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Supplemental Fat and Metabolizable Energy-to-Nutrient Ratios for Growing Turkeys1
Supplemental Fat and Metabolizable Energy-to-Nutrient Ratios for Growing Turkeys1 JERRY L. SELL and WILLIAM J. OWINGS Department of Animal Science, Iowa State University, Ames, Iowa 50011 (Received for publication February 26, 1981)
1981 Poultry Science 60:2293-2305
INTRODUCTION
The use of supplemental fat has become a vital, routine part of modern poultry feeding programs. Fats can be used to improve the physical consistency of meal-type feeds and to enhance the dispersion of microingredients within the diet mixture. Supplemental fats are used primarily, however, to increase the caloric density of diets. Biely and March (1954) reported that the inclusion of up to 10% animal tallow in diets improved efficiency of feed utilization by turkeys from 1 day to 10 weeks of age. Sunde (1954) also observed improvements in feed efficiency of turkeys fed diets supplemented with white grease, tallow, or soybean oil. Subsequently, Yacowitz et al. (1956), Waibel (1958), Pepper et al. (1960), and Joshi and Sell (1964) reported that fat supplementation of meal-type diets consistently improved feed efficiency and occasionally
'Journal Paper No. J-10191 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Project 2241.
stimulated weight gains by turkeys. In 1966, Touchburn and Naber observed that the magnitude of improvement in performance of turkeys resulting from fat supplementation exceeded that expected on the basis of the recognized contribution of energy by fat to the diet. They termed this the extracaloric effect of fat. Jensen et al. (1970) confirmed that fats exerted an extracaloric effect when added to diets of turkeys reared from 8 to 24 weeks of age. Potter et al. (1974) also observed that added fat stimulated weight gain of turkeys from 8 weeks of age onward. After examining the results of several experiments, Potter (1976) stated that feed efficiency of turkeys from 8 weeks of age onward was improved 1.5 to 2.5% for each 1% of supplemental fat. Similar results were reported by Waibel et al. (1977) and Waibel (1978). deAlbuquerque et al. (1978) reported that each 1% supplemental fat improved feed efficiency by .6% but that added fat did not affect growth rate of turkeys. Owen and Waldroup (1979) presented data showing that supplemental fat stimulated gains of male turkeys from 0 to 22 weeks with maximum
2293
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ABSTRACT Supplementing diets with an animal-vegetable fat (increasing dietary metabolizable energy) at levels ranging from 1 to 8% improved rate of gain and feed efficiency of male turkeys from 1 to 140 days of age. Average body weight increased linearly (P<.05) with increments of supplemental fat in four experiments conducted. Also, the magnitude of improvements in feed efficiency were linearly (P<.05) related to supplemental fat level. These improvements in performance were observed when experiments were conducted during summer and winter seasons. Furthermore, favorable responses to supplemental fats occurred with diets based on corn or milo, although the greatest responses generally were obtained with corn-based diets. Supplemental fat had similar effects on body weight and feed efficiency whether used in diets in which the concentration of nutrients was adjusted commensurate with changes in metabolizable energy (ME) concentration or whether used in diets in which nutrient concentrations remained constant (nonadjusted diets), irrespective of ME level. Regression analysis showed that, with one exception, 140-day body weights of toms were increased from .6 to 1.5% for each 1% supplemental fat. Improvements in feed efficiency ranged from .8 to 1.9% for each 1% of supplemental fat. Supplemental fat decreased the amount of protein consumed per kilogram weight gain of toms fed the nonadjusted diet series in four experiments. The ME consumed per kilogram gain was not affected significantly (P<.05) by diet treatment in three experiments but was decreased by supplemental fat in one experiment. (Key words: dietary fat, metabolizable energy, turkeys)
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SELL AND OWINGS
The experiments reported here were conducted to obtain additional information on the usefulness of dietary fat in turkey feeding programs. The major objectives were to document the magnitude and consistency of changes in growth rate and efficiency of feed utilization associated with increments of supplemental fat ranging from 1 to 8% of the diet and to determine the consequences of maintaining or not maintaining constant dietary ME-to-nutrient ratios when fat was used to increase the energy density of diets.
MATERIALS AND METHODS
Nicholas Large White male poults were used in four experiments. The toms were brooded and grown in total confinement. Floor pens, in which .297 to .334 m 2 were allotted per
turkey, were the experimental units. The pens were equipped with heating lamps for use in brooding the poults. A hydrolyzed animal-vegetable fat obtained from a commercial source was used in the four experiments. Samples of each batch of fat were analyzed for fatty acid composition by a commercial laboratory. The fatty acid composition varied somewhat among batches, especially with respect to stearic and linoleic acids. The ranges in fatty acid concentrations were (expressed as percentage of total fatty acids): caprylic, .07 to 1.03; capric, .05 to 0.90; lauric, .11 to 6.61; myristic, 1.28 to 3.12; palmitic, 16.43 to 18.51; palmitoleic, .29 to 2.76; stearic 4.93 to 16.54; oleic, 27.52 to 38.18; linoleic 20.58 to 45.52; linolenic, 1.25 to 5.23; arachidic, none to 1.05. The combined moisture, unsaponifiable, and insoluble impurities content of the fats ranged from 3.64 to 4.71%. The manufacturer of this fat product suggested an ME value of 8140 kcal/kg, and this value was used in calculating dietary ME levels. Least-cost, linear programming (MPSX) was used to formulate all diets. The nutrient concentrations for ingredients listed by the National Research Council (NRC, 1977) were used in diet formulation except for the ME value of supplemental fat and the protein value of milo. Laboratory analysis showed that the protein content of milo (10.14 and 10.50% for Experiments 2 and 4, respectively) deviated considerably from the value given by NRC (1977), but the protein content of corn, soybean meal, and other ingredients agreed closely with those of NRC (1977). Ingredient prices prevailing at the time of the experiment were used in the diet formulation program. To maintain consistency within and among experiments, the increase in dietary ME content of diets associated with fat supplementation was fixed at 37 kcal/kg for each 1% added fat tested in all experiments. Adjustments in nutrient and ME concentrations were made during all experiments according to six age categories (1 to 21, 21 to 42, 42 to 63, 63 to 84, 84 to 112, and 112 to 140 days). Body weights and feed consumption data were recorded at the end of each age interval. Mortality and cause of mortality records were maintained. Data were analyzed statistically by the Statistical Analysis System (SAS) (Barret a/., 1979). Experiment 1. Twenty-five poults were placed in each of 36 floor pens, and 4 floor
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effects occurring at 2 and 4% added fat. Their data also showed that feed efficiency was improved by 1.4 to 2.3% for each 1% fat included in meal-type diets, but this effect of fat was not so notable with pelleted diets. Much of the foregoing research on fats for turkeys was done with diets in which the concentration of key nutrients remained constant, irrespective of level of fat supplementation. In other instances, the concentrations of protein and amino acids were changed commensurate with changes in dietary metabolizable energy (ME) resulting from fat supplementation. The importance of maintaining acceptable dietary energy-to-nutrient ratios, as suggested by Combs and Romoser (1955), has been a commonly accepted principle of poultry nutrition. Several reports, however (Day and Hill, 1957; Balloun et al, 1959; Touchburn and Naber, 1966), indicated that widely varying ME-to-protein ratios could be used without adversely affecting performance of growing turkeys. Data presented by Jensen et al. (1970) showed that 24-week body weights of toms fed diets containing relatively low protein levels and supplemented with fat generally were numerically lower than those of toms fed higher protein levels, but there was no significant protein X dietary energy level interaction observed. Waibel (1978) also reported that, when various combinations of protein and fat levels were fed to toms from 16 to 24 weeks of age, significant main effects of protein and fat level were observed but that no protein X fat interaction occurred.
FAT FOR GROWING TURKEYS
Experiment 2. The design of Experiment 2 was similar to that of Experiment 1. Supplemental fat levels tested, however, were 0, 2, 4, 6, and 8% of the diet, and three experimental units (floor pens) containing 26 toms each were assigned to each diet treatment. Also, the experiment was conducted during the summer (April to September) and the lowest and highest average temperatures in the barns during the warmest month were 20 and 29 C, respectively. Experiment 2 was terminated when the toms were 142 days old. Each dietary fat level was tested in cornbased diets that had adjusted ME-to-nutrient ratios and in diets with nonadjusted ratios. This portion of the experiment, designated Part A, consisted of 9 diet treatments. Five additional treatments were tested in Part B. These diets
contained milo as the grain component instead of corn. Supplemental fat was tested at 0, 2, 4, 6, or 8% of milo-based diets in which the ME-to-nutrient ratios had been adjusted. The same nutrient restrictions were used in formulating diets based on milo as were used for corn-based diets. Because of the lower ME content of milo, however, milo-based diets fed from 84 to 112 and 112 to 140 days of age contained 25 and 40 kcal less ME/kg, respectively, than did corn-based diets. Experiments 3 and 4. Experiment 3 was essentially a repeat of Experiment 1 with two exceptions. Fat levels tested in both the adjusted and nonadjusted diet series were 0, 2, 4, and 8%, and the trial ended when the toms were 139 days old. Experiment 3 was a winter experiment, conducted from October to March. The lowest and highest average temperatures in the barns during the coldest month were 11 and 19 C, respectively. Experiment 4 was a second summer experiment beginning in April and ending in September. The lowest and highest average temperatures in the barns during the warmest month were 24 and 32.2 C, respectively, indicating the relatively hot summer experienced in 1980. Supplemental fat levels of 0, 2, 4, and 8% again were tested in corn-based diets that had adjusted or nonadjusted ME to nutrient ratios (Part A). These same levels of supplemental fat also were tested in milo-based diets that had nonadjusted ME to nutrient ratios. Experiment 4 was terminated when the toms were 140 days of age. Four pens of 26 poults each were used per diet treatment in Experiments 3 and 4. RESULTS
Experiment 1. Average 140-day body weight and feed efficiency were improved significantly (P<.05 and .01, respectively) by supplemental fat as compared with the control (no added fat) group (Table 3). There was a significant (P<.01) linear effect of using from 1 to 7% supplemental fat whereby the magnitudes of improvements generally became greater with each increment of fat. One exception to this pattern was the performance of toms fed the 5% fat, nonadjusted diet. For an unknown reason, 2 of the 4 pens of toms fed this diet did poorly from 112 to 140 days of age. Although final body weights of toms fed adjusted MEto-nutrient ratio diets were, on the average,
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pens were assigned to each of 9 experimental diets according to a randomized block design. This experiment was conducted from November to March, and the lowest and highest average temperatures in the barns during the coldest month of the experiment were 11 and 18 C, respectively. The 9 test diets consisted of a control (no added fat) diet and two series of 4 diets each, formulated to contain 1, 3, 5, or 7% supplemental fat. The control diet contained nutrients at levels that approximated or exceeded those recommended by NRC (1977). The ME concentration of the control diet was near the maximum obtainable with the ingredients used, excluding supplemental fat. The ingredient composition and calculated analyses of the control diets for each age interval of Experiment 1 are shown in Table 1. Four diets of the "nonadjusted" series were formulated to contain the same concentrations of protein, lysine, total sulfur amino acids (TSAA), tryptophan, calcium, and available phosphorus as the, control diet within each age interval, irrespective of level of supplemental fat. Diets of the "adjusted" series were formulated so that the same ME-to-nutrient ratios as those of the respective control diets were maintained. The concentrations of ME, protein, and TSAA and also the ME-to-protein and ME-to-TSAA ratios of the 9 starter and 9 finisher diets are shown in Table 2. The main changes in ingredient levels with each increment of supplemental fat involved corn, soybean meal, meat and bone meal, and hydrolyzed feather meal. Experiment 1 was terminated when the toms were 140 days old.
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SELL AND OWINGS la
TABLE 1. Ingredient composition of control (no added fat) diets, Experiment Age interval, days 1-21
Corn Soybean meal (48% protein) Meat and bone meal (50% protein) Dehydrated alfalfa meal (17% protein) Hydrolyzed feather meal Fish meal (menhaden) Ground limestone Dicalcium phosphate Vitamin premix 0 Mineral premix c DL-Methionine (95%) L-Lysine-HCl (78%)
48.04 42.23 None None 3.00 2.00
Calculated analysis'^ Protein, % Lysine, % Methionine, % Total sulfur amino acids, % Tryptophan, % Calcium, % Available phosphorus, % ME, kcal/kg
21-42 53.16 31.05 6.00 2.49 3.00 2.00
42-63
63-84
84-112
112-140
59.39 31.34 2.56 None 2.64 None
63.95 27.59 3.77 None 1.26 None
72.54 18.15 6.00 None
79.19 12.75 6.00 None None None
.77 .61 .50 .30 .10 .12
.44 .65 .50 .30 .09 .12
19.00 1.02
16.18
.90
.05
.62
.80
2.83
1.28
2.51
1.69
.50 .30 .20
.50 .30 .17
.50 .30 .14
.50 .30 .14
None
None
None
None
28.50 1.60
27.00 1.44
24.00 1.25
.61 .92 .35
.56 .87 .31
.49 .75
1.20
1.15
.70
.70
2805
2860
.284 1.15
22.00 1.15 .475 .70 .26
1.15 2970
.85
.364
.40
.606 .208 1.10
.53
.174 .95 .50
.50
.60
.70
2915
.91
None
3070
3145
The nutrient analysis for major ingredients given by NRC (1977) was used in formulation of the diets. Laboratory analysis for dietary protein indicated that this approach was satisfactory. Vitamin premix supplied the following per kilogram of diet: vitamin A, 3000 IU; vitamin D 3 , 1360 1U; vitamin E, 6 mg; vitamin B l 2 , 5 Mg; menadione, 1.0 mg; riboflavin, 2.7 rag; pantothenic acid, 3.0 mg; niacin, 25 mg; choline, 310 mg; folic acid, .25 mg; biotin, 75 Mg. Mineral premix supplied the following per kilogram of diet: manganese, 70 mg; zinc, 40 mg; iron, 37 mg; copper, 6 mg; iodine, .18 mg; sodium chloride, 2.61 g. Calculated analyses of control diets of all experiments were essentially the same except for the ME content of milo-based, control diets. In these instances, the highest ME concentrations attainable with the ingredients used (no added fat) were 2805, 2860, 2915, 2970, 3070, and 3145 kcal/kg for age intervals 1-21, 21-42, 4 2 - 6 3 , 6 3 - 8 4 , 84-112, and 112-140 days, respectively.
numerically greater than those of toms fed nonadjusted diets, the differences were not significant. There was a significant (P<.001) beneficial effect of feeding the adjusted diet series on feed efficiency. The kilocalories of ME required per kilogram gain by toms varied among and within dietary treatments and was not changed significantly by diet. Efficiency of protein utilization was improved significantly by a linear effect of supplemental fat, and protein utilization by toms fed the nonadjusted diet series was superior to that of toms fed adjusted diets. The benefical effect of fat on protein utilization occurred only with the nonadjusted diet series, as shown by the significant interaction (P«.01) between supplemental fat and ME-to-nutrient ratio.
Experiment 2. The patterns of response to dietary treatments were similar to those observed in Experiment 1. The inclusion of 2 to 8% fat in corn-based diets had a significant (P<.01) linear effect whereby 139-day body weight and feed efficiency were improved (Table 4). There were no significant differences between adjusted and nonadjusted diet series with respect to body weight and feed efficiency. A significant (P«.05) interaction effect between fat level and ME-to-nutrient ratio series was observed, however, for body weight, seemingly because supplemental fat increased weights of toms fed the nonadjusted diet series more consistently than those of toms fed the adjusted series. Supplemental fat also improved the efficiency of protein utilization, but this effect
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Ingredient (%)
28.5 28.5 28.5 28.5
2842 2916 2990 3064
Nonadjusted (N)
16.2 16.4 16.8 17.2 17.6 16.2 16.2 16.2 16.2
3145 3182 3256 3330 3404
3182 3256 3330 3404
Control
A A A A
N N N N
None
1 3 5 7
1 3 5 7
N N N
1 3 5 7
A A A
28.5 28.9 29.6 30.4 31.1
2805 2842 2916 2990 3064
Control Adjusted (A)
1 3 5 7
None
Dietary protein (%)
Nutrient series
Supplemental fat (%)
Dietary ME (kcal/kg)
195.8 200.4 204.9 209.5
194.4 193.6 193.7 193.7 193.8
99.7 102.3 104.9 107.5
98.4 98.4 98.5 98.4 98.4
ME: protein ratio (kcal/
TABLE 2. Metabolizahle energy, protein, and TSAA concentrations of starter and finis
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SELL AND OWINGS TALBE 3. Influence of supplemental fat on performance of turkeys, Experiment 1
Supplemental fat (%)
140-day Body weight (kg/tom)
Feed (kg)
0 (Control) lAa 3A 5A 7A
11.73 11.84 12.38 12.22 12.98
3.26 3.13 3.09 2.96 2.90
9773 9681 9739 9564 9626
.633 .627 .634 .624 .630
IN 3N 5N 7N
11.98 12.11 11.92 12.57
3.19 3.08 3.12 2.92
9723 9714 10074 9643
.629 .612 .621 .579
.35
ME (kcal)
.068
214
Protein (kg)
.0143
ities of Control vs. added fat A vs. N Linear effect of fate Fat X AN
.05
.01 .01
ns ns
ns .01
.01
.01 ns
ns ns
.01 .01
ns ns
A and N refer to diets with adjusted and nonadjusted ME-to-nutrient ratios, respectively. Standard deviation of the mean. Quadratic and cubic effects of supplemental fat were not significant at P<.10.
was not linear for the adjusted diet series. A significant (P«.01) fat X ME-to-nutrient ratio interaction occurred as a result of the linear improvement in efficiency of protein use for gain with the nonadjusted diet series. No significant treatment effects on the utilization of ME for gain were observed. In comparison with Experiment 1, toms were smaller in final body weight but utilized feed, ME, and protein more efficiently in Experiment 2. Experiment 2 was conducted in the summer and Experiment 1 in the winter. The higher temperatures of the summer trial undoubtedly affected the performance characteristics, primarily by reducing feed consumption. Experiment 3. Supplemental fat (2, 4, or 8%) increased 142-day body weights and improved feed efficiency significantly (Table 5). Also, the magnitudes of these effects of fat were linearly related to the level of fat included in the diet, irrespective of ME-to-nutrient ratio series. The ME utilization for weight gain was not changed significantly by fat level or MEto-nutrient ratio. There was, however, a significant main effect of ME-to-nutrient ratio
series on protein efficiency. Toms fed the nonadjusted series utilized protein more efficiently than toms fed the adjusted diet series. Also, within the nonadjusted series, efficiency of protein use for gain improved with increments of fat. Supplemental fat had no effect on protein utilization in the adjusted diet series, and consequently, statistical analysis showed a significant (P<.01) fat x ME-tonutrient ratio series interaction for protein utilization. In general, the results of Experiment 3 were quite similar to those of Experiment 1, which also was conducted during the winter. Experiment 4. The results of the second summer experiment are presented in Table 6. The environmental temperature was unusually high during much of Experiment 4. Consequently, average body weights of toms were less at 140 days than observed in the previous summer trial (Experiment 2). Nevertheless, the inclusion of fat in the diet increased body weight and improved feed efficiency linearly. Toms fed the adjusted or nonadjusted diet series did not differ significantly in final body weight. In addition to the linear effect of fat
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SD b
Consumed/kg gain, 1 to 140 days
FAT FOR GROWING TURKEYS
2299
TABLE 4. Influence of supplemental fat on performance of turkeys fed corn-based diets, Experiment 2
Supplemental fat (%)
139-day Body weight (kg/tom)
Feed (kg)
ME (kcal)
Protein (kg)
0 (Control) 2A a 4A 6A 8A
10.55 10.95 11.32 11.42 11.26
3.09 2.91 2.86 2.81 2.82
9402 9050 9096 9163 9403
.617 .594 .595 .598 .608
2N 4N 6N 8N
10.65 11.08 11.22 11.62
2.93 2.90 2.88 2.77
9112 9247 9407 9252
.585 .578 .575 .553
163
.010
.22
.051 lities of
Control vs. added fat A vs. N Linear effect of farc Fat X AN
.01 ns .01 .05
ns
.01
ns
.01
ns
.01
.01 ns
ns ns
ns .01
A and N refer to diets with adjusted and nonadjusted ME-to-nutrient ratios, respectively. Standard deviation of the means. Quadratic and cubic effects of supplemental fat were not significant at P<.10.
levels on body weight, a significant (P<.05) quadratic effect of fat was observed. This was the result of the relatively poor weights of toms fed the 2% fat, adjusted diet or the 2% fat, nonadjusted diet. An examination of the experimental procedure and laboratory analysis of the diets did not provide an explanation for these results. Efficiency of protein utilization was improved significantly by supplemental fat, and this improvement occurred with both the adjusted and nonadjusted diet series. Similarly, efficiency of ME utilization was improved in both diet series by supplemental fat. Efficiency of ME utilization was not affected by MEto-nutrient ratio series, but toms fed nonadjusted diets utilized protein more efficiently than did toms fed adjusted diets. Experiments 2B and 4B. These experiments were conducted ancillary to Experiments 2 and 4 (summer trials) to evaluate the effects of fat supplementation on the usefulness of milobased diets for turkey toms. The results presented in Table 7 show that supplemental fat
increased final body weight and improved feed efficiency and protein efficiency linearly when used in diets with adjusted ME to nutrient ratios (Experiment 2B) or in diets with nonadjusted ratios (Experiment 4B). The general difference between the final body weights of the two experiments probably was related to the relatively high environmental temperatures prevalent during Experiment 4B. The differences in overall protein utilization for gain between the experiments also is noteworthy. This difference was partly the result of using adjusted ME-to-nutrient ratio diets in Experiment 2B as compared with 4B. In general, the adjusted diets of Experiment 2B contained higher protein levels than the nonadjusted series of Experiment 4B. Also, erroneous laboratory analysis of the protein content of milo used in Experiment 2B resulted in dietary protein levels that averaged about .7 to .9% higher than expected for the age interval of 1 to 84 days of age. Thus, the protein intake by the toms of Experiment 2B probably was excessive. The ME utilization improved linearly with
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SD b
Consumed/kg gain, 1 to 139 days
S E L L A N D OWINGS
2300
TABLE 5. Influence of supplemental fat on performance of turkeys. Experiment 3 142-day Body weight (kg/tom)
0 (Control) 2A* 4A 8A
11.80 12.55 12.32 12.60
2N 4N 8N
12.08 12.45 12.92 .40
SD*>
Consumed/kg gain, 1 to 142 days Feed (kg)
ME (kcal)
Protein (kg)
3.17 3.02 3.00 2.87 3.00 2.98 2.90
9605 9384 9544 9541
.638 .624 .634 .639
9323 9465 9644
.605 .603 .582
255
.016
.081
Probabilities of significance Control vs.
added fat
.02
A vs. N
ns
Linear effect of fat c Fat X AN
ns
.01
.01 ns
ns
.09
ns
.01
.01
ns ns
ns .01
A and N refer to diets with adjusted and nonadjusted ME -to-nutrient ratios, respectively. Standard deviation of the means. Quadratic and cubic effects of supplemental fat were not significant at P<.10.
increments of fat in Experiment 4B, corresponding to observations made with corn-based diets of the same experiment. In contrast, supplemental fat had no effect on ME utilization for milo-based diets in Experiment 2B. Mortality, All Experiments. Mortality encountered in Experiments 1, 2B, 3, and 4B were 8, 3.9, 10.2, and 4%, respectively. Incidence of mortality was not related to specific diet treatments within an experiment. Considerable mortality as a result of aortic rupture was observed between days 63 and 98 of Experiment 1. In Experiment 3, a high incidence of "spraddle-legs" and mortality occurred when the poults were 5 to 28 days of age.
DISCUSSION
The generally favorable responses of torn turkeys to supplemental dietary fat was expected on the basis of previous research (Sunde, 1954; Touchburn and Naber, 1966; Jensen et ai, 1970; and others). An integral part of the research reported here, however, was to evaluate the consistency of fat's effects on turkey performance when tested in different ex-
periments. To facilitate this evaluation, regression analysis was done relating level of fat supplementation and each performance characteristic for all experiments. The resulting regression equations are shown in Tables 8 and 9. The regression equations were used also to calculate the percentage change that each 1% supplemental fat caused in final body weights and feed efficiency. When corn-based diets were used, the regression coefficients describing the favorable effects of supplemental fat on final body weights were highly significant with one exception. The exception was the regression coefficient for the adjusted diet series of Experiment 3. In addition to this exception, there were some inconsistencies in the magnitude of the effect of fat on body weight, especially with diets having adjusted MEto-nutrient ratios. The percentage improvement in final body weight for each 1% fat tested in the adjusted diet series ranged from .1 (nonsignificant) to 1.5%. Variability among experiments was somewhat less for the nonadjusted diet series than for the adjusted series, although the magnitude of improvement in body weight was only .6% for each 1% of fat in Experiment 1 as compared
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Supplemental fat (%)
FAT FOR GROWING TURKEYS
2301
TABLE 6. Influence of supplemental fat on performance of turkeys fed corn-based diets, Experiment 4
Supplemental fat (%)
140-day Body weight (kg/tom)
Feed (kg)
ME (kcal)
Protein (kg)
0 (Control) 2A a 4A 8A
10.25 9.92 10.82 11.28
3.07 3.00 2.83 2.61
9483 9480 9146 8814
.561 .563 .545 .527
2N 4N 8N
10.12 10.52 11.05
2.93 2.80 2.71
9250 9069 9115
.539 .516 .497
.26
.08
262
.016
„_., , .,... Control vs. added fat A vs. N Linear effects of fate Fat X AN
ns
c
. .,.
.01
ns .01 ns
.07
ns
ns
.01 ns
ns
.04
.01 .01
.01 ns
A and N refer to diets with adjusted and nonadjusted ME-to-nutrient ratios, respectively. Standard deviation of the means. c
Quadratic effects of supplemental fat were not significant at P<.10. Cubic effect of supplemental fat was significant (P<.05) for body weight only.
with 1.3, 1.2, and 1.1% for Experiments 2, 3, and 4, respectively. The regression coefficients (Table 9) show that fat also had significant favorable effects on body weights of toms fed milo-based diets, but the magnitudes of increase were relatively small (.6 and .7% for each 1% fat in Experiments 2B and 4B, respectively). There was also a quadratic component of the regression equation for body weights of Experiment 4B, which was significant at (P<.08), indicating that the extent of favorable effect of fat on this parameter declined as level of supplemental fat increased. The improvements in body weight at approximately 140 days of age, resulting from fat supplementation of corn-based diets in our experiments, fell within ranges of values reported by others. The data reported by Jensen et al. (1970) showed that body weight increased .5 to 1.3% per 1% added fat when diets containing relatively high protein levels were fed from 8 to 24 weeks of age. Corresponding values for diets with lower protein levels ranged from .85 to 1.0%. Sullivan (1979) also reported that fat supplementation of corn-based diets
increased torn weights by 1.3% for each 1% fat. The growth responses reported by Potter (1976) and Waibel (1978), .36 and .5% per 1% supplemental fat, respectively, were somewhat lower than those observed in three of the four experiments reported herein. In one instance there was essentially no increase associated with fat supplementation, but in the other three instances, body weights were increased .6 to 1.5% per 1% supplemental fat, with the most consistent improvements obtained with nonadjusted diets (expanding ME-to-nutrient ratios). In the research described here, toms were fed supplemental fats continuously from 1 to about 140 days of age. Most published data, however, including those of Potter (1976) and Waibel (1978), were obtained from trials performed with turkeys 8 weeks of age and older. Supplementing milo-based diets with 2 to 8% fat increased 140-day body weight by .6 to .7% per each 1% fat in the experiments reported here. Recently, Sullivan (1979) found that increasing the level of added fat in milo diets from 2.5 to 5.0% increased body weights of 22-week-old toms by .4% per each 1% fat.
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SDb
Consumed/kg gain, 1 to 140 days
SELL AND OWINGS
2302
TABLE 7. Influence of supplemental fat on performance of turkeys fed milo-based diets, Experiments 2B and 4B Consumed/kg gain, 1 to 139 days
Body weight a (kg/tom)
Feed (kg)
ME (kcal)
Protein (kg)
Experiment 2B 0 (Control) 2A b 4A 6A 8A
11.04 11.33 11.49 11.57 11.55
3.08 3.03 2.95 2.81 2.80
9273 9358 9330 9092 9248
.636 .638 .638 .625 .624
SDC
.35
Experiment 4B 0 (Control) 2N 4N 8N
.026
10.22 10.62 10.88 10.90
3.19 3.07 2.98 2.78
.29
.10
SD
„ Experiment 2B Control vs. added fat Linear effect of fat d
, , .,.,._
85
r
.
.01
9762 9599 9544 9324
.584 .564 .549 .512
319
.018
.„.
.02
ns
ns
.05
.01
ns
.02
Experiment 4B Control vs. added fat
.01
.01
ns
.02
Linear effect of fat e
.01
.01
ns
.05
.01
139-day and 140-day body weights for Experiments 2B and 4B, respectively. A and N refer to adjusted and nonadjusted ME-to-nutrient ratios for Experiments 2B and 4B, respectively. Standard deviation of the means. Quadratic and cubic effects of supplemental fat were not significant at P<.10. Quadratic effect was significant (P<.08) for body weight only.
When supplemental fat has been tested in corn-based diets, relatively consistent, substantial improvements in feed efficiency of turkeys have been reported. The improvements have ranged from 1.3 to 2.1% per 1% supplemental fat (Jensen et al, 1970; Potter, 1976; Waibel, 1978; Sullivan, 1979). Fat supplementation of corn-based and milo-based diets in the current research also improved feed efficiency but to a slightly lesser degree tlian previously reported. Feed efficiency was improved by .8 to 1.6% per 1% added fat in the four experiments. There was no consistent effect of season of the year or adjustment in ME to nutrient ratios on changes in feed efficiency elicited by 1 to 8% supplemental fat. The magnitude of the effect of fat on feed
efficiency in our experiments generally was less than that reported by other researchers despite the fact that changes in dietary ME concentration associated with fat supplementation were similar to those used previously. For example, all diets in the research reported here were formulated so that ME concentration of the diet increased 37 kcal/kg with each 1% supplemental fat. Changes in ME concentrations were approximately 26, 44, and 40 kcal/kg of diet with each 1% fat in the research of Jensen et al. (1970), Potter et al. (1974), and Waibel (1978), respectively. Age intervals during which the toms were fed supplemental fat may have contributed to the lower responses in feed efficiency reported here. In our experiments, toms were fed fat-
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Supplemental fat, %
FAT FOR GROWING TURKEYS
2303
TABLE 8. Regression of final body weight and feed efficiency on level of supplemental fat in corn-based diets
Experiment
Reg,•ession equation
ME-to-nutrient ratio
Season
n
J
Significance of linear coefficient
Improvement for each 1% supplemental fat (%)
"I
Winter Summer Winter Summer
A A A A
Y Y Y Y
= = = =
11.72 + 10.72 + 12.04+ 10.03 +
.180Xa .073X .017X .154X
.001 .004 ns .001
1.5 .7 .1 1.5
1 2 3 4
Winter Summer Winter Summer
N N N N
Y Y Y Y
= = = =
11.78 10.48 11.82 10.09
.077X .141X .142X .112X
.02 .001 .001 .001
.6 1.3 1.2 1.1
1 2 3 4
Winter Summer Winter Summer
A A A A
Y Y Y Y
= = = =
3.20 3.03 3.13 3.08
- .047X - .027X -.026X - .060X
.001 .002 .015 .001
1.5 .9 .8 1.9
1 2 3 4
Winter Summer Winter Summer
N N N N
Y Y Y Y
= = = =
3.21 3.11 3.12 3.03
- .043X - .029X -.030X - .044X
.001 .001 .001 .001
1.3 .9 1.0 1.5
+ + + +
Y = Final body weight (kg) or kilogram of feed per kilogram gain and X = percent supplemental fat.
supplemented diets from 1 to about 140 days of age. The aforementioned researchers used toms from 56 to 168 days of age. After reviewing published data, Potter (1976) concluded that supplemental fat had the greatest effect on feed efficiency after the turkeys were 56 days of age. An examination of feed efficiency data of our experiments supports this
conclusion. For example, data obtained from regression analysis showed that each 1% supplemental fat improved 63-day cumulative feed efficiency by an average of .8% over all experiments, whereas each 1% supplemental fat improved 140-day cumulative feed efficiency by 1.05%. Fat supplementation did not change the
TABLE 9. Regression of final body weight and feed efficiency on level of supplemental fat in milo-based diets
Experiment
Season
ME-to-nutrient ratio
Significance of linear coefficient
Regression equation „
j
._,_
2B 4B
Summer Summer
A N
Y = 11.15 + . 0 6 3 X a Y = 10.26 + .079X - .01 9X2b
.05 .01
2B 4B
Summer Summer
A N
Y= Y=
.001 .001
a
3.09-.039X 3.18-.051X
Improvement for each 1% supplemental fat (%)
.6 .7
1.3 1.6
Y = Final body weight (kg) or kilogram of feed per kilogram gain and X = percent supplemental fat. Quadratic coefficient for weight gain, Experiment 4B was significant at P<.08.
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1 2 3 4
2304
SELL AND OWINGS
Efficiency of protein utilization was improved consistently when fat was included in diets with nonadjusted ME-to-nutrient ratios. This effect of fat was most prominent in the summer experiments when feed and protein intakes were relatively low. It is doubtful that supplemental fat exerted a sparing effect on dietary protein (Waibel, 1978), but supplemental fat may have contributed to the attainment of a more nearly optimum available energy to amino acid balance for metabolism, especially when environmental temperatures were high. Generally, the protein efficiency data suggest that the protein concentrations of the adjusted diet series were higher than necessary to support satisfactory performance of toms reared during cool or warm weather conditions. The ME-to-nutrient ratios of diets of the nonadjusted diet series, however, were not excessively wide as compared with NRC (1977), at least through the 84-days-of-age interval. The ratios in our diets ranged from 98 to 108, 106 to 117, 122 to 134, 135 to 148, 162 to 177, and 194 to 212 for age intervals of 1 to 21, 21 to 42, 42 to 63, 63 to 84, 84 to 112, and 112 to 140 days, respectively. Corresponding ratios obtained from NRC (1977) data were 100, 112, 136, 163, and 194 for similar age intervals. Efficiency of protein utilization data were calculated in the current research by assuming that the chemical composition of weight gains was similar, irrespective of diet treatment. Chemical analysis of turkey carcasses was not done. Visual appraisal of carcasses of the turkeys processed at the Iowa State University
Meats Laboratory for subcutaneous fat, leaf fat, and yield of carcass components indicated that diet treatments did not alter carcass composition noticeably. These data will be the subject of a future report. The experiments reported here show that increasing dietary energy concentration by using supplemental fat at levels of 1 to 8% of the diet improves rate of growth and feed efficiency of torn turkeys to 140 days of age. These effects of fat were most consistent with feed efficiency. Also, the beneficial effects of fat supplementation of diets with nonadjusted ME-to-nutrient ratios were similar to those observed with diets of the adjusted series. This observation may be an important consideration in using supplemental fats to greatest economic advantage in turkey production. ACKNOWLEDGMENT This research was supported, in part, by grants from the Iowa Turkey Marketing Council and the Fats and Proteins Research Foundation, Inc., Des Plaines, IL. The animalvegetable fat was kindly supplied by C. W. Meyer Co., Bloomington, MN, and Feed Energy Co., Des Moines, I A. The technical assistance of William Larson and Irven Williams is gratefully acknowledged. REFERENCES Balloun, S. L., W. J. Owings, J. L. Sell, and R. E. Phillips, 1959. Energy and protein requirements for turkey starting diets. Poultry Sci. 38:13281340. Barr, A. J., J. H. Goodnight, J. P. Sail, W. H. Blair, and D. M. Chilko, 1979. SAS users guide. J. T. Helwig and K. A. Council, eds., SAS Institute, Inc., Raleigh, NC. Biely, J., and B. E. March, 1954. Fat studies in poultry. 2. Fat supplements in chick and poult rations. Poultry Sci. 33:1220-1227. Combs, G. F., and G. L. Romoser, 1955. A new approach to poultry feed formulation. Maryland Agric. Exp. Sta. Misc. Publ. 226. Dale, N. M., and H. L. Fuller, 1980. Effect of diet composition on feed intake and growth of chicks under heat stress. II. Constant vs. cycling temperatures. Poultry Sci. 59:1434—1441. Day, E. J., and J. E. Hill, 1957. The effect of calorie: protein ratio of the ration on growth and feed efficiency of turkeys. Poultry Sci. 36: 773-779. deAlbuquerque, K., A. T. Leighton, Jr., J. P. Mason, Jr., and L. M. Potter, 1978. The effects of environmental temperature, sex and dietary energy levels on growth performance of large white turkeys. Poultry Sci. 57:353-362. Jensen, L. S., G. W. Schumaier, and J. D. Latshaw,
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dietary ME consumed per kg weight gain in three of the four experiments. In Experiment 4, however, fat supplementation of corn-based or milo-based diets improved utilization of ME. The beneficial effect of fat on energy utilization may have been related to the unusually high environmental temperatures encountered during Experiment 4. Average daily high temperatures in the building were 27.8, 32.2, and 30.6 C during June, July, and August, respectively. Research with broiler chickens (Dale and Fuller, 1980) indicated that supplemental fat alleviated part of the adverse effects of high temperatures on performance. deAlbuquerque et al. (1978), however, reported that supplemental fat was of no greater benefit for turkeys reared at 35 C than for those kept at IOC.
FAT FOR GROWING TURKEYS
and milo diets on performance of market turkeys. Poultry Sci. 58:1113. (Abstr.) Sunde, M. L., 1954. The use of animal fats in poultry feeds. J. Amer. Oil Chem. Soc. 31:49-52. Touchburn, S. P., and E. C. Naber, 1966. The energy value of fats for growing turkeys. Pages 190—195 in Proc. 13th World's Poultry Congr., Kiev, USSR. Waibel, P. E., 1958, Effectiveness of unknown growth factors, antibiotic and animal fat in turkey poult rations. Poultry Sci. 37:1144-1149. Waibel, P. E., 1978. Studies on protein and energy requirements of turkeys during the growing period. Pages 143—154 in Proc. 39th Minnesota Nutr. Conf., Univ. Minnesota, St. Paul, MN. Waibel, P. E., G. Devegowda, and J. Palarski, 1977. Estimation of the value of animal fat in diets for turkeys. Pages 33—46 in Proc. 38th Minnesota Nutr. Conf., Univ. Minnesota, St. Paul, MN. Yacowitz, H., R. D. Carter, J. Wyne, and M. G. McCartney, 1956. Effects of varying protein and fat levels in a finishing ration for turkey broilers. Poultry Sci. 35:227-229.
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1970. Extra-caloric effect of dietary fat for developing turkeys as influenced by calorie: protein ratio. Poultry Sci. 49:1697-1704. Joshi, S. K., and J. L. Sell, 1964. Comparative dietary value of soybean oil, sunflower oil, rapeseed oil and animal tallow for turkey poults. Can. J. Anim. Sci. 4 4 : 3 4 - 3 8 . National Research Council, 1977. Nutrient requirements of poultry. 7th ed. National Academy of Sciences, Washington, DC. Owen, J. A., and P. W. Waldroup, 1979. Response of growing turkeys to diets varying in energy content. Poultry Sci. 58:1090-1091. (Abstr.) Pepper, W. F., S. J. Slinger, and J. D. Summers, 1960. Studies with chickens and turkeys on the relationship between fat, unidentified factors and pelleting. Poultry Sci. 39:66-74. Potter, L. M., 1976. Fat in turkey diets: how much it's worth. Turkey World 5 1 : 6 - 8 . Potter, L. M., J. R. Shelton, and L. G. Melton, 1974. Zinc bacitracin and added fat in diets of growing turkeys. Poultry Sci. 53:2072-2081. Sullivan, T. W., 1979. Effect of added fat level in corn
2305
1981 Poultry Science 60:2293-2305
INTRODUCTION
The use of supplemental fat has become a vital, routine part of modern poultry feeding programs. Fats can be used to improve the physical consistency of meal-type feeds and to enhance the dispersion of microingredients within the diet mixture. Supplemental fats are used primarily, however, to increase the caloric density of diets. Biely and March (1954) reported that the inclusion of up to 10% animal tallow in diets improved efficiency of feed utilization by turkeys from 1 day to 10 weeks of age. Sunde (1954) also observed improvements in feed efficiency of turkeys fed diets supplemented with white grease, tallow, or soybean oil. Subsequently, Yacowitz et al. (1956), Waibel (1958), Pepper et al. (1960), and Joshi and Sell (1964) reported that fat supplementation of meal-type diets consistently improved feed efficiency and occasionally
'Journal Paper No. J-10191 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Project 2241.
stimulated weight gains by turkeys. In 1966, Touchburn and Naber observed that the magnitude of improvement in performance of turkeys resulting from fat supplementation exceeded that expected on the basis of the recognized contribution of energy by fat to the diet. They termed this the extracaloric effect of fat. Jensen et al. (1970) confirmed that fats exerted an extracaloric effect when added to diets of turkeys reared from 8 to 24 weeks of age. Potter et al. (1974) also observed that added fat stimulated weight gain of turkeys from 8 weeks of age onward. After examining the results of several experiments, Potter (1976) stated that feed efficiency of turkeys from 8 weeks of age onward was improved 1.5 to 2.5% for each 1% of supplemental fat. Similar results were reported by Waibel et al. (1977) and Waibel (1978). deAlbuquerque et al. (1978) reported that each 1% supplemental fat improved feed efficiency by .6% but that added fat did not affect growth rate of turkeys. Owen and Waldroup (1979) presented data showing that supplemental fat stimulated gains of male turkeys from 0 to 22 weeks with maximum
2293
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ABSTRACT Supplementing diets with an animal-vegetable fat (increasing dietary metabolizable energy) at levels ranging from 1 to 8% improved rate of gain and feed efficiency of male turkeys from 1 to 140 days of age. Average body weight increased linearly (P<.05) with increments of supplemental fat in four experiments conducted. Also, the magnitude of improvements in feed efficiency were linearly (P<.05) related to supplemental fat level. These improvements in performance were observed when experiments were conducted during summer and winter seasons. Furthermore, favorable responses to supplemental fats occurred with diets based on corn or milo, although the greatest responses generally were obtained with corn-based diets. Supplemental fat had similar effects on body weight and feed efficiency whether used in diets in which the concentration of nutrients was adjusted commensurate with changes in metabolizable energy (ME) concentration or whether used in diets in which nutrient concentrations remained constant (nonadjusted diets), irrespective of ME level. Regression analysis showed that, with one exception, 140-day body weights of toms were increased from .6 to 1.5% for each 1% supplemental fat. Improvements in feed efficiency ranged from .8 to 1.9% for each 1% of supplemental fat. Supplemental fat decreased the amount of protein consumed per kilogram weight gain of toms fed the nonadjusted diet series in four experiments. The ME consumed per kilogram gain was not affected significantly (P<.05) by diet treatment in three experiments but was decreased by supplemental fat in one experiment. (Key words: dietary fat, metabolizable energy, turkeys)
2294
SELL AND OWINGS
The experiments reported here were conducted to obtain additional information on the usefulness of dietary fat in turkey feeding programs. The major objectives were to document the magnitude and consistency of changes in growth rate and efficiency of feed utilization associated with increments of supplemental fat ranging from 1 to 8% of the diet and to determine the consequences of maintaining or not maintaining constant dietary ME-to-nutrient ratios when fat was used to increase the energy density of diets.
MATERIALS AND METHODS
Nicholas Large White male poults were used in four experiments. The toms were brooded and grown in total confinement. Floor pens, in which .297 to .334 m 2 were allotted per
turkey, were the experimental units. The pens were equipped with heating lamps for use in brooding the poults. A hydrolyzed animal-vegetable fat obtained from a commercial source was used in the four experiments. Samples of each batch of fat were analyzed for fatty acid composition by a commercial laboratory. The fatty acid composition varied somewhat among batches, especially with respect to stearic and linoleic acids. The ranges in fatty acid concentrations were (expressed as percentage of total fatty acids): caprylic, .07 to 1.03; capric, .05 to 0.90; lauric, .11 to 6.61; myristic, 1.28 to 3.12; palmitic, 16.43 to 18.51; palmitoleic, .29 to 2.76; stearic 4.93 to 16.54; oleic, 27.52 to 38.18; linoleic 20.58 to 45.52; linolenic, 1.25 to 5.23; arachidic, none to 1.05. The combined moisture, unsaponifiable, and insoluble impurities content of the fats ranged from 3.64 to 4.71%. The manufacturer of this fat product suggested an ME value of 8140 kcal/kg, and this value was used in calculating dietary ME levels. Least-cost, linear programming (MPSX) was used to formulate all diets. The nutrient concentrations for ingredients listed by the National Research Council (NRC, 1977) were used in diet formulation except for the ME value of supplemental fat and the protein value of milo. Laboratory analysis showed that the protein content of milo (10.14 and 10.50% for Experiments 2 and 4, respectively) deviated considerably from the value given by NRC (1977), but the protein content of corn, soybean meal, and other ingredients agreed closely with those of NRC (1977). Ingredient prices prevailing at the time of the experiment were used in the diet formulation program. To maintain consistency within and among experiments, the increase in dietary ME content of diets associated with fat supplementation was fixed at 37 kcal/kg for each 1% added fat tested in all experiments. Adjustments in nutrient and ME concentrations were made during all experiments according to six age categories (1 to 21, 21 to 42, 42 to 63, 63 to 84, 84 to 112, and 112 to 140 days). Body weights and feed consumption data were recorded at the end of each age interval. Mortality and cause of mortality records were maintained. Data were analyzed statistically by the Statistical Analysis System (SAS) (Barret a/., 1979). Experiment 1. Twenty-five poults were placed in each of 36 floor pens, and 4 floor
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effects occurring at 2 and 4% added fat. Their data also showed that feed efficiency was improved by 1.4 to 2.3% for each 1% fat included in meal-type diets, but this effect of fat was not so notable with pelleted diets. Much of the foregoing research on fats for turkeys was done with diets in which the concentration of key nutrients remained constant, irrespective of level of fat supplementation. In other instances, the concentrations of protein and amino acids were changed commensurate with changes in dietary metabolizable energy (ME) resulting from fat supplementation. The importance of maintaining acceptable dietary energy-to-nutrient ratios, as suggested by Combs and Romoser (1955), has been a commonly accepted principle of poultry nutrition. Several reports, however (Day and Hill, 1957; Balloun et al, 1959; Touchburn and Naber, 1966), indicated that widely varying ME-to-protein ratios could be used without adversely affecting performance of growing turkeys. Data presented by Jensen et al. (1970) showed that 24-week body weights of toms fed diets containing relatively low protein levels and supplemented with fat generally were numerically lower than those of toms fed higher protein levels, but there was no significant protein X dietary energy level interaction observed. Waibel (1978) also reported that, when various combinations of protein and fat levels were fed to toms from 16 to 24 weeks of age, significant main effects of protein and fat level were observed but that no protein X fat interaction occurred.
FAT FOR GROWING TURKEYS
Experiment 2. The design of Experiment 2 was similar to that of Experiment 1. Supplemental fat levels tested, however, were 0, 2, 4, 6, and 8% of the diet, and three experimental units (floor pens) containing 26 toms each were assigned to each diet treatment. Also, the experiment was conducted during the summer (April to September) and the lowest and highest average temperatures in the barns during the warmest month were 20 and 29 C, respectively. Experiment 2 was terminated when the toms were 142 days old. Each dietary fat level was tested in cornbased diets that had adjusted ME-to-nutrient ratios and in diets with nonadjusted ratios. This portion of the experiment, designated Part A, consisted of 9 diet treatments. Five additional treatments were tested in Part B. These diets
contained milo as the grain component instead of corn. Supplemental fat was tested at 0, 2, 4, 6, or 8% of milo-based diets in which the ME-to-nutrient ratios had been adjusted. The same nutrient restrictions were used in formulating diets based on milo as were used for corn-based diets. Because of the lower ME content of milo, however, milo-based diets fed from 84 to 112 and 112 to 140 days of age contained 25 and 40 kcal less ME/kg, respectively, than did corn-based diets. Experiments 3 and 4. Experiment 3 was essentially a repeat of Experiment 1 with two exceptions. Fat levels tested in both the adjusted and nonadjusted diet series were 0, 2, 4, and 8%, and the trial ended when the toms were 139 days old. Experiment 3 was a winter experiment, conducted from October to March. The lowest and highest average temperatures in the barns during the coldest month were 11 and 19 C, respectively. Experiment 4 was a second summer experiment beginning in April and ending in September. The lowest and highest average temperatures in the barns during the warmest month were 24 and 32.2 C, respectively, indicating the relatively hot summer experienced in 1980. Supplemental fat levels of 0, 2, 4, and 8% again were tested in corn-based diets that had adjusted or nonadjusted ME to nutrient ratios (Part A). These same levels of supplemental fat also were tested in milo-based diets that had nonadjusted ME to nutrient ratios. Experiment 4 was terminated when the toms were 140 days of age. Four pens of 26 poults each were used per diet treatment in Experiments 3 and 4. RESULTS
Experiment 1. Average 140-day body weight and feed efficiency were improved significantly (P<.05 and .01, respectively) by supplemental fat as compared with the control (no added fat) group (Table 3). There was a significant (P<.01) linear effect of using from 1 to 7% supplemental fat whereby the magnitudes of improvements generally became greater with each increment of fat. One exception to this pattern was the performance of toms fed the 5% fat, nonadjusted diet. For an unknown reason, 2 of the 4 pens of toms fed this diet did poorly from 112 to 140 days of age. Although final body weights of toms fed adjusted MEto-nutrient ratio diets were, on the average,
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pens were assigned to each of 9 experimental diets according to a randomized block design. This experiment was conducted from November to March, and the lowest and highest average temperatures in the barns during the coldest month of the experiment were 11 and 18 C, respectively. The 9 test diets consisted of a control (no added fat) diet and two series of 4 diets each, formulated to contain 1, 3, 5, or 7% supplemental fat. The control diet contained nutrients at levels that approximated or exceeded those recommended by NRC (1977). The ME concentration of the control diet was near the maximum obtainable with the ingredients used, excluding supplemental fat. The ingredient composition and calculated analyses of the control diets for each age interval of Experiment 1 are shown in Table 1. Four diets of the "nonadjusted" series were formulated to contain the same concentrations of protein, lysine, total sulfur amino acids (TSAA), tryptophan, calcium, and available phosphorus as the, control diet within each age interval, irrespective of level of supplemental fat. Diets of the "adjusted" series were formulated so that the same ME-to-nutrient ratios as those of the respective control diets were maintained. The concentrations of ME, protein, and TSAA and also the ME-to-protein and ME-to-TSAA ratios of the 9 starter and 9 finisher diets are shown in Table 2. The main changes in ingredient levels with each increment of supplemental fat involved corn, soybean meal, meat and bone meal, and hydrolyzed feather meal. Experiment 1 was terminated when the toms were 140 days old.
2295
2296
SELL AND OWINGS la
TABLE 1. Ingredient composition of control (no added fat) diets, Experiment Age interval, days 1-21
Corn Soybean meal (48% protein) Meat and bone meal (50% protein) Dehydrated alfalfa meal (17% protein) Hydrolyzed feather meal Fish meal (menhaden) Ground limestone Dicalcium phosphate Vitamin premix 0 Mineral premix c DL-Methionine (95%) L-Lysine-HCl (78%)
48.04 42.23 None None 3.00 2.00
Calculated analysis'^ Protein, % Lysine, % Methionine, % Total sulfur amino acids, % Tryptophan, % Calcium, % Available phosphorus, % ME, kcal/kg
21-42 53.16 31.05 6.00 2.49 3.00 2.00
42-63
63-84
84-112
112-140
59.39 31.34 2.56 None 2.64 None
63.95 27.59 3.77 None 1.26 None
72.54 18.15 6.00 None
79.19 12.75 6.00 None None None
.77 .61 .50 .30 .10 .12
.44 .65 .50 .30 .09 .12
19.00 1.02
16.18
.90
.05
.62
.80
2.83
1.28
2.51
1.69
.50 .30 .20
.50 .30 .17
.50 .30 .14
.50 .30 .14
None
None
None
None
28.50 1.60
27.00 1.44
24.00 1.25
.61 .92 .35
.56 .87 .31
.49 .75
1.20
1.15
.70
.70
2805
2860
.284 1.15
22.00 1.15 .475 .70 .26
1.15 2970
.85
.364
.40
.606 .208 1.10
.53
.174 .95 .50
.50
.60
.70
2915
.91
None
3070
3145
The nutrient analysis for major ingredients given by NRC (1977) was used in formulation of the diets. Laboratory analysis for dietary protein indicated that this approach was satisfactory. Vitamin premix supplied the following per kilogram of diet: vitamin A, 3000 IU; vitamin D 3 , 1360 1U; vitamin E, 6 mg; vitamin B l 2 , 5 Mg; menadione, 1.0 mg; riboflavin, 2.7 rag; pantothenic acid, 3.0 mg; niacin, 25 mg; choline, 310 mg; folic acid, .25 mg; biotin, 75 Mg. Mineral premix supplied the following per kilogram of diet: manganese, 70 mg; zinc, 40 mg; iron, 37 mg; copper, 6 mg; iodine, .18 mg; sodium chloride, 2.61 g. Calculated analyses of control diets of all experiments were essentially the same except for the ME content of milo-based, control diets. In these instances, the highest ME concentrations attainable with the ingredients used (no added fat) were 2805, 2860, 2915, 2970, 3070, and 3145 kcal/kg for age intervals 1-21, 21-42, 4 2 - 6 3 , 6 3 - 8 4 , 84-112, and 112-140 days, respectively.
numerically greater than those of toms fed nonadjusted diets, the differences were not significant. There was a significant (P<.001) beneficial effect of feeding the adjusted diet series on feed efficiency. The kilocalories of ME required per kilogram gain by toms varied among and within dietary treatments and was not changed significantly by diet. Efficiency of protein utilization was improved significantly by a linear effect of supplemental fat, and protein utilization by toms fed the nonadjusted diet series was superior to that of toms fed adjusted diets. The benefical effect of fat on protein utilization occurred only with the nonadjusted diet series, as shown by the significant interaction (P«.01) between supplemental fat and ME-to-nutrient ratio.
Experiment 2. The patterns of response to dietary treatments were similar to those observed in Experiment 1. The inclusion of 2 to 8% fat in corn-based diets had a significant (P<.01) linear effect whereby 139-day body weight and feed efficiency were improved (Table 4). There were no significant differences between adjusted and nonadjusted diet series with respect to body weight and feed efficiency. A significant (P«.05) interaction effect between fat level and ME-to-nutrient ratio series was observed, however, for body weight, seemingly because supplemental fat increased weights of toms fed the nonadjusted diet series more consistently than those of toms fed the adjusted series. Supplemental fat also improved the efficiency of protein utilization, but this effect
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Ingredient (%)
28.5 28.5 28.5 28.5
2842 2916 2990 3064
Nonadjusted (N)
16.2 16.4 16.8 17.2 17.6 16.2 16.2 16.2 16.2
3145 3182 3256 3330 3404
3182 3256 3330 3404
Control
A A A A
N N N N
None
1 3 5 7
1 3 5 7
N N N
1 3 5 7
A A A
28.5 28.9 29.6 30.4 31.1
2805 2842 2916 2990 3064
Control Adjusted (A)
1 3 5 7
None
Dietary protein (%)
Nutrient series
Supplemental fat (%)
Dietary ME (kcal/kg)
195.8 200.4 204.9 209.5
194.4 193.6 193.7 193.7 193.8
99.7 102.3 104.9 107.5
98.4 98.4 98.5 98.4 98.4
ME: protein ratio (kcal/
TABLE 2. Metabolizahle energy, protein, and TSAA concentrations of starter and finis
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2298
SELL AND OWINGS TALBE 3. Influence of supplemental fat on performance of turkeys, Experiment 1
Supplemental fat (%)
140-day Body weight (kg/tom)
Feed (kg)
0 (Control) lAa 3A 5A 7A
11.73 11.84 12.38 12.22 12.98
3.26 3.13 3.09 2.96 2.90
9773 9681 9739 9564 9626
.633 .627 .634 .624 .630
IN 3N 5N 7N
11.98 12.11 11.92 12.57
3.19 3.08 3.12 2.92
9723 9714 10074 9643
.629 .612 .621 .579
.35
ME (kcal)
.068
214
Protein (kg)
.0143
ities of Control vs. added fat A vs. N Linear effect of fate Fat X AN
.05
.01 .01
ns ns
ns .01
.01
.01 ns
ns ns
.01 .01
ns ns
A and N refer to diets with adjusted and nonadjusted ME-to-nutrient ratios, respectively. Standard deviation of the mean. Quadratic and cubic effects of supplemental fat were not significant at P<.10.
was not linear for the adjusted diet series. A significant (P«.01) fat X ME-to-nutrient ratio interaction occurred as a result of the linear improvement in efficiency of protein use for gain with the nonadjusted diet series. No significant treatment effects on the utilization of ME for gain were observed. In comparison with Experiment 1, toms were smaller in final body weight but utilized feed, ME, and protein more efficiently in Experiment 2. Experiment 2 was conducted in the summer and Experiment 1 in the winter. The higher temperatures of the summer trial undoubtedly affected the performance characteristics, primarily by reducing feed consumption. Experiment 3. Supplemental fat (2, 4, or 8%) increased 142-day body weights and improved feed efficiency significantly (Table 5). Also, the magnitudes of these effects of fat were linearly related to the level of fat included in the diet, irrespective of ME-to-nutrient ratio series. The ME utilization for weight gain was not changed significantly by fat level or MEto-nutrient ratio. There was, however, a significant main effect of ME-to-nutrient ratio
series on protein efficiency. Toms fed the nonadjusted series utilized protein more efficiently than toms fed the adjusted diet series. Also, within the nonadjusted series, efficiency of protein use for gain improved with increments of fat. Supplemental fat had no effect on protein utilization in the adjusted diet series, and consequently, statistical analysis showed a significant (P<.01) fat x ME-tonutrient ratio series interaction for protein utilization. In general, the results of Experiment 3 were quite similar to those of Experiment 1, which also was conducted during the winter. Experiment 4. The results of the second summer experiment are presented in Table 6. The environmental temperature was unusually high during much of Experiment 4. Consequently, average body weights of toms were less at 140 days than observed in the previous summer trial (Experiment 2). Nevertheless, the inclusion of fat in the diet increased body weight and improved feed efficiency linearly. Toms fed the adjusted or nonadjusted diet series did not differ significantly in final body weight. In addition to the linear effect of fat
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SD b
Consumed/kg gain, 1 to 140 days
FAT FOR GROWING TURKEYS
2299
TABLE 4. Influence of supplemental fat on performance of turkeys fed corn-based diets, Experiment 2
Supplemental fat (%)
139-day Body weight (kg/tom)
Feed (kg)
ME (kcal)
Protein (kg)
0 (Control) 2A a 4A 6A 8A
10.55 10.95 11.32 11.42 11.26
3.09 2.91 2.86 2.81 2.82
9402 9050 9096 9163 9403
.617 .594 .595 .598 .608
2N 4N 6N 8N
10.65 11.08 11.22 11.62
2.93 2.90 2.88 2.77
9112 9247 9407 9252
.585 .578 .575 .553
163
.010
.22
.051 lities of
Control vs. added fat A vs. N Linear effect of farc Fat X AN
.01 ns .01 .05
ns
.01
ns
.01
ns
.01
.01 ns
ns ns
ns .01
A and N refer to diets with adjusted and nonadjusted ME-to-nutrient ratios, respectively. Standard deviation of the means. Quadratic and cubic effects of supplemental fat were not significant at P<.10.
levels on body weight, a significant (P<.05) quadratic effect of fat was observed. This was the result of the relatively poor weights of toms fed the 2% fat, adjusted diet or the 2% fat, nonadjusted diet. An examination of the experimental procedure and laboratory analysis of the diets did not provide an explanation for these results. Efficiency of protein utilization was improved significantly by supplemental fat, and this improvement occurred with both the adjusted and nonadjusted diet series. Similarly, efficiency of ME utilization was improved in both diet series by supplemental fat. Efficiency of ME utilization was not affected by MEto-nutrient ratio series, but toms fed nonadjusted diets utilized protein more efficiently than did toms fed adjusted diets. Experiments 2B and 4B. These experiments were conducted ancillary to Experiments 2 and 4 (summer trials) to evaluate the effects of fat supplementation on the usefulness of milobased diets for turkey toms. The results presented in Table 7 show that supplemental fat
increased final body weight and improved feed efficiency and protein efficiency linearly when used in diets with adjusted ME to nutrient ratios (Experiment 2B) or in diets with nonadjusted ratios (Experiment 4B). The general difference between the final body weights of the two experiments probably was related to the relatively high environmental temperatures prevalent during Experiment 4B. The differences in overall protein utilization for gain between the experiments also is noteworthy. This difference was partly the result of using adjusted ME-to-nutrient ratio diets in Experiment 2B as compared with 4B. In general, the adjusted diets of Experiment 2B contained higher protein levels than the nonadjusted series of Experiment 4B. Also, erroneous laboratory analysis of the protein content of milo used in Experiment 2B resulted in dietary protein levels that averaged about .7 to .9% higher than expected for the age interval of 1 to 84 days of age. Thus, the protein intake by the toms of Experiment 2B probably was excessive. The ME utilization improved linearly with
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SD b
Consumed/kg gain, 1 to 139 days
S E L L A N D OWINGS
2300
TABLE 5. Influence of supplemental fat on performance of turkeys. Experiment 3 142-day Body weight (kg/tom)
0 (Control) 2A* 4A 8A
11.80 12.55 12.32 12.60
2N 4N 8N
12.08 12.45 12.92 .40
SD*>
Consumed/kg gain, 1 to 142 days Feed (kg)
ME (kcal)
Protein (kg)
3.17 3.02 3.00 2.87 3.00 2.98 2.90
9605 9384 9544 9541
.638 .624 .634 .639
9323 9465 9644
.605 .603 .582
255
.016
.081
Probabilities of significance Control vs.
added fat
.02
A vs. N
ns
Linear effect of fat c Fat X AN
ns
.01
.01 ns
ns
.09
ns
.01
.01
ns ns
ns .01
A and N refer to diets with adjusted and nonadjusted ME -to-nutrient ratios, respectively. Standard deviation of the means. Quadratic and cubic effects of supplemental fat were not significant at P<.10.
increments of fat in Experiment 4B, corresponding to observations made with corn-based diets of the same experiment. In contrast, supplemental fat had no effect on ME utilization for milo-based diets in Experiment 2B. Mortality, All Experiments. Mortality encountered in Experiments 1, 2B, 3, and 4B were 8, 3.9, 10.2, and 4%, respectively. Incidence of mortality was not related to specific diet treatments within an experiment. Considerable mortality as a result of aortic rupture was observed between days 63 and 98 of Experiment 1. In Experiment 3, a high incidence of "spraddle-legs" and mortality occurred when the poults were 5 to 28 days of age.
DISCUSSION
The generally favorable responses of torn turkeys to supplemental dietary fat was expected on the basis of previous research (Sunde, 1954; Touchburn and Naber, 1966; Jensen et ai, 1970; and others). An integral part of the research reported here, however, was to evaluate the consistency of fat's effects on turkey performance when tested in different ex-
periments. To facilitate this evaluation, regression analysis was done relating level of fat supplementation and each performance characteristic for all experiments. The resulting regression equations are shown in Tables 8 and 9. The regression equations were used also to calculate the percentage change that each 1% supplemental fat caused in final body weights and feed efficiency. When corn-based diets were used, the regression coefficients describing the favorable effects of supplemental fat on final body weights were highly significant with one exception. The exception was the regression coefficient for the adjusted diet series of Experiment 3. In addition to this exception, there were some inconsistencies in the magnitude of the effect of fat on body weight, especially with diets having adjusted MEto-nutrient ratios. The percentage improvement in final body weight for each 1% fat tested in the adjusted diet series ranged from .1 (nonsignificant) to 1.5%. Variability among experiments was somewhat less for the nonadjusted diet series than for the adjusted series, although the magnitude of improvement in body weight was only .6% for each 1% of fat in Experiment 1 as compared
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Supplemental fat (%)
FAT FOR GROWING TURKEYS
2301
TABLE 6. Influence of supplemental fat on performance of turkeys fed corn-based diets, Experiment 4
Supplemental fat (%)
140-day Body weight (kg/tom)
Feed (kg)
ME (kcal)
Protein (kg)
0 (Control) 2A a 4A 8A
10.25 9.92 10.82 11.28
3.07 3.00 2.83 2.61
9483 9480 9146 8814
.561 .563 .545 .527
2N 4N 8N
10.12 10.52 11.05
2.93 2.80 2.71
9250 9069 9115
.539 .516 .497
.26
.08
262
.016
„_., , .,... Control vs. added fat A vs. N Linear effects of fate Fat X AN
ns
c
. .,.
.01
ns .01 ns
.07
ns
ns
.01 ns
ns
.04
.01 .01
.01 ns
A and N refer to diets with adjusted and nonadjusted ME-to-nutrient ratios, respectively. Standard deviation of the means. c
Quadratic effects of supplemental fat were not significant at P<.10. Cubic effect of supplemental fat was significant (P<.05) for body weight only.
with 1.3, 1.2, and 1.1% for Experiments 2, 3, and 4, respectively. The regression coefficients (Table 9) show that fat also had significant favorable effects on body weights of toms fed milo-based diets, but the magnitudes of increase were relatively small (.6 and .7% for each 1% fat in Experiments 2B and 4B, respectively). There was also a quadratic component of the regression equation for body weights of Experiment 4B, which was significant at (P<.08), indicating that the extent of favorable effect of fat on this parameter declined as level of supplemental fat increased. The improvements in body weight at approximately 140 days of age, resulting from fat supplementation of corn-based diets in our experiments, fell within ranges of values reported by others. The data reported by Jensen et al. (1970) showed that body weight increased .5 to 1.3% per 1% added fat when diets containing relatively high protein levels were fed from 8 to 24 weeks of age. Corresponding values for diets with lower protein levels ranged from .85 to 1.0%. Sullivan (1979) also reported that fat supplementation of corn-based diets
increased torn weights by 1.3% for each 1% fat. The growth responses reported by Potter (1976) and Waibel (1978), .36 and .5% per 1% supplemental fat, respectively, were somewhat lower than those observed in three of the four experiments reported herein. In one instance there was essentially no increase associated with fat supplementation, but in the other three instances, body weights were increased .6 to 1.5% per 1% supplemental fat, with the most consistent improvements obtained with nonadjusted diets (expanding ME-to-nutrient ratios). In the research described here, toms were fed supplemental fats continuously from 1 to about 140 days of age. Most published data, however, including those of Potter (1976) and Waibel (1978), were obtained from trials performed with turkeys 8 weeks of age and older. Supplementing milo-based diets with 2 to 8% fat increased 140-day body weight by .6 to .7% per each 1% fat in the experiments reported here. Recently, Sullivan (1979) found that increasing the level of added fat in milo diets from 2.5 to 5.0% increased body weights of 22-week-old toms by .4% per each 1% fat.
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SDb
Consumed/kg gain, 1 to 140 days
SELL AND OWINGS
2302
TABLE 7. Influence of supplemental fat on performance of turkeys fed milo-based diets, Experiments 2B and 4B Consumed/kg gain, 1 to 139 days
Body weight a (kg/tom)
Feed (kg)
ME (kcal)
Protein (kg)
Experiment 2B 0 (Control) 2A b 4A 6A 8A
11.04 11.33 11.49 11.57 11.55
3.08 3.03 2.95 2.81 2.80
9273 9358 9330 9092 9248
.636 .638 .638 .625 .624
SDC
.35
Experiment 4B 0 (Control) 2N 4N 8N
.026
10.22 10.62 10.88 10.90
3.19 3.07 2.98 2.78
.29
.10
SD
„ Experiment 2B Control vs. added fat Linear effect of fat d
, , .,.,._
85
r
.
.01
9762 9599 9544 9324
.584 .564 .549 .512
319
.018
.„.
.02
ns
ns
.05
.01
ns
.02
Experiment 4B Control vs. added fat
.01
.01
ns
.02
Linear effect of fat e
.01
.01
ns
.05
.01
139-day and 140-day body weights for Experiments 2B and 4B, respectively. A and N refer to adjusted and nonadjusted ME-to-nutrient ratios for Experiments 2B and 4B, respectively. Standard deviation of the means. Quadratic and cubic effects of supplemental fat were not significant at P<.10. Quadratic effect was significant (P<.08) for body weight only.
When supplemental fat has been tested in corn-based diets, relatively consistent, substantial improvements in feed efficiency of turkeys have been reported. The improvements have ranged from 1.3 to 2.1% per 1% supplemental fat (Jensen et al, 1970; Potter, 1976; Waibel, 1978; Sullivan, 1979). Fat supplementation of corn-based and milo-based diets in the current research also improved feed efficiency but to a slightly lesser degree tlian previously reported. Feed efficiency was improved by .8 to 1.6% per 1% added fat in the four experiments. There was no consistent effect of season of the year or adjustment in ME to nutrient ratios on changes in feed efficiency elicited by 1 to 8% supplemental fat. The magnitude of the effect of fat on feed
efficiency in our experiments generally was less than that reported by other researchers despite the fact that changes in dietary ME concentration associated with fat supplementation were similar to those used previously. For example, all diets in the research reported here were formulated so that ME concentration of the diet increased 37 kcal/kg with each 1% supplemental fat. Changes in ME concentrations were approximately 26, 44, and 40 kcal/kg of diet with each 1% fat in the research of Jensen et al. (1970), Potter et al. (1974), and Waibel (1978), respectively. Age intervals during which the toms were fed supplemental fat may have contributed to the lower responses in feed efficiency reported here. In our experiments, toms were fed fat-
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Supplemental fat, %
FAT FOR GROWING TURKEYS
2303
TABLE 8. Regression of final body weight and feed efficiency on level of supplemental fat in corn-based diets
Experiment
Reg,•ession equation
ME-to-nutrient ratio
Season
n
J
Significance of linear coefficient
Improvement for each 1% supplemental fat (%)
"I
Winter Summer Winter Summer
A A A A
Y Y Y Y
= = = =
11.72 + 10.72 + 12.04+ 10.03 +
.180Xa .073X .017X .154X
.001 .004 ns .001
1.5 .7 .1 1.5
1 2 3 4
Winter Summer Winter Summer
N N N N
Y Y Y Y
= = = =
11.78 10.48 11.82 10.09
.077X .141X .142X .112X
.02 .001 .001 .001
.6 1.3 1.2 1.1
1 2 3 4
Winter Summer Winter Summer
A A A A
Y Y Y Y
= = = =
3.20 3.03 3.13 3.08
- .047X - .027X -.026X - .060X
.001 .002 .015 .001
1.5 .9 .8 1.9
1 2 3 4
Winter Summer Winter Summer
N N N N
Y Y Y Y
= = = =
3.21 3.11 3.12 3.03
- .043X - .029X -.030X - .044X
.001 .001 .001 .001
1.3 .9 1.0 1.5
+ + + +
Y = Final body weight (kg) or kilogram of feed per kilogram gain and X = percent supplemental fat.
supplemented diets from 1 to about 140 days of age. The aforementioned researchers used toms from 56 to 168 days of age. After reviewing published data, Potter (1976) concluded that supplemental fat had the greatest effect on feed efficiency after the turkeys were 56 days of age. An examination of feed efficiency data of our experiments supports this
conclusion. For example, data obtained from regression analysis showed that each 1% supplemental fat improved 63-day cumulative feed efficiency by an average of .8% over all experiments, whereas each 1% supplemental fat improved 140-day cumulative feed efficiency by 1.05%. Fat supplementation did not change the
TABLE 9. Regression of final body weight and feed efficiency on level of supplemental fat in milo-based diets
Experiment
Season
ME-to-nutrient ratio
Significance of linear coefficient
Regression equation „
j
._,_
2B 4B
Summer Summer
A N
Y = 11.15 + . 0 6 3 X a Y = 10.26 + .079X - .01 9X2b
.05 .01
2B 4B
Summer Summer
A N
Y= Y=
.001 .001
a
3.09-.039X 3.18-.051X
Improvement for each 1% supplemental fat (%)
.6 .7
1.3 1.6
Y = Final body weight (kg) or kilogram of feed per kilogram gain and X = percent supplemental fat. Quadratic coefficient for weight gain, Experiment 4B was significant at P<.08.
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1 2 3 4
2304
SELL AND OWINGS
Efficiency of protein utilization was improved consistently when fat was included in diets with nonadjusted ME-to-nutrient ratios. This effect of fat was most prominent in the summer experiments when feed and protein intakes were relatively low. It is doubtful that supplemental fat exerted a sparing effect on dietary protein (Waibel, 1978), but supplemental fat may have contributed to the attainment of a more nearly optimum available energy to amino acid balance for metabolism, especially when environmental temperatures were high. Generally, the protein efficiency data suggest that the protein concentrations of the adjusted diet series were higher than necessary to support satisfactory performance of toms reared during cool or warm weather conditions. The ME-to-nutrient ratios of diets of the nonadjusted diet series, however, were not excessively wide as compared with NRC (1977), at least through the 84-days-of-age interval. The ratios in our diets ranged from 98 to 108, 106 to 117, 122 to 134, 135 to 148, 162 to 177, and 194 to 212 for age intervals of 1 to 21, 21 to 42, 42 to 63, 63 to 84, 84 to 112, and 112 to 140 days, respectively. Corresponding ratios obtained from NRC (1977) data were 100, 112, 136, 163, and 194 for similar age intervals. Efficiency of protein utilization data were calculated in the current research by assuming that the chemical composition of weight gains was similar, irrespective of diet treatment. Chemical analysis of turkey carcasses was not done. Visual appraisal of carcasses of the turkeys processed at the Iowa State University
Meats Laboratory for subcutaneous fat, leaf fat, and yield of carcass components indicated that diet treatments did not alter carcass composition noticeably. These data will be the subject of a future report. The experiments reported here show that increasing dietary energy concentration by using supplemental fat at levels of 1 to 8% of the diet improves rate of growth and feed efficiency of torn turkeys to 140 days of age. These effects of fat were most consistent with feed efficiency. Also, the beneficial effects of fat supplementation of diets with nonadjusted ME-to-nutrient ratios were similar to those observed with diets of the adjusted series. This observation may be an important consideration in using supplemental fats to greatest economic advantage in turkey production. ACKNOWLEDGMENT This research was supported, in part, by grants from the Iowa Turkey Marketing Council and the Fats and Proteins Research Foundation, Inc., Des Plaines, IL. The animalvegetable fat was kindly supplied by C. W. Meyer Co., Bloomington, MN, and Feed Energy Co., Des Moines, I A. The technical assistance of William Larson and Irven Williams is gratefully acknowledged. REFERENCES Balloun, S. L., W. J. Owings, J. L. Sell, and R. E. Phillips, 1959. Energy and protein requirements for turkey starting diets. Poultry Sci. 38:13281340. Barr, A. J., J. H. Goodnight, J. P. Sail, W. H. Blair, and D. M. Chilko, 1979. SAS users guide. J. T. Helwig and K. A. Council, eds., SAS Institute, Inc., Raleigh, NC. Biely, J., and B. E. March, 1954. Fat studies in poultry. 2. Fat supplements in chick and poult rations. Poultry Sci. 33:1220-1227. Combs, G. F., and G. L. Romoser, 1955. A new approach to poultry feed formulation. Maryland Agric. Exp. Sta. Misc. Publ. 226. Dale, N. M., and H. L. Fuller, 1980. Effect of diet composition on feed intake and growth of chicks under heat stress. II. Constant vs. cycling temperatures. Poultry Sci. 59:1434—1441. Day, E. J., and J. E. Hill, 1957. The effect of calorie: protein ratio of the ration on growth and feed efficiency of turkeys. Poultry Sci. 36: 773-779. deAlbuquerque, K., A. T. Leighton, Jr., J. P. Mason, Jr., and L. M. Potter, 1978. The effects of environmental temperature, sex and dietary energy levels on growth performance of large white turkeys. Poultry Sci. 57:353-362. Jensen, L. S., G. W. Schumaier, and J. D. Latshaw,
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dietary ME consumed per kg weight gain in three of the four experiments. In Experiment 4, however, fat supplementation of corn-based or milo-based diets improved utilization of ME. The beneficial effect of fat on energy utilization may have been related to the unusually high environmental temperatures encountered during Experiment 4. Average daily high temperatures in the building were 27.8, 32.2, and 30.6 C during June, July, and August, respectively. Research with broiler chickens (Dale and Fuller, 1980) indicated that supplemental fat alleviated part of the adverse effects of high temperatures on performance. deAlbuquerque et al. (1978), however, reported that supplemental fat was of no greater benefit for turkeys reared at 35 C than for those kept at IOC.
FAT FOR GROWING TURKEYS
and milo diets on performance of market turkeys. Poultry Sci. 58:1113. (Abstr.) Sunde, M. L., 1954. The use of animal fats in poultry feeds. J. Amer. Oil Chem. Soc. 31:49-52. Touchburn, S. P., and E. C. Naber, 1966. The energy value of fats for growing turkeys. Pages 190—195 in Proc. 13th World's Poultry Congr., Kiev, USSR. Waibel, P. E., 1958, Effectiveness of unknown growth factors, antibiotic and animal fat in turkey poult rations. Poultry Sci. 37:1144-1149. Waibel, P. E., 1978. Studies on protein and energy requirements of turkeys during the growing period. Pages 143—154 in Proc. 39th Minnesota Nutr. Conf., Univ. Minnesota, St. Paul, MN. Waibel, P. E., G. Devegowda, and J. Palarski, 1977. Estimation of the value of animal fat in diets for turkeys. Pages 33—46 in Proc. 38th Minnesota Nutr. Conf., Univ. Minnesota, St. Paul, MN. Yacowitz, H., R. D. Carter, J. Wyne, and M. G. McCartney, 1956. Effects of varying protein and fat levels in a finishing ration for turkey broilers. Poultry Sci. 35:227-229.
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1970. Extra-caloric effect of dietary fat for developing turkeys as influenced by calorie: protein ratio. Poultry Sci. 49:1697-1704. Joshi, S. K., and J. L. Sell, 1964. Comparative dietary value of soybean oil, sunflower oil, rapeseed oil and animal tallow for turkey poults. Can. J. Anim. Sci. 4 4 : 3 4 - 3 8 . National Research Council, 1977. Nutrient requirements of poultry. 7th ed. National Academy of Sciences, Washington, DC. Owen, J. A., and P. W. Waldroup, 1979. Response of growing turkeys to diets varying in energy content. Poultry Sci. 58:1090-1091. (Abstr.) Pepper, W. F., S. J. Slinger, and J. D. Summers, 1960. Studies with chickens and turkeys on the relationship between fat, unidentified factors and pelleting. Poultry Sci. 39:66-74. Potter, L. M., 1976. Fat in turkey diets: how much it's worth. Turkey World 5 1 : 6 - 8 . Potter, L. M., J. R. Shelton, and L. G. Melton, 1974. Zinc bacitracin and added fat in diets of growing turkeys. Poultry Sci. 53:2072-2081. Sullivan, T. W., 1979. Effect of added fat level in corn
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