% replacing wheat bran, maize and alfalfa with or without 50ppm of zinc bacitracin supplementation. They found that date pits supported chick growth as efficiently as the control for all diets, also found no abnormalities of all organ of chicken. Afifi et al (1966) found that chickens fed partially on date stone meal showed accelerated growth proportional to increased feed intake which suggested growth promotion. Also, Al-Hiti and Rous (1978)  have reported when feeding date waste to broilers by partial replacement of cereals at of 50,100 and 150g/kg of feed reported higher weight gains at the cost intake/kg gained. However, Vandepouliere et al (1995) conducted two broiler and quail breeder studies to evaluate dietary potential of dates, date pits meat using 8-43% dates , 16-43 date meat and 5-27% date pits for the broiler and 10-30% dates, 4-24% date meat and 5-15% date for the quail breeders. Where, Al-Yousef et al (1989) reported that NaoH treatment of date pits increased the rate of in-vitro digestibility by solubolizing some of the unavailable fiber components of the cell wall.  Also Obese et al (2001) have been used chemical composition and in-vitro digestibility techniques to assess feeding value of untreated defatted and NaOH treated palm press fiber and found that defattening and NaOH treatment improved dry matter and organic matter digestibility (0.196 vs 0.145).

The objective of this study to investigate the possibility of improving the nutritive value of date pits by alkali treatment using NaoH solution. Also to improve the quality of a cheap fibrous by –product as a potential alternative for expensive conventional energy feed using the high carbohydrate content of date pits. For this investigation response of broiler to partial replacement of maize by alkali treated date pits (TDP) was studied taking parameters of broiler growth , feed intake, feed conversion ratios (FCR), health and survival rates and economic returns..


Material and methods

The study falls into two parts:                                                                                              

1. Alkali treatment of date pits   

2. Feeding alkali-treated date pits to broilers

Sodium hydroxide treatment of date pits

Here the effect on physical characteristics, digestibility, and chemical composition upon treating date pits with NaOH solution of five different concentrations i.e. (0, 3, 6,9, 12 %) was studied.  

Preparation of NaOH solution

The following plan was used to prepare sodium hydroxide solutions of varying strengths:

1- 0 g NaOH granules were dissolved in 1000 ml of distilled water, using automatic stirrer, to yield a solution with 0% NaOH. 

2- 30 g of NaOH granules were dissolved in 1000 ml of distilled water using automatic stirrer to yield a solution with 3% NaOH.

3- 60 g of NaOH granules were dissolved in 1000 ml of distilled water, using automatic stirrer, to yield a solution with 6% NaOH.

4- 90 g of NaOH granules were dissolved in 1000 ml of distilled water, using automatic stirrer, to yield a solution with 9% NaOH.

5- 120 g of NaOH granules were dissolved in 1000 ml of distilled water, using automatic stirrer, to yield a solution with 12% NaOH.

Treatment of date pits with  NaOH solutions

Thirty kg of finely pulverized date pits were purchased from the Dates Factory of Al-Ahsa Development Company in Al-Ahsa town in Eastern Saudi Arabia on 1/1/2003.The date pits were obtained from the production of 2002. 

Several pilot trials were conducted in the laboratory to find out the best mixing rate of date pits with NaOH that would saturate date pits without wasting sodium hydroxide. It has been finally decided to add   550 ml of sodium hydroxide solution to every 1 kg of pulverized date pits. The assigned NaOH quantity was gradually added to the date pits in a plastic container while working with both hands on the date pits to ensure even distribution and mixing for NaOH solution with the date pits. The date pits thus treated with NaOH was allowed to stay overnight for 24 hours at room temperature in the same plastic container. Then it was evenly spread on the laboratory bench and allowed to dry for 48 -72 hours.  

Chemical analysis of treated date pits      

Dry samples, weighing 200 g, each, were obtained   from date pits treated with 0, 3, 6, 9 or 12 % sodium hydroxide solution. These samples were analyzed, in triplicates ,to yield information on :moisture content , crude protein , ether extract , total ash , acid detergent fiber, neutral detergent fiber, in-vitro digestibility coefficients, gross energy, calcium, sodium, potassium and phosphorous content of the treated date pits. The procedures of the Association of Official Analytical Chemists (1975) were used. Chemical analyses for moisture content, crude protein, ether extract and total ash were carried out at the Nutrition laboratory of the College of Veterinary Medicine and Animal Resources, King Faisal University. The remaining analyses were carried out at the reference laboratory of ARASCO (Arab Agricultural Service Company) in Riyadh, Saudi Arabia.  

Preparation of large quantities of treated date pits

To prepare large quantities of treated date pits (for use in subsequent feeding trial) an automatic feed mixture of 5 kg holding capacity was used. Using this mixer 2020 ml of sodium hydroxide solution of a given concentration (either 0, 3 and 6 %) was slowly added to 4 kg of pulverized date pits while the mixer was in operation for 15 minutes. The treated date pits were then evenly spread on a plastic sheet on the laboratory floor and allowed to dry for two days. Subsequently, the dry treated date pits were placed in a plastic bag and stored for later use as a partial substitute of maize in broiler diet. A total of 48 kilograms of treated date pits (24 kg from each level of treatment) were thus prepared and stored for use in feeding trials.  

Feeding alkali-treated date pits (TDP) to broilers 

The effect of feeding (TDP) on broiler growth, survival rate and economic returns was studied. 396 day-old (nine groups of  44 chicks each) commercial broiler chicks from the Hybro commercial strain.  The chicks were obtained from a private hatchery at Al-Ahsa town in Eastern Saudi Arabia on June 3^rd 2003. 

On arrival to the site of the experiment at the Veterinary and Animal Production Training Center in Al-Ahsa the chicks were weighed and divided into nine groups of 44 chicks each.

The groups were randomely assigned to 9 experimental diets of 4 replicates, 11 chicks each. Birds of all treatments were reared on sand litter under similar environmental and management conditions throughout the 42 days of the feeding period. All chicks were vaccinated against Newcastle disease and Gumboro at 15 and 30 days of age. Feeders and waterers were cleaned twice daily at early morning and mid-day. The litter was mixed twice a week to keep it dry. All management and rearing procedures followed the recommendations of the Commercial Chicken Production Manual (1981). 

Feeding intake, body weight and mortality were recorded daily for each replicate pen separately. 

Feeding trial 

A control conventional diet composed of maize, soybean and concentrate table 1 was used.  

Experimental diets with similar composition as the control were prepared by partial replacements of 15.4 , 30.8%, 46.2% and 61.8% for maize for each feed treatment of (TDP) as shown in table 2. 3 % and 6% NaoH solution were used in the feeding trials.  

Data analysis  

Live weight growth curves were plotted for all treatment groups. Survival rates, feed conversion ratios were computed and likewise weekly rate of growth. Analysis of variance was carried to investigate the effect of treatment on all parameters. Least square means and standard errors were computed and compared. The procedures of the Statistical Analysis  Systems (SAS 1986) were used.
 

Results     

Table 3 shows that there were noticeable changes in normal date pits color after the treatment with sodium hydroxide. The magnitude in color change depended on NaOH concentration. The initial color of untreated date pits was light brown .On mixing it with 3% NaOH color changed to black brown. The addition of 6% NaOH resulted into black color; and further mixing of date pits with 9 or 12% NaOH resulted in dark brown color. These color changes resulted from the caustic effect of NaOH on date pits. 

Table 4  shows the chemical composition of treated date pits (TDP) versus untreated date pits (UDP) samples. Both  UDP and TDP were low in  nitrogen (51-57 g/kg) .Dry matter ranged between  900-903 g/kg kg) oil (68.6-59.9 g/kg) but was high in fiber (188.2-149.7 g/kg) and neutral detergent fiber (70-73%). Acid detergent fiber ranged between (37.5-54.8 g/kg) NaOH treatment improved dry matter digestibility. The dry matter digestibility coefficient of UNDP. The in-vitro dry-matter digestibility increased progressively with the increase in the strength of NaOH used to treat date pits.  

Feeding alkali treated date pits (TDP)

Growth performance was recorded on weekly basis in terms of means for body weight gain, feed intake, and gain per bird per day and feed conversion. Records were made for the control and each treatment for every week of the 6 weeks of the feeding periods. The growth performance is shown table 5.   

Table 5 above shows that treatment did not affect total feed consumption, weight gain or Food Conversion Ratio. Generally, feed consumption did not vary considerably between treatments and mean total feed consumption varied between 3042-3243g. The control group was better feed converter than all treatment groups. Using 1 degree of freedom contrast chicks raised on the control diet consumed 3042 g and had FCR of 1.807 corresponding mean values for chicks raised on (TDP) diets were 3152 and 2.582, respectively.  

On computing feed efficiency and efficiency for inclusion levels of (TDP), irrespective, of the NaoH solution concentration used for the treatment, feed consumption values were , 3042, 3169, 3130, 3140 and 3169g for diets containing 0,10, 20, 30, and 40% (TDP), respectively, and the corresponding FCR were 1.807, 2.180, 2.420, 2.540 and 2.980, respectively. 

The growth curves described changes in the mean live weight of broilers of the nine treatments are shown in Figure 1 . Bars at the points showing the mean live weight at a certain week are standard errors (s.e) and where (s.e) at a certain week overlap, this indicates that differences between the mean weights of treatement groups were not significant. Also curves were indistinguishable at the earlier phases of the study but with progress of the feeding trails, specially the last three weeks differences between the control group and (TDP) groups started to widen.

The survival rates for the different treatments were recorded daily and examined on weekly interval. The best survival rate was shown by the control at 95.46% and the lowest was 75% in the treatment 40/3% NaoH due to a short transitional cooling system failure. Data in the table 6 present difficulty to relate survival rate to inclusion level or strength of NaoH solution used in the treatment of data pits.

By computing survival rates for inclusion levels of (TDP), irrespective of NaoH solution concentration used in the treatments, survival rates would be 95.46% for 10% TDP, 86.36% for 20% TDP, 89.77% for 30% TDP and 78.4% TDP. Apparently, 40% TDP inclusion in broiler diets affected survival rate negatively. On other hand, irrespective of inclusion rate of (TDP) survival rate would be 85.23% and 85.77% for diets containing 3% and 6% NaoH ,respectively, and both are lower than the control diet of (UTDP). Using 1 degree of freedom contrast chicks raised on the control diet had 95.46% survival rate and for broilers on (TDP) was 85.5% survival rate. 

Economic appraisal

Analysis of financial returns for the nine treatments are shown in table 7. The two major inputs considered in the economic analysis were the purchase price of one day old broiler chicks and feed cost. When calculating feed cost, mortality was considered and included in the calculations and the total weight yield for each treatment was calculated for survivors only.

As shown in table 7 feed cost on the control treatment was the highest while those on 40%/3 and 40%/6 were the lowest 24.1 and 50.1% of the control profit, respectively. The best profit margin of (TDP) group was shown by 10/3% TDP at 77.9% of the control treatment.

Discussion

The aim of this study was to investigate the effects of partial replacement Maize by Alkali-treated date pits on broiler growth, survival rate and economic returns.

One of the noticeable changes that took place in date pits on treatment with 3% NaOH solution was the change from its normal light brown color to black color. This was probably caused by the caustic effect of (NaOH) on the chemical components of cell wall (including the cell wall pigments) of date pits. Increasing the concentration of the NaOH solution to 6% augmented the caustic and bleaching effects of NaOH resulting into a stronger coffee dark color. Further increase in the strength of the NaOH solution used for treating date pits to 9 and 12% produced similar color changes as the 6% strength. This suggests that the 6% solution resulted into permanent stable color changes in date pits (this color shows effective treatment effect on date pits, this is also observed with ammonia treatment).

The present results showed  that date pits had low protein and high fiber  contents in line with the findings of Gabrial et al (1981), Sawaya et al (1984) and Shurafa et al (1982). The low protein and high fiber contents of date pits are major disadvantages that limit the use of date pits for feeding poultry as birds require less fiber and more protein in their diets. Date pits fiber, however, could provide a cheap source of energy to birds if its digestibility is improved.

The alkali treatment of date pits in this study improved dry matter digestibility in a linear manner with the increase in the concentration of NaOH used for treatment from 3% to 12%. This is congruent with the findings of Al-Yousef et al (1989) who also showed that treatment of date pits with 2.4, 4.8 and 9.6% NaOH solution, increased in vitro digestion rates. Likewise, alkali treated straw (Barreveld 1993) has a linearly higher digestibility coefficient (from 45% to 71% for respectively 0 to 120 g NaOH per kg of treated straw).  By the same token Obese et al (2001) found sodium hydroxide treatment of palm press fiber to improve dry matter and organic matter digestibility (0.196 vs. 0.145 for treated and untreated palm press fiber, respectively) .

The mechanism of alkali treatment is not exactly known but is most likely based on displacement of intra-fibril hydrogen linkages by much larger Na-ions, and breakage of bonds between lignin and cellulose (Barreveld 1993).  The result is a material with more accessible nutritive compounds and which is physically more attractive for the animal to ingest because the material becomes softer. The disadvantage is that the animal's water intake is greatly increased to remove excess sodium (Barreveld 1993).

The growth performance of the final weights was attained by the various treatment groups at the end of the feeding period are of great economical importance because they affect the sale price of broilers that are normally marketed on body weight basis. However, to understand how these final differences were brought about it is imperative to look into weekly performance of the treatment groups. For this reason growth performance of treatment groups was examined at weekly intervals in terms of mean weekly body weight /bird, mean body weight gain/bird, mean daily weight gain/bird and mean feed conversion ratio.

As is shown in Table 5 birds on the control treatment achieved the heaviest (1731 g) final body weight with a difference of 66 g from the next heaviest (1645 g) treatment group (i.e. treatment that contained 10% of 3% NaOH treated date pits). The lightest (1006 g) final body weight was displayed by the group of chicks that was raised on the diet with 40% of 3% NaOH treated date pits. Using 1 degree of freedom contrast the mean final body weight of chicks raised on the control diet was 1731 g and that of chicks raised on diets containing treated date pits was 1295g leaving a difference of 436 g between the two categories of broilers. This is a large difference which resulted from slow growth of broilers on diets containing treated date pits as compared to chicks fed on the control diet. On computing final body weight  for inclusion levels of treated  date pits , irrespective of the  concentration of NaOH solution used for treatment, final body weights  would be  as follows: 1731, 1502, 1356, 1199 and 1121 g for  diets that contained 0,10,20, 30 or 40% treated date pits, respectively. It is clear that inclusion of date pits by replacing parts of maize in broiler’s diet had a linear negative impact on final body weight; final body weight declined as the rate of replacement of maize by treated date pits increased. Similar negative response by broilers on feeding date pits has been reported by Jumah et al (1983) .Conversely, better growth performance over the control chicks has been reported for chicks that were fed on a diet in which date stone meal replaced   10% of barley (Afifi et al 1966) or in chicks that received 10 g of ground date stones daily in addition to the normal control diet (Sharaf 1969). It must be emphasized here that in the latter two studies date pits were fed to broilers at low levels. Indeed Kamel et al (1981) showed that when ground dates replaced maize at respectively 5, 10 and 30% of a diet for broilers growth was efficiently supported as the control, but at 47.7% replacement rate of the maize growth was depressed and feed utilization reduced.

The broilers that were fed diets containing treated date pits ate more feed than the control chicks to gain the same weight as the control chicks Table 1. Using 1 degree of freedom contrast the mean feed conversion ratio of control chicks was 1.807 and that of chicks raised on diets containing treated date pits was 2.582.

On computing feed conversion ratios  for inclusion levels of treated  date pits , irrespective of the  concentration of NaOH solution used for treatment, feed conversion values  would be  as follows:1.807, 2.183, 2.42, 2.759 and 2.985 for  diets that contained 0,10,20, 30 or 40% treated date pits, respectively. Thus feed conversion efficiency declined progressively as the proportion of date pits in the diet increased. Al-Hiti and Rous (1978) showed that when date waste partially replaced cereals in broiler diet at the rate of respectively 0, 50, 100 and 150 g per kg of feed higher weight gains than control chicks were recorded  but at the cost of higher feed intake per kg gained. The corresponding feed conversion ratios were 2.07, 2.22, 2.26 and 2.26, for diets containing 0, 50, 100 and 150 g of date waste per kg of feed. Unlike the latter study inclusion of date pits  in broiler’s  diet did not support higher weight gain than the control, probably because the rate of inclusion of date pits in this study was considerably higher (100, 200, 300 and 400 g/kg of feed) than in the study of Al-Hiti and Rous (1978). Moreover, Onifade and Babatunde (1998) indicated that different fibrous ingredients elicit different responses when fed to broiler chickens.

It has been noted here that feed consumption of chicks fed on diets containing treated date pits was greater than feed consumption of chicks on the control diet. This result may partly be ascribed to the greater fiber content of the former diets.  The increased feed consumption is definitively a response to energy dilution of the diets and the attempt by the birds to consume adequate amount for maintenance as well as growth (Onifade 1993; Onifade and Babtunde 1998).

It has been noted here (Table 6) that the negative effect of date pits on growth performance was pronounced at the last two weeks of the trial where differences in body weight between the control birds and experimental bird widened. Whether or not this is attributed to a cumulative effect of date pits is not clear.

The present results clearly show that treated date pits was not utilized by chicks as effectively as they utilized maize and consequently it can not replace equal amount of maize and yet give similar or better weight gains. The ultimate result of incorporating date pits in broiler’s diet is a lighter final body weight than that of birds fed on the control conventional diet. How much  weight difference from control birds  is encountered on feeding date pits depends on the  rate at which it was included in the diet, 86 and 274 g  weight differences from the final weight of control chicks were recorded  when 3%NaOH treated date pits was included at the rate of 10% and 20%, respectively. These differences may be acceptable provided that economical returns on using date pits are larger than in conventional control diet and that carcass and meat quality are not drastically affected. In the coming paragraphs the effect of the treatment on carcass and meat quality as well as economical returns are dealt with.

The outcome of the economical evaluation of the present trial revealed that the best margin of profit was encountered when chicks were raised on the conventional control diet. The next  best margin of profit  (a proportion of  0.779 of the returns on the control diet) was obtained on rearing chicks on the diet that contained 10% of 3% treated date pits. The lowest returns ( a proportion of 0.241 of the returns on the control diet ) were encountered  on feeding chicks  the diet that  contained 40% of 3% NaOH treated date pits .The chicks that were fed on the latter diet suffered from both poor growth and low survival  rate.

NaOH treated date pits is not the ideal alternative to maize in broiler diets according to the present results. Its inclusion resulted into reduced growth performance and reduced financial returns. More research studies should be devoted to the technology of date pits treatment to improve its digestibility and ultimately its utilization as energy source for poultry rather for ruminants that can effectively replace expensive imported energy feeds such as maize.

 

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Received 18 April 2007; Accepted 17 July 2007; Published 4 September 2007

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