Effect of processing systems on protein quality of feather meals and hog hair meals

Effect of Processing Systems on Protein Quality of Feather Meals and Hog Hair Meals X. WANG and C. M. PARSONS1 Department of Animal Sciences, University of Illinois, Urbana, Illinois 61801 of the FM varied among processing systems (e.g., lysine digestibility range was 58 to 72%, PER range was 0.71 to 1.13). Increasing the temperature during processing had no significant effect on protein quality of one FM and one HH. Digestibilities of AA in the FM water-soluble fraction collected after cooking were higher than those in the insoluble fraction. True amino acid digestibility coefficients for FM were higher than those for HH, whereas the PER of several FM were lower than those of HH. The latter response was probably due to the higher Lys content in the HH. The results of this study suggested that type of commercial processing system or conditions can affect the protein quality of FM.

(Key words: feather meal, protein quality, processing, amino acids) 1997 Poultry Science 76:491–496

protein quality of FM is markedly influenced by type of commercial processing system. Therefore, the objective of this study was to evaluate the effects of commercial processing systems, and to a lesser extent temperature within processing system, on in vivo protein and amino acid quality of six FM. In addition, two commercially processed hog hair meals (HH), which also contain high amounts of keratin protein, were evaluated as a comparison to FM.

INTRODUCTION Because of the large growth of the poultry industry, a great quantity of feather meal (FM) is available for use in animal feeds. Although FM is deficient in several amino acids, such as Met, Lys, His, and Trp (Baker et al., 1981), it is high in protein and Cys and its price is relatively low. Thus, FM has potential to be an important protein source for animal production. However, the variability in protein quality of FM is one of the most important concerns regarding its use in poultry and livestock rations. Feather meal may vary greatly in nutrient composition (Papadopoulos et al., 1985) and nutrient bioavailability (Sullivan and Stephenson, 1957; Naber et al., 1961; Papadopoulos et al., 1985). Type of processing has been reported to be one of the primary factors influencing FM protein quality (Papadopoulos et al., 1985; Papadopoulos, 1987; Latshaw, 1990). However, research studies on FM processing have generally evaluated experimental or laboratory processing conditions, not commercial processing systems or conditions. It is of interest to know whether the

MATERIALS AND METHODS

Feather Meals and Hog Hair Meals Six FM and two HH meals were obtained from various companies using different commercial processing systems, temperatures, and cooking times. The FM contained feathers only and the feathers were from broiler chickens. The description of the processing conditions for the FM and HH is presented in Table 1. The processing systems (hydrolyzer/dryer) were (in random order): Batch/Heil; Batch/rotary; Atlas/Atlas; Griffin/tube; and ANCO/ Stord. The first two FM (1 and 2) and the two HH were each prepared in the same processing plant at two different processing or drying temperatures on the same day, so that raw material composition of each pair of products was similar. The other FM (3 to 6) were prepared

Received for publication June 28, 1996. Accepted for publication October 30, 1996. 1To whom correspondence should be addressed: 284 Animal Sciences Laboratory, 1207 W. Gregory Drive, Urbana, IL 61801.

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ABSTRACT Experiments were conducted to evaluate the effects of five commercial processing systems and to a lesser extent, processing temperature within system, on protein quality of feather meals (FM). Two hog hair meals (HH) were also evaluated. True digestibilities of AA were determined with a 48-h excreta collection assay using cecectomized cockerels. Protein efficiency ratio (PER; grams of gain:grams of CP consumed) was determined with chicks by feeding Met-fortified 15% CP diets containing a FM or HH as the sole source of dietary protein. The six FM samples averaged 88.7% CP, 1.99% Lys, 4.83% Cys, and 0.71% Met on a DM basis. For HH, these values were 92.6, 2.78, 3.76, and 0.85%, respectively. True digestibilities of amino acids and PER

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WANG AND PARSONS TABLE 1. Description of feather meals (FM) and hog hair meals (HH)

Product

Processing system1

Processing temp of cooker/dryer2

Time in cooker/dryer2

FM1 FM2 FM3 FM4 FM5 FM6 HH1 HH2

A A B C D E E E

(C) 160/83 160/56 NA/74 NA/96 149/NA 150/110 150/125 150/110

(min) 15/30 15/30 NA/30 NA/120 NA/80 20/240 20/240 20/240

1Processing systems (hydrolyzer/dryer) were (in random order): Batch/Heil; Batch/rotary; Atlas/Atlas; Griffin/tube; and ANCO/Stord. 2NA = not available.

Balance Assay for True AA Digestibility and TMEn Single Comb White Leghorn cecectomized roosters, 36 wk of age, were used. Cecectomy was performed

2Degussa

Corp., Allendale, NJ 07401.

Chick Assay for Protein Quality One-week-old female chicks from the cross of New Hampshire males × Columbian Plymouth Rock females were used. All chicks were housed in thermostatically controlled starter batteries with raised wire floors. Feed and water were consumed ad libitum, and light was provided 24 h daily. The chicks were fed a 23% CP cornsoybean meal pretest diet during the 1st wk posthatching. After an overnight period without feed, the chicks were weighed, wing-banded, and triplicate groups of six chicks were assigned to each dietary treatment as described by Sasse and Baker (1973). Dietary treatments consisted of a N-free basal diet (Willis and Baker, 1980) or 15% CP Met-fortified diets in which one of the FM or HH was the only source of protein. The FM or HH replaced some of the cornstarch and dextrose in the basal diet. The diets were fortified with 0.3% Met so that Lys would be the first-limiting AA in the diets (Baker et al., 1981). Lysine is the AA that would probably be the most sensitive to processing effects (Carpenter, 1973). The experimental diets were fed from 8 to 18 d of age. Body weight gain, protein efficiency ratio (PER; body weight gain/CP intake) and net protein ratio [NPR; (body weight gain minus body weight gain of chicks fed N-free diet)/CP intake] were calculated for each treatment.

Statistical Analyses Complete randomized designs were used in all assays (Steel and Torrie, 1980). Data were subjected to ANOVA procedures using SAS (SAS Institute, 1985). The least significant difference test (SAS Institute, 1985) was used to detect differences among treatment means. Correlations

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in different plants with different processing systems. Provided information on cooking and drying temperatures and times was incomplete in some cases. However, cooking temperature and time were probably in the range of 150 to 160 C for 15 to 20 min for all systems. Temperature and time in the dryer were much more variable than those for the cooker, with time in the dryer varying from 30 to 240 min and dryer temperature varying from 56 to 110 C. After the initial digestibility evaluation of FM 1 to 6, a second digestibility assay was conducted to further evaluate FM6. The FM6 had been obtained from a plant that had removed the water-soluble fraction (WSF) of the FM immediately after cooking or feather hydrolyzation. Because this procedure was not used for FM 1 to 5 and there is no published information on the AA content or digestibility of the WSF, an additional sample of FM6 and its WSF were obtained and evaluated for AA digestibility and TMEn. The WSF from feather hydrolyzation was concentrated to 38% solids after collection and then was spray-dried with an inlet temperature of 200 C and outlet temperature of 118 C. Crude protein of all FM and HH samples was determined by the micro-Kjeldahl method according to the procedures of the Association of Official Analytical Chemists (AOAC, 1980). Amino acids were analyzed by ion-exchange chromatography (Spackman et al., 1958) following hydrolysis of samples in 6 N HCl for 24 h at 110 C. Analyses of Met and Cys were performed separately after performic oxidation (Moore, 1963). In addition, lanthionine concentrations were analyzed on nonoxidized samples.2

according to the procedure of Parsons (1985) when the birds were 20 wk of age. The birds were housed in an environmentally controlled room and kept in individual cages with raised wire floors and subjected to photoperiod of 16 h light and 8 h dark daily. Feed and water were supplied for ad libitum consumption before the start of the experiment. Following a 24-h period without feed, four roosters were given 30 g of a FM or HH via crop intubation. A plastic tray was placed under each cage and excreta were collected quantitatively for 48 h after crop intubation. Endogenous dry matter, N, and AA excretion were measured from birds that were deprived of feed throughout the assay. The excreta were freeze-dried, ground, and N, AA, and gross energy concentrations were determined according to the procedures described previously. True digestibility of AA were calculated according to the method of Sibbald (1979) and TMEn by the method of Parsons et al. (1982). As mentioned earlier, two balance or digestibility assays were conducted. The original six FM samples were evaluated in the first assay. A second sample of FM6 and the WSF obtained after cooking/ feather hydrolyzation were evaluated in the second assay.

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PROCESSING AND FEATHER MEAL QUALITY TABLE 2. Dry matter, CP, and amino acid content of feather meals (FM) and hog hair meal (HH)1 Component

FM1

FM2

FM3

FM4

DM CP Thr Cys Val Met Ile Leu Phe Tyr Lys His Arg Asp Ser Glu Pro Gly Ala Lanthionine

98 90 4.29 4.47 7.00 0.75 4.77 7.69 4.59 2.65 2.05 0.62 6.59 6.05 10.5 10.5 9.70 7.39 4.20 2.14

97 88 4.02 4.29 5.96 0.65 4.23 7.09 4.21 2.55 1.88 0.57 6.10 5.52 10.0 9.72 8.84 6.87 3.96 2.37

89 78 3.34 4.32 5.29 0.56 3.71 5.94 3.55 2.01 1.55 0.49 5.13 4.74 8.45 8.14 7.43 5.66 3.30 1.71

92 81 3.61 5.35 6.32 0.57 4.21 6.68 3.99 2.24 1.74 0.54 5.77 5.24 9.51 9.04 8.78 6.19 3.60 1.27

FM5

FM6

HH1

HH2

96 81 3.79 4.36 6.14 0.69 4.23 6.90 3.98 2.29 1.98 0.65 6.12 5.56 9.56 9.87 8.01 6.63 3.95 2.22

92 89 3.61 4.00 5.24 0.72 3.95 6.71 3.89 1.82 2.05 0.63 5.82 5.47 8.92 8.89 9.00 6.11 3.86 1.59

96 89 3.82 3.68 5.09 0.80 3.54 6.81 3.06 2.34 2.45 0.85 7.27 5.81 7.28 12.10 9.03 6.21 5.20 3.15

92 85 3.74 3.38 4.96 0.79 3.58 6.74 3.24 2.55 2.78 0.69 6.99 5.58 8.11 10.21 8.66 5.84 4.30 3.13

(%)

protein and amino acids expressed on an air-dry basis. Values are means of duplicate analyses.

for dryer temperature among systems, time in the dryer, moisture, and lanthionine vs selected in vivo protein quality measurements (i.e., PER and Lys, Met, and Cys digestibility) were assessed using Pierson’s linear test (Steel and Torrie, 1980).

RESULTS The amino acid and CP content of the six FM and two HH are presented in Table 2. The average CP for FM and HH was 84 and 87%, respectively, and the FM ranged from 78 to 90%. Concentrations of AA varied substantially among products. For example, the Cys content of the FM varied from 4 to 5.4%, respectively. The HH generally contained higher levels of Lys and Arg and lower levels of Cys than the FM. The

lanthionine content of HH was much higher than FM. With the exception of Met and Cys, the digestibility of AA in FM6 were generally lower (P < 0.05) than the AA in the other FM (Table 3). The digestibility of Lys in FM3, FM4, and FM5 was significantly higher (P < 0.05) than FM1 and FM6. Methionine digestibility of the FM averaged 77% and did not differ significantly among FM. Digestibility of Cys in the FM was lowest of all AA (mean = 55%) and was variable, ranging from 47 to 62%. Digestibility of Cys in FM3 and FM4 was significantly higher than in FM1 and FM6. Processing temperature had no significant effect on AA digestibility in FM1 and 2. There were no significant differences (P > 0.05) in true digestibilities of most AA between the two HH, except for Ile, and values were generally lower than those for the FM.

TABLE 3. True digestibility of amino acids and TMEn in feather meals (FM) and hog hair meals (HH)1 Component

FM1

FM2

FM3

FM4

FM5

FM6

HH1

HH2

SEM

Thr Cys Val Met Ile Leu Tyr Phe Lys His Arg Mean TMEn, kcal/kg DM

71.0ab 46.8de 87.7a 78.6a 90.9a 85.7a 80.7a 86.6a 63.4b 60.5a 84.1a 76.0a 3,220bc

73.9a 51.7bcd 87.0a 74.3a 90.1a 86.0a 80.9a 85.8a 66.0b 61.5a 85.2a 76.6a 3,212bc

76.3a 58.9ab 88.7a 75.2a 91.4a 87.6a 81.7a 87.2a 71.2a 67.5a 87.0a 79.3a 3,624a

76.4a 62.0a 88.0a 73.6a 89.6a 85.3a 77.6ab 85.1a 70.7a 65.1a 86.6a 78.2a 3,601a

(%) 74.4a 54.6bc 88.2a 76.2a 90.3a 86.4a 82.6a 87.2a 71.7a 68.2a 85.2a 78.6a 3,370b

67.0b 50.5cd 80.4b 74.2b 85.6b 80.2b 69.3bc 79.0b 58.3c 48.8b 78.7b 70.2b 3,043c

51.3c 39.7ef 66.0c 66.9c 72.9c 70.7c 59.3d 67.0c 57.0c 41.1c 66.2c 59.8c 1,994d

53.6c 34.2f 68.2ab 72.4c 75.9c 72.2c 66.3cd 70.7c 57.0c 37.7c 68.4c 61.5c 2,133d

1.49 2.46 1.01 1.99 0.99 1.11 2.95 1.27 1.42 2.22 1.05 1.90 72.2

a–fMeans 1Values

within rows with no common superscript differ significantly (P < 0.05). are means of four cecectomized roosters.

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1Crude

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WANG AND PARSONS TABLE 4. Amino acid composition and digestibility and TMEn in a second sample of feather meal 6 (FM6) and the water-soluble fraction (WSF) obtained after cooking/feather hydrolyzation Composition1

Digestibility2

Component

FM6

WSF

DM CP Thr Cys Val Met Ile Leu Phe Tyr Lys His Arg Mean Lanthionine TMEn, kcal/kg DM

92 90 4.46 4.57 5.53 1.12 3.75 7.39 4.20 2.66 2.36 0.83 6.52

91 83 3.31 1.49 3.91 1.05 2.90 5.99 2.99 1.98 2.87 0.97 5.38

2.11

1.18

FM6

WSF

SEM

(%)

80.0a 64.8a 86.4a 79.3a 89.6a 88.4a 83.2a 82.2a 79.3a 75.8a 87.8a 81.5a . . . 3,618a

1.84 3.76 1.39 2.52 1.26 1.32 1.33 1.39 1.74 2.16 2.14 2.18 55

a–bMeans

within rows with no common superscript differ significantly (P < 0.05). protein and amino acids are expressed on an air-dry basis. Values are means of duplicate analyses. 2Values are means of four cecectomized roosters. 1Crude

The TMEn content varied among FM, with FM3 and 4 being significantly higher (P < 0.05) than the other FM. The TMEn values for the two HH were similar and much lower (P < 0.05) than those for the FM. The DM, CP, AA composition, AA digestibility, and TMEn of the second sample of FM6 and the WSF are shown in Table 4. The AA composition varied substantially between samples. The FM6 contained higher levels of CP and essential AA than did the WSF, with the exception of Lys, His, and Met. The Cys content of FM6 was more than threefold higher than WSF. The lanthionine content of FM6 was 1.8 times higher than WSF.

Digestibilities of all AA were higher (P < 0.05) for WSF than for FM6. These differences exceeded 10 percentage units for several AA. The TMEn of WSF was 19% higher (P < 0.05) than that of FM6. Although the second FM6 sample contained higher levels of CP and AA than the first one (Table 2), the digestibilities of all AA except Met and His were similar for the two samples. Weight gain, feed efficiency, PER, and NPR varied (P < 0.05) among the FM, with FM3 and 5 yielding the highest values and FM1, FM2, and FM4 yielding the lowest values (Table 5). Weight gains of chicks fed the HH were generally higher (P < 0.05) than those of chicks

TABLE 5. Determination of protein quality of feather meals (FM) and hog hair meals (HH) by chick assay1

Treatment 1. Basal 2. As 1 3. As 1 4. As 1 5. As 1 6. As 1 7. As 1 8. As 1 9. As 1 SEM

(N-free)3 + FM14 + FM2 + FM3 + FM4 + FM5 + FM6 + HH1 + HH2

a–eMeans

Weight gain

Gain:feed ratio

PER2

NPR2

(g) –5.0e 9.0d 9.3d 17.7b 9.9d 14.1c 13.5c 22.1a 19.1ab 1.0

(g:g) –0.058e 0.106d 0.115cd 0.169ab 0.119cd 0.157ab 0.142bc 0.186a 0.160ab 0.009

(g/g) . . . 0.71d 0.76cd 1.13ab 0.79cd 1.05ab 0.94bc 1.24a 1.06ab 0.07

(g/g) . . . 1.11d 1.18cd 1.45ab 1.20cd 1.43ab 1.30bcd 1.52a 1.34ab 0.07

within a column with no common superscript differ significantly (P < 0.05). of three replicates of six chicks each from 8 to 18 d posthatching. Average initial weight was 82 g. 2PER = protein efficiency ratio = weight gain (grams) divided by protein intake (grams); NPR = net protein ratio = [weight gain (grams) of birds fed test diet minus weight gain (grams) of birds fed the N-free diet] divided by protein intake (grams). 3Composition (percentage of ppm): cornstarch:dextrose (2:1), 89.23; soybean oil, 5; mineral mix, 5.37; choline chloride, 0.20; vitamin premix, 0.20; a-tocopheryl acetate, 20 ppm; and ethoxyquin, 125 ppm (Willis and Baker, 1980). 4Each FM supplied 15% CP and each diet contained 0.3% supplemental DL-Met. 1Means

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65.8b 50.3b 78.6b 57.5b 84.4b 81.1b 77.0b 76.1b 58.9b 64.4b 75.9b 70.0b . . . 3,029b

PROCESSING AND FEATHER MEAL QUALITY

fed the FM. The PER and NPR values of the two HH were similar to the highest values for the FM (Samples 3 and 5). The correlation analyses indicated that TMEn values were correlated with Lys and Cys digestibility (r = 0.88 and 0.86, respectively). No other significant correlations were found.

DISCUSSION

unit of CP for HH, because the diets were formulated to be first limiting in Lys. The TMEn values obtained in our study generally agreed with those reported by Han and Parsons (1991) and Dale (1992). As discussed earlier for AA digestibility, TMEn values varied among FM. The TMEn values were highly correlated with Lys and Cys digestibility, indicating that the FM having the highest AA digestibility also had the highest TMEn. The lower TMEn values for HH compared to FM were probably at least partially due to the lower AA digestibility. Our results clearly showed that digestibility of AA in the WSF of FM is much higher than that of the waterinsoluble fraction. Because the WSF comprises approximately 20% of the total DM in FM (G. Pearl, Fats and Protein Research Foundation, Inc., Bloomington, IL 61701), the removal of the WSF from FM6 probably accounted for its lower AA digestibility compared with several of the other FM. When considering and excluding the latter source of variation in AA digestibility among the FM evaluated herein, the differences among processing systems were reduced. Thus, although the results of the current study suggest that type of processing system significantly influences FM protein quality, the effects are probably not great.

ACKNOWLEDGMENT Appreciation is expressed to the Fats and Proteins Research Foundation, Inc. for financial support of this study.

REFERENCES Association of Official Analytical Chemists, 1980. Official Methods of Analysis. 13th ed. Association of Official Analytical Chemists, Washington, DC. Baker, D. H., R. C. Blitenthal, K. P. Boebel, G. L. Czarnecki, L. L. Southern, and G. M. Willis, 1981. Protein-amino acid evaluation of steam-processed feather meal. Poultry Sci. 60:1865–1872. Carpenter, K. J., 1973. Damage to lysine in food processing: its measurement and its significance. Nutr. Abst. Rev. 43: 423–451. Dale, N., 1992. True metabolizable energy of feather meal. J. Appl. Poult. Res. 1:331–334. Han, Y., and C. M. Parsons, 1991. Protein and amino acid quality of feather meals. Poultry Sci. 70:812–822. Johnston, J., and C. N. Coon, 1979. A comparison of six protein quality assays using commercially available protein meals. Poultry Sci. 58:919–927. Latshaw, J. D., 1990. Quality of feather meal as affected by feather processing conditions. Poultry Sci. 69:953–958. Moore, S., 1963. On the determination of cystine as cysteic acid. J. Biol. Chem. 238:235–237. Naber, E. C., S. P. Touchburn, B. D. Barnett, and C. L. Morgan, 1961. Effect of processing methods and amino acids supplementation on dietary utilization of feather meal protein by chicks. Poultry Sci. 40:1234–1245. Papadopoulos, M. C., A. R. El Boushy, and E. H. Ketelaars, 1985. Effect of different processing conditions on amino acid digestibility of feather meal determined by chick assay. Poultry Sci. 64:1729–1741.

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In general, the AA composition data for the FM agreed with those reported by Sibbald (1986), Han and Parsons (1991) and Papadopoulos et al. (1985). However, the levels of AA did vary substantially among FM samples, particularly for Cys. Much of the variation in AA for most FM could be explained by differences in CP content. However, some of the latter variation was not related to CP content, suggesting that raw material source or processing conditions may have contributed to the variation. The levels of Cys did not correlate well with CP. Thus, much of the variation in Cys may be associated with processing system or conditions, because it is well known that processing can greatly affect the level of Cys in FM (Papadopoulos et al., 1985; Latshaw, 1990). Although most of protein in FM and HH is keratin, the AA composition of the two varied considerably for some AA, particularly for Cys, wherein FM contained much higher levels than did HH. The true AA digestibility and PER assays showed that there were substantial differences in AA digestibility and protein quality among the eight FM evaluated. These results suggested that the different processing systems affected protein or AA quality. However, there was no consistent relationship or significant correlation of cooking or drying time and temperature among systems on PER or AA digestibility. In addition, lanthionine varied greatly among the FM; however, there was no correlation between lanthionine and AA digestibility, as was reported by Han and Parsons (1991). The latter findings may be largely due to the small number of FM and the widely differing processing conditions evaluated. The FM AA digestibility values were in general agreement with those reported by Papadopoulos et al. (1985), Sibbald (1986), and Han and Parsons (1991). The low PER values of FM in our study are in general agreement with the values reported by Johnston and Coon (1979) and Han and Parsons (1991). Although processing conditions within system had little or no effect on AA digestibility or PER of FM 1 and 2 or HH 1 and 2, conclusions on these results are limited or tentative because only one system was evaluated for each. The results suggest that more diverse processing conditions are necessary to elicit major changes in AA digestibility. Although digestibility of AA in HH were lower than in FM, the PER of HH was similar to or slightly higher than that of FM. The latter response was probably due to the higher digestible Lys content per

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Sibbald, I. R., 1986. The TME system of feed evaluation: methodology, feed composition data, and bibliography. Bulletin 1986-4E, Agriculture Canada, Ottawa, ON, Canada. Spackman, D. H., W. H. Stein, and S. Moore, 1958. Automatic recording apparatus for use in the chromatography of amino acids. Anal. Chem. 30:1190–1206. Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures of Statistics. A Biometrical Approach. 2nd ed. McGrawHill Book Co., Inc., New York, NY. Sullivan, T. W., and E. L. Stephenson, 1957. Effect of processing methods on the utilization of hydrolyzed poultry feathers by growing chicks. Poultry Sci. 36:361–365. Willis, G. M., and D. H. Baker, 1980. Evaluation of turfgrass clippings as a dietary ingredient for the growing chick. Poultry Sci. 59:404–411. Downloaded from http://ps.oxfordjournals.org/ at RMIT Central Library on August 20, 2014