COMPOSITION OF SPENT HEN PRODUCED BY RENDERING'

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1 01997 Applied Poultry Science, Inc. NUTRIENT MEALS COMPOSITION OF SPENT HEN PRODUCED BY RENDERING' J. H. KERSEY Poultry Science Depamnent, University of Arkansas, Fayetteville, AR C. M. PARSONS Depament ofanima1 Sciences, University of Illinois, Urbana, IL N. M. DALE Department of Poultry Science, The University of Georgia, Athens, GA J. E. MARR Cal-Maine Foods, Jackson, MS p. w WALDROU~~ Poultry Science Depamnent, University of Arkansas, Fayetteville, AR Phone: (50I) FAX: (501) Primary Audience: Nutritionists, Renderers, Layer Producers, Purchasing Agents DESCRIPTION OF PROBLEM Approximately250 million laying hens are produced annually in the United States to provide table eggs for human consumption. I their laying cycle ("spent hens") has become increasingly difficult. Genetic selection for smaller body weights has reduced the amount of edible meat that can be obtained from the carcass. Bone breakage and residual bone 1 Published with the approval of the Director, Arkansas Agricultural Experiment Station. Manuscript number To whom correspondence should be addressed

2 320 SPENT HEN MEAL, undesirable. Difficulties in disposal of spent hens often lead producers to retain hens for longer production cycles, which can exacerbate problems associated with excessive egg production. Extrusion or fermentation systems have been developed to process daily mortalities or spent fowl [l, 2, 3, 4, 5, 6, 7J. However, implementation of these procedures typically requires considerable capital investment to develop a system capable of handling flocks at the termination of lay. A well-established rendering industry, however, already exists. As a result of the reduced demand for meat from spent hens and the need to dispose of the carcasses in an economical manner, there has been an increased interest in rendering spent hens to produce a by-product meal, as proposed by Hamm [8]. The rendering industry has been producing poultry by-product meal and feather meal from poultry processing wastes for a number of years, and the literature contains considerable information regarding nutritive content of such products [9, 10, 11, 12,131. Little knowledge, however, is available on methods of processing a whole carcass, including feathers [ 141, or the nutritional value of poultry meal produced from spent hens. The objective of the present study was to determine the nutritive value of different samples of spent hen meal produced by conventional rendering processes. MATERIALS AND METHODS Spent hens from end-of-lay commercial poultry flocks were processed at commercial renderers in three different locations (Bastrop, TX, Tulsa, OK, and Omaha, NE) using proprietary procedures. Carcasses were stabilized with ethoxyquin. No attempts were made to remove feathers from the hens prior to processing. Meal from each renderer was analyzed for content of major nutrients (crude protein, ash, calcium, phosphorus, sodium, chloride, potassium, fat, and crude fiber) and moisture at four different commercial laboratories, using procedures of the Association of Official Analytical Chemists [15]. Total amino acid content of each meal was also determined by four different laboratories specializing in amino acid analysis. True amino acid digestibility was determined using cecectomized cockerels (four birds per sample), following the procedure described by Parsons et al. [16]. True metabolizable energy of each sample was determined as described by Dale et al. [ l?, using 10 birds per sample. Samples of each meal were subjected to pepsin digestibility by a commercial laboratory according to the procedure of AOAC [15], using both 0.2 and 0.002% pepsin solutions. To examine the potential consistency of a rendered spent hen meal, weekly pooled samples of spent hen meal from a commercial renderer were obtained over a 27-wk period. A commercial laboratory evaluated the samples' moisture, phosphorus, calcium, ash, fat, and crude protein content. Means and standard deviations were calculated. RESULTS AND DISCUSSION Table 1 shows nutrient content of spent hen meals from three different commercial renderers. Meal produced by the three renderers varied considerably in nutrient content. Crude protein ranged from to 70.91%, fat from 8.78 to 11.25%, calcium from 3.34 to 4.79%, and phosphorus from 1.93 to 2.28%. Levels of other nutrients varied similarly. Monitoring nutrient content would therefore be an important part of a quality control program for producers including spent hen meal in poultry diets. The determined TMEn content of the samples ranged from 3416&61 kcavkg to kcalkg on a dry matter basis. These values were considerably higher than would TABLE 1. Nutrient analysis of spent hen products (meanksd) I NUTRIENT TULSA OMAHA BASI'ROP) Moisture. YO CP, % TM& kcal/kg (dry matter basis) 5.11k k k0.17 I70.91t1.57 I64.59k2.69 I66.37t1.29 Fat. % k0.73 I 10.40k k0.34 Sodium. % Chloride, % I 0.48k0.08 I 0.53_'0.01 I 0.63k0.12 Potassium. Yo I 0.73k k0.01 I 0.67k k rt k83

3 KERSEY et al. Research Report 321 be estimated by the equations reported by Dale et al. [17] for poultry offal meal. Additional research is needed to develop prediction equations for spent hen meal. As would be expected from the differences in crude protein content, the amino acid content expressed as a percentage of the total sample also varied widely (Table 2), although good agreement among laboratories was noted for most of the amino acids. The majority of amino acids, especially those of practical importance, showed relatively little variability when expressed as a percentage of the crude protein. Table 3 shows true digestibility of amino acids in the spent hen meals. Amino acid digestibility varied somewhat among sources, but overall agreement was good. The values in Table 3 should provide guidelines for estimating digestible amino acid content of spent hen meals produced by conventional ren- dering procedures. As expected, digestibility of cystine was low for all samples, reflecting difficulties in processing residual feathers. Some means of removing feathers from the carcass prior to rendering may improve this value; recent studies by Ahmad et al. [ 181 and Webster et al. (191 have suggested means of removing feathers from spent hens prior to rendering. Mean amino acid digestibility among sources was not directly associated with digestibility in 0.2 or 0.002% pepsin. The sample with the lowest overall amino acid digestibility (Omaha) had the lowest pepsin digestibility, but the sample with the highest pepsin digestibility was intermediate among the samples in amino acid digestibility. Johnston and Coon [20, 211 have suggested that digestibility determinations using 0.002% pepsin were more sensitive in detecting poorly processed animal proteins than the 0.2% recommended by AOAC [15].

4 322 JNR SPENT HEN MEAL Digestibility in 0.2% pepsin Digestibility in 0.002% pepsin Table 4 shows the nutrient content of pooled weekly samples of spent hen meal produced by a commercial renderer over a 27-wk period. The samples nutrient levels appeared reasonably consistent. Average nutrient content of the product was % crude protein (meanksd), % calcium, % phosphorus, and % fat. Meal obtained from this plant for the amino acid digestibility study contained 70.91% CP, 3.79% Ca, 2.11% P, and 11.25% fat and thus should be considered as a representative sample for this particular plant. It is difficult to compare the values obtained in the present study to previous reports dealing with extrusion or fermentation of spent hens or layer hen mortalities [l, 2,3,4, 5, 6, 71; extrusion of spent hens has generally involved mixing the carcasses with grain or cereal by-products, and fermentation typically results in considerable production of bacterial protein. A whole hen meal produced by autoclaving [SI contained 73% protein, 13.6% ash, and 5% fat. A meal produced by rendering of layer mortalities held in frozen storage [22] was considerably lower in protein (55.7%) and higher in fat (22.9%) than the meals in the present study. Because this meal was composed of buds that died during the course of a productive year, it is possible that the body composition of these birds was altered by cessation of production, disease, decomposition, or some other condition. This indicates that mortalities may yield products with nutrient content significantly different from that of spent hen meals. As with any animal byproduct meal, an effective quality control program is recommended to monitor nutrient composition of spent hen meals for effective use in poultry diets.

5 KERSEY et ai. Research Report Mean SD & CONCLUSIONS AND APPLICATIONS 1. Whole spent hens cam be converted to poultry by-product meal through rendering. Because of variations in nutrient content, producers including spent hen meal in poultry diets need to monitor its nutrient levels as part of a quality control program. 2. Amino acid content as percentage of spent hen meal varied among renderers. When it was expressed as percentage of protein, less variability among renderers was observed, especially for amino acids of practical concern. 3. Although amino acid digestibility varied somewhat among sources, overall agreement was good. Values in the present study should provide guidelines for estimating digestible amino acid content of spent hen meals produced by conventional rendering.

6 324 JAPR SPENT HEN MEAL 4. Mean amino acid digestibility among sources was not directly associated with digestibility in 0.2 or 0.002% pepsin. 5. Nutrient content of samples produced by a commercial renderer over a 27-wk period appeared reasonably consistent in nutrient content. 1. Shih, J.C.H., Recent development in oultry waste digestion and feather utilization -A review. goultry Sci. 72: Urlings, H.A.P., P.G.H. Bijker, and J.G. van LogteslUn, Fermentation of raw poultry byproducts for animal nutrition. J. him. Sci. 71:242& Barbour, G.W., R Nemaseloni, M.S. Lilburn, M. Werling, and AG. Yersin, The effect of enzyme predigestion on the quality of poultry by- duct meal from whole turkey mortality. Poultry Sci & Bachmann, W., Recycling poultry into feed. Feed Management 46(1): Sander, J.E, T. Cai, and H.M. Barnhart, Jr., Evaluation of amino acids, fatty acids, protein, fat, and ash in poultry carcasses fermented with Lactobacillus bacteria. J. Agric. Food Chem Haque, A.K.M.A., J. J. Lyons, and J. M. Vandepopuliere, Extrusion processing of broiler starter diets containing ground whole hens, poultry byproduct meal, feather meal, or ground feathers. Poultry Sci. 70: Lyons, J.J. and J.M. Vandepopuliere, Spent leghorn hens converted into a feedstuff. J. Appl. Poultry Res. 5:1& Hamm, D., Use of spent laying hens in rendered products. Poultry Sci Potter, D.K. and H.L Fuller, The nutritional value of poultry offal meal in chick diets. Poultry Sci Burgos! A, J.L Floyd, and EL Stephenson, The amino acid composition and availabili of different samples of poultry by-product meal and xather meal. Poultry Sci. 53: Bhargava, K.K. and J.B. O Neil, Corn sition and utilization of poultry by-product and hydroced feather meal in broiler diets. Poultry Sci. 54: McNaughlon, J.L, J.D. May, andkc. Strickland, Compositions of poultry offal meal from various processing plants. Poultry Sci REFERENCES AND NOTES 13.McNanghlon, J.L, H A Pasha, EJ. Day, andb.c. Dihorth, Effect of ressure and temperature on poultry offal meal quality. Foultry Sci. 56: Anonymous, Alternatives for Leghorn hen dis osition: Rendering at the farm. World Poultry-Misset 1146): Association of Official Analytical Chemists, Official Methods of Analysis. 13th Edition. Assn. Offic. Anal. Chem., Washington, DC. 16. Parsons, C.M., F. Castanon, and Y. Hen, Protein and amino acid quality of meat and bone meal. Poultry Sci. 76: Dale, N., B. Fancher, M. Zumbado, and A Viuacres, Metabolizable ener content of poultry offal meal. J. Appl. Poultry Res. 24L Ahmad, H.A., D.A. Roland, Sr., and S.S. Sohail, Effect of time of feed withdrawal and lulling before processing on defeathering of spent hens. J. Appl. Poultry Res. 5: Webster, AB., D.L Fletcher, and S.I. Savage, Feather removal from spent hens up to 24-hr postmortem. J. Appl. Poultry Res. 5: Johnston, J. and C.N. Coon, The use of varying levels of pepsin for pepsin digestibility studies with animal proteins. Poultry SCI. 58: Johnston, J. and C.N. Coon, A comparison of six protein quality assays using commercially available protein meals. Poultry Sci. 58: Christmas, R.B., B.L Damron, and M.D. Ouarl, The performance of commercial broilers when fed various levels of rendered whole-hen meal. Poultry Sci. 75: ACKNOWLEDGEMENTS The spent hen meals were generously provided by Griffin Industries, Cold S ring KY and Darling International, Irving, TX y5038: This study was supported by a grant from the U.S. Poultry and Egg Association, Tucker, GA