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Use of triticale as a replacement for wheat middlings in diets for Atlantic salmon
90 (1990) 173-178 Elsevier Science Publishers B.V., Amsterdam
Aquacufture,
173
IJse of triticale as a replacement for wheat middlings in diets for Atlantic salmon Steven G. Hughes US. Fish and Wildlife Service, Tunison Laboratory, Monell Chemical Senses Center. 3500 Market Street, Philadelphia, PA 19104 (U.S.A.)
(Accepted 9 April 1990)
ABSTRACT Hughes, S.G., 1990. Use of triticale as a replacement for wheat middlings in diets for Atlantic salmon. Aquaculture, 90: 173-178. A study was conducted to determine the value of triticale (a hybrid between rye and wheat) as a substitute for wheat middlings in the diet of Atlantic salmon (Salmo salar). Data on growth and carcass composition of fish fed the experimental diets containing triticale were comparable to those of fish fed the control diet with wheat middlings. No differences in diet acceptability were apparent when triticale was substituted for wheat middlings in the basal ration. Though the effect of triticale substitution on pellet quality (i.e., durability) is not known, the results indicated that this hybrid grain can ‘be used as a nutritional substitute for wheat middlings in the diet of salmonids, and that further evaluation of this potential feed ingredient is warranted.
INTRODUCTION
As a general rule, diets for salmonids are formulated to contain relatively low (i.e., < 5%) concentrations of fiber due to the inability of these fish to effectively handle larger amounts (Smith, 197 1; Poston, 1986). With this general rule in mind, feed manufacturers are constantly searching for ingredients that will help to supply the protein requirement of salmonids on the one hand, and not add significant amounts of fiber to the diet on the other. Triticale, a genetic cross between rye and wheat, is a relatively new feedstuff that is just beginning to become available in large quantities on the commodities market. Its production is expected to continue to increase in North America and in many other countries worldwide. One of the primary low protein feedstuffs used in fish feeds in the United States is wheat middlings, but the use of this feedstuff is often limited by its high fiber content and the need to reach relatively high percentages (45-60%) of protein in certain fish feed formulations. The protein content is higher and fiber is lower in triticale than in wheat middlings. Many studies have been conducted on its use in diets for 0044-848’6/90/$03.50
0 1990 - Elsevier Science Publishers B.V.
174
S.G. HUGHES
poultry (Sell et al., 1962; Bragg and Sharby, 1970; Femandez et al., 1973; Femandez and McGinnis, 1974; Marquez and Avila, 1974; Yagoob and Netke, 1975; Davidson and Davidson, 1979; Halvorson et al., 1983; Nilipour et al., 1987; Proudfoot and Hulan, 1988; Rundgren, 1988) and swine (Comejo et al., 1973; Erickson et al., 1979; Farrell et al., 1983; Batterham et al., 1988; Rundgren, 1988; Myer et al., 1989), but no studies to date have been conducted on its use in diets for lish. In view of the relatively poor digestibility of fiber by salmonids, triticale may provide an alternative to wheat middlings in diets where a low-protein feedstuff is needed to act as a filler. A study was undertaken to examine both the economic and nutritional feasibility of using triticale in diets for Atlantic salmon (Sulmo salar). METHODS
A random sample of 270 Atlantic salmon (average weight 11.6 g ) was obtained from a population maintained at the Tunison Laboratory of Fish Nutrition, Cortland, NY, and randomly assigned them to nine 6.5-l Plexiglass hatchery jars (30 fish/jar) supplied with aerated well water (8.5-8.9”C) at 1.5 l/min. The diets were based on the federal specification diet PR6 (Piper et al., 1982), which was used as the control ration (Table 2). Triticale was substituted for wheat middlings on the basis of either an equal unit of nitrogen ( Trit-N ) or an equal weight (T&-W). All diets were mixed immediately before the start of the experiment, pelleted, and stored in sealed plastic bags at 0’ C. Each diet was randomly assigned to the fish in three of the nine jars. The fish were fed live times daily for the experimental period of 14 weeks. During the experiment, the amount of food fed was based on a hatchery constant of 5.5, calculated according to the method of Buterbaugh and Willoughby ( 1967 ). Amounts of feed required were calculated weekly and fish were observed daily for unusual behavior and morphologic changes. Total fish weight of each replicate was determined biweekly and weight gains and feed efficiency ratios were determined from these data. Samples of each diet and the triticale and wheat middlings used in the diets were taken for composition analyses. Also, at the end of the study, five fish from each replicate were sacrificed for carcass composition analyses. In all of these analyses, the methods described in the manual of the Association of Official Analytical Chemists ( 1984) were followed for carcass protein, fat and ash content. Carcass moisture was determined by using the method described by Hughes ( 198 8 ) in which a lyophilizer is used. Dried carcasses were ground, and duplicate subsamples were analyzed for protein, fat, and ash. The analyses of the feed ingredients are shown in Table 1 and of the diets in Table 2.
TRITICALE: IN DIETS FOR ATLANTIC SALMON
175
TABLE 1 Percent composition
(as fed) of triticale and wheat middlings used in this study
Component
Triticale
Wheat
Moisture Protein (Nx6.25) Fat Ash Fiber
10.6 16.9 1.6 2.2 3.2
10.1 15.9 3.0 9.1 1.5
TABLE 2 Percent and proximate composition
of control and experimental
Ingredient
Control
T&-N”
T&-W”
Herring meal Soybean rneal Alfalfa meal Corn gluten meal Wheat middlings Whey, dried Soy oil Vitamin mix #30b Mineral mix # 1b Choline chloride (70%) Ascorbic acid Distillers solubles & grains Brewers yeast Perma-Pe I Triticale
35.0 10.0 3.0 6.0 18.1 10.0 3.0 0.4 0.1 0.3 0.1 8.0 5.0
35.0 10.0 3.0 6.0
35.0 10.0 3.0 6.0
10.0 3.0 0.4 0.1 0.3 0.1 8.0 5.0 1.2 16.9
10.0 3.0 0.4 0.1 0.3 0.1 8.0 5.0
40.8 9.5 9.2 8.9
40.0 9.3 8.9 9.6
Proximate composition Protein Fat Ash Moisture
(as fed) 40.5 10.0 10.1 9.0
diets
18.1
“Triticale replaced the wheat middlings in the control diet on either a unit nitrogen (Trit-N) or weight (T&-W ) basis. bSee Hughes ( 1988 ) for composition of these mixes.
The means of all data were subjected to one-way analysis of variance (Steel and Torrie, 1980) using PI 0.25. RESULTS
The weight gain of Atlantic salmon fed either of the experimental diets was equal to that of the fish fed the control diet (Table 3 ) . Carcass composition
S.G. HUGHES
176 TABLE 3
Final weight, weight gain, and feed efficiency (FE)” values for Atlantic salmon fingerlings (initial average weight 11.6 g/fish) fed a control diet containing wheat middlings or one of two experimental diets where triticale replaced the wheat middlings on either a unit nitrogen (N) or weight (W) basis. All values represent means of three replicates ( k s.d.). Differences between treatments within a column were not significant (P20.25) Diet description
Final weight (g)
Total gain (9)
FE (%)
Control Triticale (N) Triticale (W)
28.9f0.4 28.9k0.3 29.0k0.7
17.3f0.5 17.4k0.2 17.5kO.7
77.1 k 1.3 78.9f2.7 80.6k2.5
“FE = 100 (total weight gained, g) / (total food fed, g).
data showed no differences between fish fed the experimental or the control diet (average values as percent of dry weight were 69.1% protein, 20.2% fat, 9.7% ash; moisture was 75.2% of wet weight). No deaths or physical abnormalities occurred in any of the fish in this experiment. Also, no differences in diet acceptability were noted when triticale was substituted for wheat middlings.
DISCUSSION
Though further research is needed to ascertain the effect of the substitution of triticale on pellet durability, the present results indicated that this grain can be used as a nutritional substitute for wheat middlings in the diet of Atlantic salmon and that further study of this new feed ingredient is warranted. Because of the current glut of wheat in United States’ markets (National Research Council, 1989) and its more competitive price (cost of triticale is about 1.4 times that of wheat middlings), it is most likely that, for the time being, most of the triticale grown in the United States will find its way into the animal feedstuff market in spite of projected increases in production (National Research Council, 1989). This availability in the feedstuff market should bode well for fish feed manufacturers located in areas where triticale is grown in quantity (e.g., the northwestern and southeastern United States) who should find this grain in good supply at a reasonable cost. When this increased availability is factored in with the results of the present study, the higher protein and lower fiber content of triticale may lead to its incorporation into certain feed formulations such as starter diets, despite this additional cost, where ingredients with a lower fiber content are generally desired and used.
TRITICALE IN DIETS FOR ATLANTIC SALMON
177
ACKNOWLEDGEMENT
I thank Gary Reistenberg, International Nutrition and Genetics Corp., Perham, MN, for providing the triticale used in this study.
REFERENCES Association of Official Analytical Chemists, 1984. S. Williams (Editor), Official Methods of Analysis of the Association of Official Analytical Chemists, 14th edition. Association of Official Analytical Chemists, Arlington, VA, 1141 pp. Batterham, E.S., Saini, H.S. and Andersen, L.M., 1988. Nutritional value and carbohydrate content of triticale and wheat for growing pigs. Nutr. Rep. Int., 38: 643-653. Bragg, D.B. and Sharby, T.F., 1970. Nutritive value of triticale for broiler chick diets. Poult. Sci., 40: 1022-1027. Buterbau&, G.L. and Willoughby, H., 1967. A feeding guide for brook, brown and rainbow trout. :Prog. Fish-Cult., 29: 2 10-2 15. Cornejo, !S., Potocnjak, J., Holmes, H.G. and Robinson, D.W., 1973. Comparative nutritional value of triticale for swine. J. Anim. Sci., 36: 87-89. Davidson, J. and Davidson, A.J., 1979. The nutritive value of triticale in diets for laying hens. J. Sci. Food Agric., 30: 286-290. Erickson, J.P., Miller, E.R., Elliot, F.C., Ku, P.K. and Ullrey, D.E., 1979. Nutritional evaluation of triticale in swine starter and grower diets. J. Anim. Sci., 48: 547-553. Farrell, D.J., Chan, C., McCrae, F. and McKenzie, R.J., 1983. A nutritional evaluation of trititale w:lth pigs. Anim. Feed Sci. Technol., 9: 49-62. Femandez. R. and McGinnis, J., 1974. Nutritive value of triticale for young chicks and effect of diff;:rent amino acid supplements on growth. Poult. Sci., 53: 47-53. Femandez, R., Kim, S.M., Buenrostro, J.L. and McGinnis, J., 1973. Triticale and rye as main ingredients in diets for laying hens. Poult. Sci., 52: 2244-2252. Halvorso:n, J.C., Shehata, M.A. and Waibel, P.E., 1983. White lupins and triticale as feedstuffs in diets for turkeys. Poult. Sci., 62: 1038-1044. Hughes, S.G., 1988. Effect of dietary propylene glycol on growth, survival, histology, and carcass composition of Atlantic salmon. Prog. Fish-Cult., 50: 12-l 5. Marquez, V.A. and Avila, E.G., 1974. Effect of amino acid supplementation to triticale diets. Poult. Sci., 53: 1231-1233. Myer, R.O., Bamett, R.D., Cornell, J.A. and Combs, G.E., 1989. Nutritive value of diets containing triticale and varying mixtures of triticale and maize for growing-finishing swine. Anim. Feed Sci. Technol., 22: 217-225. National Research Council, 1989. Triticale: a Promising Addition to the World’s Cereal Grains. National Academy Press, Washington, DC, 103 pp. Nilipour, A.H., Savage, T.F. and Nakaue, H.S., 1987. The influence of feeding triticale (Var: Flora) and varied crude protein diets on the seminal production of medium white turkey breeder toms. Nutr. Rep. Int., 36: 15 l-l 60. Piper, R.G., McElwain, I.B., Orme, L.E., McCraren, J.P., Fowler, L.G. and Leonard, J.R., 1982. Fish Hatchery Management. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, 5 17 pp. Poston, H.A., 1986. Response of lake trout and rainbow trout to dietary cellulose. Fish and Wildlife Technical Report 5. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, 6 pp.
178
S.G. HUGHES
Proudfoot, F.G. and Hulan, H.W., 1988. Nutritive value of triticale as a feed ingredient for broiler chickens. Poult. Sci., 67: 1743- 1749. Rundgren, M., 1988. Evaluation of triticale given to pigs, poultry and rats. Anim. Feed Sci. Technol., 19: 359-375. Sell, J.L., Hodgson, G.C. and Shebeski, L.H., 1962. Triticale as a potential component of chick rations. Can. J. Anim. Sci., 42: 158-l 66. Smith, R.R., 197 1. A method of measuring digestibility and metabolizable energy of fish feeds. Prog. Fish-Cult., 33: 132-l 34. Steel, R.G.D. and Tonie, J.H., 1980. Principles and Procedures of Statistics, 2nd edition. McGraw-Hill, New York, NY, 633 pp. Yaqoob, M.M. and Netke, S.P., 1975. Studies on the incorporation of triticale in diets for growing chicks. Br. Poult. Sci., 16: 45-54.
Aquacufture,
173
IJse of triticale as a replacement for wheat middlings in diets for Atlantic salmon Steven G. Hughes US. Fish and Wildlife Service, Tunison Laboratory, Monell Chemical Senses Center. 3500 Market Street, Philadelphia, PA 19104 (U.S.A.)
(Accepted 9 April 1990)
ABSTRACT Hughes, S.G., 1990. Use of triticale as a replacement for wheat middlings in diets for Atlantic salmon. Aquaculture, 90: 173-178. A study was conducted to determine the value of triticale (a hybrid between rye and wheat) as a substitute for wheat middlings in the diet of Atlantic salmon (Salmo salar). Data on growth and carcass composition of fish fed the experimental diets containing triticale were comparable to those of fish fed the control diet with wheat middlings. No differences in diet acceptability were apparent when triticale was substituted for wheat middlings in the basal ration. Though the effect of triticale substitution on pellet quality (i.e., durability) is not known, the results indicated that this hybrid grain can ‘be used as a nutritional substitute for wheat middlings in the diet of salmonids, and that further evaluation of this potential feed ingredient is warranted.
INTRODUCTION
As a general rule, diets for salmonids are formulated to contain relatively low (i.e., < 5%) concentrations of fiber due to the inability of these fish to effectively handle larger amounts (Smith, 197 1; Poston, 1986). With this general rule in mind, feed manufacturers are constantly searching for ingredients that will help to supply the protein requirement of salmonids on the one hand, and not add significant amounts of fiber to the diet on the other. Triticale, a genetic cross between rye and wheat, is a relatively new feedstuff that is just beginning to become available in large quantities on the commodities market. Its production is expected to continue to increase in North America and in many other countries worldwide. One of the primary low protein feedstuffs used in fish feeds in the United States is wheat middlings, but the use of this feedstuff is often limited by its high fiber content and the need to reach relatively high percentages (45-60%) of protein in certain fish feed formulations. The protein content is higher and fiber is lower in triticale than in wheat middlings. Many studies have been conducted on its use in diets for 0044-848’6/90/$03.50
0 1990 - Elsevier Science Publishers B.V.
174
S.G. HUGHES
poultry (Sell et al., 1962; Bragg and Sharby, 1970; Femandez et al., 1973; Femandez and McGinnis, 1974; Marquez and Avila, 1974; Yagoob and Netke, 1975; Davidson and Davidson, 1979; Halvorson et al., 1983; Nilipour et al., 1987; Proudfoot and Hulan, 1988; Rundgren, 1988) and swine (Comejo et al., 1973; Erickson et al., 1979; Farrell et al., 1983; Batterham et al., 1988; Rundgren, 1988; Myer et al., 1989), but no studies to date have been conducted on its use in diets for lish. In view of the relatively poor digestibility of fiber by salmonids, triticale may provide an alternative to wheat middlings in diets where a low-protein feedstuff is needed to act as a filler. A study was undertaken to examine both the economic and nutritional feasibility of using triticale in diets for Atlantic salmon (Sulmo salar). METHODS
A random sample of 270 Atlantic salmon (average weight 11.6 g ) was obtained from a population maintained at the Tunison Laboratory of Fish Nutrition, Cortland, NY, and randomly assigned them to nine 6.5-l Plexiglass hatchery jars (30 fish/jar) supplied with aerated well water (8.5-8.9”C) at 1.5 l/min. The diets were based on the federal specification diet PR6 (Piper et al., 1982), which was used as the control ration (Table 2). Triticale was substituted for wheat middlings on the basis of either an equal unit of nitrogen ( Trit-N ) or an equal weight (T&-W). All diets were mixed immediately before the start of the experiment, pelleted, and stored in sealed plastic bags at 0’ C. Each diet was randomly assigned to the fish in three of the nine jars. The fish were fed live times daily for the experimental period of 14 weeks. During the experiment, the amount of food fed was based on a hatchery constant of 5.5, calculated according to the method of Buterbaugh and Willoughby ( 1967 ). Amounts of feed required were calculated weekly and fish were observed daily for unusual behavior and morphologic changes. Total fish weight of each replicate was determined biweekly and weight gains and feed efficiency ratios were determined from these data. Samples of each diet and the triticale and wheat middlings used in the diets were taken for composition analyses. Also, at the end of the study, five fish from each replicate were sacrificed for carcass composition analyses. In all of these analyses, the methods described in the manual of the Association of Official Analytical Chemists ( 1984) were followed for carcass protein, fat and ash content. Carcass moisture was determined by using the method described by Hughes ( 198 8 ) in which a lyophilizer is used. Dried carcasses were ground, and duplicate subsamples were analyzed for protein, fat, and ash. The analyses of the feed ingredients are shown in Table 1 and of the diets in Table 2.
TRITICALE: IN DIETS FOR ATLANTIC SALMON
175
TABLE 1 Percent composition
(as fed) of triticale and wheat middlings used in this study
Component
Triticale
Wheat
Moisture Protein (Nx6.25) Fat Ash Fiber
10.6 16.9 1.6 2.2 3.2
10.1 15.9 3.0 9.1 1.5
TABLE 2 Percent and proximate composition
of control and experimental
Ingredient
Control
T&-N”
T&-W”
Herring meal Soybean rneal Alfalfa meal Corn gluten meal Wheat middlings Whey, dried Soy oil Vitamin mix #30b Mineral mix # 1b Choline chloride (70%) Ascorbic acid Distillers solubles & grains Brewers yeast Perma-Pe I Triticale
35.0 10.0 3.0 6.0 18.1 10.0 3.0 0.4 0.1 0.3 0.1 8.0 5.0
35.0 10.0 3.0 6.0
35.0 10.0 3.0 6.0
10.0 3.0 0.4 0.1 0.3 0.1 8.0 5.0 1.2 16.9
10.0 3.0 0.4 0.1 0.3 0.1 8.0 5.0
40.8 9.5 9.2 8.9
40.0 9.3 8.9 9.6
Proximate composition Protein Fat Ash Moisture
(as fed) 40.5 10.0 10.1 9.0
diets
18.1
“Triticale replaced the wheat middlings in the control diet on either a unit nitrogen (Trit-N) or weight (T&-W ) basis. bSee Hughes ( 1988 ) for composition of these mixes.
The means of all data were subjected to one-way analysis of variance (Steel and Torrie, 1980) using PI 0.25. RESULTS
The weight gain of Atlantic salmon fed either of the experimental diets was equal to that of the fish fed the control diet (Table 3 ) . Carcass composition
S.G. HUGHES
176 TABLE 3
Final weight, weight gain, and feed efficiency (FE)” values for Atlantic salmon fingerlings (initial average weight 11.6 g/fish) fed a control diet containing wheat middlings or one of two experimental diets where triticale replaced the wheat middlings on either a unit nitrogen (N) or weight (W) basis. All values represent means of three replicates ( k s.d.). Differences between treatments within a column were not significant (P20.25) Diet description
Final weight (g)
Total gain (9)
FE (%)
Control Triticale (N) Triticale (W)
28.9f0.4 28.9k0.3 29.0k0.7
17.3f0.5 17.4k0.2 17.5kO.7
77.1 k 1.3 78.9f2.7 80.6k2.5
“FE = 100 (total weight gained, g) / (total food fed, g).
data showed no differences between fish fed the experimental or the control diet (average values as percent of dry weight were 69.1% protein, 20.2% fat, 9.7% ash; moisture was 75.2% of wet weight). No deaths or physical abnormalities occurred in any of the fish in this experiment. Also, no differences in diet acceptability were noted when triticale was substituted for wheat middlings.
DISCUSSION
Though further research is needed to ascertain the effect of the substitution of triticale on pellet durability, the present results indicated that this grain can be used as a nutritional substitute for wheat middlings in the diet of Atlantic salmon and that further study of this new feed ingredient is warranted. Because of the current glut of wheat in United States’ markets (National Research Council, 1989) and its more competitive price (cost of triticale is about 1.4 times that of wheat middlings), it is most likely that, for the time being, most of the triticale grown in the United States will find its way into the animal feedstuff market in spite of projected increases in production (National Research Council, 1989). This availability in the feedstuff market should bode well for fish feed manufacturers located in areas where triticale is grown in quantity (e.g., the northwestern and southeastern United States) who should find this grain in good supply at a reasonable cost. When this increased availability is factored in with the results of the present study, the higher protein and lower fiber content of triticale may lead to its incorporation into certain feed formulations such as starter diets, despite this additional cost, where ingredients with a lower fiber content are generally desired and used.
TRITICALE IN DIETS FOR ATLANTIC SALMON
177
ACKNOWLEDGEMENT
I thank Gary Reistenberg, International Nutrition and Genetics Corp., Perham, MN, for providing the triticale used in this study.
REFERENCES Association of Official Analytical Chemists, 1984. S. Williams (Editor), Official Methods of Analysis of the Association of Official Analytical Chemists, 14th edition. Association of Official Analytical Chemists, Arlington, VA, 1141 pp. Batterham, E.S., Saini, H.S. and Andersen, L.M., 1988. Nutritional value and carbohydrate content of triticale and wheat for growing pigs. Nutr. Rep. Int., 38: 643-653. Bragg, D.B. and Sharby, T.F., 1970. Nutritive value of triticale for broiler chick diets. Poult. Sci., 40: 1022-1027. Buterbau&, G.L. and Willoughby, H., 1967. A feeding guide for brook, brown and rainbow trout. :Prog. Fish-Cult., 29: 2 10-2 15. Cornejo, !S., Potocnjak, J., Holmes, H.G. and Robinson, D.W., 1973. Comparative nutritional value of triticale for swine. J. Anim. Sci., 36: 87-89. Davidson, J. and Davidson, A.J., 1979. The nutritive value of triticale in diets for laying hens. J. Sci. Food Agric., 30: 286-290. Erickson, J.P., Miller, E.R., Elliot, F.C., Ku, P.K. and Ullrey, D.E., 1979. Nutritional evaluation of triticale in swine starter and grower diets. J. Anim. Sci., 48: 547-553. Farrell, D.J., Chan, C., McCrae, F. and McKenzie, R.J., 1983. A nutritional evaluation of trititale w:lth pigs. Anim. Feed Sci. Technol., 9: 49-62. Femandez. R. and McGinnis, J., 1974. Nutritive value of triticale for young chicks and effect of diff;:rent amino acid supplements on growth. Poult. Sci., 53: 47-53. Femandez, R., Kim, S.M., Buenrostro, J.L. and McGinnis, J., 1973. Triticale and rye as main ingredients in diets for laying hens. Poult. Sci., 52: 2244-2252. Halvorso:n, J.C., Shehata, M.A. and Waibel, P.E., 1983. White lupins and triticale as feedstuffs in diets for turkeys. Poult. Sci., 62: 1038-1044. Hughes, S.G., 1988. Effect of dietary propylene glycol on growth, survival, histology, and carcass composition of Atlantic salmon. Prog. Fish-Cult., 50: 12-l 5. Marquez, V.A. and Avila, E.G., 1974. Effect of amino acid supplementation to triticale diets. Poult. Sci., 53: 1231-1233. Myer, R.O., Bamett, R.D., Cornell, J.A. and Combs, G.E., 1989. Nutritive value of diets containing triticale and varying mixtures of triticale and maize for growing-finishing swine. Anim. Feed Sci. Technol., 22: 217-225. National Research Council, 1989. Triticale: a Promising Addition to the World’s Cereal Grains. National Academy Press, Washington, DC, 103 pp. Nilipour, A.H., Savage, T.F. and Nakaue, H.S., 1987. The influence of feeding triticale (Var: Flora) and varied crude protein diets on the seminal production of medium white turkey breeder toms. Nutr. Rep. Int., 36: 15 l-l 60. Piper, R.G., McElwain, I.B., Orme, L.E., McCraren, J.P., Fowler, L.G. and Leonard, J.R., 1982. Fish Hatchery Management. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, 5 17 pp. Poston, H.A., 1986. Response of lake trout and rainbow trout to dietary cellulose. Fish and Wildlife Technical Report 5. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, 6 pp.
178
S.G. HUGHES
Proudfoot, F.G. and Hulan, H.W., 1988. Nutritive value of triticale as a feed ingredient for broiler chickens. Poult. Sci., 67: 1743- 1749. Rundgren, M., 1988. Evaluation of triticale given to pigs, poultry and rats. Anim. Feed Sci. Technol., 19: 359-375. Sell, J.L., Hodgson, G.C. and Shebeski, L.H., 1962. Triticale as a potential component of chick rations. Can. J. Anim. Sci., 42: 158-l 66. Smith, R.R., 197 1. A method of measuring digestibility and metabolizable energy of fish feeds. Prog. Fish-Cult., 33: 132-l 34. Steel, R.G.D. and Tonie, J.H., 1980. Principles and Procedures of Statistics, 2nd edition. McGraw-Hill, New York, NY, 633 pp. Yaqoob, M.M. and Netke, S.P., 1975. Studies on the incorporation of triticale in diets for growing chicks. Br. Poult. Sci., 16: 45-54.