Evaluation of different processing methods on the nutrient composition of broiler litter and its utilization by weaner pigs in the tropics

E O Akinfala and O B Komolafe

Department of Animal Sciences, Obafemi Awolowo University, Ile Ife Nigeria.
oakinfala@yahoo.com   or   akinfala@oauife.edu.ng

Abstract

This study was carried out to evaluate the effect of different processing methods on the nutrient composition of broiler litter and its replacement value with palm kernel cake in the diets of weaner pigs on the performance, hematological indices and economics of production of growing pigs for eight weeks. Four experimental diets were formulated.  Diet 1 which had 0% processed broiler litter served as the control, while diets 2, 3 and 4 contained 20% of ensiled, composted and sun-dried broiler litter respectively.  A total of about ten weeks old sixteen weaner pigs (large white x Hampshire) with an initial mean body weight of 8.41 + 2.59kg were used in this study in a completely randomized design.  There were four pigs per treatment and each pig represents a replicate.

The results of this study showed that the different processing methods of ensiling, composting and sun drying affected (p < 0.05) the nutrient composition of broiler litter especially at the level of crude protein and crude fibre.  The results further showed that average final body weight (20.0 – 21.2kg) and feed/gain ratio (2.35 – 2.64) were not affected (p > 0.05) by the dietary treatments. The average daily gain (218 – 246g) with highest value occurring in diet 1 and lowest in diet 4 and average daily feed intake (560 – 578g) with highest value in diet 1 and lowest value in diet 3 were affected (p < 0.05)  by the dietary treatments.  The hematological indices such as packed cell volume (29 – 33%), red blood cell (6.70 – 7.00 x 10⁶/mol³) and white blood cell (9,600 – 11,800 x 10³ul) were not affected (p>0.05) by the dietary treatments.   The economics of production results obtained showed that it was more economical to raise pigs using broiler litter at 20% of the diet. The results obtained from this study showed that processing methods such as ensiling, composting and sun-drying improved the nutrient composition of broiler litter and more over, processed broiler litter can be included up to 20% in the diet of growing pigs without any deleterious affect on the performance, hematological indices and economics of production in the diet of growing pig in the tropics. 

Key words: Broiler litter, experimental animals, experimental diets, hematology, heterotrophic bacteria, nutrient composition, performance, processed broiler litter, weaner pigs

Introduction

The research thrusts of most animal nutritionists in developing country currently are aimed at identifying potential feed resources that have little or no demand by humans.  Not only this, the identified feed resources must be available and cheap, and have the potential of bringing down cost of feeding which has been undisputedly put at 60-80% of total cost of production in an intensively reared stocks  such as poultry and pigs.  According to Salem et al (2000), chronic feed deficit represents a major constraint to animal production in many developing countries; therefore, the expansion of the feed resource base through utilization of non-conventional feed resources (NCFRs), especially those that do not compete with human for food has become a compelling task.  Research findings in Nigeria have shown that high cost of feeding in intensive animal production can be reduced significantly by the inclusion of non-conventional feed stuff which presents an acceptable nutrient profile.     

Several researchers have investigated the potentials of some non-conventional feed stuffs such as whole cassava plant meat (Akinfala et al 2002 and 2007), abattoir wastes (Odunsi, 2003) and poultry litter/manure (Babatunde et al 1979;Onimisi and Omage 2006; Aro and Tewe 2007) as feed stuffs for monogastrics animals. The use of poultry waste to feed monogastric is presently receiving attention among animal nutritionists in Nigeria. The improper handling of poultry waste can lead to a serious environmental problem (AAFC 1990) which may cause human and animal health problem or death in individual plant or animal and may in the long run result in decreased species diversity (Cecil Hammond 1996).

The solutions to these environmental problems have been advanced through different options like composting the waste to produce organic fertilizer, production of biogas and fertilization of fish ponds.  Besides these, the incorporation of the wastes into practical livestock diets has also been canvassed as a way out of its inherent environmental problems (Eusebio 1980).

Although, there is paucity of information as the use of poultry litter in he diets of pigs, however, findings from earlier research efforts stimulated the current investigation on the use of differently processed broiler litter as substitute for Palm kernel cake (PKC) in the diet of weaner pigs. 

Hence, the objective of this study was to evaluate the effects of different processing methods on nutrient composition of broiler litter and its replacement value with PKC in the diets of weaner pigs in the tropics.

Materials and methods

Collection and processing of test ingredient

The broiler litter used for this study was collected from the poultry unit of Obafemi Awolowo University Teaching and Research Farm, Ile-Ife, Nigeria.  The broiler litter which was about a week old was sieved to separate the fine litter from clod litter and fresh wood shavings.  The fine sieved litter was subjected to three different processing methods which were sun-drying, composting and ensiling.  For the sun-drying method, the sieved litter was sun-dried on a concrete floor for about 2-3 days to about 12% moisture content depending on the intensity of sunlight.  For the composting method, the sieved broiler litter was mixed well with water (8 liters of water to 50kg of litter) to enhance the activities of microbial bacterial but not to the level of soaking the litter. The litter was packed into compost bins.  The mixing of composted litter was being carried out at 4-5 days interval to allow for even thermophilic condition in the litter.  The compositing was carried out for 6 weeks after which it was allowed to cure before incorporation into the diet. For the ensiling method, silage was prepared in an air tight wooden container (90 x 50 x 50cm) lined with black polythene material.  The sieved broiler litter was mixed with water (26%).  The litter was creamed (20mm screen) to remove any wood, feathers and compost materials.  The litter was covered with black polythene sheet with container pressed with heavy stone.  The preparation of the silage was completed in a day and the air tight wooden container was opened after a termination period of 8 weeks.  The ensiled litter was allowed to cure before incorporation into the diet.

Experimental diets

Four experimental diets were formulated to meet the nutrient requirement of growing pigs in the tropics.  Diet 1 had 0% inclusion of processed broiler litter and served as the control.  Diets 2, 3, and 4 had 20% of palm kernel cake (PKC) in diet 1 (weight for weight) replaced with ensiled, composted and sun-dried broiler litter respectively (Table 1). 

Management of experimental animals

About ten weeks old sixteen weaner pigs (large white x Hampshire) with an initial mean weight of 8.41 + 2.59kg were randomly assigned to four dietary treatments. There were four animals per treatment and each animal served as a replicate.  The study was conducted for eight weeks.  The animals were housed individually in a concrete floor pens equipped with watering and feeding facilities.  The animals were fed at about 6% of their body weight daily and water was supplied to the animals ad libitum throughout the period of the study.  Routine management practices were followed.  Records of feed consumption and weight gained each week were kept on dietary treatment basis.

Blood collection

This was done at the end of the eight week study.  Three animals were randomly selected from each dietary treatment for the purpose of blood collection.  Blood samples were collected from each animal with the aid of sterilized 10-gauge needles made through the anterior vena cava.  The bleeding was done in the morning before feeding.  Ethylene Diamine Tetra Acetic Acid (EDTA) an anticoagulant was added to the test tubes meant for hematological indices such as packed cell volume, hemoglobin, red blood cell and white blood cell. Hematological measurements were determined using methods outlined by Kelly (1979).

Estimation of total heterotrophic bacteria in the broiler litter samples    

This was done by plate count technique.  In this technique, one gramme of the broiler litter was hydrated with 100ml sterile distilled water in a conical flask in the first instance.  Hundred folds serial dilution of the mixture was carried out five times in a set of test tubes each containing 99ml sterile distilled water. 1ml of each dilution was plated out respectively in duplicates employing the use of nutrient agar medium (sterile) kept at 40-44⁰C.  Pour plate method was adopted.  The culture plates having allowed the agar medium to set were incubated aerobically at 35% for 36-48hrs, thus enumerating for only aerobes and facultative heterotrophic bacterial.  The plates were observed for growth and selected for count after the expiration of the incubational period.  The culture plate on which the number of colonies was less than 300 (and its duplicate) for each sample was selected.  The average count was multiplied by dilution factor and expressed as the cell forming unit (CFU) per gramme of the original sample.

Chemical and statistical analyses

The proximate composition of the test ingredients and diets was determined by methods outlined by AOAC (1995). Gross energy was determined using a ballistic bomb calorimeter.  Data obtained were subject to statistical analysis using SAS (2000).

General health of the animals

The animals were generally healthy before, during and after the study.  There was no lesion or physical disability arising from the treatment effect. Prior to the commencement of the study, the animals were administered IVOMEC at 1ml/50kg body weight to take care of both endo and ecto parasites.

Results

Proximate composition of test ingredients and experimental diets

The proximate composition of the test ingredients is shown on Table 2 while that of the experimental diets is shown in Table 3.  For the test ingredient, the crude protein which was affected by processing (p< 0.05) ranged from 19.2% to 26.9%.  Unprocessed broiler litter had the lowest value while highest value occurred with ensiled broiler litter. The crude fibre decreased with the processing of broiler litter and ranged from 23.8% - 27.1%.  The ash content which ranged from 25.0% to 26.0% decreased with the processing of broiler litter.  For the experimental diets, the crude protein ranged from 18.1% to 22.0% with highest value occurring in the diet that had ensiled broiler litter. The crude fibre ranged from 6.76% to 11.9 %, while the ash content ranged from 8.65% to 13.6%.

Performance characteristics

As shown in Table 4, the weight gain per pig per day ranged from 218g to 246g with diet 1 having the highest value (P< 0.05) to diets 3 and 4 and not to diet 2 (P > 0.05). The feed intake per pig per day ranged from 560g to 578g with diet 1 having the highest value (P< 0.05) and diet 3 with lowest value.  The feed to gain ratio ranged from 2.35 for pigs on diet 1 to 2.64 for pigs on diet 4 (P> 0.05).  Feed cost per kg gain ranged from $0.98 in diet 2 to $1.09 in diet 4 (P> 0.05). (Table 5). 

Hematological indices

As shown in Table 6, the packed cell volume ranged 29% to 33% with highest value occurring with pigs in diet 1 and lowest with pigs on diet 2 (P> 0.05).  The red blood cell ranged from 6.70 x 10⁶/mol³ to 7.00 x 10⁶/mol^3.  Highest value occurred with pigs on diets 2 and 4 and lowest value occurred with pigs on diets 1 and 3 (P>0.05).  The white blood cell ranged from 9,600 x 10³ul to 11,800 x 10³ul.  Highest value occurred with pigs on diet 1 while lowest value occurred with pigs on diet 2 (P> 0.05).

Microbial analysis of processed and unprocessed broiler litter

Table 7 showed the cell forming unit in the processed and unprocessed broiler litter.  The cell form unit (CFU) ranged from 10.3 x 10⁷/g to 210 x 10⁷/g with highest value occurring in unprocessed broiler litter and lowest value occurring in sun-dried broiler litter (P< 0.05).

Discussion

The proximate composition of the test ingredients showed that crude protein ranged from 19.2 to 26.9%.  This falls within the range reported by Bagley and Evans (1998) and Van Ryssen (2000). The proximate composition of experimental diets showed that crude protein which ranged from 18.1 to 22.0% falls within the range recommended by Balogun and Fetuga (1990) for growing pigs in the tropics.  The crude fibre which ranged from 6.76 to 11.9 was above the range recommended by Adesehinwa (1997) for growing pigs in the tropics.  This high crude fibre content of the diets that contained broiler litter may be due to the presence of bedding materials which is known to be highly fibrous.  The ether extract which ranged from 5.32 to 6.49% had diet 4 having he highest value, which may be due probably to the activities of aerobic bacterial during sun-drying.  The ash content increased with the inclusion of processed broiler litter.  This may be due to high fibre content of the processed broiler litter due to low energy and high silica (Babatunde et al 1979).

The average daily gain was depressed by 2%, 8% and 11% respectively with ensiled, composted and sun-dried broiler litter while feed/gain ratio was depressed by 1%, 5% and 11% with ensiled, composted and sun-dried broiler litter respectively. This observed performance may be due to ability of ensiling to improve palatability, feed intake and greater nitrogen digestibility of the total ensiled diet (Jacob et al 1997).  Besides, the poor performance of the animals on diets 3 and 4 may be due to higher values of crude fibre in these diets.  This agrees with the findings of Souffrank (2001), Wenk (2001) and Wilfrat (2007) that an increase in dietary fibre level reduces the digestibility of other feed components.  Although AAFRD, (1996) reported that when dried poultry manure exceeds 10% in the diets of pigs, growth rate and feed to gain ratio will be negatively affected because poultry manure is low in the essential amino acids needed by pigs and it is also excessively high in calcium. Findings in this study appeared not to support this assertion because despite the inclusion of broiler litter at 20% of the diet, the pigs still performed satisfactorily especially when ensiled compared with the control diet.

The packed cell volume (PCV), red blood cell (RBC) and white blood cell (WBC) were affected (P> 0.05) by the inclusion of processed broiler litter in the diets of weaner pigs. The reason for these observed values for these hematological indices may be due to absence of metabolites and constituents in broiler litter which can clinically affect the pigs.

The heterotrophic bacteria plate count was (P< 0.05) affected by the processing of broiler litter.  Expectedly, highest value was found in the unprocessed broiler litter while lowest value was found in sun-dried broiler litter.  Though poultry litter could be a potential source of pathogenic microorganisms, if properly processed prior to feeding (Fontenont and Hancock, 2001), the presence of pathogens may not be a serious problem.  This may be the reason for the good health of the experimental animals during and after the study.  Besides there were no lesions or physical disability arising from the treatment effect.

The economics of production showed that it was economical to raise weaner pigs using broiler litter at 20% of diet.  The cost of feed consumed which was lower (P< 0.05) in all the broiler litter diets.  The cost of feed per kilogramme weight gain was lowest in all the processed broiler litter diets (P<0.05).  This agrees with the findings of Aro and Tewe (2006).

Conclusion

• The results obtained from this study showed that processed broiler litter can be included at 20% of the diet without any negative effect on the performance and hematological indices of weaner pigs.  Ensiled broiler litter diet showed a lower feed cost per kilogramme weight gain.  Moreover, compositing, sun-drying and ensiling methods of processing broiler litter significantly reduced the heterotrophic bacterial count in the broiler litter.

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Received 27 May 2011; Accepted 15 September 2011; Published 4 November 2011

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