- Email: [email protected]
Full-Fat Soybeans for Growing and Finishing Large White Turkeys
Full-Fat Soybeans for Growing and Finishing Large White Turkeys 2. EFFECT ON TISSUE FATTY ACIDS AND ORGANOLEPTIC EVALUATION E. T. MORAN, JR., 1 E. LARMOND2 AND JAMES SOMERS1 (Received for publication September 14, 1972)
POULTRY SCIENCE 52: 1942-1948, 1973
INTRODUCTION
F
ULL-FAT soybeans as a primary dietary source of protein and energy have been investigated for the Large White turkey by Moran et al. (1973). Favorable live performance results were obtained by avoiding the more precarious starting period and feeding the extrusion processed bean to the older bird. While the extensive quantities of soybean oil encountered with full-fat meal use did not detract from the finish grade of the well chilled carcass, the concerned skin depot areas were noticably softer than if the more saturated animal tallow served as dietary fat. These softer fat depots were undoubtedly the result of alterations in constituent fat properties. In addition to an "oily" cast of the carcass there were pockets of oil formed in the larger depot areas as room temperature was approached. A greater proportion of unsaturated dietary fat not only lends to a 1. Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario NIG 2WI, Canada. 2. Food Research Institute, Canada Department of Agriculture, Ottawa, Ontario.
less desirable carcass in appearance but it could have an effect on eating quality. Carlson et al. (1969) compared large turkeys fed rations with and without 4% added corn oil. While dramatic increases in linoleic acid primarily at the expense of oleic were found, there were no marked or consistent effects on flavor, tenderness or juiciness. With the bovine carcass Waldman et al. (1965) reported that there were significant positive correlations between panel juiciness scores and myristic, as well as palmitic acid levels. More recently, Dryden and Marchello (1970) found the Longissimus dorsi of steers to have juiciness negatively correlated with linoleic acid and flavor enhanced by oleic. Similar fatty acid changes with the turkey, however, need not lead to parallel alterations in eating quality noted for the bovine. Turkeys from the previously mentioned experiment of Moran et al. (1973) were expected to provide extremes in carcass fatty acid profile that could normally be encountered under practical circumstances. Rendered animal tallow added large quantities of saturated fatty acids to the diet. At the
1942
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
ABSTRACT Whole soybeans were presented to male turkeys from 8 to 23 weeks of age either raw or extrusion processed while the commercial meal was given in conjunction with added soybean oil or animal tallow to act as controls. Carcasses from each treatment were selected for analysis and evaluation on the basis of equal grade. Iodine numbers and fatty acid analysis confirmed a high degree of unsaturation with neutral lipid extracts of skin, breast and gastrocnemius muscle whenever soybean oil was predominant in the ration. Animal tallow as the dietary fat resulted in the highest degree of saturation. These alterations were primarily the consequence of shifts in oleic and linoleic acid. Evaluation in the eating quality of breast meat by an experienced panel indicated that differences were apparent and more associated with dietary fat source than the state of the soybean fed. Flavor of birds receiving soybean oil was significantly better than those given tallow, however, the reverse was true with respect to juiciness. No effect on tenderness was noted with any treatment.
FULL-FAT SOYBEANS FOR TURKEYS
opposite extreme, soybean oil either mixed with its meal or in the form of the full-fat bean led to a very high proportion of unsaturated fatty acids. Relying on these same carcasses, it was the purpose of the present study to ascertain the extent of which these practical type diets altered tissue fatty acids and whether or not eating quality was influenced as a consequence. EXPERIMENTAL PROCEDURE
The complete samples of back skin and both muscles were then lyopholized and soxhlet extracted with petroleum ether to
remove only the neutral lipid fraction. The ether-lipid extracts were then filtered through cotton and anhydrous sodium sulfate. Most of the solvent was removed by a rotary vacuum apparatus operating at 55° C. The near dry extracts were then transferred to culture tubes and taken to dryness under nitrogen. An aliquot of this lipid was used for iodine number as determined by standard procedure with Wijs solution (American Association of Cereal Chemists Method, 58-30, 1961). Fatty acids for analysis were prepared from 100 mg. lipid samples dissolved in one ml. of benzene. This lipid solution was then added to a glass culture tube containing 3 ml. of a 3% boron trifluoride in methanol and incubated for one hour at 70° C. The methyl esters were recovered by adding 1 to 2 ml. of water and petroleum ether. The ether phase after appropriate dilution was used for analysis. Qualitative determinations of fatty acids were conducted with a Barber-Colman Series 5000 gas chromatograph (Model A-5660) equipped with a hydrogen flame ionization detector. The glass column (182.9 x 2.5 cm.) was packed with 15% Hi-EFF-2BP on 80-100 mesh gas chrom P. The column, detector and injector were operated at 185, 225 and 250° C , respectively. Nitrogen acted as the carrier gas with a flow rate of 80 ml. /minute. Fatty acid standards both by themselves and in combination with the samples, were used to identify component peaks of the chromatogram. Flavour, tenderness and juiciness of the turkeys were examined by a panel of 8 judges using the method of paired comparisons. These evaluations were made within an incomplete block statistical design with 15 blocks of 4 birds each (Cochran and Cox, 1957). A total of 10 birds from each of the 6 dietary treatments was assessed. The frozen turkey halves for each day's testing were allowed to thaw overnight in cold running water. On each day of experi-
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
An exact description of the diets employed, rationale for each and live performance may be obtained by referring to Moran et at. (1973). Immediately after chilling (12 hour ice slush) and grading, 3 carcasses from each of the 4 replicate groups respective of treatment were selected on the basis of having conformation and fleshing in the A category. Because the quantity of carcass fat has been shown to influence eating quality of the turkey broiler (Richards and Morrison, 1969), selection for an equal finish was more specific. Only those carcasses having an average A (not A+ or A - ) on both the breast and back areas were used. Under these conditions fat quantity would not confound evaluation. A triangular section of skin from the lower back area was subsequently taken from all carcasses and saved for analysis (Moran et al., 1969). The carcasses were then cut in half lengthwise. The right side was vacuumpacked in a vapor-proof shrinkable film bag and frozen (—20° C.) for later organoleptic evaluation. The left half of the carcass was the source of muscle samples for analysis. Representing the extreme in white fiber content and corresponding area for taste panel study, the major breast muscle was sampled by cross section at the center. The gastrocnemius having the greatest proportion of red muscle fibers was taken in its entirety to represent the opposite extreme.
1943
1944
E. T. MORAN JR. , E. LARMOND AND J. SOMERS
mentation the carcass half of the 4 treatments tested for that day were randomly assigned to 4 ovens. After weighing, each carcass was loosely covered with aluminum foil and roasted at 167° C. until the internal breast temperature reached 85° C. The cooked turkeys were then cooled to room temperature, drained and reweighed before being portioned for sensory testing. Pan drippings were weighed and allowed to separate in a graduated cylinder so that the amount of fat could be ascertained.
RESULTS AND DISCUSSION
The average chilled weights of the carcasses representing each treatment were not alike even though all samples were judged to be equivalent in every aspect of grade (Table 1). As expected these differences paralleled those noted previously for live weight prior to slaughter (Moran et al., 1973). Determination of total neutral lipid in the tissues showed the skin to contain overwhelming amounts relative to either of the muscles. The gastrocnemius having predominantly red fibers contained substantially more lipid than the white fiber based breast muscle. This difference between the red and white muscle of the Large White turkey had previously been noted by Acousta et al. (1963) in terms of total lipids in the 16 week old bird; however, the values obtained were considerably lower. The relative immaturity as exemplified by the known poor finish at 16 weeks probably accounts for these absolute differences. As intended through carcass
selection
TABLE 1.—The lipid content and its iodine number of selected tissues from turkey carcasses: the effect of feeding full-fat soybeans as opposed to commercial meal with added fats' Back skin
Treatment
Neutral Chilled lipid % carcass dry weight g. weight
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (with 15 DF)
10,205ab3 10,064bc 9,793c 9,960bc 10,439a 10,123abc 256
83.4 83.7 83.4 8' ' 83.0 85.0 2.2
Breast muscle
Iodine no.
Neutral lipid % dry weight
98.8a 68.0d 96.8a 89.3bc 94.5ab 82.0c 4.8
6.6 6.3 6.0 6.7 5.3 5.1 1.1
Gastrocnemius
Iodine no.
Neutral lipid % dry weight
Iodine no.
74.0a 53.5b 74.3a 71.0a 73.5a 70.3a 7.6
9.8 10.9 8.7 9.6 10.6 10.9 1.6
84.5ab 63.8c 81.0ab 79.0b 89.3a 73.5b 4.7
'All values are the average from 4 of 8 replicate groups with each group being represented by 3 carcasses. The carcasses were judged to be equivalent in conformation, fleshing and finish grade on2 the breast and back. Those treatments without a common letter are significantly different at the 5% level of significance (Duncan's multiple range test).
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
The breast muscle was portioned into 24 pieces for each carcass. These portions were presented as sample pairs (from 2 different treatments) to a panel of 8 experienced judges. Based on the method of paired comparisons each pair of samples was evaluated in terms of flavor, tenderness and juiciness with no ties allowed. In order to eliminate the effect that position on the muscle might superimpose, the sample pair originated from the same place on the 2 different carcasses. For any one day of testing each judge received the 6 pairs necessary to have a complete set of comparisons between each of the 4 treatments involved. The order of presentation
of pairs was randomized for each judge and samples were appropriately coded.
1945
FULL-FAT SOYBEANS FOR TURKEYS
TABLE 2.—The fatty acid composition of neutral lipids from selected tissues of turkey carcasses: the effect of feeding full-fat soybeans as opposed to the commercial meal with added fats' Neutral lipid fatty acids, % 18:0 16:1 18:1 Back skin
14:0
16:0
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (with 15 D.F.)
1.3 0.8 0.6 1.3 1.8 1.0 0.5
15.7 19.1 15.2 16.1 15.1 17.2 2.4
25.9c 7.7 3.9bc 34.0a 6.4 7.3a 26.0c 6.1 3.9bc 28.9b 6.1 5.7abc 25.5a 6.9 3.4c 28.9b 6.1 6.lab 1.5 1.2 1.3 1Breast muscle
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (with 15 D.F.)
0.6c 1.4a 0.8bc 0.8bc 0.4c l.lab 0.2
14.2 14.5 13.8 14.7 14.3 14.2 1.8
6.6b 9.8a 5.7b 8.0ab 7.1b 9.7a 1.4
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-29)—tallow (20-23) Sx (with 15 D.F.) 1 See footnotes 1 and 2, Table 1.
0.9 1.2 1.2 1.1 1.6 1.0 0.6
16.1 15.2 14.2 16.3 14.1 16.3 2.0
6.6b 11.1a 3.6c 8.0b 7.1b 8.2b 1.8
5.4bc 7. lab 5.1c 7.lab 6.1abc 7.5a 1.0
18:2
18:3
40.1ab 29.1c 42.5a 36.0b 41.8a 36.6b 2.9
5.9 2.6 5.6 5.9 5.3 4.2 2.0
23.7bc 29.1a 23.7bc 24.8bc 22.4c 26.1b 1.9
42.4a 32.0b 44.2a 33.8b 39.9a 32.6b 3.6
6.8ab 4.1b 6.2ab 8.1a 7.7a 6.7ab 1.5
23.8b 29.9a 23.9b 26.5ab 23.6b 26.2ab 2.5
38. lab 28.7d 40.3a 35.0bc 36.4abc 33.2c 2.6
5.1 3.4 6.4 4.4 7.9 4.9 2.5
Leg Muscle
based heavily on finish grade there were no significant alterations in the neutral lipid content of any tissue due to dietary treatment. However, iodine number determinations gave ready evidence that the dietary fats involved in each treatment had marked effects on the degree of saturation. Rations which contained soybean oil either as derived from the whole bean or added to the commercial meal consistently led to tissues with lipid having the greatest degree of unsaturation. If, however, animal tallow was the primary dietary fat offered throughout the entire experimental period then iodine numbers were the lowest. Having the rations changed from full-fat soybeans to the animal tallow containing control during the final 3 week finishing period led to lower iodine numbers regardless of whether prior treatment involved the raw or processed bean. Particularly noteworthy
8.2 9.1 7.6 7.7 7.8 7.8 1.8
in this respect was the apparent difference in response among tissues. Significant reductions were noted with the neutral lipid extracts from both skin and gastrocnemius. Iodine numbers for the breast muscle indicated a similar decrease but were not statistically significant. Subsequent fatty acid analysis of these same lipids indicated that the changes in iodine number were largely the consequence of alterations in oleic, linoleic and to a lesser degree, palmitoleic acid (Table 2). Regardless of treatment there were considerably greater proportions of linoleic acid at the expense of oleic and palmitic acids when soybean oil as opposed to when animal tallow was the primary dietary fat. Those groups which changed fat source during the finishing period basically exhibited values between the extremes encountered from continuous feeding.
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
Treatment
1946
E. T. MORAN JR., E. LARMONDAND J. SOMERS
The carcass fatty acids that each dietary fat-type encouraged, is expected to have some visual impact upon preparation by the consumer. The data on cooking performance shown in Table 3 indicate that having carcass lipid with a high degree of unsaturation lends to a larger amount of fat in the pan drippings. This observation is not limited to birds fed soybean oil. Salmon and O'Neil (1971) found a greater percentage of fat in the drip upon cooking turkeys fed rapeseed oil as compared to palm oil. Similarly, Jen et al. (1971) noted
more drip fat with broiler chickens given corn oil than those where beef tallow was incorporated into the ration. These authors suggest that there is a relationship between the ratio of solid to liquid fat in tissue lipid and the amount of loss occurring during preparation. Evaluation of the cooked breast meat by an experienced panel indicated that dietary treatment also influenced the eating quality of the carcass. Treatments involving the commercial source soybean meal to which either soybean oil or animal tallow were added yielded the most outstanding differences (Table 4). Flavor of the birds receiving the oil was considered significantly more desirable than from those given tallow, however, the reverse was true with respect to juiciness. No treatment was found to affect tenderness. The assessment of birds given extruded full-fat soybeans was comparable to those receiving the meal with added oil, but when the raw beans were fed then flavor was poorer while juiciness was significantly better. Changing from whole soybeans to the ration having tallow as the predominant dietary fat during the finishing period did little to alter evaluation when the beans were processed. If, however, the soybeans had been offered raw then juiciness was found to be significantly reduced. Because alterations in eating quality occurred more so when dietary fat source was different than if the commercial meal versus the full-fat bean were compared, carcass lipid
TABLE 3.—The effect of feeding full-fat soybeans as opposed to the commercial meal with added fats: the cooking performance of the carcass Treatment Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (40 D.F.) 1
Drip loss
Cooking loss, %
% O.R. wt.
34.0 33.2 31.9 31.8 32.5 32.4 1.2
5.6 6.1 5.7 5.4 6.3 6.7 0.8
%fat 65.6a2 48.4ab 54.3ab 51.4ab 47.8ab 29.9b 7.3
Cooking time, min./kg. 55.1 58.6 50.4 56.5 53.2 57.4 4.0
% of oven ready weight. Those treatments without a common letter are significantly different at the 5% level of significance.
2
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
The similarity of the fatty acid profiles obtained from the lipids of skin, gastrocnemius and breast muscle would at first seem in conflict with their widely varying iodine numbers. It must be borne in mind, however, that the proportion of triglyceride in the neutral fat from these 3 sources is expected to vary extensively. Marion and Woodroof (1965) have shown with the broiler chicken that muscle contains considerably more cholesterol and cholesterol esters than does skin lipid. Furthermore, the concentration of steroids in the neutral fraction as compared to triglyceride is much greater for breast muscle than thigh. Having these non-reactive compounds occupy varying proportions of the neutral lipid explains the different iodine numbers with each tissue in the face of similar fatty acid profiles. The fatty acid composition of the same lipid fraction was noted by Marion and Woodroof (1965) not to vary appreciably between tissues.
1947
FULL-FAT SOYBEANS FOR TURKEYS
TABLE 4.—The effect of feeding full-fat soybeans as opposed to the commercial meal with added fats: estimates of preference parameters for flavor, tenderness and juiciness' Treatment Flavor Tenderness Juiciness 2.16c 1.44a2 1.59a Meal + soy oil (8-23 wks.) 1.59ab 1.84a 2.12c Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) 1.38a 1.95a 2.04bc Beans (8-20)—tallow (20-23) 1.94bc 1.86a 2.01bc 1.97bc 1.87a Beans—extruded (8-23 wks.) 1.63ab Beans (8-20)—tallow (20-23) 1.93bc 1.69a 1.71abc Sx3 0.12 0.12 0.12 1 Lower values of preference parameters donate better quality. The estimates are given in log scale and2 have been multiplied by - 1 . Those treatments without a common letter are significantly different at the 5% level of significance. 'Effective standard error of the parameter estimate in log scale.
From a practical standpoint, use of large amounts of dietary soybean oil did not adversely affect consumer acceptability of the turkey carcass. Although there were greater amounts of fat lost in the drip this may not be a disadvantage in this calorie conscious world other than lending to a reduced juiciness. The benefit of an enhanced flavor as noted by an experienced panel is difficult to assess in terms of the public-at-large where
condiments, as well as method of preparation, have large and confounding effect. Perhaps the most important result is that adverse opinions were not encountered with these practical extremes. REFERENCES
Acousta, S. O., W. W. Marion and R. H. Forsythe, 1963. Total lipid and phospholipid in turkey tissues. Poultry Sci. 42: 1251. American Association of Cereal Chemists, 1961. Methods of Analysis. Method 58-30. Carlson, C. W., E. Guenthner, K. C. Schneider, L. P. Guild, D. Deethardt and Y. A. Grerchus, 1969. Effects of corn oil and lysine on growth, fatty acid composition and palatability of Large Broad White turkeys. Poultry Sci. 48: 1027-1033. Cochran, W. G., and G. M. cox, 1950. Experimental Design. John Wiley and Sons, New York. Dryden, F. D., and J. A. Marchello, 1970. Influence of total lipid and fatty acid composition upon the palatability of three bovine muscles. J. Anim. Sci. 31: 36-41. Jen, J. J., W. P. Williams, Jr., J. C. Acton and V. A. Paynter, 1971. Effect of dietary fats on the fatty acid contents of chicken adipose tissue. J. Food Sci. 36: 925-909. Marion, J. E., and J. G. Woodroof, 1965. Lipid fractions of chicken broiler tissues and their fatty acid composition. J. Food Sci. 30: 38-43. Moran, E. T., Jr., J. Somers and E. Larmond, 1973. Full-fat soybeans for growing and finishing large white turkeys 1. Live performance and carcass quality. Poultry Sci. 52: 1936-1941. Moran, E. T., Jr., J. D. Summers and H. L. Orr, 1969. The effect of absolute alterations in energy concentration of developing and finishing diets for the large white turkey on performance and carcass
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
is likely the primary factor responsible for the noted changes in flavor and juiciness. Considering the large shifts in oleic and linoleic acids by the tissues as a consequence of dietary fat substitutions it is tempting to directly implicate these fatty acids. However, the analyses were only performed on the tryglyceride containing neutral lipid. While the vast majority of total lipid in the skin of the broiler chicken is attributable to the neutral fraction that in the breast muscle contains no more than a third (Marion and Woodroof, 1965). Phospholipids comprise most of the remaining polar lipid where oleic and linoleic acids play a considerably smaller role. To what extent the various lipid fractions of the breast were altered by heating and / o r influenced quantitatively upon disruption of cellular integrity by cooking remains to be determined. Under these terms any present attempts to extrapolate fatty acid changes in the raw state to consumer preferences after cooking would be precarious at best.
1948
E. T. MORAN JR., E. LARMOND AND J. SOMERS
quality with a note on back skin fat and grade of finish. Br. Poultry Sci. 10: 127-138. Richards, J. F., and B. C. Morrison, 1969. A study of fat grade, fat content and sensory properties of turkey broilers. Can. Inst. Food Technol. J. 2: 6-8. Salmon, R. E., and J. B. O'Neil, 1971. The effect of the level and source of dietary fat on the growth,
feed efficiency, grade and carcass composition of turkeys. Poultry Sci. 50: 1456-1467. Waldman, R. C , G. G. Suess, R. W. Lewis, R. W. Bray and V. H. Brungardt, 1965. Certain fatty acids of bovine tissue and their association with carcass characteristics. J. Animal Sci. 24: 819.
Some Physiological Responses of Turkeys Selected for High and Low Adrenal Response to Cold Stress
(Received for publication February 14, 1973)
ABSTRACT Two lines were developed from the Ohio Randombred Control (RBC) population on the basis of their plasma corticosterone level after cold stress. One line (HL) was selected for increased plasma corticosterone, while the other line (LL) was selected for low corticosterone level after cold stress. By the F6 generation the mean corticosterone level after cold stress of the HL (14.8 (ig.%) was nearly double that of the LL (7.6 ng.%). Correlated responses measured were body weight, egg production, fertility, hatchability, resistance to disease, response to ACTH, and response to heat stress. At four weeks of age the LL was significantly heavier than the RBC or the HL birds in all generations. The LL birds produced significantly more eggs than the RBC or HL birds after the 4th generation. Although there were few significant differences among lines for fertility and hatchability, the trend was toward slightly better reproductive performance for the LL. This, coupled with better egg production, resulted in superior over-all reproductive performance for the LL. Both natural mortality and mortality due to cold stress and blood collection were significantly lower in the LL than in the RBC and the HL for the F3 through F7 generations. In addition, it appears that the response to cold stress is negatively correlated with resistance to Mycoplasma meleagridis. The response to heat stress in the HL and the LL birds was similar to that from cold stress indicating that the response was nonspecific. The HL birds were nearly twice as sensitive to ACTH injections as the LL birds. The response to ACTH injections strongly suggests that genetic selection altered the adrenal response to ACTH. POULTRY SCIENCE 52: 1948-1954, 1973 INTRODUCTION
ASED on a review of the literature and a limited amount of data obtained here, it was postulated that animals (turkeys) which can adapt to stress conditions without initiating the General Adaptation Syndrome (G.A.S.) or, which at least, respond by a low release of adaptation hormones should grow faster, convert feed more efficiently, reproduce more efficiently and be more resistant to a wide variety of stress conditions (Brown, 1959, 1968). Previously Brown (1968) reported on turkey lines selected for high and low adrenal
B
response to cold stress (plasma corticosterone) through three generations. This paper presents the data through seven generations. In addition, physiological evidence is presented which indicates selection for high or low plasma corticosterone folowing cold stress changed the adrenals sensitivity to ACTH. MATERIALS AND METHODS
Selection Methods. Two lines were developed from the Ohio Randombred Control population (McCartney, 1961, 1964) on the basis of their plasma corticosterone level after
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
K E I T H I. BROWN AND K A R L E . NESTOR
Department of Poultry Science, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691
POULTRY SCIENCE 52: 1942-1948, 1973
INTRODUCTION
F
ULL-FAT soybeans as a primary dietary source of protein and energy have been investigated for the Large White turkey by Moran et al. (1973). Favorable live performance results were obtained by avoiding the more precarious starting period and feeding the extrusion processed bean to the older bird. While the extensive quantities of soybean oil encountered with full-fat meal use did not detract from the finish grade of the well chilled carcass, the concerned skin depot areas were noticably softer than if the more saturated animal tallow served as dietary fat. These softer fat depots were undoubtedly the result of alterations in constituent fat properties. In addition to an "oily" cast of the carcass there were pockets of oil formed in the larger depot areas as room temperature was approached. A greater proportion of unsaturated dietary fat not only lends to a 1. Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario NIG 2WI, Canada. 2. Food Research Institute, Canada Department of Agriculture, Ottawa, Ontario.
less desirable carcass in appearance but it could have an effect on eating quality. Carlson et al. (1969) compared large turkeys fed rations with and without 4% added corn oil. While dramatic increases in linoleic acid primarily at the expense of oleic were found, there were no marked or consistent effects on flavor, tenderness or juiciness. With the bovine carcass Waldman et al. (1965) reported that there were significant positive correlations between panel juiciness scores and myristic, as well as palmitic acid levels. More recently, Dryden and Marchello (1970) found the Longissimus dorsi of steers to have juiciness negatively correlated with linoleic acid and flavor enhanced by oleic. Similar fatty acid changes with the turkey, however, need not lead to parallel alterations in eating quality noted for the bovine. Turkeys from the previously mentioned experiment of Moran et al. (1973) were expected to provide extremes in carcass fatty acid profile that could normally be encountered under practical circumstances. Rendered animal tallow added large quantities of saturated fatty acids to the diet. At the
1942
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
ABSTRACT Whole soybeans were presented to male turkeys from 8 to 23 weeks of age either raw or extrusion processed while the commercial meal was given in conjunction with added soybean oil or animal tallow to act as controls. Carcasses from each treatment were selected for analysis and evaluation on the basis of equal grade. Iodine numbers and fatty acid analysis confirmed a high degree of unsaturation with neutral lipid extracts of skin, breast and gastrocnemius muscle whenever soybean oil was predominant in the ration. Animal tallow as the dietary fat resulted in the highest degree of saturation. These alterations were primarily the consequence of shifts in oleic and linoleic acid. Evaluation in the eating quality of breast meat by an experienced panel indicated that differences were apparent and more associated with dietary fat source than the state of the soybean fed. Flavor of birds receiving soybean oil was significantly better than those given tallow, however, the reverse was true with respect to juiciness. No effect on tenderness was noted with any treatment.
FULL-FAT SOYBEANS FOR TURKEYS
opposite extreme, soybean oil either mixed with its meal or in the form of the full-fat bean led to a very high proportion of unsaturated fatty acids. Relying on these same carcasses, it was the purpose of the present study to ascertain the extent of which these practical type diets altered tissue fatty acids and whether or not eating quality was influenced as a consequence. EXPERIMENTAL PROCEDURE
The complete samples of back skin and both muscles were then lyopholized and soxhlet extracted with petroleum ether to
remove only the neutral lipid fraction. The ether-lipid extracts were then filtered through cotton and anhydrous sodium sulfate. Most of the solvent was removed by a rotary vacuum apparatus operating at 55° C. The near dry extracts were then transferred to culture tubes and taken to dryness under nitrogen. An aliquot of this lipid was used for iodine number as determined by standard procedure with Wijs solution (American Association of Cereal Chemists Method, 58-30, 1961). Fatty acids for analysis were prepared from 100 mg. lipid samples dissolved in one ml. of benzene. This lipid solution was then added to a glass culture tube containing 3 ml. of a 3% boron trifluoride in methanol and incubated for one hour at 70° C. The methyl esters were recovered by adding 1 to 2 ml. of water and petroleum ether. The ether phase after appropriate dilution was used for analysis. Qualitative determinations of fatty acids were conducted with a Barber-Colman Series 5000 gas chromatograph (Model A-5660) equipped with a hydrogen flame ionization detector. The glass column (182.9 x 2.5 cm.) was packed with 15% Hi-EFF-2BP on 80-100 mesh gas chrom P. The column, detector and injector were operated at 185, 225 and 250° C , respectively. Nitrogen acted as the carrier gas with a flow rate of 80 ml. /minute. Fatty acid standards both by themselves and in combination with the samples, were used to identify component peaks of the chromatogram. Flavour, tenderness and juiciness of the turkeys were examined by a panel of 8 judges using the method of paired comparisons. These evaluations were made within an incomplete block statistical design with 15 blocks of 4 birds each (Cochran and Cox, 1957). A total of 10 birds from each of the 6 dietary treatments was assessed. The frozen turkey halves for each day's testing were allowed to thaw overnight in cold running water. On each day of experi-
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
An exact description of the diets employed, rationale for each and live performance may be obtained by referring to Moran et at. (1973). Immediately after chilling (12 hour ice slush) and grading, 3 carcasses from each of the 4 replicate groups respective of treatment were selected on the basis of having conformation and fleshing in the A category. Because the quantity of carcass fat has been shown to influence eating quality of the turkey broiler (Richards and Morrison, 1969), selection for an equal finish was more specific. Only those carcasses having an average A (not A+ or A - ) on both the breast and back areas were used. Under these conditions fat quantity would not confound evaluation. A triangular section of skin from the lower back area was subsequently taken from all carcasses and saved for analysis (Moran et al., 1969). The carcasses were then cut in half lengthwise. The right side was vacuumpacked in a vapor-proof shrinkable film bag and frozen (—20° C.) for later organoleptic evaluation. The left half of the carcass was the source of muscle samples for analysis. Representing the extreme in white fiber content and corresponding area for taste panel study, the major breast muscle was sampled by cross section at the center. The gastrocnemius having the greatest proportion of red muscle fibers was taken in its entirety to represent the opposite extreme.
1943
1944
E. T. MORAN JR. , E. LARMOND AND J. SOMERS
mentation the carcass half of the 4 treatments tested for that day were randomly assigned to 4 ovens. After weighing, each carcass was loosely covered with aluminum foil and roasted at 167° C. until the internal breast temperature reached 85° C. The cooked turkeys were then cooled to room temperature, drained and reweighed before being portioned for sensory testing. Pan drippings were weighed and allowed to separate in a graduated cylinder so that the amount of fat could be ascertained.
RESULTS AND DISCUSSION
The average chilled weights of the carcasses representing each treatment were not alike even though all samples were judged to be equivalent in every aspect of grade (Table 1). As expected these differences paralleled those noted previously for live weight prior to slaughter (Moran et al., 1973). Determination of total neutral lipid in the tissues showed the skin to contain overwhelming amounts relative to either of the muscles. The gastrocnemius having predominantly red fibers contained substantially more lipid than the white fiber based breast muscle. This difference between the red and white muscle of the Large White turkey had previously been noted by Acousta et al. (1963) in terms of total lipids in the 16 week old bird; however, the values obtained were considerably lower. The relative immaturity as exemplified by the known poor finish at 16 weeks probably accounts for these absolute differences. As intended through carcass
selection
TABLE 1.—The lipid content and its iodine number of selected tissues from turkey carcasses: the effect of feeding full-fat soybeans as opposed to commercial meal with added fats' Back skin
Treatment
Neutral Chilled lipid % carcass dry weight g. weight
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (with 15 DF)
10,205ab3 10,064bc 9,793c 9,960bc 10,439a 10,123abc 256
83.4 83.7 83.4 8' ' 83.0 85.0 2.2
Breast muscle
Iodine no.
Neutral lipid % dry weight
98.8a 68.0d 96.8a 89.3bc 94.5ab 82.0c 4.8
6.6 6.3 6.0 6.7 5.3 5.1 1.1
Gastrocnemius
Iodine no.
Neutral lipid % dry weight
Iodine no.
74.0a 53.5b 74.3a 71.0a 73.5a 70.3a 7.6
9.8 10.9 8.7 9.6 10.6 10.9 1.6
84.5ab 63.8c 81.0ab 79.0b 89.3a 73.5b 4.7
'All values are the average from 4 of 8 replicate groups with each group being represented by 3 carcasses. The carcasses were judged to be equivalent in conformation, fleshing and finish grade on2 the breast and back. Those treatments without a common letter are significantly different at the 5% level of significance (Duncan's multiple range test).
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
The breast muscle was portioned into 24 pieces for each carcass. These portions were presented as sample pairs (from 2 different treatments) to a panel of 8 experienced judges. Based on the method of paired comparisons each pair of samples was evaluated in terms of flavor, tenderness and juiciness with no ties allowed. In order to eliminate the effect that position on the muscle might superimpose, the sample pair originated from the same place on the 2 different carcasses. For any one day of testing each judge received the 6 pairs necessary to have a complete set of comparisons between each of the 4 treatments involved. The order of presentation
of pairs was randomized for each judge and samples were appropriately coded.
1945
FULL-FAT SOYBEANS FOR TURKEYS
TABLE 2.—The fatty acid composition of neutral lipids from selected tissues of turkey carcasses: the effect of feeding full-fat soybeans as opposed to the commercial meal with added fats' Neutral lipid fatty acids, % 18:0 16:1 18:1 Back skin
14:0
16:0
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (with 15 D.F.)
1.3 0.8 0.6 1.3 1.8 1.0 0.5
15.7 19.1 15.2 16.1 15.1 17.2 2.4
25.9c 7.7 3.9bc 34.0a 6.4 7.3a 26.0c 6.1 3.9bc 28.9b 6.1 5.7abc 25.5a 6.9 3.4c 28.9b 6.1 6.lab 1.5 1.2 1.3 1Breast muscle
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (with 15 D.F.)
0.6c 1.4a 0.8bc 0.8bc 0.4c l.lab 0.2
14.2 14.5 13.8 14.7 14.3 14.2 1.8
6.6b 9.8a 5.7b 8.0ab 7.1b 9.7a 1.4
Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-29)—tallow (20-23) Sx (with 15 D.F.) 1 See footnotes 1 and 2, Table 1.
0.9 1.2 1.2 1.1 1.6 1.0 0.6
16.1 15.2 14.2 16.3 14.1 16.3 2.0
6.6b 11.1a 3.6c 8.0b 7.1b 8.2b 1.8
5.4bc 7. lab 5.1c 7.lab 6.1abc 7.5a 1.0
18:2
18:3
40.1ab 29.1c 42.5a 36.0b 41.8a 36.6b 2.9
5.9 2.6 5.6 5.9 5.3 4.2 2.0
23.7bc 29.1a 23.7bc 24.8bc 22.4c 26.1b 1.9
42.4a 32.0b 44.2a 33.8b 39.9a 32.6b 3.6
6.8ab 4.1b 6.2ab 8.1a 7.7a 6.7ab 1.5
23.8b 29.9a 23.9b 26.5ab 23.6b 26.2ab 2.5
38. lab 28.7d 40.3a 35.0bc 36.4abc 33.2c 2.6
5.1 3.4 6.4 4.4 7.9 4.9 2.5
Leg Muscle
based heavily on finish grade there were no significant alterations in the neutral lipid content of any tissue due to dietary treatment. However, iodine number determinations gave ready evidence that the dietary fats involved in each treatment had marked effects on the degree of saturation. Rations which contained soybean oil either as derived from the whole bean or added to the commercial meal consistently led to tissues with lipid having the greatest degree of unsaturation. If, however, animal tallow was the primary dietary fat offered throughout the entire experimental period then iodine numbers were the lowest. Having the rations changed from full-fat soybeans to the animal tallow containing control during the final 3 week finishing period led to lower iodine numbers regardless of whether prior treatment involved the raw or processed bean. Particularly noteworthy
8.2 9.1 7.6 7.7 7.8 7.8 1.8
in this respect was the apparent difference in response among tissues. Significant reductions were noted with the neutral lipid extracts from both skin and gastrocnemius. Iodine numbers for the breast muscle indicated a similar decrease but were not statistically significant. Subsequent fatty acid analysis of these same lipids indicated that the changes in iodine number were largely the consequence of alterations in oleic, linoleic and to a lesser degree, palmitoleic acid (Table 2). Regardless of treatment there were considerably greater proportions of linoleic acid at the expense of oleic and palmitic acids when soybean oil as opposed to when animal tallow was the primary dietary fat. Those groups which changed fat source during the finishing period basically exhibited values between the extremes encountered from continuous feeding.
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
Treatment
1946
E. T. MORAN JR., E. LARMONDAND J. SOMERS
The carcass fatty acids that each dietary fat-type encouraged, is expected to have some visual impact upon preparation by the consumer. The data on cooking performance shown in Table 3 indicate that having carcass lipid with a high degree of unsaturation lends to a larger amount of fat in the pan drippings. This observation is not limited to birds fed soybean oil. Salmon and O'Neil (1971) found a greater percentage of fat in the drip upon cooking turkeys fed rapeseed oil as compared to palm oil. Similarly, Jen et al. (1971) noted
more drip fat with broiler chickens given corn oil than those where beef tallow was incorporated into the ration. These authors suggest that there is a relationship between the ratio of solid to liquid fat in tissue lipid and the amount of loss occurring during preparation. Evaluation of the cooked breast meat by an experienced panel indicated that dietary treatment also influenced the eating quality of the carcass. Treatments involving the commercial source soybean meal to which either soybean oil or animal tallow were added yielded the most outstanding differences (Table 4). Flavor of the birds receiving the oil was considered significantly more desirable than from those given tallow, however, the reverse was true with respect to juiciness. No treatment was found to affect tenderness. The assessment of birds given extruded full-fat soybeans was comparable to those receiving the meal with added oil, but when the raw beans were fed then flavor was poorer while juiciness was significantly better. Changing from whole soybeans to the ration having tallow as the predominant dietary fat during the finishing period did little to alter evaluation when the beans were processed. If, however, the soybeans had been offered raw then juiciness was found to be significantly reduced. Because alterations in eating quality occurred more so when dietary fat source was different than if the commercial meal versus the full-fat bean were compared, carcass lipid
TABLE 3.—The effect of feeding full-fat soybeans as opposed to the commercial meal with added fats: the cooking performance of the carcass Treatment Meal + soy oil (8-23 wks.) Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) Beans (8-20)—tallow (20-23) Beans—extruded (8-23 wks.) Beans (8-20)—tallow (20-23) Sx (40 D.F.) 1
Drip loss
Cooking loss, %
% O.R. wt.
34.0 33.2 31.9 31.8 32.5 32.4 1.2
5.6 6.1 5.7 5.4 6.3 6.7 0.8
%fat 65.6a2 48.4ab 54.3ab 51.4ab 47.8ab 29.9b 7.3
Cooking time, min./kg. 55.1 58.6 50.4 56.5 53.2 57.4 4.0
% of oven ready weight. Those treatments without a common letter are significantly different at the 5% level of significance.
2
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
The similarity of the fatty acid profiles obtained from the lipids of skin, gastrocnemius and breast muscle would at first seem in conflict with their widely varying iodine numbers. It must be borne in mind, however, that the proportion of triglyceride in the neutral fat from these 3 sources is expected to vary extensively. Marion and Woodroof (1965) have shown with the broiler chicken that muscle contains considerably more cholesterol and cholesterol esters than does skin lipid. Furthermore, the concentration of steroids in the neutral fraction as compared to triglyceride is much greater for breast muscle than thigh. Having these non-reactive compounds occupy varying proportions of the neutral lipid explains the different iodine numbers with each tissue in the face of similar fatty acid profiles. The fatty acid composition of the same lipid fraction was noted by Marion and Woodroof (1965) not to vary appreciably between tissues.
1947
FULL-FAT SOYBEANS FOR TURKEYS
TABLE 4.—The effect of feeding full-fat soybeans as opposed to the commercial meal with added fats: estimates of preference parameters for flavor, tenderness and juiciness' Treatment Flavor Tenderness Juiciness 2.16c 1.44a2 1.59a Meal + soy oil (8-23 wks.) 1.59ab 1.84a 2.12c Meal + tallow (8-23 wks.) Beans—raw (8-23 wks.) 1.38a 1.95a 2.04bc Beans (8-20)—tallow (20-23) 1.94bc 1.86a 2.01bc 1.97bc 1.87a Beans—extruded (8-23 wks.) 1.63ab Beans (8-20)—tallow (20-23) 1.93bc 1.69a 1.71abc Sx3 0.12 0.12 0.12 1 Lower values of preference parameters donate better quality. The estimates are given in log scale and2 have been multiplied by - 1 . Those treatments without a common letter are significantly different at the 5% level of significance. 'Effective standard error of the parameter estimate in log scale.
From a practical standpoint, use of large amounts of dietary soybean oil did not adversely affect consumer acceptability of the turkey carcass. Although there were greater amounts of fat lost in the drip this may not be a disadvantage in this calorie conscious world other than lending to a reduced juiciness. The benefit of an enhanced flavor as noted by an experienced panel is difficult to assess in terms of the public-at-large where
condiments, as well as method of preparation, have large and confounding effect. Perhaps the most important result is that adverse opinions were not encountered with these practical extremes. REFERENCES
Acousta, S. O., W. W. Marion and R. H. Forsythe, 1963. Total lipid and phospholipid in turkey tissues. Poultry Sci. 42: 1251. American Association of Cereal Chemists, 1961. Methods of Analysis. Method 58-30. Carlson, C. W., E. Guenthner, K. C. Schneider, L. P. Guild, D. Deethardt and Y. A. Grerchus, 1969. Effects of corn oil and lysine on growth, fatty acid composition and palatability of Large Broad White turkeys. Poultry Sci. 48: 1027-1033. Cochran, W. G., and G. M. cox, 1950. Experimental Design. John Wiley and Sons, New York. Dryden, F. D., and J. A. Marchello, 1970. Influence of total lipid and fatty acid composition upon the palatability of three bovine muscles. J. Anim. Sci. 31: 36-41. Jen, J. J., W. P. Williams, Jr., J. C. Acton and V. A. Paynter, 1971. Effect of dietary fats on the fatty acid contents of chicken adipose tissue. J. Food Sci. 36: 925-909. Marion, J. E., and J. G. Woodroof, 1965. Lipid fractions of chicken broiler tissues and their fatty acid composition. J. Food Sci. 30: 38-43. Moran, E. T., Jr., J. Somers and E. Larmond, 1973. Full-fat soybeans for growing and finishing large white turkeys 1. Live performance and carcass quality. Poultry Sci. 52: 1936-1941. Moran, E. T., Jr., J. D. Summers and H. L. Orr, 1969. The effect of absolute alterations in energy concentration of developing and finishing diets for the large white turkey on performance and carcass
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
is likely the primary factor responsible for the noted changes in flavor and juiciness. Considering the large shifts in oleic and linoleic acids by the tissues as a consequence of dietary fat substitutions it is tempting to directly implicate these fatty acids. However, the analyses were only performed on the tryglyceride containing neutral lipid. While the vast majority of total lipid in the skin of the broiler chicken is attributable to the neutral fraction that in the breast muscle contains no more than a third (Marion and Woodroof, 1965). Phospholipids comprise most of the remaining polar lipid where oleic and linoleic acids play a considerably smaller role. To what extent the various lipid fractions of the breast were altered by heating and / o r influenced quantitatively upon disruption of cellular integrity by cooking remains to be determined. Under these terms any present attempts to extrapolate fatty acid changes in the raw state to consumer preferences after cooking would be precarious at best.
1948
E. T. MORAN JR., E. LARMOND AND J. SOMERS
quality with a note on back skin fat and grade of finish. Br. Poultry Sci. 10: 127-138. Richards, J. F., and B. C. Morrison, 1969. A study of fat grade, fat content and sensory properties of turkey broilers. Can. Inst. Food Technol. J. 2: 6-8. Salmon, R. E., and J. B. O'Neil, 1971. The effect of the level and source of dietary fat on the growth,
feed efficiency, grade and carcass composition of turkeys. Poultry Sci. 50: 1456-1467. Waldman, R. C , G. G. Suess, R. W. Lewis, R. W. Bray and V. H. Brungardt, 1965. Certain fatty acids of bovine tissue and their association with carcass characteristics. J. Animal Sci. 24: 819.
Some Physiological Responses of Turkeys Selected for High and Low Adrenal Response to Cold Stress
(Received for publication February 14, 1973)
ABSTRACT Two lines were developed from the Ohio Randombred Control (RBC) population on the basis of their plasma corticosterone level after cold stress. One line (HL) was selected for increased plasma corticosterone, while the other line (LL) was selected for low corticosterone level after cold stress. By the F6 generation the mean corticosterone level after cold stress of the HL (14.8 (ig.%) was nearly double that of the LL (7.6 ng.%). Correlated responses measured were body weight, egg production, fertility, hatchability, resistance to disease, response to ACTH, and response to heat stress. At four weeks of age the LL was significantly heavier than the RBC or the HL birds in all generations. The LL birds produced significantly more eggs than the RBC or HL birds after the 4th generation. Although there were few significant differences among lines for fertility and hatchability, the trend was toward slightly better reproductive performance for the LL. This, coupled with better egg production, resulted in superior over-all reproductive performance for the LL. Both natural mortality and mortality due to cold stress and blood collection were significantly lower in the LL than in the RBC and the HL for the F3 through F7 generations. In addition, it appears that the response to cold stress is negatively correlated with resistance to Mycoplasma meleagridis. The response to heat stress in the HL and the LL birds was similar to that from cold stress indicating that the response was nonspecific. The HL birds were nearly twice as sensitive to ACTH injections as the LL birds. The response to ACTH injections strongly suggests that genetic selection altered the adrenal response to ACTH. POULTRY SCIENCE 52: 1948-1954, 1973 INTRODUCTION
ASED on a review of the literature and a limited amount of data obtained here, it was postulated that animals (turkeys) which can adapt to stress conditions without initiating the General Adaptation Syndrome (G.A.S.) or, which at least, respond by a low release of adaptation hormones should grow faster, convert feed more efficiently, reproduce more efficiently and be more resistant to a wide variety of stress conditions (Brown, 1959, 1968). Previously Brown (1968) reported on turkey lines selected for high and low adrenal
B
response to cold stress (plasma corticosterone) through three generations. This paper presents the data through seven generations. In addition, physiological evidence is presented which indicates selection for high or low plasma corticosterone folowing cold stress changed the adrenals sensitivity to ACTH. MATERIALS AND METHODS
Selection Methods. Two lines were developed from the Ohio Randombred Control population (McCartney, 1961, 1964) on the basis of their plasma corticosterone level after
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 2, 2015
K E I T H I. BROWN AND K A R L E . NESTOR
Department of Poultry Science, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691