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Dietary Fat in the Nutrition of the Growing Chick1
Dietary Fat in the Nutrition of the Growing Chick 1 N. T. RAND, 2 H. M. SCOTT AND F. A. KUMMEROW Departments of Food Technology and Animal Science, University of Illinois, Urbana, Illinois (Received for publication February 6, 1958)
March and Biely (1954) and Biely and March (1954) recognized that the response to supplemental fat was influenced by the composition of the basal diet. They showed that 7 percent tallow depressed growth and feed efficiency on a diet containing 19 percent protein, but when the protein level was raised to 2428 percent, the tallow had no adverse
1 This work was supported by research grant No. H-1819 from the National Institute of Health, U. S. Public Health Service, Department of Health, Education and Welfare. 2 Present Address: VioBin Corporation, Monticello, Illinois.
effect on growth and improved the efficiency of feed utilization. Scott et al. (1955) studied the effect of tallow on growth and feed efficiency at three levels of protein (20, 25, and 30 percent) by substituting the fat for corn in one diet and for cerelose in another. They showed that 7 and 14 percent tallow depressed growth on the 20 percent protein diet, but that 7 percent tallow improved growth at the higher protein levels. The best growth was obtained when 7 percent tallow was added to the 30 percent protein diet. Waibel (1955) reported that 10 percent tallow improved growth on high protein diets. Donaldson et al. (1955) reported that the ratio of productive energy to the protein content in the ration affected growth rate and feed efficiency, and that supplemental fat tended to impair growth by widening the calorie/protein ratio. Leong et al. (1955) reported similar observations on the effect of the calorie/protein ratio on chick growth and feed efficiency. Sunde (1956) and Donaldson et al. (1956) as well as others have interpreted their results on the basis of the calorie/ protein ratio. It is apparent that in these studies the response to fat has been influenced by differences in the intake of energy, protein and other nutrients. The specific effect of fat on the performance of the chick can be determined only when the intake of other nutrients is kept constant. In pursuing the investigation reported herein, due cognizance was given to this concept.
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OUPPLEMENTAL fat in the diet of ^ the growing chick has been shown to have deleterious effects in some cases and beneficial effects in others. Henderson and Irwin (1940) reported that soybean oil was detrimental to chick growth when added at levels higher than 10 percent. Fraps (1943) also showed that the growth rate of chicks was markedly depressed as the level of dietary cottonseed oil was raised from 10 to 30 percent. Kummerow et al. (1949) reported that 25 percent linseed oil depressed growth and increased the incidence of perosis in chicks. Reiser and Pearson (1949) reported that the addition of cottonseed oil to a riboflavin deficient diet accentuated the effects of riboflavin deficiency in the chick. Yacowitz (1953) reported that while 2 | to 5 percent of supplemental fat improved growth, higher levels (10 to 15 percent) exerted an adverse influence on growth and feathering.
1076
N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW TABLE 2.—Treatment diets of experiment 1
EXPERIMENTAL
Isocaloric diets were formulated on the basis of the metabolizable energy values of the nutrients, as reported by Anderson and Hill (1955) and Hill and Renner (1957). Thus 7 parts of corn oil (9.0 Cal./g.) were considered equal in their TABLE 1.—Basal Drackett protein diets Ing edient
20 percent protein
Cerelose 69.23 percent Drackett Assay Protein C-1 23.53 percent DL methionine 0.50 percent Glycine 0.20 percent Corn oil1 1.00 percent Glista salts 2 5.34 percent Choline chloride 0.20 percent Vitamin premix 3 Procaine penicillin 4 11 mg./kg. DPPDi 62 mg./kg.
+
100.00 percent 1 2
30 percent protein 57.11 35.30 0.75 0.30 1.00 5.34 0.20 11 62
percent percent percent percent percent percent percent
+mg./kg. mg./kg.
100.00 percent
In some experiments only 0.5 percent corn oil was used. Glista salts—0.88 percent NaCI, 0.002 percent ZnCU, 0.002 C u S 0 4 - 5 H 2 0 0.0009 percent H3BO3, 0.0001 percent C0SO4' 7H 2 0, 0.004 percent KI, 0.14 percent Fe citrate, 0.25 percent M g S 0 4 * 7H 2 0, 0.90 percent K 2 HP04, 0.065 percent MnSC-4 • H 2 0 , 0.30 percent CaCOs, 2.80 percent Ca3(P0 4 )2. 3 Vitamin premix—Per kg. diet: 100 mg. Thiamine HC1, 100 mg. Niacin, 16 mg. Riboflavin, 20 mg. Ca Pantothenate, .02 mg. Vitamin B12, 6 mg. Pyridoxine HC1, 0.6 mg. Biotin, 4 mg. Folic acid, 100 mg. Inositol, 2 mg. P-aminobenzoic acid, 5 mg. Menadione, 250 mg. Ascorbic acid, 20 mg. alpha-tocopherol acetate, 10,000 I.U. Vitamin A acetate, 600 I.C.U. vitamin Da. 4 Omitted in Experiment 1.
Lot
1
2
3
4
Drackett protein DL methionine Glycine Glista salts Choline chloride Vitamin premix Cerelose Corn oil Solka fioc
23.53% 0.50% 0.20% 5.34% 0.20%
23.53% 0.50% 0.20% 5.34% 0.20%
35.30% 0.75% 0.30% 5.34% 0.20%
35.30% 0.75% 0.30% 5.34% 0.20%
+
69.23% 1.00%
— 100.00%
Percent protein calculated determined Percent fat calculated determined Metabolizable energy Calorie/g.
+
+
52.23% 8.00% 10.00%
57.11% 1.00%
100.00%
100.00%
—
+
40.11% 8.00% 10.00% 100.00%
20.0 20.1
20.0 20.2
30.0 29.4
30.0 29.4
1.0 0.8
8.0 7.5
1.0 0.8
8.0 7.5
3.62
3.62
3.64
3.64
metabolizable energy content to 17 parts of cerelose (3.7 Cal./g.). The metabolizable energy value of Drackett assay C-1 protein was calculated from the casein value and assumed to be (4.0 Cal./g.). No caloric value was assigned to cellulose (Solka floe), Rand et al. (1956). In experiments 1, 2, and 3, the metabolizable energy content of the diets was kept constant at each protein level by the replacement of 17 g. multiples of cerelose (63 Calories) by multiples of 7 g. corn oil (63 Calories) and 10 g. Solka floe (0 Calories). Two levels of corn oil, 1 and 8 percent, were used in experiment 1, and both were fed at marginal (20 percent) and adequate (30 percent) protein levels. These "treatment" diets are shown in Table 2. Five levels of corn oil at two protein levels were used in experiments 2 and 3, the design of which appears in Table 3. At the highest fat level of 14.5 percent, the corn oil contributed 36 percent of the total dietary calories. Female chicks were used in experiments 1 and 3, and male chicks in experiment 2. The chicks were fed daily in a manner to insure an equal intake of feed by all experimental groups at a given level of protein. In experiments 4 and 5 the final diets were prepared from two basal premixes
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All chicks used in the investigation originated from the mating of New Hampshire males and Columbian females. The chicks were placed on a purified basal diet containing 30 percent protein (NX6.25) for a period of 7 days, individually wing banded and distributed into the experimental lots on the basis of their body weight in a manner to insure that the average starting weight was equal for all groups. The chicks were placed in thermostatically controlled electrically heated batteries equipped with raised wire floors. Each experimental diet was fed to 3 replicates of 10 chicks each. All the experimental diets were formulated by the modification of the basal Drackett protein diets shown in Table 1. Supplements were added at the expense of cerelose and the protein quality was kept constant at all protein levels.
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FAT FOR GROWING CHICKS TABLE 3.—Treatment diets of experiments Z and 3 Lot 1 2 3 4 5
Percent fat
Treatment
1
30 percent protein, parts
20 percent protein basal 0.5 (1) + 3 . 5 percent corn o i l + 5 percent Solka floe 4.0 (l)-f-7.0 percent corn oil+10 percent Solka floe 7.5 (1)4-10.5 ) -i- 1 0 ^ pnei irrcr penntt cr norrtni onil i l-+I -115^percent npi-r^n t-Solka SnlVa floe fln^ 11. 11.0 x "( D -4-14.0 percent corn o i l + 2 0 percent Solka floe 14.5
Cerelose Drackett protein DL methionine Glycine Glista salts Corn oil Solka floe Choline chloride Vitamin premix1 DPPD 1 Procaine penicillin1
19.785 17.65 0.375 0.15 5.34 0.50 5.00 0.20
1.61 35.30 0.75 0.30 5.34 0.50 5.00 0.20
20.4 percent by chemical analysis; 3.60 Calories/g. 30.4 percent by chemical analysis; 3.63 Calories/g.
+ + +
+ + +
equivalent to 15 and 30 percent protein shown in Table 4. Five percent Solka floe was included in the basal mixtures to improve the physical properties of the diets containing the higher levels of corn oil. In the absence of supplemental corn oil 51 parts of cerelose were added to 49 parts of the basal premix. When, however, corn oil replaced cerelose the substitution was made in terms of their caloric ratio, i.e., 7 parts of corn oil for 17 parts of cerelose. It follows therefore that whenever corn oil was added, the final diets would not add up to 100 parts. W7ith this procedure it was possible to maintain a constant ratio of metabolizable energy to the pro-
Total parts
49.000
49.000
1
I n a m o u n t s as shown in T a b l e 1.
tein and all other nutrients in the treatment diets. This method of formulation facilitated the addition of higher levels of corn oil than could have been used if cellulose had been added to control-the level of metabolizable energy. The composition of the diets used in experiments 4 and 5 is given in Table 5. Three replicates of 10 male chicks were used in both experiments. In experiment 4, feeding was done on an ad libitum basis, while in experiment 5 the replicates were
TABLE 5.—Treatment diets of experiments 4 and 5 Lot 15 percent protein premix 30 percent protein premix cerelose corn oil Total parts Percent fat calculated determined Percent protein calculated determined Met. energy Cal./g. Calorie/protein 1 Percent fat energy of total energy non protein energy 1
49 51 00
49
49
49
34 7
17 14
21
90
80
70
—
—
—
—
49 51
49 34 7
49 17 14
49
90
80
70
100
21
0.5 0.6
8.3 8.3
18.1 18.1
30.7 30.9
0.5 0.6
8.3 8.4
18.1 18.2
30.7 31.1
15.0 15.1 3.39 22.6
16.7 16.8 3.77 22.6
18.8 18.8 4.24 22.6
21.4 21.2 4.84 22.6
30.0 30.0 3.44 11.5
33.3 33.4 3.82 11.5
37.5 37.7 4.30 11.5
42.8 42.3 4.91 11.5
1.3 1.6
19.9 24.5
38.5 47.3
57.1 70.1
1.3 2.3
19.6 33.9
37.9 65.6
56.3 97.2
Calorie/protein = Calories per 1 g. protein.
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15 percent protein, parts
Ingredient
1
0.5 30 percent protein basal 2 (6)4-3.5 percent corn oil4-5 percent Solka floe 4.0 (6)4-7.0 percent corn o i l + 1 0 percent Solka floe 7.5 (6)+10.5 p e r c e n t c o r n o i l + 1 5 percent Solka floe LX.U 11.0 (6) + 14.0 percent corn oil + 2 0 percent Solka floe 14.5 2
TABLE 4.—Basal premixes of experiments 4 and 5
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N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW TABLE 6.—Results of experiment 1 (21 days)-equalized feed intake Lot
Percent dietary protein Percent dietary fat Percent solka floe
2
3
4
20 1
20 8 10
30 1
30 8 10
245 201 354 .568 1,280 71 19.1 46.8 39.8 56.2
246 202 359 .563 1,310 108 19.9 48.9 41.9 38.9
— 228 184 354 .520 1,280 71 19.1 43.5 36.5 51.6
—
261 217 359 .604 1,310 108 19.9 51.9 44.9 41.7
1
Protein retention = carcass protein gain/protein intake. Statistical analysis Weight gain Treatment F 25.S**2 L.S.R. ( P < 5 percent) 10 g. 2 ** Significant at 1% probability level. * Significant at 5% probability level.
fed on a daily basis of group equalized nutrient intake at each of the two protein levels in a randomized block design. Thus controlling the consumption of diets 1, 2, 3, and 4 at the ratio of 100:90:80:70 respectively resulted in identical intakes of all nutrients with the only variable being the source of calories. Diets 5, 6, 7, and 8 were fed in a like manner. The experiments were terminated at 21 days of age in experiments 1 and 2, 31 days of age in experiment 3 and 28 days of age in experiments 4 and 5. The two median chicks in each replicate were sacrificed for carcass analysis by the acid hydrolysis method outlined by Rand (1957). Thus the average carcass composition was derived from six individual chicks and the average gain was obtained from 30 individual chicks. The results were subjected to statistical treatment for the analysis of variance and " F " tests using the procedure of Snedecor (1946). The main effects and their interactions were determined by factorial analysis. The least significant range (LSR)
Protein gain 5.10** 1.8 g.
was determined by the method of Duncan (1955). RESULTS
The results of experiment 1 indicated that when the intake of protein, energy and all other nutrients was equalized, growth was significantly improved when 7 percent corn oil was added to the basal diets (Table 6). Since protein and metabolizable energy intakes were constant at each protein level, the response to corn oil in terms of weight gain reflected the same relative response in feed efficiency and in the utilization of dietary protein and energy. The analysis of the carcass composition revealed that the growth promoting effect of supplemental corn oil represented a true increase in carcass protein. Thus the beneficial effect of corn oil on growth reflected a significant increase in protein deposition and protein retention at both dietary levels of protein. The results of experiments 2 and 3 are given in Tables 7 and 8 respectively. In experiment 2, there was only a slight,
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Final weight (g.) Weight gain (g.) Feed intake (g.) Gain/feed Caloric intake Protein intake (g.) Percent carcass protein Total carcass protein (g.) Carcass protein gain (g.) Percent protein retention 1
1
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FAT FOR GROWING CHICKS TABLE 7.—Results of experiment 2 (21 days)-equalized feed intake Lot Percent dietary protein Percent dietary fat Percent solka floe Final weight (g:) Weight gain (g.) Feed intake (g.) Gain/feed
1 20 0.5
—
232 156 311
.502
2
3
4
5
20 4.0 5 235 159 311 .511
20 7.5 10 233 157 311 .505
20 11.0 15 235 159 311 .511
20 14.5 20 238 162 311 .521
6 30 0.5 231 155 286
— .542
7
8
9
10
30 4.0 5 241 165 286 .577
30 7.5 10 242 166 286 .580
30 11.0 15 249 173 286 .605
30 14.5 20 257 181 286 .633
Treatment F =2.94* (in weight gain). L.S.R. (P<5 percent) = 13 g. (in weight gain).
The data of experiments 2 and 3 were combined in constructing the curves of Figure 1 to shown the average response of the chick to increased levels of corn oil at both levels of protein. As will be noted the response from corn oil at the 30 percent protein level was considerably
greater than the response at the 20 percent protein level. The results of experiments 4 and 5 appear in Tables 9 and 10 respectively. With ad libitum feeding (experiment 4), a significant improvement in growth was noted when fat calories replaced carbohydrate calories while maintaining the same calorie/protein ratio. The most notable increase was shown when supplemental fat was raised from 0.5 percent to 8.3 percent. However, growth continued to improve slightly up to the highest level
PERCENT
CORN
OIL
FIG. 1. The response of chicks to corn oil. (Combined data of experiments 2 and 3 for weight gains and nutrient utilization.)
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if any, improvement in growth when the 20 percent protein diet was supplemented with corn oil. The improvement at the 30 percent level was much more pronounced and was statistically significant. In experiment 3, the beneficial effects noted for increments of corn oil was significant at both levels of protein. The most notable improvement in growth was observed with the first increment of corn oil (from J to 4 percent). However, while the improvement due to further increments of corn oil was only slight for one increment at a time, it was apparent that the trend was significant. Because of the equalized feeding techniques, the effect of the supplemental corn oil was proportionally the same for growth, feed efficiency and nutrient utilization. The analysis of the carcass composition in experiment 3 confirmed the previous finding that the supplemental corn oil resulted in a significant improvement in the gain and in the retention of carcass protein. This was most evident at the first increment of the added fat. No further improvement could be detected beyond the 1 1 % level of corn oil for either level of protein.
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The results of experiment 5 showed t h a t differences in feed consumption would not account for the growth stimulating effect of corn oil, since in this instance the intake of nutrients was equalized. However, while the overall performance improved notably as the level of corn oil was increased from 0.5 percent to 8.3 percent, there was a much smaller effect between 8.3 and 18.1 percent levels of corn oil, and a significant decline resulted when the level of corn oil was further increased to 30.7 percent. This depression might have occurred because of the reduced weight of feed consumed b y the chicks on the highest fat diet. Since the feed was given only once every 24 hours, the chicks on the 30.7 percent fat diets were without feed for the major part of the day, having consumed their allotment of feed within a few hours after feeding. However, it is conceivable t h a t in this instance the reduced growth on the highest fat level represented a true depression in the utilization of the nutrients. Nevertheless, the performance on the 30.7 percent corn oil diet, where the fat contributed u p to 97 percent of the non-protein calories, was still significantly superior to the low fat diets, indicating t h a t the chick's toler-
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of corn oil (30.7 percent). I t was apparent, however, t h a t the response to corn oil in experiment 4 was due in p a r t to the greater intake of all nutrients. The efficiency in nutrient utilization as measured by the protein efficiency ratio (gain/protein intake) and energy efficiency ratio (gain/Calorie intake) reached its peak at a level of 8 . 3 % fat. A slight depression from this peak was noted at the higher (18.1 percent and 30.7 percent) fat levels. Nevertheless, the efficiency in nutrient utilization at these high levels of dietary fat was considerably superior to the efficiency on the basal diets containing 0.5 percent fat.
O 00 O N 00 iO O N
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SCOTT AND F. A.
1081
FAT FOR GROWING CHICKS TABLE 9.—Results of experiment 4 (28 days)-a,d libitum feeding Lot
1 15.0 0.5 1.3 22.6 363 283 626 .452 2,120 .133 94 3.01 17.7 64.3 51.1 54.4
2 16.7 8.3 19.9 22.6 410 330 617 .535 2,320 .142 103 3.20 18.4 75.4 62.2 60.4
Statistical analysis Treatment F L.S.R. ( P < 5 percent)
3 18.8 18.1 38.5 22.6 401 321 543 .591 2 ,300 .140 102 3.15 18.1 72.6 59.4 58.3
4 21.4 30.7 57.1 22.6 418 338 502 .674 2,420 .140 107 3.16 17.7 74.0 60.8 56.8
Weight gain 27. 2»* 19 g.
6
5 30.0 0.5 1.3 11.5 398 318 586 .543 2,020 .157 176 1.80 18.8 74.8 6.16 35.0
33.3 8.3 19.6 11.5 439 359 545 .658 2 ,080 .173 182 1.97 18.9 83.0 69.8 38.4
7 37.5 18.1 37.9 11.5 436 356 496 .718 2,130 .167 186 1.92 18.6 81.1 67.9 36.5
8 42.8 30.7 56.3 11.5 453 373 456 .818 2,230 .168 193 1.93 18.7 78.4 71.5 37.1
Protein gain 4.31" 2 .9 g .
ance for fat per se is essentially unlimited. A comparison between experiments 4 and 5 is illustrated in Figure 2. The average response in weight gain due to corn oil in experiment 4 was 15.2 percent over that of the basal ration while in experiment 5 the average response was 10.2 percent. This indicated that approximately one third of the response in the ad libitum feeding (experiment 4) was due to the indirect effect of fat in increasing the nutrient intake, perhaps by improving the texture of the feed. In both experiments food conversion steadily improved with each increment of corn oil, reaching a maximum conversion of .819 g. gain per
g. of feed consumed on the high protein diet containing 30.7 percent fat. The data of all the experiments, illustrating the growth response due to higher fat levels, are given in Figure 3. The average beneficial effect of the corn oil was more pronounced at the high protein level by more than one third. The best overall performance for growth and nutrient utilization occurred when the fat contributed between 20 and 38 percent of the total metabolizable energy, or between 34 and 48 percent of the non-protein energy of the diets. Protein retention improved as the percentage of metabolizable energy originat-
TABLE 10.—Results of experiment 5 (28 days)-equalized nutrient intake Lot Percent dietary protein Percent dietary fat Percent fat energy Calorie/gm. protein Final weight (g.) Weight gain (g.) Feed intake (g.) Gain/intake Calorie intake Gain/Calorie intake Protein intake (g.) Gain/protein intake Percent carcass protein Total carcass protein (g.) Carcass protein gain (g.) Percent protein retention Statistical analysis Treatment F L.S.R. ( P < 5 percent)
1 15.0 0.5 1.3 22.6 358 278 647 .430 2,190 .127 97 2.86 17.8 63.7 50.5 52.1
2
3
16.7 8.3 19.9 22.6 382 302 582 .519 2,190 .138 97 3.11 18.4 70.3 57.1 58.9
18.8 18.1 38.5 22.6 399 319 517 .617 2 ,190 .146 97 3.29 18.2 72.6 59.4 61.2
Weight gain 66. 5** 12!
4 21.4 30.7 57.1 22.6 371 291 453 .642 2,190 .133 97 3.00 17.8 66.1 53.9 55.6
5 30.0 0.5 1.3 11.5 405 325 617 .527 2,120 .153 185 1.76 18.8 76.1 62.9 34.0
6 33.3 8.3 19.6 11.5 449 369 555 .665 2,120 .174 185 1.99 19.0 85.3 72.1 39.0
Protein gain 6 .16** 2• l g .
7 37.5 18.1 37.9 11.5 440 360 493 .730 2,120 .170 185 1.95 18.6 81.9 68.7 37.1
8 42.8 30.7 56.3 11.5 434 354 432 .819 2,120 .167 185 1.92 18.7 81.2 68.0 36.8
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Percent dietary protein Percent dietary fat Percent fat Calories Calorie/gm. protein Final weight (g.) Weight gain (g.) Feed intake (g.) Gain/feed Calorie intake Gain/Calorie intake Protein intake (g.) Gain/protein intake Percent carcass protein Total carcass protein (g.) Carcass protein gain (g.) Percent protein retention
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N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW
METABOLIZABLE L • PERCENT
CORN
ENERGY
FROM CORN
OIL
I 18 OIL
L_ 31
FIG. 2. Relationship of feeding method to the effect of corn oil on weight gains. (Experiments 4 and 5.)
80%
PERCENT METABOLIZABLE
i
i
PROTEIN
The beneficial effect of corn oil in increasing protein retention was more pronounced at the high protein levels. On the average, the improvement at the high (30 percent) protein level was 25 percent better than the- improvement at the low (15-20 percent) protein levels.
ENERQY FROM CORN OIL
i
:
7 PERCENT PERCENT METABOLIZABLE
FIG. 3. The relationship of protein level to the chick response for corn oil. (Combined data of all experiments.)
ENERGY FROM
CORN
OIL
FIG. 4. The effect of corn oil on protein retention. (Summary of all experiments.)
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PERCENT I
ing from corn oil was increased. In experiment 4, maximum protein retention occurred at the 8.3 percent fat level for both low and high protein diets. In experiment 5, the peaks were at the 18.1 percent fat level on the low protein diet, and at the 8.3 percent fat level on the high protein diet. In all cases, there was a significant decrease in protein retention following the peaks. However, the protein retention at the highest level of corn oil was still significantly better than at the lower level of fat. These results seemed to indicate that protein retention was maximal when the percentage of metabolizable energy derived from corn oil was within the range of 20 to 38 percent which corresponded to a fat contribution of 34 to 48 percent of the non-protein energy of the diets (Figure 4).
FAT FOR GROWING CHICKS
DISCUSSION
(1949) reported that the heat increment of rats was lowered from 36 to 16 percent of the total heat production when the fat level was isocalorically increased from 2 to 30 percent. These findings tend to indicate that fat improved the retention of protein primarily by improving overall energy utilization due to the net increase in the consumption of utilizable energy by the growing chick. This is in agreement with the report of Robel et al. (1956) to the effect that a higher energy intake consistently improved the retention of dietary protein in chicks and with the report of Forbes et al. (1955) that a lower energy intake lowered the biological value of protein in rats. However, this interpretation is not universally accepted. Thomson and Munro (1955) and Metta and Mitchell (1956) concluded that the replacement of carbohydrates by fat did not improve protein utilization by growing rats. Donaldson et al. (1957) reported that while supplemental dietary fat tended to increase growth rate, it actually improved the utilization of dietary protein and calories only in one case out of five experiments. They, however, concluded that chicks could tolerate up to 33.8 percent fat in the rations. Baldini and Rosenberg (1957) also claimed that fat, per se (as beef tallow) had no effect on the performance of the growing chick. However, these reports were based on experiments where chicks were fed ad libitum, and the energy value of fat was assessed in terms of productive energy. Since Hill and Anderson (1955) reported that the productive energy values were highly variable while metabolizable energy values were highly reproducible, the use of metabolizable energy values are to be preferred to productive energy values in formulating isocaloric diets. A specific relationship in the metabo-
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The use of equalized feed and nutrient intake techniques of feeding demonstrated conclusively that the inclusion of moderate levels of corn oil in the diet of the growing chick resulted in an improvement in true growth, efficiency of protein, and energy utilization and protein retention. This response was obviously due to the corn oil per se, because it could not be attributed either to variations in intake of other nutrients, or to the essential fatty acids, since the latter was always present in the basal diet. It is conceivable that the effect of the corn oil was exerted through one or more of the following means: A) by increasing the efficiency of the utilization of the metabolizable energy; B) by improving the utilization of dietary protein; C) by providing an unidentified growth factor. The assumption that the chick's response to fat could be explained by the effect of fat on the energy metabolism seems to have a great deal of support. The observation that the best growth response was obtained when the corn oil contributed between 34 and 48 percent of the non-protein calories to the diet was similar to results obtained with rats as the experimental animals. Forbes and Swift (1944) reported that dietary fat reduced significantly the amount of the heat increment wasted by rats, indicating that the addition of fat markedly improved the utilization of metabolizable energy. Forbes et al. (1946) showed that on a constant intake of protein and energy, the digestibility and retention of protein as well as the growth rate was improved when the fat level of the rat diet increased from 2 to 30 percent. French et al. (1948) showed further that high fat diets increased weight gains in rats and decreased heat production when the intake of nutrients was held constant. Swift and Black
1083
1084
N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW
SUMMARY
When chicks were fed isonitrogenousisocaloric diets, the substitution of fat calories for glucose calories resulted in improved weight gains and greater protein and energy utilization and protein retention. This was true for ad libitum feeding as well as when nutrient intake was equalized for all experimental groups. Highly significant differences in growth were noted even though the calorie/protein ratios were constant. The best overall per-
formance was obtained when the fat contributed between 20 and 38 percent of the total metabolizable energy of the diet. However, the beneficial effect of fat on both weight gain and protein retention was pronounced even at the highest fat level. At this point the fat contributed 57 percent of the total metabolizable energy and up to 97 percent of the non-protein calories of the diet, indicating that the chick's tolerance for fat, per se, is essentially unlimited. The beneficial effect of the fat was apparent at all levels of protein, but it was most pronounced at the highest protein level. REFERENCES Anderson, D. L., and F. W. Hill, 1955. Determination of metabolizable energy values for chicks of pure carbohydrates, cellulose, fat and casein. Poultry Sci. 34:1176. Arscott, G. H., 1956. Complexity of a chick growth response to egg yolk, animal fat and fish solubles additions to the diet. Poultry Sci. 35: 338-342. Arscott, G. H., P. H. Weswig and J. R. Schubert, 1957. Multiple nature of chick growth responses to fractions of dried egg yolk. Poultry Sci. 36: 513-516. Baldini, J. T., and H. R. Rosenberg, 1957. The effect of calorie source in a chick diet on growth, feed utilization and body composition. Poultry Sci. 36: 432-435. Biely, J., and B. March, 1954. Fat studies in poultry. 2. Fat supplements in chick and poultry rations. Poultry Sci. 33:1220-1227. Denton, C. A., R. J. Lillie and J. R. Sizemore, 1954. Effect of egg yolk, fat and fish solubles on growth of chicks. Fed. Proc. 13: 455. Donaldson, W. E., G. F. Combs, G. L. Romoser and W. C. Supplee, 1955. Body composition, energy intake, feed efficiency, growth rate and feather condition of growing chickens as influenced by the calorie-protein ratio of the ration. Poultry Sci. 34: 1190. Donaldson, W. E., G. F. Combs, and G. L. Romoser, 1956. Studies on energy levels in poultry rations. 1. The effect of calorie-protein ratio of the ration on growth, nutrient utilization and body composition of chicks. Poultry Sci. 35: 1100-1105. Donaldson, W. E., G. F. Combs, G. L. Romoser and W. C. Supplee 1957. Studies on energy levels in
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lism of fat and protein may be inferred since higher protein levels tended to enhance the beneficial effects of the corn oil. Actual evidence supporting this relationship was presented by Pearson and Panzer (1949). They showed that on an equal intake of protein, the isocaloric addition of 8 percent corn oil significantly lowered the excretion of valine, lysine, and methionine by growing rats and increased protein retention. The fact that the improvement in growth and in protein retention was greatest at the first increment of corn oil seems to indicate that an unidentified factor may have been involved. This should not be surprising since several workers have concluded that fats contain an unidentified factor(s) required for maximum chick growth. Thus Denton et al. (1954) reported that animal fat contained an unidentified growth factor which they postulated as the same factor found in fish solubles. This conclusion was confirmed by Arscott (1956). Menge et al. (1957) reported that an unidentified factor, found in the non-saponifiable portion of egg yolk fat, increased chick growth by 18 percent at 4 weeks of age. Arscott et al. (1957) also reported on the growth promoting effect of dried egg yolk. The present studies did not clarify whether refined corn oil contained any of these factors.
FAT FOR GROWING CHICKS
Unidentified growth factor in egg yolk. Fed. Proc. 16: 392-393. Metta, V. C , and H. H. Mitchell, 1956. A comparison of the biological values of dietary protein incorporated in high-and low-fat diets. J. Nutr. 59: 501-513. Pearson, P. B., and F. Panzer, 1949. Effect of fat in the diet of rats on their growth and their excretion of amino acids. J. Nutr. 38: 257-265. Rand, N. T., H. M. Scott and F. A. Kummerow, 1956. The relationship of protein, fiber and fat in the diet of the growing chick. Poultry Sci. 35: 1166. Rand, N. T., 1957. The utilization of fat by the growing chick. Doctoral Thesis. University of Illinois. Reiser, R., and P. B. Pearson, 1949. The influence of high levels of fat with suboptimum levels of riboflavin on the growth of chicks. J. Nutr. 38: 247-256. Robel, E. J., G. F. Combs and G. L. Romoser, 1956. Protein requirement of chicks for maintenance of nitrogen balance and growth. Poultry Sci. 35: 1168. Scott, H. M., L. C. Sims and D. L. Staheli, 1955. The effect of varying protein and energy on the performance of chicks. Poultry Sci. 34: 1220. Snedecor, G. W., 1946. Statistical Methods. 4th edition, The Collegiate Press. Ames, Iowa. Sunde, M. L., 1956. A relationship between protein level and energy level in chick rations. Poultry Sci. 35:350-354. Swift, R. W., and A. Black, 1949. Fats in relation to caloric efficiency. J. Am. Oil. Chem. Soc. 26: 171-176. Thomson, W. S. T., and H. N. Munro, 1955. The relation of carbohydrate metabolism to protein metabolism. 4. The effect of substituting fat for dietary carbohydrate. J. Nutr. 56: 139-150. Waibel, P. E., 1955. Effect of dietary protein level and added tallow on growth and carcass composition of chicks. Poultry Sci. 34:1226. Yacowitz, H., 1953. Supplementation of corn-soybean oil meal rations with penicillin and various fats. Poultry Sci. 32:930.
NEWS AND NOTES {Continued from page 1070) abstracts, housing arrangements, and registration. The scientific program is planned to include a series of panel discussions and presentations of original work by invited speakers on such subjects as: Human Nutritional Problems and Their Assess-
ment; Food Processing; Lipids in Health and Disease; Animal Nutrition and Feeding for Maximal Production; Nutrition in Maternal and Infant Feeding; Proteins and Amino Acids in Nutrition. Also, the customary ten-minute papers reporting original 1090)
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poultry rations. 2. Tolerance of growing chicks to dietary fat. Poultry Sci. 36: 807-815. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Forbes, E. B., and R. W. Swift, 1944. Associative dynamic effects of protein, carbohydrate and fat. J. Nutr. 27:453-468. Forbes, E. B., R. W. Swift, R. F. Elliot and W. H. James, 1956. Relation of fat to economy of food utilization. I. By the growing albino rat. J. Nutr. 31: 203-212. Forbes, R. M., and M. Yohe, 1955. Effect of energy intake on the biological value of protein fed to rats. J. Nutr. 55: 499-506. Fraps, G. S., 1943. Relation of the protein, fat and energy of the ration to the composition of chickens. Poultry Sci. 22: 421-424. French, C. E., A. Black and R. W. Swift, 1948. Further experiments on the relation of fat to economy of food utilization. 3. Low protein intake. J. Nutr. 35: 83-88. Henderson, E. W., and W. E. Irwin, 1940. The tolerance of growing chicks for soybean oil in their ration. Poultry Sci. 19: 389-395. Hill, F. W., and D. L. Anderson, 1955. Comparison of productive energy and metabolizable energy determinations with chicks. Poultry Sci. 34: 1201. Hill, F. W., and R. Renner, 1957. Metabolizable energy values of feedstuffs for poultry and their use in formulation of rations. Proc. Cornell Nutr. Conf. 22-32. Kummerow, F. A., R. Weaver and H. Honstead, 1949. The choline replacement value of ethanolamine in chickens kept on a high fat ration. Poultry Sci. 28: 475^78. Leong, K. C , M. L. Sunde, H. R. Bird and C. A. Elvehjem, 1955. Effect of energy: protein ratio on growth rate, efficiency, feathering and fat deposition in chickens. Poultry Sci. 34: 1206-1207. March, B. E., and J. Biely, 1954. The nutritive value of fats of different origin in chick starters. Poultry Sci. 33: 1069. Menge, H., R. J. Lillie and C. A. Denton, 1957.
1085
March and Biely (1954) and Biely and March (1954) recognized that the response to supplemental fat was influenced by the composition of the basal diet. They showed that 7 percent tallow depressed growth and feed efficiency on a diet containing 19 percent protein, but when the protein level was raised to 2428 percent, the tallow had no adverse
1 This work was supported by research grant No. H-1819 from the National Institute of Health, U. S. Public Health Service, Department of Health, Education and Welfare. 2 Present Address: VioBin Corporation, Monticello, Illinois.
effect on growth and improved the efficiency of feed utilization. Scott et al. (1955) studied the effect of tallow on growth and feed efficiency at three levels of protein (20, 25, and 30 percent) by substituting the fat for corn in one diet and for cerelose in another. They showed that 7 and 14 percent tallow depressed growth on the 20 percent protein diet, but that 7 percent tallow improved growth at the higher protein levels. The best growth was obtained when 7 percent tallow was added to the 30 percent protein diet. Waibel (1955) reported that 10 percent tallow improved growth on high protein diets. Donaldson et al. (1955) reported that the ratio of productive energy to the protein content in the ration affected growth rate and feed efficiency, and that supplemental fat tended to impair growth by widening the calorie/protein ratio. Leong et al. (1955) reported similar observations on the effect of the calorie/protein ratio on chick growth and feed efficiency. Sunde (1956) and Donaldson et al. (1956) as well as others have interpreted their results on the basis of the calorie/ protein ratio. It is apparent that in these studies the response to fat has been influenced by differences in the intake of energy, protein and other nutrients. The specific effect of fat on the performance of the chick can be determined only when the intake of other nutrients is kept constant. In pursuing the investigation reported herein, due cognizance was given to this concept.
1075
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OUPPLEMENTAL fat in the diet of ^ the growing chick has been shown to have deleterious effects in some cases and beneficial effects in others. Henderson and Irwin (1940) reported that soybean oil was detrimental to chick growth when added at levels higher than 10 percent. Fraps (1943) also showed that the growth rate of chicks was markedly depressed as the level of dietary cottonseed oil was raised from 10 to 30 percent. Kummerow et al. (1949) reported that 25 percent linseed oil depressed growth and increased the incidence of perosis in chicks. Reiser and Pearson (1949) reported that the addition of cottonseed oil to a riboflavin deficient diet accentuated the effects of riboflavin deficiency in the chick. Yacowitz (1953) reported that while 2 | to 5 percent of supplemental fat improved growth, higher levels (10 to 15 percent) exerted an adverse influence on growth and feathering.
1076
N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW TABLE 2.—Treatment diets of experiment 1
EXPERIMENTAL
Isocaloric diets were formulated on the basis of the metabolizable energy values of the nutrients, as reported by Anderson and Hill (1955) and Hill and Renner (1957). Thus 7 parts of corn oil (9.0 Cal./g.) were considered equal in their TABLE 1.—Basal Drackett protein diets Ing edient
20 percent protein
Cerelose 69.23 percent Drackett Assay Protein C-1 23.53 percent DL methionine 0.50 percent Glycine 0.20 percent Corn oil1 1.00 percent Glista salts 2 5.34 percent Choline chloride 0.20 percent Vitamin premix 3 Procaine penicillin 4 11 mg./kg. DPPDi 62 mg./kg.
+
100.00 percent 1 2
30 percent protein 57.11 35.30 0.75 0.30 1.00 5.34 0.20 11 62
percent percent percent percent percent percent percent
+mg./kg. mg./kg.
100.00 percent
In some experiments only 0.5 percent corn oil was used. Glista salts—0.88 percent NaCI, 0.002 percent ZnCU, 0.002 C u S 0 4 - 5 H 2 0 0.0009 percent H3BO3, 0.0001 percent C0SO4' 7H 2 0, 0.004 percent KI, 0.14 percent Fe citrate, 0.25 percent M g S 0 4 * 7H 2 0, 0.90 percent K 2 HP04, 0.065 percent MnSC-4 • H 2 0 , 0.30 percent CaCOs, 2.80 percent Ca3(P0 4 )2. 3 Vitamin premix—Per kg. diet: 100 mg. Thiamine HC1, 100 mg. Niacin, 16 mg. Riboflavin, 20 mg. Ca Pantothenate, .02 mg. Vitamin B12, 6 mg. Pyridoxine HC1, 0.6 mg. Biotin, 4 mg. Folic acid, 100 mg. Inositol, 2 mg. P-aminobenzoic acid, 5 mg. Menadione, 250 mg. Ascorbic acid, 20 mg. alpha-tocopherol acetate, 10,000 I.U. Vitamin A acetate, 600 I.C.U. vitamin Da. 4 Omitted in Experiment 1.
Lot
1
2
3
4
Drackett protein DL methionine Glycine Glista salts Choline chloride Vitamin premix Cerelose Corn oil Solka fioc
23.53% 0.50% 0.20% 5.34% 0.20%
23.53% 0.50% 0.20% 5.34% 0.20%
35.30% 0.75% 0.30% 5.34% 0.20%
35.30% 0.75% 0.30% 5.34% 0.20%
+
69.23% 1.00%
— 100.00%
Percent protein calculated determined Percent fat calculated determined Metabolizable energy Calorie/g.
+
+
52.23% 8.00% 10.00%
57.11% 1.00%
100.00%
100.00%
—
+
40.11% 8.00% 10.00% 100.00%
20.0 20.1
20.0 20.2
30.0 29.4
30.0 29.4
1.0 0.8
8.0 7.5
1.0 0.8
8.0 7.5
3.62
3.62
3.64
3.64
metabolizable energy content to 17 parts of cerelose (3.7 Cal./g.). The metabolizable energy value of Drackett assay C-1 protein was calculated from the casein value and assumed to be (4.0 Cal./g.). No caloric value was assigned to cellulose (Solka floe), Rand et al. (1956). In experiments 1, 2, and 3, the metabolizable energy content of the diets was kept constant at each protein level by the replacement of 17 g. multiples of cerelose (63 Calories) by multiples of 7 g. corn oil (63 Calories) and 10 g. Solka floe (0 Calories). Two levels of corn oil, 1 and 8 percent, were used in experiment 1, and both were fed at marginal (20 percent) and adequate (30 percent) protein levels. These "treatment" diets are shown in Table 2. Five levels of corn oil at two protein levels were used in experiments 2 and 3, the design of which appears in Table 3. At the highest fat level of 14.5 percent, the corn oil contributed 36 percent of the total dietary calories. Female chicks were used in experiments 1 and 3, and male chicks in experiment 2. The chicks were fed daily in a manner to insure an equal intake of feed by all experimental groups at a given level of protein. In experiments 4 and 5 the final diets were prepared from two basal premixes
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All chicks used in the investigation originated from the mating of New Hampshire males and Columbian females. The chicks were placed on a purified basal diet containing 30 percent protein (NX6.25) for a period of 7 days, individually wing banded and distributed into the experimental lots on the basis of their body weight in a manner to insure that the average starting weight was equal for all groups. The chicks were placed in thermostatically controlled electrically heated batteries equipped with raised wire floors. Each experimental diet was fed to 3 replicates of 10 chicks each. All the experimental diets were formulated by the modification of the basal Drackett protein diets shown in Table 1. Supplements were added at the expense of cerelose and the protein quality was kept constant at all protein levels.
1077
FAT FOR GROWING CHICKS TABLE 3.—Treatment diets of experiments Z and 3 Lot 1 2 3 4 5
Percent fat
Treatment
1
30 percent protein, parts
20 percent protein basal 0.5 (1) + 3 . 5 percent corn o i l + 5 percent Solka floe 4.0 (l)-f-7.0 percent corn oil+10 percent Solka floe 7.5 (1)4-10.5 ) -i- 1 0 ^ pnei irrcr penntt cr norrtni onil i l-+I -115^percent npi-r^n t-Solka SnlVa floe fln^ 11. 11.0 x "( D -4-14.0 percent corn o i l + 2 0 percent Solka floe 14.5
Cerelose Drackett protein DL methionine Glycine Glista salts Corn oil Solka floe Choline chloride Vitamin premix1 DPPD 1 Procaine penicillin1
19.785 17.65 0.375 0.15 5.34 0.50 5.00 0.20
1.61 35.30 0.75 0.30 5.34 0.50 5.00 0.20
20.4 percent by chemical analysis; 3.60 Calories/g. 30.4 percent by chemical analysis; 3.63 Calories/g.
+ + +
+ + +
equivalent to 15 and 30 percent protein shown in Table 4. Five percent Solka floe was included in the basal mixtures to improve the physical properties of the diets containing the higher levels of corn oil. In the absence of supplemental corn oil 51 parts of cerelose were added to 49 parts of the basal premix. When, however, corn oil replaced cerelose the substitution was made in terms of their caloric ratio, i.e., 7 parts of corn oil for 17 parts of cerelose. It follows therefore that whenever corn oil was added, the final diets would not add up to 100 parts. W7ith this procedure it was possible to maintain a constant ratio of metabolizable energy to the pro-
Total parts
49.000
49.000
1
I n a m o u n t s as shown in T a b l e 1.
tein and all other nutrients in the treatment diets. This method of formulation facilitated the addition of higher levels of corn oil than could have been used if cellulose had been added to control-the level of metabolizable energy. The composition of the diets used in experiments 4 and 5 is given in Table 5. Three replicates of 10 male chicks were used in both experiments. In experiment 4, feeding was done on an ad libitum basis, while in experiment 5 the replicates were
TABLE 5.—Treatment diets of experiments 4 and 5 Lot 15 percent protein premix 30 percent protein premix cerelose corn oil Total parts Percent fat calculated determined Percent protein calculated determined Met. energy Cal./g. Calorie/protein 1 Percent fat energy of total energy non protein energy 1
49 51 00
49
49
49
34 7
17 14
21
90
80
70
—
—
—
—
49 51
49 34 7
49 17 14
49
90
80
70
100
21
0.5 0.6
8.3 8.3
18.1 18.1
30.7 30.9
0.5 0.6
8.3 8.4
18.1 18.2
30.7 31.1
15.0 15.1 3.39 22.6
16.7 16.8 3.77 22.6
18.8 18.8 4.24 22.6
21.4 21.2 4.84 22.6
30.0 30.0 3.44 11.5
33.3 33.4 3.82 11.5
37.5 37.7 4.30 11.5
42.8 42.3 4.91 11.5
1.3 1.6
19.9 24.5
38.5 47.3
57.1 70.1
1.3 2.3
19.6 33.9
37.9 65.6
56.3 97.2
Calorie/protein = Calories per 1 g. protein.
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15 percent protein, parts
Ingredient
1
0.5 30 percent protein basal 2 (6)4-3.5 percent corn oil4-5 percent Solka floe 4.0 (6)4-7.0 percent corn o i l + 1 0 percent Solka floe 7.5 (6)+10.5 p e r c e n t c o r n o i l + 1 5 percent Solka floe LX.U 11.0 (6) + 14.0 percent corn oil + 2 0 percent Solka floe 14.5 2
TABLE 4.—Basal premixes of experiments 4 and 5
1078
N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW TABLE 6.—Results of experiment 1 (21 days)-equalized feed intake Lot
Percent dietary protein Percent dietary fat Percent solka floe
2
3
4
20 1
20 8 10
30 1
30 8 10
245 201 354 .568 1,280 71 19.1 46.8 39.8 56.2
246 202 359 .563 1,310 108 19.9 48.9 41.9 38.9
— 228 184 354 .520 1,280 71 19.1 43.5 36.5 51.6
—
261 217 359 .604 1,310 108 19.9 51.9 44.9 41.7
1
Protein retention = carcass protein gain/protein intake. Statistical analysis Weight gain Treatment F 25.S**2 L.S.R. ( P < 5 percent) 10 g. 2 ** Significant at 1% probability level. * Significant at 5% probability level.
fed on a daily basis of group equalized nutrient intake at each of the two protein levels in a randomized block design. Thus controlling the consumption of diets 1, 2, 3, and 4 at the ratio of 100:90:80:70 respectively resulted in identical intakes of all nutrients with the only variable being the source of calories. Diets 5, 6, 7, and 8 were fed in a like manner. The experiments were terminated at 21 days of age in experiments 1 and 2, 31 days of age in experiment 3 and 28 days of age in experiments 4 and 5. The two median chicks in each replicate were sacrificed for carcass analysis by the acid hydrolysis method outlined by Rand (1957). Thus the average carcass composition was derived from six individual chicks and the average gain was obtained from 30 individual chicks. The results were subjected to statistical treatment for the analysis of variance and " F " tests using the procedure of Snedecor (1946). The main effects and their interactions were determined by factorial analysis. The least significant range (LSR)
Protein gain 5.10** 1.8 g.
was determined by the method of Duncan (1955). RESULTS
The results of experiment 1 indicated that when the intake of protein, energy and all other nutrients was equalized, growth was significantly improved when 7 percent corn oil was added to the basal diets (Table 6). Since protein and metabolizable energy intakes were constant at each protein level, the response to corn oil in terms of weight gain reflected the same relative response in feed efficiency and in the utilization of dietary protein and energy. The analysis of the carcass composition revealed that the growth promoting effect of supplemental corn oil represented a true increase in carcass protein. Thus the beneficial effect of corn oil on growth reflected a significant increase in protein deposition and protein retention at both dietary levels of protein. The results of experiments 2 and 3 are given in Tables 7 and 8 respectively. In experiment 2, there was only a slight,
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Final weight (g.) Weight gain (g.) Feed intake (g.) Gain/feed Caloric intake Protein intake (g.) Percent carcass protein Total carcass protein (g.) Carcass protein gain (g.) Percent protein retention 1
1
1079
FAT FOR GROWING CHICKS TABLE 7.—Results of experiment 2 (21 days)-equalized feed intake Lot Percent dietary protein Percent dietary fat Percent solka floe Final weight (g:) Weight gain (g.) Feed intake (g.) Gain/feed
1 20 0.5
—
232 156 311
.502
2
3
4
5
20 4.0 5 235 159 311 .511
20 7.5 10 233 157 311 .505
20 11.0 15 235 159 311 .511
20 14.5 20 238 162 311 .521
6 30 0.5 231 155 286
— .542
7
8
9
10
30 4.0 5 241 165 286 .577
30 7.5 10 242 166 286 .580
30 11.0 15 249 173 286 .605
30 14.5 20 257 181 286 .633
Treatment F =2.94* (in weight gain). L.S.R. (P<5 percent) = 13 g. (in weight gain).
The data of experiments 2 and 3 were combined in constructing the curves of Figure 1 to shown the average response of the chick to increased levels of corn oil at both levels of protein. As will be noted the response from corn oil at the 30 percent protein level was considerably
greater than the response at the 20 percent protein level. The results of experiments 4 and 5 appear in Tables 9 and 10 respectively. With ad libitum feeding (experiment 4), a significant improvement in growth was noted when fat calories replaced carbohydrate calories while maintaining the same calorie/protein ratio. The most notable increase was shown when supplemental fat was raised from 0.5 percent to 8.3 percent. However, growth continued to improve slightly up to the highest level
PERCENT
CORN
OIL
FIG. 1. The response of chicks to corn oil. (Combined data of experiments 2 and 3 for weight gains and nutrient utilization.)
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if any, improvement in growth when the 20 percent protein diet was supplemented with corn oil. The improvement at the 30 percent level was much more pronounced and was statistically significant. In experiment 3, the beneficial effects noted for increments of corn oil was significant at both levels of protein. The most notable improvement in growth was observed with the first increment of corn oil (from J to 4 percent). However, while the improvement due to further increments of corn oil was only slight for one increment at a time, it was apparent that the trend was significant. Because of the equalized feeding techniques, the effect of the supplemental corn oil was proportionally the same for growth, feed efficiency and nutrient utilization. The analysis of the carcass composition in experiment 3 confirmed the previous finding that the supplemental corn oil resulted in a significant improvement in the gain and in the retention of carcass protein. This was most evident at the first increment of the added fat. No further improvement could be detected beyond the 1 1 % level of corn oil for either level of protein.
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The results of experiment 5 showed t h a t differences in feed consumption would not account for the growth stimulating effect of corn oil, since in this instance the intake of nutrients was equalized. However, while the overall performance improved notably as the level of corn oil was increased from 0.5 percent to 8.3 percent, there was a much smaller effect between 8.3 and 18.1 percent levels of corn oil, and a significant decline resulted when the level of corn oil was further increased to 30.7 percent. This depression might have occurred because of the reduced weight of feed consumed b y the chicks on the highest fat diet. Since the feed was given only once every 24 hours, the chicks on the 30.7 percent fat diets were without feed for the major part of the day, having consumed their allotment of feed within a few hours after feeding. However, it is conceivable t h a t in this instance the reduced growth on the highest fat level represented a true depression in the utilization of the nutrients. Nevertheless, the performance on the 30.7 percent corn oil diet, where the fat contributed u p to 97 percent of the non-protein calories, was still significantly superior to the low fat diets, indicating t h a t the chick's toler-
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^
l > . CO CO
O CO ON O co CN
T-ir^-ocs
KUMMEROW
of corn oil (30.7 percent). I t was apparent, however, t h a t the response to corn oil in experiment 4 was due in p a r t to the greater intake of all nutrients. The efficiency in nutrient utilization as measured by the protein efficiency ratio (gain/protein intake) and energy efficiency ratio (gain/Calorie intake) reached its peak at a level of 8 . 3 % fat. A slight depression from this peak was noted at the higher (18.1 percent and 30.7 percent) fat levels. Nevertheless, the efficiency in nutrient utilization at these high levels of dietary fat was considerably superior to the efficiency on the basal diets containing 0.5 percent fat.
O 00 O N 00 iO O N
co T-( cs •<* N O OJ
ro
SCOTT AND F. A.
1081
FAT FOR GROWING CHICKS TABLE 9.—Results of experiment 4 (28 days)-a,d libitum feeding Lot
1 15.0 0.5 1.3 22.6 363 283 626 .452 2,120 .133 94 3.01 17.7 64.3 51.1 54.4
2 16.7 8.3 19.9 22.6 410 330 617 .535 2,320 .142 103 3.20 18.4 75.4 62.2 60.4
Statistical analysis Treatment F L.S.R. ( P < 5 percent)
3 18.8 18.1 38.5 22.6 401 321 543 .591 2 ,300 .140 102 3.15 18.1 72.6 59.4 58.3
4 21.4 30.7 57.1 22.6 418 338 502 .674 2,420 .140 107 3.16 17.7 74.0 60.8 56.8
Weight gain 27. 2»* 19 g.
6
5 30.0 0.5 1.3 11.5 398 318 586 .543 2,020 .157 176 1.80 18.8 74.8 6.16 35.0
33.3 8.3 19.6 11.5 439 359 545 .658 2 ,080 .173 182 1.97 18.9 83.0 69.8 38.4
7 37.5 18.1 37.9 11.5 436 356 496 .718 2,130 .167 186 1.92 18.6 81.1 67.9 36.5
8 42.8 30.7 56.3 11.5 453 373 456 .818 2,230 .168 193 1.93 18.7 78.4 71.5 37.1
Protein gain 4.31" 2 .9 g .
ance for fat per se is essentially unlimited. A comparison between experiments 4 and 5 is illustrated in Figure 2. The average response in weight gain due to corn oil in experiment 4 was 15.2 percent over that of the basal ration while in experiment 5 the average response was 10.2 percent. This indicated that approximately one third of the response in the ad libitum feeding (experiment 4) was due to the indirect effect of fat in increasing the nutrient intake, perhaps by improving the texture of the feed. In both experiments food conversion steadily improved with each increment of corn oil, reaching a maximum conversion of .819 g. gain per
g. of feed consumed on the high protein diet containing 30.7 percent fat. The data of all the experiments, illustrating the growth response due to higher fat levels, are given in Figure 3. The average beneficial effect of the corn oil was more pronounced at the high protein level by more than one third. The best overall performance for growth and nutrient utilization occurred when the fat contributed between 20 and 38 percent of the total metabolizable energy, or between 34 and 48 percent of the non-protein energy of the diets. Protein retention improved as the percentage of metabolizable energy originat-
TABLE 10.—Results of experiment 5 (28 days)-equalized nutrient intake Lot Percent dietary protein Percent dietary fat Percent fat energy Calorie/gm. protein Final weight (g.) Weight gain (g.) Feed intake (g.) Gain/intake Calorie intake Gain/Calorie intake Protein intake (g.) Gain/protein intake Percent carcass protein Total carcass protein (g.) Carcass protein gain (g.) Percent protein retention Statistical analysis Treatment F L.S.R. ( P < 5 percent)
1 15.0 0.5 1.3 22.6 358 278 647 .430 2,190 .127 97 2.86 17.8 63.7 50.5 52.1
2
3
16.7 8.3 19.9 22.6 382 302 582 .519 2,190 .138 97 3.11 18.4 70.3 57.1 58.9
18.8 18.1 38.5 22.6 399 319 517 .617 2 ,190 .146 97 3.29 18.2 72.6 59.4 61.2
Weight gain 66. 5** 12!
4 21.4 30.7 57.1 22.6 371 291 453 .642 2,190 .133 97 3.00 17.8 66.1 53.9 55.6
5 30.0 0.5 1.3 11.5 405 325 617 .527 2,120 .153 185 1.76 18.8 76.1 62.9 34.0
6 33.3 8.3 19.6 11.5 449 369 555 .665 2,120 .174 185 1.99 19.0 85.3 72.1 39.0
Protein gain 6 .16** 2• l g .
7 37.5 18.1 37.9 11.5 440 360 493 .730 2,120 .170 185 1.95 18.6 81.9 68.7 37.1
8 42.8 30.7 56.3 11.5 434 354 432 .819 2,120 .167 185 1.92 18.7 81.2 68.0 36.8
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Percent dietary protein Percent dietary fat Percent fat Calories Calorie/gm. protein Final weight (g.) Weight gain (g.) Feed intake (g.) Gain/feed Calorie intake Gain/Calorie intake Protein intake (g.) Gain/protein intake Percent carcass protein Total carcass protein (g.) Carcass protein gain (g.) Percent protein retention
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N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW
METABOLIZABLE L • PERCENT
CORN
ENERGY
FROM CORN
OIL
I 18 OIL
L_ 31
FIG. 2. Relationship of feeding method to the effect of corn oil on weight gains. (Experiments 4 and 5.)
80%
PERCENT METABOLIZABLE
i
i
PROTEIN
The beneficial effect of corn oil in increasing protein retention was more pronounced at the high protein levels. On the average, the improvement at the high (30 percent) protein level was 25 percent better than the- improvement at the low (15-20 percent) protein levels.
ENERQY FROM CORN OIL
i
:
7 PERCENT PERCENT METABOLIZABLE
FIG. 3. The relationship of protein level to the chick response for corn oil. (Combined data of all experiments.)
ENERGY FROM
CORN
OIL
FIG. 4. The effect of corn oil on protein retention. (Summary of all experiments.)
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PERCENT I
ing from corn oil was increased. In experiment 4, maximum protein retention occurred at the 8.3 percent fat level for both low and high protein diets. In experiment 5, the peaks were at the 18.1 percent fat level on the low protein diet, and at the 8.3 percent fat level on the high protein diet. In all cases, there was a significant decrease in protein retention following the peaks. However, the protein retention at the highest level of corn oil was still significantly better than at the lower level of fat. These results seemed to indicate that protein retention was maximal when the percentage of metabolizable energy derived from corn oil was within the range of 20 to 38 percent which corresponded to a fat contribution of 34 to 48 percent of the non-protein energy of the diets (Figure 4).
FAT FOR GROWING CHICKS
DISCUSSION
(1949) reported that the heat increment of rats was lowered from 36 to 16 percent of the total heat production when the fat level was isocalorically increased from 2 to 30 percent. These findings tend to indicate that fat improved the retention of protein primarily by improving overall energy utilization due to the net increase in the consumption of utilizable energy by the growing chick. This is in agreement with the report of Robel et al. (1956) to the effect that a higher energy intake consistently improved the retention of dietary protein in chicks and with the report of Forbes et al. (1955) that a lower energy intake lowered the biological value of protein in rats. However, this interpretation is not universally accepted. Thomson and Munro (1955) and Metta and Mitchell (1956) concluded that the replacement of carbohydrates by fat did not improve protein utilization by growing rats. Donaldson et al. (1957) reported that while supplemental dietary fat tended to increase growth rate, it actually improved the utilization of dietary protein and calories only in one case out of five experiments. They, however, concluded that chicks could tolerate up to 33.8 percent fat in the rations. Baldini and Rosenberg (1957) also claimed that fat, per se (as beef tallow) had no effect on the performance of the growing chick. However, these reports were based on experiments where chicks were fed ad libitum, and the energy value of fat was assessed in terms of productive energy. Since Hill and Anderson (1955) reported that the productive energy values were highly variable while metabolizable energy values were highly reproducible, the use of metabolizable energy values are to be preferred to productive energy values in formulating isocaloric diets. A specific relationship in the metabo-
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The use of equalized feed and nutrient intake techniques of feeding demonstrated conclusively that the inclusion of moderate levels of corn oil in the diet of the growing chick resulted in an improvement in true growth, efficiency of protein, and energy utilization and protein retention. This response was obviously due to the corn oil per se, because it could not be attributed either to variations in intake of other nutrients, or to the essential fatty acids, since the latter was always present in the basal diet. It is conceivable that the effect of the corn oil was exerted through one or more of the following means: A) by increasing the efficiency of the utilization of the metabolizable energy; B) by improving the utilization of dietary protein; C) by providing an unidentified growth factor. The assumption that the chick's response to fat could be explained by the effect of fat on the energy metabolism seems to have a great deal of support. The observation that the best growth response was obtained when the corn oil contributed between 34 and 48 percent of the non-protein calories to the diet was similar to results obtained with rats as the experimental animals. Forbes and Swift (1944) reported that dietary fat reduced significantly the amount of the heat increment wasted by rats, indicating that the addition of fat markedly improved the utilization of metabolizable energy. Forbes et al. (1946) showed that on a constant intake of protein and energy, the digestibility and retention of protein as well as the growth rate was improved when the fat level of the rat diet increased from 2 to 30 percent. French et al. (1948) showed further that high fat diets increased weight gains in rats and decreased heat production when the intake of nutrients was held constant. Swift and Black
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1084
N. T. RAND, H. M. SCOTT AND F. A. KUMMEROW
SUMMARY
When chicks were fed isonitrogenousisocaloric diets, the substitution of fat calories for glucose calories resulted in improved weight gains and greater protein and energy utilization and protein retention. This was true for ad libitum feeding as well as when nutrient intake was equalized for all experimental groups. Highly significant differences in growth were noted even though the calorie/protein ratios were constant. The best overall per-
formance was obtained when the fat contributed between 20 and 38 percent of the total metabolizable energy of the diet. However, the beneficial effect of fat on both weight gain and protein retention was pronounced even at the highest fat level. At this point the fat contributed 57 percent of the total metabolizable energy and up to 97 percent of the non-protein calories of the diet, indicating that the chick's tolerance for fat, per se, is essentially unlimited. The beneficial effect of the fat was apparent at all levels of protein, but it was most pronounced at the highest protein level. REFERENCES Anderson, D. L., and F. W. Hill, 1955. Determination of metabolizable energy values for chicks of pure carbohydrates, cellulose, fat and casein. Poultry Sci. 34:1176. Arscott, G. H., 1956. Complexity of a chick growth response to egg yolk, animal fat and fish solubles additions to the diet. Poultry Sci. 35: 338-342. Arscott, G. H., P. H. Weswig and J. R. Schubert, 1957. Multiple nature of chick growth responses to fractions of dried egg yolk. Poultry Sci. 36: 513-516. Baldini, J. T., and H. R. Rosenberg, 1957. The effect of calorie source in a chick diet on growth, feed utilization and body composition. Poultry Sci. 36: 432-435. Biely, J., and B. March, 1954. Fat studies in poultry. 2. Fat supplements in chick and poultry rations. Poultry Sci. 33:1220-1227. Denton, C. A., R. J. Lillie and J. R. Sizemore, 1954. Effect of egg yolk, fat and fish solubles on growth of chicks. Fed. Proc. 13: 455. Donaldson, W. E., G. F. Combs, G. L. Romoser and W. C. Supplee, 1955. Body composition, energy intake, feed efficiency, growth rate and feather condition of growing chickens as influenced by the calorie-protein ratio of the ration. Poultry Sci. 34: 1190. Donaldson, W. E., G. F. Combs, and G. L. Romoser, 1956. Studies on energy levels in poultry rations. 1. The effect of calorie-protein ratio of the ration on growth, nutrient utilization and body composition of chicks. Poultry Sci. 35: 1100-1105. Donaldson, W. E., G. F. Combs, G. L. Romoser and W. C. Supplee 1957. Studies on energy levels in
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lism of fat and protein may be inferred since higher protein levels tended to enhance the beneficial effects of the corn oil. Actual evidence supporting this relationship was presented by Pearson and Panzer (1949). They showed that on an equal intake of protein, the isocaloric addition of 8 percent corn oil significantly lowered the excretion of valine, lysine, and methionine by growing rats and increased protein retention. The fact that the improvement in growth and in protein retention was greatest at the first increment of corn oil seems to indicate that an unidentified factor may have been involved. This should not be surprising since several workers have concluded that fats contain an unidentified factor(s) required for maximum chick growth. Thus Denton et al. (1954) reported that animal fat contained an unidentified growth factor which they postulated as the same factor found in fish solubles. This conclusion was confirmed by Arscott (1956). Menge et al. (1957) reported that an unidentified factor, found in the non-saponifiable portion of egg yolk fat, increased chick growth by 18 percent at 4 weeks of age. Arscott et al. (1957) also reported on the growth promoting effect of dried egg yolk. The present studies did not clarify whether refined corn oil contained any of these factors.
FAT FOR GROWING CHICKS
Unidentified growth factor in egg yolk. Fed. Proc. 16: 392-393. Metta, V. C , and H. H. Mitchell, 1956. A comparison of the biological values of dietary protein incorporated in high-and low-fat diets. J. Nutr. 59: 501-513. Pearson, P. B., and F. Panzer, 1949. Effect of fat in the diet of rats on their growth and their excretion of amino acids. J. Nutr. 38: 257-265. Rand, N. T., H. M. Scott and F. A. Kummerow, 1956. The relationship of protein, fiber and fat in the diet of the growing chick. Poultry Sci. 35: 1166. Rand, N. T., 1957. The utilization of fat by the growing chick. Doctoral Thesis. University of Illinois. Reiser, R., and P. B. Pearson, 1949. The influence of high levels of fat with suboptimum levels of riboflavin on the growth of chicks. J. Nutr. 38: 247-256. Robel, E. J., G. F. Combs and G. L. Romoser, 1956. Protein requirement of chicks for maintenance of nitrogen balance and growth. Poultry Sci. 35: 1168. Scott, H. M., L. C. Sims and D. L. Staheli, 1955. The effect of varying protein and energy on the performance of chicks. Poultry Sci. 34: 1220. Snedecor, G. W., 1946. Statistical Methods. 4th edition, The Collegiate Press. Ames, Iowa. Sunde, M. L., 1956. A relationship between protein level and energy level in chick rations. Poultry Sci. 35:350-354. Swift, R. W., and A. Black, 1949. Fats in relation to caloric efficiency. J. Am. Oil. Chem. Soc. 26: 171-176. Thomson, W. S. T., and H. N. Munro, 1955. The relation of carbohydrate metabolism to protein metabolism. 4. The effect of substituting fat for dietary carbohydrate. J. Nutr. 56: 139-150. Waibel, P. E., 1955. Effect of dietary protein level and added tallow on growth and carcass composition of chicks. Poultry Sci. 34:1226. Yacowitz, H., 1953. Supplementation of corn-soybean oil meal rations with penicillin and various fats. Poultry Sci. 32:930.
NEWS AND NOTES {Continued from page 1070) abstracts, housing arrangements, and registration. The scientific program is planned to include a series of panel discussions and presentations of original work by invited speakers on such subjects as: Human Nutritional Problems and Their Assess-
ment; Food Processing; Lipids in Health and Disease; Animal Nutrition and Feeding for Maximal Production; Nutrition in Maternal and Infant Feeding; Proteins and Amino Acids in Nutrition. Also, the customary ten-minute papers reporting original 1090)
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poultry rations. 2. Tolerance of growing chicks to dietary fat. Poultry Sci. 36: 807-815. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Forbes, E. B., and R. W. Swift, 1944. Associative dynamic effects of protein, carbohydrate and fat. J. Nutr. 27:453-468. Forbes, E. B., R. W. Swift, R. F. Elliot and W. H. James, 1956. Relation of fat to economy of food utilization. I. By the growing albino rat. J. Nutr. 31: 203-212. Forbes, R. M., and M. Yohe, 1955. Effect of energy intake on the biological value of protein fed to rats. J. Nutr. 55: 499-506. Fraps, G. S., 1943. Relation of the protein, fat and energy of the ration to the composition of chickens. Poultry Sci. 22: 421-424. French, C. E., A. Black and R. W. Swift, 1948. Further experiments on the relation of fat to economy of food utilization. 3. Low protein intake. J. Nutr. 35: 83-88. Henderson, E. W., and W. E. Irwin, 1940. The tolerance of growing chicks for soybean oil in their ration. Poultry Sci. 19: 389-395. Hill, F. W., and D. L. Anderson, 1955. Comparison of productive energy and metabolizable energy determinations with chicks. Poultry Sci. 34: 1201. Hill, F. W., and R. Renner, 1957. Metabolizable energy values of feedstuffs for poultry and their use in formulation of rations. Proc. Cornell Nutr. Conf. 22-32. Kummerow, F. A., R. Weaver and H. Honstead, 1949. The choline replacement value of ethanolamine in chickens kept on a high fat ration. Poultry Sci. 28: 475^78. Leong, K. C , M. L. Sunde, H. R. Bird and C. A. Elvehjem, 1955. Effect of energy: protein ratio on growth rate, efficiency, feathering and fat deposition in chickens. Poultry Sci. 34: 1206-1207. March, B. E., and J. Biely, 1954. The nutritive value of fats of different origin in chick starters. Poultry Sci. 33: 1069. Menge, H., R. J. Lillie and C. A. Denton, 1957.
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