ATJTOCLAVING SESAME MEAL 1 Association of Official Agricultural Chemists, 1960. Official Methods of Analysis. 9th Ed., Association of Official Agricultural Chemists, Washington, D. C. Kratzer, F. H., J. B. Allred, P. N. Davis, B. J. Marshall and P. Vohra, 1959. The effect of autoclaving soybean protein and the addition of ethylenediaminetetracetic acid on the biological availability of dietary zinc for turkey poults. J. Nutrition, 68: 313-321. Lease, J. G., B. D. Barnett, E. J. Lease and D. E. Turk, 1960. The biological unavailability to the chick of zinc in a sesame meal ration. J. Nutrition, 72: 66-70. Likuski, H. J. A., and R. M. Forbes, 1964. Effect of phytic acid on the availability of zinc in amino acid and casein diets fed to chicks. J. Nutrition, 84: 145-148. McCall, J. T., J. V. Mason and G. K. Davis, 1961. INTRODUCTION IN recent years, an increasing proportion of the broilers marketed in the U. S. were processed beyond the fresh-market stage and sold as processed commodities. These items may be whole meat products, or meat combined with other foodstuffs. This trend has emphasized the importance of producing broilers with a fairly uniform body composition, and has further emphasized the importance of studying factors which might influence carcass composition and stability. Changes in dietary regimes and rearing practices were shown by Harshaw (1936) to influence the carcass composition of 'Journal Series No. 519, Georgia Experiment Station, Experiment, Georgia. Effect of source and level of dietary protein on the toxicity of zinc to the rat. J. Nutrition, 74: 51-57. Norris, L. C, and P. N. Davis, 1960. The metalbinding properties of soybean protein. Feedstuffs, 32: 35-36. O'Dell, B. L., 1962. Mineral availability and metalbinding constituents of the diet. Proc. Cornell Nutrition Conf. p. 77-83. O'Dell, B. L., J. M. Yohe and J. E. Savage, 1964. Zinc availability in the chick as affected by phytate, calcium and ethylenediaminetetraacetate. Poultry Sci. 43 : 415-419. Pringle, W. J. S., and T. Moran, 1942. Phytic acid and its destruction in baking. J. Soc. Chem. Ind. 61: 108-110. Scott, M. L., and T. R. Zeigler, 1963. Evidence for natural chelates which aid in the utilization of zinc by chicks. Agr. Food Chem. 11: 123-125. Composition and Stability of Broiler Carcasses as Affected by Dietary Protein and Fat 1 J. E. MARION AND J. G. WOODROOF Food Science Department, Georgia Experiment Station, Experiment, Georgia (Received for publication August 25, 1965) chickens. Fraps (1943) observed that by adjusting dietary constituents, it was possible to produce chickens with widely varying amounts of body fat. More recently, other workers (Donaldson et al., 1956; Newell et al., 1956; Rand et al., 1957; Spring and Wilkinson, 1957; Summers et al., 1965) have noted that specific changes in either dietary protein, fat, or energy level produced changes in total body composition of chickens. These composition changes were chiefly in the ratio of moisture to fat, with protein level remaining relatively constant. Dansky and Hill (1952) and Essary and Dawson (1965) have further demonstrated that changes in fat deposition in the chicken are primarily in skin and adipose tissues, with less marked changes occurring in muscle tissue. Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20
2 J. E. MARION AND J. G. WOODROOF TABLE 1.Composition of protein basal ration Ingredient Yellow corn meal Soybean meal (50 prot.) Corn gluten meal Alfalfa leaf meal (17 prot.) Defluorinated phosphate Ground limestone Sodium chloride Zinc oxide Mineral mixture 1 Choline chloride (25) Vitamin A (325,000 U.S.P./gm.) Vitamin D 3 (325,000 U.S.P./gm.) Vitamin B«(6 mg./454 gms.) Vitamin mixture 2 Methionine hydroxy analog (90) Terramycin (50 gms./454 gms.) Antioxidant 3 gms./loo gms. 56.6 36.4 2.0 2.0 0.004 5 0.10 0.002 0.0001 0.01 0.15 0.15 0.01 0.01 1 Mineral mixture contains: Mn, 6; Fe, 2; Cu, ; I, 0.12; Co, 0.02; Ca, 26.5. 2 Vitamin mixture contains: riboflavin, 4; calcium pantothenate, 8; niacin, 1.98; choline chloride, 2.20; folic acid, 13.22. 3 l,2-dihydro-6, ethoxy-2,2,4-trimethyl quinoline, Monsanto Chem. Co., St. Louis. With the exception of feeding different fats to chickens, very little information is in the literature on the influence of dietary factors on the stability, or conversely, the rate of oxidation development, of poultry meat. Darrow and Essary (19S5) concluded that the addition of beef tallow, cottonseed foots, or soybean foots in broiler diets at low levels did not adversely affect the quality of poultry when held under frozen storage for 9 months. The feeding of highly unsaturated oils, such as linseed oil (Chu and Kummerow, 1950) and fish oil (Carlson et al., 1957), resulted in offflavors in poultry meat which were presumably due to oxidized lipids. The present research was conducted to evaluate the influence of two dietary protein levels and four dietary fats on certain characteristics of broiler carcasses. These characteristics are: dressing percentage, meat-to-bone ratio, moisture and fat deposition, fatty acid composition, and rate of oxidation development during refrigerated storage. EXPERIMENTAL Ten different corn-soybean meal diets were used in this study; 5 were formulated with protein, and 5 with protein. At each protein level, a basal diet with no added fat was compared with 4 other diets which had 5 fat substituted for an equal weight of corn. The fats used were either beef tallow, coconut oil, safflower oil, or menhaden oil. The protein diet was composed of yellow corn meal, soybean meal and other minor ingredients as shown in Table 1. The protein diets were obtained by varying the ratio of corn and soybean meal. The fatty acid composition of each diet was determined by gas-liquid chromatography. Each diet was fed to 12 male broilertype chicks from hatching to 58 days of age. The experiment was replicated twice. All values reported are means of observations for both replications except tissue fatty acids which were determined only in the second replication. The chickens were housed in battery brooders and allowed free access to feed and water. The chickens were weighed and slaughtered at 58 days of age after withholding the feed for 8 hours. After scalding, the carcasses were picked on a drum-type picker, eviscerated, cooled for 2 hours in ice water, weighed (with giblets), and split into halves. The right half of each carcass was weighed and placed with 83 C. water in 404 X 700 cans. The cans were sealed, autoclaved for 20 minutes at 1 C, cooled, stored, and later opened for analysis. After opening, the contents were re-weighed, and the bones separated from the meat and weighed. The meat and fluids were then homogenized in a one-gallon Waring Blendor, and a portion of the homogenate transferred to tared bottles. The bottles were weighed, the samples freeze-dried, and the bottles re-weighed. Portions of the dried Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20
DIET AND CARCASS MPOSITION 3 TABLE 2.Fatty acid composition of 10 different diets Protein Added fat 1 Fatty acid 2 8:0 10:0 12:0 14:0 14:1 :0 :1 :2 17:0 18:0 18:1 18:2 18:3 20:2 18:4 20:3 20:4 20:5 22:5 22:6 None 0.1 13.2 2.4 31.3 5 1.6. None 3.7 5.0 19.2 14.0 11.9 2.9 18.6 23.7 3.0 22.6 2.1 19.3 29.1 2 1.2 10.1 2.6 2 65.5 4.9 17.9 6.0 3.8 22.9 23.0 1.2 1.6 8.4 6.5 0.1 13.1 2.5 3 51.3 1.6 3.6 6.2 21.4.1 12.4 2.8.3 2 3.0 22.1 1.8 19.7 3 18.9 1.5 11.4 1.8 18.8 67.2 Total fat 3 3.2 8.1.1.1 2.6 7.4 7.4 7.4 7.4 4.9 18.9 6.4 3.9 22.5 19.9 1.4 2.2 9.1 6.7 1 = coconut oil; =beef tallow; = safflower oil; = menhaden oil. 2 Fatty acid denoted by carbon chain length and number of double bonds. Each fatty acid expressed as a percent of total fatty acids. 3 Fat was determined in basal diets and estimated in supplemented diets. samples were extracted with chloroform as outlined by Marion et al. (1965). From the data obtained on the right half, meat-tobone ratio, and the levels of moisture, fat, and fat-free solids (F.F.S.) were calculated for each carcass. The fatty acid composition of each chloroform extract from the second replication was determined by G.L.C. as reported previously (Marion and Woodroof, 1963). The left half of each carcass was placed in a polyethylene bag, stored for 12 days at 2 C, and then sampled for oxidation tests. Samples of both white meat and skin were excised from the carcass and analyzed for oxidation development by the 2-thiobarbituric acid (TBA) method of Tarladgis et al. (1960). With the exception of feed conversion values, all data obtained were subjected to an analysis of variance. Individual treatment significance was determined by the multiple range test of Duncan (1955). RESULTS AND DISCUSSION Table 2 shows the total fat and the fatty acid composition of all 10 experimental diets. The low protein basal diet contained a higher proportion of corn to soybean meal and had more extractable fat than the high protein basal diet. Within each protein level the different added fats provided a wide range of available fatty acids, differing both in carbon chain length and degree of unsaturation. The effects of the different experimental diets on various growth and carcass characteristics are shown in Table 3. Chickens fed the high protein diets had significantly higher body weights at 58 days of age than those fed the low protein diets. Also, the addition of coconut oil or beef tallow to the Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20
4 J. E. MARION AND J. G. WOODROOF TABLE 3.Effect of diet on body weight, feed conversion, dressing percentage, and carcass composition Dietary protein Added fat 1 type none none Body weight 2 gms. 1535» 1501 1525" 1558" 1570 1762" 19" 1913" 1863 b 1764 b Feed conv. 3 2.35 2.34 2.34 2. 2.34 2.19 1.96 2.04 1.96 2.07 Dressed carcass 2,4 75.7" 76.5" 77.6 b 76.7"b 77.5" 77.6" 77.2b 76> b 77. &> 77.lt> Carcass yield 2,6 Bone Meat 1 11.2 1 1 1 11.2 1 11.2 11.4 11.6 89 1 88 8 89 0 89 4 89 0 88 8 89 4 88 8 88 6 88 4 Meat composition 2 H 2 0 Lipid FFS 68.2" 66.4 b 65. 6 66.0 b 66.6 h 72.2 d 68.2» 69.6» 69.6" 70.1" 1 = coconut oil; =bee tallow; = safflower oil; = menhaden oil. 2 Values with the same superscript letter are not significantly different (P<0.05). 3 Grams of feed consumed/grams of weight gain. 4 Dressed carcass wt.+giblets/live body wt.xloo. 6 Bone (or meat) wt. in carcass/carcass wt.xloo. Protein added fat 1 Fatty acid 2 10:0 12:0 14:0 14:1 :0 :1 18:0 18:1 18:2 18:3 18:4 20:5 15.2» 15.8".6» 17.8 b 17.O b 8.8 13.0 d 12.4 d 11.6 d 9.6 CS.6» b 19.3 cd 17.8 b0.2» 15.6» 19.0" 1 18.9 cd 18.2" 18.8^ 2 d high protein diets significantly increased body weights. An increase in growth rate due to added fat at the higher protein level might be expected as a result of creating a more favorable calorie-protein ratio. However, no explanation, other than differences in metabolizable energy values of the different fats, can be offered for the variations in growth response to the various fats at the high protein level. The differences noted were consistent for the two replications. Feed conversion values were reduced by increasing protein level or by adding either fat to the high protein basal diet. Carcass dressing percentages ranged from a mean of 75.7 for the low protein basal diet to 77.6 for two of the high protein diets. Adding fat or raising the protein level appeared to increase dressing percentages although the differences were not large. Essary et al. (1965) reported that varying dietary protein and fat levels did TABLE 4.Fatty acid composition of carcasses as affected by dietary protein and fat None 23.6 7.5 5.7 41.9 19.8 14.9 7.7 19.9 4.8 4.8 29.9 15.8 2.2 23.0 7.4 6.7 44.2 14.5 17.4 3.5 4.4 26.6 47.0 3.1.9 9.2 3.3 33.5 18.5 2.8 None 25.7 7.4 6.2 38.6 20.1 17.5 11.3 1.3 2 3.8 4.6 23.0.1 2.4 1.2 25.3 5.8 8.8 38.2.5 1.5 14.4 2.2 4.5 2 56.6 3.9 23.4 8.1 6.7 29.1 22.2 2.9 1.7 1 = coconut oil; =beef tallow; = safflower oil; = menhaden oil. 2 Fatty acid denoted by carbon chain length and number of double bonds. Each fatty acid expressed as a percent_of total fatty acids. Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20
DIET AND CARCASS MPOSITION 5 not appreciably influence dressing percentages of 10-week old broilers. In the present study the proportion of bone to meat in carcasses was not significantly influenced by changes in either dietary protein or fat. Meat composition, or the proportion of moisture, lipids, and fat-free solids, was significantly influenced by diet. Moisture and lipid levels were inversely related, as reported by Donaldson et al. (1956), and were affected by diet more than the level of fat-free solids. Meat moisture levels were generally lower when fat supplemented and low proteins diets were fed. Fat-free solids were generally higher when the high protein diets were fed or when coconut oil or beef tallow was added to the low protein basal diet. The increased deposition of carcass lipids at the expense of tissue moisture, due to feeding low protein or fat supplemented diets in the present experiment, adds weight to the conclusion of Donaldson et al. (1956) and Rand et al. (1957) that carcass fat deposition is controlled primarily by dietary protein level, or calorie-protein ratio. Table 4 shows the fatty acid composition of the homogenized carcass meat. No fatty TABLE 5.Statistical significance of dietary induced changes in carcass fatty acids Fatty acid 1 10:0 12:0 14:0 14:1 :0 :1 18:0 18:1 18:2 18:3 18:4 20:5 Protein level 2 Fat source Protein X fat 1 Fatty acid denoted by carbon chain length and number of double bonds. 2 = not statistically significant; and = significance at the 5 and 1 level of probability; = not analyzed statistically. TABLE 6.TBA values of tissues as affected by dietary protein and fat Dietary protein Added fat 1 type Breast 6 ab 4» b 0 5 ab 1.72= 1.76" 1.68 cd 1.44 d 9 b 2.08 TBA value 2 Skin 1.75 b 1.59 b 1.28" 2.00 ab 6.02 2.51 b 2.17" b 2.14» b 2.71 b 6. 1 = coconut oil; = beef tallow; = safflower oil; = menhaden oil. 2 Values with the same superscript letter are not significantly different (P<0.05). TBA value = mg. malonaldehyde/1,000 gms. meat. acids beyond linolenic acid (18:3) were detected except when menhaden oil was fed, in which case eicosapentaenoic acid (20:5) was the most unsaturated acid detected. It appeared that appreciable quantities of most of the major fatty acids in each dietary fat were deposited in carcass meat. This resulted in carcasses having widely different fatty acid compositions and, consequently, very different physical characteristics. The particular fatty acid changes associated with feeding different dietary fats were similar to those noted for adipose and skin tissues in a previous study (Marion and Woodroof, 1963). More palmitic (:0), stearic (18:0), linoleic (18:2), and linolenic acids, and less palmitoleic (.1) and oleic acids (18.1) were deposited in carcasses of chickens that received the high protein diets than in those fed the low protein diets. Table 5 shows the results of a factorial statistical analysis of dietary induced changes in carcass fatty acids. The analysis revealed that most of the major fatty acids were influenced significantly by dietary protein and fat, and showed a significant Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20
6 J. E. MARION AND J. G. WOODEOOF interaction between protein level and fat source. Mean TBA values for each dietary treatment are shown in Table 6. For each treatment, TBA values in skin tissue were higher than the values observed in breast muscle. Generally, the breast muscle and skin tissues from chickens reared on high protein diets oxidized more rapidly than those fed low protein diets. Oxidation levels also appeared to be related to the unsaturation of tissue fatty acids. Slightly lower values were noted for carcasses from coconut oil or beef tallow diets, while values for carcasses from menhaden oil diets, and sometimes safflower oil diets, were higher than those for the basal diets. From the work of Chu and Kummerow (1950), Essary and Darrow (1955), and Carlson et al. (1957), some of the above differences observed when the various fat supplemented diets were fed could have been predicted. This report, however, is the first to show such pronounced differences in the stability of poultry meat resulting from feeding diets differing in protein level. Several factors should be considered before this phenomenon is attributed to protein level per se. One of these is the possibility that naturally occurring antioxidants, as well as the added ones, in the diet were concentrated in the carcasses of chickens on the low protein diets as a result of poorer feed conversion. Another possibility is that the higher level of carcass fat (primarily neutral lipids) which was deposited as a result of feeding low protein diets may have physically "protected" the polar tissue lipids which are primarily responsible for oxidative changes. Some differences in oxidation values might be expected as a result of the differences in fatty acid composition of the high and low protein diets. However, the variations in fatty acids resulting from feeding different protein levels were not very large and would not be expected to account for the relatively large differences in TBA values. SUMMARY Male, broiler-type chicks were reared to 58 days of age on corn-soybean meal diets containing either or protein, and one of the following added fats: none, coconut oil, beef tallow, safflower oil, or menhaden oil. Dressing percentages were significantly, but not markedly, influenced by diet, while the proportion of meat to bones in dressed carcasses was not changed by diet. Carcass moisture levels were significantly lower when either low protein or fat supplemented diets were fed. Carcass lipid levels were inversely related to moisture levels. Feeding different fats resulted in an increased carcass deposition of the major fatty acids present in each fat. Also, birds fed high protein diets deposited less oleic and more linoleic acid in their carcasses. TBA values, determined on breast muscle and skin after storage of carcasses for 12 days at 2 C, were significantly higher in carcasses from high protein or menhaden oil diets. Diets containing coconut oil or beef tallow produced carcasses with lower TBA values, and feeding safflower oil caused slightly higher values in skin tissue only. REFERENCES Carlson, D., L. M. Potter, L. D. Matterson, E. P. Singsen, G. L. Gilpin, R. A. Redstrom and E. H. Dawson, 1957. Palatability of chickens fed diets containing different levels of fish oil or tallow. I. Evaluation by a consumer-type panel. II. Evaluation by a trained panel. Food Tech. 11: 615-620. Chu, T. K., and F. A. Kummerow, 1950. The deposition of linolenic acid in chickens fed linseed oil. Poultry Sci. 29 : 846-851. Dansky, L. M., and F. W. Hill, 1952. The influence of dietary energy level on the distribution of fat in various tissues of the growing chickens. Poultry Sci. 31: 912. Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20
DIET AND CARCASS MPOSITION 7 Darrow, M. I., and E. O. Essary, 1955. Influence of fats in rations on storage equality of poultry, Poultry Sci. 34: 427-431. Donaldson, W. E., G. F. Combs and G. L. Romoser, 1956. Studies on energy levels in poultry rations. I. The effect of calorie-to-protein ratio of the ration on growth, nutrient utilization and body composition of chicks. Poultry Sci. 35: 1100-1105. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Essary, E. O., and L. E. Dawson, 1965. Quality of fryer carcasses as related to protein and fat levels in the diet. I. Fat deposition and moisture pick-up during chilling. Poultry Sci. 44: 7-15. Essary, E. O., L. E. Dawson, E. L. Wisman and C. E. Holmes, 1965. Influence of different levels of fat and protein in broiler rations on live weight, dressing percentage and specific gravity of carcasses. Poultry Sci. 44: 304-305. Fraps, G. S., 1943. Relation of the protein, fat and energy of the rations to the composition of chickens. Poultry Sci. 22: 421-4. Harshaw, H. M., 1936. Effect of diet, range, and fattening on the physical and chemical composition of cockerels. J. Agri. Res. 53: 357-368. Marion, J. E., and J. G. Woodroof, 1963. The fatty acid composition of breast, thigh, and INTRODUCTION THORNTON et al. (1957) and Waibel and Johnson (1961) have demonstrated that ration protein levels of 11 to 13 percent in corn-soybean meal rations will support a reasonable level of egg production when such rations are supplemented with certain amino acids. Bray (1960) and (1964) using corn-soybean meal laying rations found that low-protein rations supported satisfactory egg production and maintained desirable egg weights when properly supplemented with amino acids. Little information is available concernskin tissues of chicken broilers as influenced by dietary fats. Poultry Sci. 42: 1202-1207. Marion, J. E., J. G. Woodroof and R. E. Cook, 1965. Some physical and chemical properties of eggs from hens of five different stocks. Poultry Sci. 44: 529-534. Newell, G. W., J. L. Fry and R. H. Thayer, 1956. The effect of fat in the ration on fat deposition in broilers. Poultry Sci. 35: 12-13. Rand, N. T., F. A. Kummerow and H. M. Scott, 1957. The relationship of dietary protein, fat, and energy on the amount, composition and origin of chick carcass fat. Poultry Sci. 36: 1151. Spring, J. L., and W. S. Wilkinson, 1957. The influence of dietary protein and energy level on body composition of broilers. Poultry Sci. 36: 1159. Summers, J. D., S. J. Slinger and G. C. Ashton, 1965. The effect of dietary energy and protein on carcass composition with a note on a method for estimating carcass composition. Poultry Sci. 44: 501-509. Tarladgis, B. G., B. M. Watts, M. T. Younathan and L. Dugan, Jr., 1960. A distillation method for the quantitative determination of malonaldehyde in rancid foods. J. Amer. Oil Chemists' Soc. 37: 44-48. Wheat-Soybean Meal Rations for Laying Hens J. L. SELL AND G. C. HODGN Department of Animal Science, The University of Manitoba, Winnipeg 19, Manitoba, Canada (Received for publication August 26, 1965) ing the efficacy of low-protein, wheat-soybean meal laying hen rations, with or without amino acid supplementation. March and Biely (1963) reported that the addition of lysine and methionine to diets containing 14 protein had a dramatic effect on egg weight. The diets used were composed primarily of wheat and soybean meal, and although the study was of relatively short duration, level of egg production was good. The data reported herein describe the use of low-protein, wheat-soybean meal rations for laying hens and the influence of Downloaded from http://ps.oxfordjournals.org/ at Penn State University (Paterno Lib) on September, 20