Abstract

Four alligator feeds were prepared from spent laying hens. The spent hens were divided into two groups consisting of plucked hens (Plucked-Hens) and whole or un-plucked hens (Whole-Hens). Both groups were fine-ground and a supplement containing salt, phosphate, vitamins, minerals, protein, amino acids, and fat was added (10% w/w). The ground supplemented material was designated Fry-Preparations made from either Whole-Hens or Plucked-Hens. Two Extruder-Preparations were nude by adding stone-ground wheat flour (40% w/w) to samples of each of the two Fry-Preparations. The Fry-Preparations were cooked by deep-flying in soy oil for 90 seconds at 190° C to 200° C. Extruder-Preparations were cooked in a Wenger model 85 extruder for 1 minute at 72° C to produce a soft moist product. The protein, fat and ash, were determined for the 4 preparations and 4 moist cooked products. Amino acid and fatty acid profiles were determined for the 4 cooked products. Results for each determination of a critical nutrient in the finished feeds were compared with a theoretically ideal feed in nutrient density and containing the nutrient in question at levels required for optimum feed utilization and rapid growth in a hatchling alligators. Microbial analysis consisting of total aerobes, total anaerobes, coliforms and E.coli were made for the 4 preparations and 4 cooked products at day 0 and for the extruded products at day 7 when stored at 23° C. Microbial analysis was performed on the 4 cooked products at days 14, 42 and 56 when stored at 4° C. Shelf-fife was detected by the period time that total aerobic counts remained under 1 million per gram. Soft moist extruded products had a shelf life of about 45 days at 4° C. Vacuum-packaged fried products can be stored for longer that 56 days at 4° C. It was believed that the cooking procedures destroyed most pathogens. Salmonella was not isolated from any cooked products after storage at 56 days.

Introduction

Spent hens are currently disposed of by rendering for use as supplements in feed, for traditional livestock feeds, processing as human food, burial or on. Rendering and processing for human food cost North Central Florida layer operations 2 to 3 cents per hen for disposal. Research has been performed to enhance the marketability of spent hens over the past decade but there is still a large surplus. Most research on the disposal of spent hens has focused on increasing the palatability of spent time hens either by tenderization^4,7 or creating further processed products.^3,6 However, only limited research bas been performed on utilizing spent hens in the development of specialized feeds for non-traditional livestock, such as alligators, that can better utilize spent hens.

Alligator farming has been a serious industry in the Southeastern United States for about 25 years.¹ Nutritional requirements of the hatchlings has been investigated and several recommendations for starter feeds have been made¹ Recommendations for grow-out and for breeders have also been made.¹ Several companies make dry commercial alligator feeds and supplements, but because of limited financial resources and the small market when compared to other animal industries, little commercial research has been put into the refinement of feed manufacture. Many alligator farmers so use nutrient-supplemented waste-meats because of palatability, growth performance and other problems with the commercial dry feeds available.^1,2

Disposal of spent hens costs the U.S. Egg Industry approximately $7.4 million per year. Spent hen disposal methods currently include rendering for use as supplements in feeds for traditional livestock, processing as human food, burial and incineration. The utilization of spent hens as a primary ingredient in feeds for non-traditional livestock such as carnivorous reptiles and fish may increase the demand for spent hens and reduce the cost of their disposal. Florida produces about 30,000 alligators each year that consume approximately 7,500 tons of feed per year. The total alligator production in the Southeastern U.S. is about five times this figure and uses approximately 37,500 tons of feed annually. There are commercial alligator feeds available; however, alligator farmers still widely use unprocessed fresh meat in alligator diets. Thus, there is the need for a fresh meat substitute that has a shelf-life of several weeks. In this report we describe methods for preparing an alligator feed from whole and plucked spent hens. The product was supplemented with a protein fat, free amino acid, vitamin, mineral, salt, phosphate mix and either fried into nuggets or extuded into pelleted alligator feed. The raw and finished products were assayed for protein fat, ash, amino acid and fatty acid profiles and bacterial content. Quantities of critical nutrients in the finished products were compared with a theoretical feed with the correct nutrient density and containing the nutrients in question at levels required for optimum feed utilization (feed gain ratio of 1.0) and rapid growth in a hatchling alligators. The project goal was to produce a finished feed having the correct nutrient density and containing all critical nutrients at levels so that a feed gain ratio of < 2.0 was theoretically possible with a growth rate of at least 2.5 mm per day for hatchling alligators.

Materials and Methods

1.  Supplemented Raw Ground Product from Plucked or Unplucked Hens Single Comb
White Leghorn, spent laying-hens were obtained from the University of Florida Poultry Science Department. The hens had an average weight of 3.5 lbs and were killed by cervical disarticulation either manually or by using a mechanical cervical disarticulation instrument. Feathers were removed from approximately half the hens (Plucked-Hens) by scalding and either hand plucking or by using a mechanical plucker. The unplucked hens (Whole-Hens) were processed directly. Both groups (plucked and whole) of the killed hens were placed in a bowl-chopper for approximately 30 minutes and a 55% protein meal supplement,¹ containing vitamins, minerals, free amino acids, fat, salt and phosphate was added (10%, w/w) during the chopping and allowed to mix into the preparations. The supplemented-chopped preparation were then ground through a 2.5 cm diameter plate using a 5 BP Hobart model 4146 grinder and the two preparations were identified as Fry-Preparations. Stone ground wheat flour (40% w/w) was mixed with samples of each of the two Fry-Preparations (Plucked-Hens and Whole-Hens) which were to be extruded and these were identified as Extruder-Preparations.

2.  Fried Nuggets from Plucked and Whole-Hens
Nuggets were prepared by grinding the Fry-Preparations through a 2.5 cm plate attached to the grinder which made them into 2.5 cm diameter x 3.75 cm long cylindrically shaped nuggets. Feather remnants in the Whole-Hen preparations assisted in holding the nuggets together but nuggets made from Plucked-Hens did not have the consistency to make satisfactory cylindrical nuggets. Therefore, a "meat ball" type of nugget, 3.75 cm to 5 cm diameter, was made. The nuggets and "meat-balls" were fried in soy oil using deep-fat fryers. Oil temperatures varied between 190° C to 200° C and frying time was 90 seconds. Cooking yield from the Plucked-Hen preparations was 81% and 70% from the Whole-Hen preparations. The fried moist nuggets had a rubbery consistency and would float in water for > 30 minutes. Raw nuggets from Whole-Hens contained an average (n=6) of 50% moisture; 22% protein; 22% fat; 5.5% ash, 2,990 calories/kg; while raw nuggets from Plucked-Hens contained an average (n=6) of 55% moisture; 20% protein; 20% fat; 5.6% ash, 2,700 calories/kg. Fried nuggets from Whole-Hens contained an average (n=6) of. 32% moisture; 28 % protein; 33% fat; 6.4% ash; 4,255 calories/kg. Fried nuggets from Plucked-Hens contained an average (n=6 of- 39% moisture; 27% protein; 26% fat; 7.3% ash, 3,550 calories/kg.

3.  Extruded Pellets from Plucked and Whole Hens
The average raw Extruder-Preparation (n=6) from Whole-Hens contained: 34% moisture; 22% protein; 17% fat; 4.9% ash, 2,715 calories/kg; while the average raw Extruder-Preparation from Plucked-Hens (n=6) contained: 40% moisture, 20% protein; 16% fat; 5.4% ash, 2,320 calories/kg. The 1.25 cm x 2.75 an (approx) diameter moist extruded pellets had been cooked at 72° C for 1 minute using a Wenger model 85 cooking extruder. Extruded pellets were soft and moist but sank. They held their shape under water for over 24 hours. The average extruded moist pellets (n=6) from Plucked Hens contained: 35% moisture; 20% protein; 17% fat; 5.0% ash, 2,415 calories/kg. The average (n=6) extruded moist pellets from Whole-Hens contained: 35% moisture; 22% protein; 16% fat; 5.0% ash, 3,200 calories/kg.

4.  Amino Acid and Fatty Acid Composition and Concentrations
Amino Acid and fatty acid profiles were determined on 6 samples of the Fry-Products. Three were made from Whole-Hens and 3 from Plucked-Hens. Limiting amino acid calculations of the feed products were made using the protein concentration of the feed and the percent amino acid concentration of the protein. Amino acid concentrations of the products were compared to a theoretical 23% protein (correct nutrient density) alligator feed having the estimated optimum concentration for each amino acid and producing a feed/gain ratio of 1.0. Digestion coefficients, for both feeds were assumed to be 100%. The following limiting amino acid concentrations as percent of the protein were estimated to be optimal for the theoretical feed: lysine (11%); tryptophane (1.75%); threonine (7%); isoleucine (5. 1 %). An amino acid was considered to be limiting if the quantity of the amino acid in the product consumed (adjusted for a feed/gain of 1.7) was less than that in the theoretically optimum feed (considered to have a feed/gain of 1.0). Fatty acid composition of dietary fat (% of total fatty acids) of the products were compared to the estimated optimum compositions for fast growth of alligator hatchlings.^5,8 Deficiencies are reported as percentages of the estimated optimum compositions. Optimum compositions of critical fatty acids and fatty acid groups are as follows based on previous studies;^5,8 saturated, 37.8%; omega-3, 5.52%;omega-6, 13.85%, oleic acid+ linoleic acid (infert acids ) 17.0%; linoleic acid + linolenic acid (HiEggVol acids), 13.7%; palmitic acid (16:0), 31.9%; palmitoleic acid (16:1), 11.2%; stearic acid (18:0), 5.9%; linoleic acid (18:1), 31.6%; linolenic acid (18:3) 2.59%; timnodonic acid (20:5), 1.27%; cervonic acid (22:6) 1.25%.

5.  Energy Requirements
The energy requirements of the preparations are based on proton content of the product and 100% digestibility, 100% incorporation into allegator protein and 21 calories required for the incorporation of one gm of product protein into alligator protein. Thus, the theoretical minimum dietary energy required for complete utilization of the dietary protein is the protein concentration of the product in grams x 21.

6.  Microbiology
Microbial content of the raw and cooked product were determined using standard plating methods to determine CFU (colony forming units). Total CFU were determined for aerobic, anaerobic, coliform and E.coli organisms. The determinations were nude on the raw and cooked Fry and Extruded Preparations nude from Plucked and Whole-Hens. Samples from the raw products were taken on day 0. Samples were taken for counting at days 0, 14, 28, 42 and 56 for all cooked products stored at 4° C and for the extruded products stored at 23°C on day 7.

7.  Statistics
Statistics were performed using the SAS system with an Alpha = 0.05 for significant difference.

Results

1.  Cooking Yields
Cooking yields from Fried Whole-Hens (80.9%; n=9) were significantly higher than those from fried Plucked-Hens (70.0%; n=9); while, yields from extruded Whole-Hens (88.4%; n=3) and extruded Plucked-Hens (89.8% n=3) were not significantly different. Cooking yields from extrusion (89. 1%; n=6) were significantly higher than from frying (75.5%; n=6).

2.  Protein Content of Preparations
There was no significant difference in the dry-matter protein content (37.7%; n=24) of pooled Whole Hen preparations versus pooled Plucked-Hen preparations (37.5%; n=24). There was also no significant difference in dry-matter protein content of either the raw (43.5%; n=12) versus cooked (43.1%; n=12) fry-preparations or the raw (32.1%; n=12) versus cooked (31.8%; n=12) extrusion products. However, fry-preparations (43.3%; n=24) had significantly more dry-matter protein than the extrusion-preparations (31.9%; n=24) to which 40% (w/w) stone-ground wheat flour had been added.

3.  Fat Content of Preparations
There was no significant difference in the dry-matter fat content (35.6%; n=24) of pooled Whole-Hen preparations versus pooled Plucked-Hen preparations (34.2%; n=4). There was also no significant difference in dry-matter fat content of either the raw (44.0%; n=12) versus cooked (45.2%; n=12) fry preparations or the raw (25.2%; n=12) versus cooked (25.1%; n=12) extrusion products. However, fry-preparations (44.6%; n=24) had significantly more dry-matter fat than extrusion-preparations (25.1%; n=24) to which 40%(w/w) stone-ground wheat flour had been added.

4.  Ash Content of Preparations
Pooled dry-matter ash content of fry preparations (11.2%; n=24) were significantly higher (30% increase) than extruder preparations (7.8% n=24). The dry-matter ash content (10.1%; n=24) of the pooled plucked-bird preparations were significantly higher (44% increase) than the pooled whole-bird preparations (8.85%; n=24). Raw Fry-Preparations (11.6% n=12) had a small but significantly higher dry-matter ash content than cooked Fry-Preparations (10.7%; n=12). The pooled cooked products, Extruder-Preparations + Fry Preparations, (9.2%; n=24) were not significantly different from the pooled raw products (9.7%; n=24).

5.  Moisture Content of Preparations
The moisture content of pooled Plucked-Hen preparations (40.8%; n=24) was higher (8.8%) than Whole-Hen preparations (37.5% n=24) but the difference was not statistically significant. The moisture content of raw Fry-Preparations (52.1%; n=12) was significantly higher (51.5% increase) than raw Extruder-preparations (34.4; n=12). Cooked Fry-Preparations (35.6%; n=12) had 37.1% less moisture than the raw Fry-Preparations. There was no significant difference in the moisture content of raw Extruder-Preparations (34.2% n=12) and cooked Extruder-Preparations (34.5%; n=12).

6.  Essential Amino Acid Concentrations
All of the amino acid concentrations were found to be present in adequate quantities for feed/gain ratios > 2.2. Four amino acids were determined to be in limiting quantities at feed/gain ratios > 1.7 but < 2.2. Lysine was determined to be the first limiting amino acid in extruded products, and would require a feed/gain ratio of approximately 2.2 to supply the supply the quantity of lysine present in the theoretically optimum diet (feed/gain ratio of 1.0). The lysine content of protein in the pooled Extruded-Products (5.11; n=6) was significantly lower (10%) than in pooled Fry-Products (5.62%; n=6). Tryptophane would become a limiting amino acid in all preparations if feed/gain ratios were less than 2. Tryptophane concentrations (2.32%; n=5) in the protein of Plucked-Hens preparations was higher (4.1%) than in Whole-Hens (2.23%; n=7) but the difference was not statistically significant. Threonine would also theoretically become a limiting amino acid for Extruded-Products at feed/gain ratios < 2. The protein of Fry-Preparations had 3.1% more threonine (4.1%; n=6) than Extruder-Preparations and Whole-Hen products (4.12%;n=6) had 2.7% more threonine than Plucked-Hen products (4.03%; n=5) but these differences were not statistically significant. Isoleucine was the last amino acid considered to be theoretically limiting for feed/gain ratios > 1.7. There were no significant differences in the isoleucine content of all products with a pooled mean of 3.45% n=12). Extruded- Products from Plucked-Hens (3.40%; n=4) of all products, had the highest feed/gain ratio (1.72) required to supply the quantity of isoleucine present in the optimum diet.

7.  Fatty Acid Composition (% of total Fatty Acids
There were no significant differences in fatty acid compositions in preparations of Plucked-Hens versus Whole-Hens. Neither Fry-Products nor Extruded-Products were below the optimum compositions⁵ in omega-6 fatty acids, stearic acid+linoleic acid (the infert-group), ⁵ linoleic acid+linoleic acid (the HiEggVol-group), ⁵ the omega-6 fatty acids, stearic acid, oleic acid and linoleic acid. The arachidonic acid composition was not significantly different in all preparations which contained approximately 15% of the optimum composition. Fatty acid composition of Extruded-Products (Ext) and Fry-Products (Fry) were significantly different and below optimum composition for the following fatty acids (% of optimum composition): Saturated (Ext 87%, Fry 68%); omega-3 (Ext 33%, Fry 68%); palmitic (Ext 77%, Fry 60%); palmitoleic (Ext 53%, Fry 28%); linoleic (Ext 56%, Fry 28%); timnodonic 60%, Fry 9%); cervonic (Ext 78%, Fry 39%).

8.  Minimum Required Energy Content of the Products
The energy content of the Extruded-Product from Plucked-Hens was 11 cal/gram protein (theoretically 52% of the minimum energy required for a feed/gain ratio of 1.0) and the least feed/gain ratio theoretically possible would be 1.9. The extruded product from Whole-Hens contained 12 calories per gram or 57% of the minimum required energy for a feed/gain ratio of 1 and had least feed/gain ratio theoretically possible of 1.75. The energy content of the Fry-Product from Plucked-Hens was 13 calories per gram or 62% of the minimum energy required for a feed/gain ratio of 1.0 and the least feed/gain ratio theoretically possible would be 1.6. The energy content of the Fry-Product from Whole-Hens was 12 calories per gram or 57% of the minimum required energy required for a feed/gain ratio of 1.0 and the least feed/gain ratio theoretically possible would be 1.75.

9.  Microbial Content of the Product
Raw products from all preparations had approximately the following CFU (colony forming units) per gram: 300,000 aerobic, 300,000 anaerobic, 500 coliforms and 500 F-coli. The results were for preparations from either whole or plucked hens. Frying at 190° C to 200° C for 90 seconds resulted in a 1 to 3 log reduction in the aerobic CFU (to total CFU of less than 100 in some cases). A similar reduction in numbers was observed for anaerobic, conform, and E coli CFU. Extrusion at 72° C for one minute also resulted in a 3 log reduction in CFU. Total CFU of the moist products in ordinary packaging increased several logs in 7 days. However, storage at 4 C could be done for over 56 days for the fried products without logarithmic increases in CFU. Total CFU for the extruded products began to increase sharply by day 42 to approximately levels found in the raw product and by day 56 many of the samples had total CFU of over 1 million per grain. At the end of storage Salmonella was not isolated from any of the product and there was no visible mold growth.

10.  Shelf Life
Shelf life was considered over when total aerobic CFU exceeded 1 million per gram product. Aerobic CFU for vacuum-packaged, moist (30 to 40% moisture) fried nuggets decreased during refrigerated storage (4 C) for 56 days. Typically there were <10 CFU per gram for aerobic organisms, coliforms and E. coli. Fried vacuum-packaged nuggets have been kept for 9 months with no visible signs of mold growth. Moist extruded pellets can be stored at 40° C for about 1.5 months but drying would be required for longer storage.

Conclusions

A fried alligator nugget can be made utilizing about 90% whole spent hens and an extruded moist pellet containing about 54% whole spent can also be made. Preliminary tests indicate that alligators will accept both preparations. Plucked-Hens can replace Whole-Hens in both preparations but there seems to be little advantage in doing this based on laboratory analysis' of nutrients and assuming high digestibility coefficients. It was found that feather particles enhance the consistency of some products. Although the feathers must be finely ground the cost of plucking may be greater. The digestibility of the feather particles by the alligator is not known and further grinding or processing may be helpful. The products may also require the addition of essential amino acids for best feed/gain results. The critical nutrient and energy composition of all feed products would theoretically support a feed/gain ratio of< 2.2, assuming 100% digestibility. However optimum hatchling alligator growth rates may also require the addition to the feed of oils rich in arachidonic acid and omega-3 long chain fatty acids. The moist fried-nugget has a shelf-life of greater than 56 days when vacuum-packaged and the extruded pellets, without drying, could be stored at 4° C for about 45 days. A shelf life of 45 days or greater reduces the requirement of the alligator farmer for freezer space and could represent cant saving in storage costs. Longer shelf life may require drying or the addition of preservatives. Cooking reduced the microbial content of the products by several logs which improves shelf life and has the potential to destroy most and possibly all pathogens. Salmonella was not found in the product. Moist nuggets must be vacuum-packed or dried to inhibit mold growth when stored for periods longer than 2 to 3 weeks. Proper cooking and vacuum packaging appears to have the ability to provide a pathogen free product with a shelf life of more than 9 months. It is estimated that product supplementation and grinding would cost approximately $100 per ton if cooking costs were $100 per ton the production costs would be approximately $200 per ton. Although the cost of obtaining the hens and transportation costs are not known there is a margin of about $200 per ton to equal the current costs of waste-based feeds.

Acknowledgements

This work was supported by a grant from the Southeastern Poultry & Egg Association. The authors wish to thank Mr. Wayne McClellen and Mr. Joseph P. Cardeilhac for technical assistance.

References

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