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Effect of processing techniques on protein quality

Effect of processing techniques on protein quality

Abstract:-Due to ever increasing human population, more area is being used for cash crop and there is shortage of traditional feed items such as maize, wheat and soybean meal for poultry. This situation has necessitated using non-conventional feedstuffs as replacement for the conventional ones. Hatchery waste, when processed appropriately, has the potential for increasing the viable economic profitability of the poultry operation. In two experiments, the chemical and protein quality of hatchery waste was evaluated by using different processing techniques i.e., cooking, autoclaving and extrusion. The protein contents of the cooked, autoclaved and extruded HW meals were 43.67, 45.10, and 38.64%, respectively. Microbial analysis of the raw HW depicted high microbial counts. Different processing techniques reduced the microbial count of HW. Autoclaving reduced both the total viable count (TVC) and total coliform count (TCC) to the minimum as compared to other heat treatments. Protein quality of cooked, autoclaved and extruded HWM was measured in terms of protein efficiency ratio (PER) and net protein utilization (NPU).The weight gain in group consuming reference diet with casein as protein source showed significantly (P<0.05) higher weight gain (86.5 g) as compared to the other experimental groups. The PER results from all processing techniques along with NPU data supported an overall conclusion that processing HW with cooking and autoclaving is comparable in terms of NPU but significant difference is due to less CP % in extruded group. Autoclaved proved more beneficial in terms of PER. But overall values of PER and NPU revealed that processing of HWM can generate nutrient rich, palatable ingredients that was comparable to the traditional ingredients for better broiler performance.

INTRODUCTION

World human population is facing the problem of malnutrition. Due to ever increasing human population, more area is being used for cash crop and there is shortage of traditional vegetable feed items such as maize, wheat and soybean meal for poultry. The quality of different animal feed ingredients like fish meal and blood meal is too variable to be dependable and have some reservation on the part of nutritionists. This situation has necessitated using non-conventional feedstuffs as replacement for the conventional ones (Attah and Ologbenla, 1993). Many of the so-called wastes, particularly hatchery waste, if managed and processed appropriately, have the potential for increasing the viable economic profitability of the poultry operation. An estimated 140,000 t of waste are produced annually in the United States alone by hatcheries that generate commercial broilers, laying hens, and turkeys Das et al. (2002). Hatchery waste includes infertile eggs, dead embryos, egg shells from hatchlings, and unsalable chicks (Freeman, 2007).

The disposal of hatchery waste is of great concern for poultry industry. This material is usually incinerated, rendered, or taken to landfills (Miller, 1984). The high moisture content of fresh residue makes disposal and incineration costly to the producer and it may be unsafe environmentally (Vandepopuliere et al. (1977). Composition of hatchery waste indicates that by proper processing it can be converted into nutritionally dense meal. Temperature and pressure are two factors that can affect protein quality of animal meals during processing. Batterham et al. (1986) reported that Lysine availability in meat bone meal (MBM) decreased from 86 to 31% as processing temperature increased from 125oC to 150oC. As the poultry industry will continue to expand, there will be an increase in on-farm material and hatchery residue, creating a need for new and innovative ways of utilizing these resources (Blake and Donald, 1992). Tadtiyanant et al. (1993) recommended composting or rendering, or both, thereby generating potentially high quality feedstuffs. Although animal meals can contain high quality protein, it is well known that their protein quality can vary greatly (Johnston and coon, 1979). Hatchery by-products can be recycled as new feed ingredients in poultry diets (Babiker et al. (1991). It has potential to replace fish meal. The practice of disposing the hatchery waste as garbage at far flung areas is not only the wastage of valuable protein and energy sources; rather a contributing factor to the environmental pollution. The objective of the present study was to recycle hatchery waste by using different processing techniques and to determine the protein quality of different processed HWMs.

MATERIALS AND METHODS

Two experiments were conducted at Department of Food & Nutrition, University of Veterinary & Animal Sciences Lahore, to determine the protein quality of HWMs.

Experiment 1

The raw hatchery waste (HW) comprising of infertile eggs, shells, dead in shells and low grade unsalable chicks were subjected to the following three processing techniques:

Cooking

The HW was processed by cooking in the presence of water in such a way that there was double amount of waste to water (2:1). The cooking process continued until extra moisture was evaporated, then the dehydrated product was placed in an oven for drying at 60oC and ground through a laboratory mill for further analysis (Khan and Bhatti, 2001).

Autoclaving

In this method, the dried and ground HW was subjected to 125oC temperature along with 1.76 Kg/Cm2 pressure for 15 minutes. After this the material was sealed to avoid the growth of microorganism. This meal was used for further analysis Lilburn et al. (1997).

Extrusion

In this technique, the dried and ground hatchery waste was passed through extruder after subjecting to a temperature of 135oC for short time i.e., 30 seconds Haque et al. (1991) and stored for analyses and to be used in the experimental rations.

After drying the representative samples of the HWM prepared from above mentioned processing techniques were subjected to proximate, microbial and minerals analysis, (AOAC, 2000).

Experiment 2

Protein quality of cooked, autoclaved and extruded HWM was measured in terms of protein efficiency ratio (PER) and net protein utilization (NPU). For this purpose, a ten days trial was conducted to determine the protein quality of cooked, autoclaved and extruded HWM. Five poultry rations were formulated according to the standards prescribed by NRC (1994) for broiler chicks. Ration "A" was protein free, meeting all other nutritional requirements of the birds. Ration "B" was used as reference diet for experimental birds and contained casein as sole source of protein. Ration C, D and E had extruded, autoclaved and cooked HWMs, respectively as exclusive sources of protein. The composition of each ration is given in Table 1. Twenty five straight run 14-days old broiler (Hubbard) chicks were divided into five groups in such a way that there were five chicks in each group. Each group was divided into five experimental units in a way that ne chick represented as single replicate. All the birds were weighed at the start of the experiment. Five experimental rations were allocated to each group and there were five chicks on each ration. Clean water and feed were offered ad libitum to each bird throughout the experimental duration. The room temperature was maintained at 28+1oC. The daily feed offered, refusal and intake was recorded. The birds were weighed daily and weight gain was also recorded. Feces of each bird were collected daily in a separate sterilized plastic bottle containing 2% sulphuric acid. Likewise, the drop diet for each cage was collected, dried and weighed as refused feed. Faeces were dried in the oven at 70oC till constant weight. At the end of the feeding trial, the birds in each group were anesthetized with chloroform, their cranial as well as abdominal cavities opened and weighed before and after drying at 105oC to a constant weight. The dried carcass were ground and analyzed chemically for nitrogen content. Similarly, the faeces of each bird were also chemically analyzed for nitrogen content. Net protein utilization (NPU) and protein efficiency ratio (PER) were worked out by using the formula of Miller and Bender (1955), as under:

i. Net protein utilization (NPU): B - (Bk-Ik)

I

Where

B = Total body nitrogen of chicks on test diets.

Bk = Total body nitrogen of chicks on protein free diets.

I = Nitrogen intake of chicks on test diets

Ik = Nitrogen intake of chicks on protein-free diet.

ii. Protein efficiency ratio (PER) = Body weight gain (grams)

Protein consumed (grams)

Statistical analyses

The data was statistically analyzed through analysis of variance technique under complete randomized design. (Steel et al., 1997). Means were compared for significance of difference with Duncan Multiple Range Test to deduce the results and recommendations (Duncan, 1955).

RESULTS

The chemical and microbial analyses of processed HWM by using different processing techniques are depicted in Table 2 and 3 respectively.

Protein Quality

Average weight gain, feed intake, protein efficiency ratio (PER) and net protein utilization (NPU) for various rations have been presented in Table 4.

Weight gain

Average weight gain in 10 days trial in birds fed diets containing casein (standard), cooked, autoclaved and extruded HWMs were 86.50, 76.74, 74.66 and 72.22 grams, respectively. Maximum weight gain was observed in birds fed casein diet. The data regarding weight gain showed significant (P<0.05) differences among the groups. The comparison of means revealed significantly (P<0.05) higher weight gain in case of casein diet as compared to diets containing cooked (76.74g), autoclaved (74.66g) and extruded (72.22g) HWMs. Significantly (P<0.05) lower (72.22g) weight gain was observed in group fed extruded HWM as compared to diets containing cooked, autoclaved HWMs and casein. Non-significant (P>0.05) difference was found between diets containing autoclaved and cooked HWMs.

Feed Intake

The data on feed intake of birds fed experimental diets revealed that the groups fed on casein (230g) and cooked (227g)HWM were significantly (P< 0.05) different as compared to extruded (226g) and autoclaved (222g) HWM diets. Non-significant (P>0.05) difference was found between the diets containing casein and cooked HWM as well as between the groups fed on extruded and autoclaved HWMs.

Protein efficiency ratio (PER)

The PER values of cooked (1.46), autoclaved (1.50) and extruded HWM (1.38) were less than that of casein (standard) diet (1.63). The statistical analysis of data revealed that PER values of all protein sources tested, differed significantly (P<0.05) among all groups. It was observed that casein gave maximum (1.63) PER value, which was significantly (P<0.05) higher than those of cooked, autoclaved and extruded HWMs, while minimum (1.38) PER value was observed in group fed on extruded HWM.

Net protein utilization (NPU)

The NPU values of cooked (45.71), autoclaved (45.22) and extruded HWMs (40.63) were less than that of casein based diet (74.22). The statistical analysis of data revealed that NPU value of diet containing casein was significantly different (P<0.05) from rest of the three diets. It was also observed that diets fed on autoclaved and cooked HWMs showed significant (P<0.05) difference with that of extruded HWM. However, there was non- significant (P>0.05) difference between autoclaved and cooked HWMs.

Microbial Analysis

Microbial analysis using total plate count (in colony forming units) was done for raw as well as processed HWMs. Total viable bacterial count and species present in raw, processed HW meals are presented in Table 3. Total viable count (TVC) and total colifor m count (TCC) for raw HW were 8.3x107 and 1.9x105, respectively. Most prevalent species were Salmonella and E. Coli. All types of processing techniques were found efficient in counter acting TCC as there was non significant (P>0.05) in TCC of processed meals. Extrusion was most effective in reducing TCC as compared to cooked and autoclaved. Similarly, autoclaved significantly reduced (P>0.05) TCC when compared to cooked meal but TCC in all samples were in safe limit.

Both autoclaving and extrusion were found quite efficient in reducing TVC and TCC. Although the TVC and TCC were higher in cooked HWM as compared to autoclaved and extruded, but even it was under safe limit. When data for microbial count was statistically compared for differences, the processing techniques significantly (P<0.05) affected the TVC as well as TCC (Table 3). When treatments were compared among themselves irrespective of the raw HW, significant (P<0.05) differences were found between different processing techniques for TVC and non-significant (P>0.05) differences were observed for TCC.

DISCUSSION

Whatever the processing technique is used, protein content of the HWM depends upon the composition of the waste. The protein contents of the cooked, autoclaved and extruded meals were 43.67, 45.10, and 38.64%, respectively. The protein contents of the meals prepared in the present study were comparable to that of Saima et al., (2003) who reported 43.10 % and 42.99 % CP in cooked and toasted HWM, respectively. However, Ristic and Kormanjos (1988) revealed 22.4% CP in autoclaved HWM. Less CP contents in this study might be due to high shell moiety. Different factors like hatching percentage, species and shells can affect the composition of meal. Separation of shells from meal to enhance protein percentage is a common practice. In the present study the CP content of extruded HW were somewhat less than autoclaved HWM. This may be due to the reason that HW was extruded without blending. While Lilburn et al., (1997) found more CP content i.e. 44.6% in extruded as compared to 22.2% CP in autoclaved HW with 70% less lysine. This was due to the reason that hatchery residue used for both processing techniques was collected on separate day. The make up of the product on two sampling days could have been different. Same situation was observed in ash content. In the present study, ash contents were 25.81, 26.94 and 28.90% for cooked, autoclaved and extruded HWM respectively. (Ilian and Salman, 1986) reported 60.4 % and Rasool et al. (1999) found only 14 % ash in HWM. This large variation in ash composition may also be attributed to above mentioned factors. Part of this variation or inconsistency could be associated with dietary Ca and P levels, which usually vary directly with the ash content.

There were significantly high viable count in raw hatchery waste and it contained large number of pathogenic bacteria. Due to this reason, the raw HW cannot be included in the poultry diet as such. In the present study, the processing techniques did not eliminate the viable count completely but managed it to safe level. In this regard all techniques were found to be efficient with extrusion at the top. Tadiyanant et al. (1993) found that standard plate counts of pre-extrusion blended mixtures before extruding ranged from 3.2x104 cfu/g 2.5x1010 cfu/g of sample in dead turkeys to in hatchery solids. No attempt was made to characterize the representative contaminants and spoilage flora. However, no aerobic micro-organisms were observed in any of the products when analyzed just after processing by extrusion. They found high temperature short time extrusion was excellent for ingredient processing and eliminating aerobic micro-organisms.

Results of the present study are in line with findings of Haque et al. (1991) who determined that total number of aerobic micro-organism present in poultry by-product meal were 47000 cfu/g. These were completely eliminated by high temperature and short time extrusion process. (Miller, 1984) also reported that no Salmonella organisms were found when hatchery wastes were processed through high temperature extrusion. Dhaliwal et al. (1996) noted Bacillus and Streptococcus species in raw HW which were totally eliminated after processing of HW by extrusion.

The weight gain in group consuming reference diet with casein showed significantly higher weight gain (86.5+7.21g) as compared to autoclaved and cooked HW meals. The birds consuming extruded HWM showed less weight gain (72.22+6.21 g) as compared to cooked and autoclaved. The value of PER in extruded group was significantly less but this was due to less CP % of extruded HWM. The results were supported by Barbour et al. (1995) who found a reduction in feed intake and PER when diets containing 48% SBM were decreased from 20 to 16 %. The PER results from all processing techniques along with NPU data supported an over all conclusion that processing HW with cooking and autoclaving is comparable in terms of NPU but significant difference is due to less CP % in extruded group. It is notable that autoclaved proved more beneficial in terms of PER. Hackler et al. (1984) showed that regardless of the species, other factors like protein source, interaction of sources and level of protein can cause variation in PER. But overall values of PER and NPU reveal that processing of HWM can generate nutrient rich, palatable ingredients that are comparable to the traditional ingredients for better broiler performance.

Protein efficiency ratio (PER) depicted good picture of protein quality of all test diets. Casein produced better protein efficiency in chicks. Species of animals can cause variation in PER of the test diets (Khalique and Rasool, 1998). They compared the two species of animals for PER. It was observed that the chicks had greater ability to convert protein into growth. But the birds detected the protein quality better from vegetable protein sources and interaction of source and level of protein can cause variation in PER Hackler et al. (1984). In the present study, level of protein was kept same with the exception of protein source from standard diet. Michele et al. (1997) used one source of protein i.e., spent hen meal for determination of PER. They prepared spent hen meal by three different processing techniques but there was variation in PER of meal.

ACKNOWLEDGMENTS

The generous support of the Hi-tech Hatchery Lahore is greatly appreciated. The authors thank to Rafhan Maize Products, Faisalabad and National feeds (pvt) Ltd. for their cooperation which they extended for the supply of feed materials and facility for the extrusion process.

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Correspondence: Athar Mahmud, Assistant. Professor. Department of Poultry Production, University of Veterinary and Animal Sciences Lahore, Pakistan; E-mail: athar1122@yahoo.com

Table 1. Composition of experimental rations for the determination of protein quality.

100 100 100 100 100

Table 2. Chemical analysis of raw, cooked, autoclaved and extruded HWMs on dry matter basis.

HWM= Hatchery waste meal, HW= Hatchery waste, NFE= Nitrogen free extract

Table 3. Microbial count and bacterial species identified in different processed HWMs.

Different superscripts on means in a column show significant difference (P<0.05)

TVC = Total viable count, TCC = Total coliform count

Table 4. Average weight gain, feed intake, protein intake, PER and NPU values of HWM.

Different superscripts on means in a column show significant difference (P<0.05)

PER= Protein efficiency ratio, NPU= Net protein utilization, HWM=Hatchery waste meal

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