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Studies With Acidulated Cottonseed-Oil Soapstock
Studies With Acidulated Cottonseed-Oil Soapstock 1. ITS USE AS A FAT SUPPLEMENT IN PRACTICAL BROILER RATIONS 1
(Received for publication November 20, 1963)
P
REVIOUS reports from this Division have described the use of acidulated soybean-oil soapstock (Bornstein and Lipstein, 1961) and of acidulated sunflower-oil soapstock (Bornstein and Lipstein, 1963) in chick rations. These fat supplements were found to compare with tallow in terms of chick growth and feed/gain ratio. Cottonseed-oil soapstock has been used commercially in the United States as fatty acid methyl esters, but regular acidulated cottonseed-oil soapstock (ACS) has not been accepted for general use because of the possible toxicity of gossypol. An extensive literature exists on the use of cottonseed meal and on its gossypol content, but little information is available on ACS or its gossypol. Couch (1953), Naber and Morgan (1957) and Combs (1961) mention ACS in a rather incidental manner, whereas to the best of our knowledge only Curtin and Raper (1956) investigated it systematically in broilers, and Pepper et al. (1962) in laying hens. The former workers showed that gossypol found in ACS is much less toxic than that found in cottonseed meal, but they did not estimate the maximal tolerance levels. The purpose of the present study was to test a number of different local samples of ACS of various sources and to try to establish the highest permissible levels 1
Contribution from the National and University Institute of Agriculture, Rehovot, Israel. 1963 Series. No. 628-E.
of gossypol of ACS in practical broiler rations. GENERAL PROCEDURE Two 10-week and one 5-week battery trials were conducted during 1961. Commerical, day-old sexed CornishX White Rock crossbred chicks were randomly (except for sex) allocated to compartments (2 compartments per story) of either two or three-story (depending on trial) electric battery brooders with raised wire floors. Each compartment received an equal number of male and female chicks. The rations were also assigned at random to the various compartments. At 5 weeks of age, the chicks were transferred to a shed containing two-story wire cages, each cage capable of holding 7 to 8 full-grown broilers. Feed and water were supplied ad libitum at all times. Body weights and feed consumption were recorded at 3, 5, 8 and 10 weeks of age, on a group basis. At the latter two ages, the cockerels and pullets of each group were weighed separately. Up to six weeks the chicks were fed starter diets the composition of which is shown in Tables 1 and 2. The gossypol content mentioned in the latter table were determined by the method of Pons et al. (1956). From 6 to 10 weeks of age the birds were given finishing rations, which differed from the former in that 9% or 10% (diets containing 10% and more added fat) soybean meal was replaced by an equal amount of sorghum
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BlANKA LlPSTEIN AND S. BORNSTEIN Division of Poultry Husbandry, The National and University Institute of Agriculture, Rehovot, Israel
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ACIDULATED SOAPSTOCK TABLE 1.—Composition of diets Ingredients
Calculated analysis: Crude protein (%) Prod, energy (Cal./lOO gm.) 4 Cal./lOO gm. ratio % protein
%
%
%
%
%
%
%
%
0.0 28.0 62.8 0.06 9.15 —
2.0 28.0 60.8 0.06 9.15 —
3.0 29.0 57.8 0.06 9.15 —
5.0 31.0 54.8 0.07 9.15
8.0 34.0 48.8 0.08 9.15
10.0 36.0 44.5 0.09
11.0 37.0 42.5 0.10
14.0 40.0 36.5 0.12
9.4
9.4
9.4
22.7 203
22.5 209
22.6 211
23.3 217
24.2 224
24.5 228
25.0 231
25.9 238
8.9
9.3
9.3
9.3
9.3
9.3
9.2
9.2
1
Variable with regard to source of soapstock and gossypol content, see Table 2. Fish meal, 3 % ; alfalfa meal (dehyr.), 2.5%; ground oyster shells, 1.5%; D.C.P., 1.5%;mineral mix, 0.3%; vitamin mix, 0.25%; coccidiostat, 0.1%. 3 Fish meal, 3 % ; alfalfa meal (dehyr.), 2.5%; gr. oyster shells, 1.4%; D.C.P., 1.6%; mineral mix, 0.35%; coccidiostat 0.1%. The composition of the mineral and vitamin mixes and of coccidiostat has been given in a previous report (Bornstein and Lipstein, 1963). 4 Based on the assumption that acidulated soapstocks contain 560 Cal. (P.E.)/100 gm., and that soybean meal of 49% protein content contains 160 Cal./lOO gm. 2
grain in order to widen the C/P ratio (Calories of productive energy per 100 gm./percentage protein) from 9.3 to 11.4, and in that the methionine supplement was decreased by 20%. The results were subjected to an analysis of variance according to Snedecor (1956), and when significant differences were obtained Duncan's multiple range test (1955) was used to compare means. All interpretations of data are based on the 1% level of probability. EXPERIMENTAL AND RESULTS
Trial 1. The purpose of the first and preliminary experiment was to test the effect of 3 sources of crude oil obtained from 2 plants, and in one case from the production of 2 different years (Table 2), on the gossypol content of the soapstock produced from them and on the performance of broilers fed these ACS. Accordingly, 4 samples of ACS were used at 3 % and 10% levels each, and were compared with a sample of acidulated soybean-oil soapstock (ASS) employed at the same levels
and with a control diet. These 11 diets (Table 3) were fed to 616 chicks divided into 44 groups of 14 chicks each. The gossypol content of the 4 samples of ACS is given in Table 2, and the results obtained from the feeding experiment are summarized in Table 3. According to the TABLE 2.—Types of acidulated cottonseed soapstock employed in different trials Soapstock No.
Source of crude oil1
Producer2
Gossypol content, %
1 2 3 4 5 6 7 8 9
Extraction Mixed Mixed Pressing Pressing Extraction Mixed Extraction Pressing
B C C B A A C B B
0.79 1.10 1.10 1.60 0.32 0.51 0.84 1.84 2.02
1 The plants in Israel which process cottonseed use two-stage screw pressing, followed by solvent extraction (Altschul, 1960). Some refine separately the crude oil derived from pressing and that from extraction, while others mix the oils before refining; soapstock being the by-product obtained from refining any vegetable oil. 2 All soapstocks were produced during I960, except No. 2 which was the product of 1959.
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Acidulated soapstock1 Soybean meal (49% protein) Ground sorghum (milo) DL-Methionine Constant ingredients l 2 Constant ingredients 2 3
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B . L l P S T E I N AND S . B O R N S T E I N
T A B L E 3.—Effect of acidulated soybean-oil soapstock and 4 kinds of acidulated cottonseed soapstock, fed at 2 levels, on the performance of broilers {Trial i ) 1 ' 2 Soap- Gossypol 3 stock in diet none
ASS 1 2 3 4 S.E.
—
0.02 0.03 0.03 0.05
— 0.08 0.11 0.11 0.16
(gm.) 599 c
(gm.j 1,717 b
Feed/gain ratio, at age 5 weeks 1.93 c
10 weeks 2.62 c
3% Supplementary 632 b 1,740 1,797 656 ab 659 ab 1,763 1,767 637 b 642 b 1,727
soapstock 1.82 be b ab 1.82 be b 1.84c b 1.81 be b 1.86 c
2.60 2.56 2.61 2.55 2.62
be be c be c
10% Supplementary 713 a 1,906 671 a b 1,823 652 ab 1,764 637 b 1,723 410 d 1,012
soapstock 1.65 a a 1.68a ab 1.71 a b b b 1.71 ab c 1.89 c
2.37 2.43 2.43 2.52 3.11
a ab ab abc d
12.3
25.9
0.22
0.031
1 2
Averages of 4 replicates of 14 birds each. Any 2 mean values within a column not having one letter in common differ significantly (P<0.01). s Calculated on the basis of Table 2. * Mean value of the separate averages for males and females. 6 Acidulated soybean-oil soapstock. ' See Table 2.
latter, at the 3 % supplementation level of soapstock there were no significant differences in growth and feed/gain ratio at 5 and 10 weeks of age among the various soapstocks. At 5 weeks of age body weights were significantly higher in the soapstock-supplemented groups than in the control (improvements of 5.5% to 10.0%), whereas this supplementation level did not have a significant effect on weight gains at 10 weeks of age or on feed utilization at either age. At the 10% supplementation level ASS tended to improve growth to a greater extent than the 4 samples of ACS, ACS-3 tended to be inferior to ACS-1 and 2, and ACS-4 was significantly inferior to the other three ACS's. Comparing the results of the diet containing 10% ACS-4 with those of the ASS diet it becomes obvious that the toxic level of gossypol (0.16% of the diet) affected growth rate much more than it did feed/gain ratio. According to feed consumption data obtained (but not presented in Table 3) the average feed
Trial 2. The purpose of this experiment was to compare the performance of broilers fed 5 samples of ACS, chosen on the basis of their gossypol content and also of their variability in source. These samples were each used at 2 supplementation levels (3% and 10%), in comparison with parallel levels of a sample of ASS and with a control diet. These 13 diets (Table 4) were fed to 546 chicks divided into 39 groups of 14 chicks each. In accordance with the results of the previous trial, the data presented in Table 4 for the 3 % supplementation level T A B L E 4.—Performance of broilers fed either acidulated soybean-oil soapstock or 5 kinds of acidulated cottonseed soapstock, at two levels (Trial 2 ) 1 ' 2 Gossypol Soap- • j : - f 3 stock (m) {'°'
B o d y wei
S nts > a t a B e
5 weeks 10 weeks4 (
1,624 a
Feed/gain ratio, at age 5 weeks 1.78 <
10 weeks 2.45 e
3% Supplementary soapstock ASS* S« 6 7 8 9 ASS 5 6 7 8 9
—
0.01 0.02 0.03 0.06 0.06
— 0.03 0.05 0.08 0.18 0.20
574 580 598 600 567 557 10% 611 585 583 605 549 515
1.68 1.66 1.65 1.69 1.70 1.70
d cd bed d d d
2.36 2.38 2.32 2.36 2.31 2.35
cd d bed cd abed cd
Supplementary.soapstock a 1,667 a 1.55 a 1,601a 1.57 a 1,646 a 1.59 a 1,624 a 1.57 a 1,593 a 1.57 b 1,450 b 1.66
a ab abc ab ab cd
2.13 2.21 2.19 2.21 2.12 2.37
ab abed abc abed a cd
a a a a a a
1,609 1,625 1,661 1,604 1,593 1,570
a a a a a a
S.E. 1
Averages of 3 replicates of 14 birds each. J-6 See corresponding footnotes to Table 3.
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ASS' 16 2 3 4
(%) —
Body weights, a t age
intake per chick during the first 5 weeks for the 10%, ASS diet was 1,179 gm., while for the diet containing 10% ACS-4 it was 775 gm., and the respective figures up to 10 weeks of age were 4.484 kg. and 3.152 kg. The toxicity of gossypol also caused an increased mortality. Whereas the average mortality of the groups of chicks fed the other 10 diets amounted to 2.9%, 10% ACS-4 in the diet caused a mortality of 8.9% during the first 5 weeks.
689
ACIDULATED SOAPSTOCK
Trial 3. The purpose of this experiment was to determine the tolerance level of chicks to gossypol, by using 2 samples of ACS containing very different gossypol concentrations. Thus, for instance, 5% ACS-9 and 14% ACS-1 supplied similar amounts of gossypol to the diet. Moreover, the opportunity was utilized to test the effects of lysine supplementation on gossypol toxicity. Accordingly, 2 samples of ACS and one of ASS were each used at 5 levels of supplementation (Table 5) in a factorial design. As an additional experimental treatment a diet containing 14% ACS-9 was supplemented with 0.16% lysine. These 16 diets were fed for 5 weeks to 1152 chicks divided into 48 groups of 24 chicks each. In this trial there was high mortality during the first 4 days of the experiment (and almost none during the period of 1
TABLE 5.—Effect of 3 acidulated soapstocks fed at 5 levels on the performance of chicks at 5 weeks of age. {Trial 3)1-2 Gossypol in diet3 (%)
Body weight (gm.)
ASS« I* 9
Feed consumption (kg.) 2% supplementary soapstock — 658a 1.140a 0.02 648 a 1.147 a 0.04 636 a 1.110 ab
ASS 1 9
— 0.04 0.10
5% supplementary soapstock 650 a 1.103 ab 676 a 1.152 a 667 a 1.153 a
1.70 cdef 1.69 cde 1.73 def
ASS 1 9
— 0.06 0.16
8% supplementary soapstock 693 a 1.139 a 683 a 1.135 a 641a 1.097 ab
1.63 abed 1.66 bed 1.70 cdef
ASS 1 9»
— 0.09 0.22
11% supplementary soapstock 675 a 1.090 abc 677 a 1.090 abc 595 b 1.036 be
1.61 abc 1.61 abc 1.74 def
ASS 1 9' 98
14% supplementary soapstock — 666 a 1.006 c 0.11 695 a 1.088 abc 0.28 506 c 0.906 d 0.28 474 c 0.862 d
Soapstock
S.E.
0.016
Feed/gain ratio 1.73 def 1.75 def 1.76 ef
1.51a 1.56 ab 1.79 f 1.82 f 0.02
1
Averages of 3 replicates of 24 chicks each. V See corresponding footnotes to Table 3. * See footnote 5 to Table 3. « See footnote 6 to Table 3. 6 Averages of 2 replicates of 18 chicks each. 7 One replicate of 8 chicks. 8 One replicate of 8 chicks supplemented with lysine.
to 5 weeks of age), due to two reasons: (a) a marked general and non-specific mortality, apparently the fault of the hatchery, which amounted to an average of 7% (maximum of 9%) per treatment for the chicks fed the 5 levels of ASS and ACS-1 and 2% and 5% levels of ACS-9; (b) a mortality due to high concentrations of gossypol: the 3 groups fed 8% ACS-9 (0.16% dietary gossypol) lost up to 15% of their chicks, those fed 11% ACS-9 (0.22% gossypol) lost 5 1 % , and the 6 groups fed 0.28% gossypol (with and without lysine supplementation) had a mortality of 89%. At 1 week of age the survivors among the chicks fed 1 1 % ACS9 were rearranged into 2 groups of 18 chicks each, and those of the last 6 groups into 2 groups (of 8 chicks each), one with and one without lysine supplement. The growth results of this trial are summarized in Table 5 and Figure 1.
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show an absence of significant effect of type of soapstock on broiler performance at 5 and 10 weeks of age. In contrast to trial 1, growth rate up to 5 weeks of age was not accelerated by this soapstock level, but feed/gain ratio was significantly improved at both ages (by 4.7% to 7.9%). At the 10% level of supplementation with soapstock there were no significant differences between ASS and ACS-5-8, nor did these 4 samples of ACS differ among themselves. However, ACS-9 significantly reduced weight gains, and in some cases also feed utilization, in comparison with other ACS's. The S-week results indicate a greater depression on growth rate than in feed utilization due to 10% ACS-9 (0.20% gossypol) in the diet, as pointed out for ACS-4 in trial 1. At that age average feed consumption per chick fed 10% ASS was 947 gm., whereas the corresponding figure for 10% ACS-9 was 855 gm. Mortality in this trial was low and appeared accidental.
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B . LlPSTEIN AND S. BORNSTEIN
1.80
2 S \ Q UJ
1.60
1.50
-o BODY WEIGHT o FEED CONSUMPTION o FEED/GAIN RATIO
o o
0.04
0.06 0.12 0.16 0.20 % GOSSYPOL IN DIETS
0.24
0.28
FIG. 1. The effect of gossypol on body weight, feed consumption and feed/gain ratio of S-week old chicks. The percentages designate levels of soapstock in the diet.
With regard to ASS, the best weight gain response of the chicks was obtained with an 8% supplement, while additional ASS tended to decrease growth rate, to an insignificant extent, apparently due to decreased feed intake. On the other hand, there was a significant improvement in feed utilization with increasing supplementation, which reached 14.5%. As far as ACS-1 is concerned, there was a slight, insignificant trend for a steady increase in growth rate with increasing level of supplementation, and this trend
was pronounced and significant for feed utilization. On the other hand, supplementations with ACS-9 quickly caused toxic concentrations of gossypol, the first, and yet insignificant, indication appearing in the diet containing 8% of this soapstock (0.16% gossypol). Again, as in previous trials, the detrimental effect of gossypol was stronger on growth rate than on feed utilization. Figure 1, presenting the effects of dietary gossypol concentration on chick performance, demonstrates in two ways
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1.70
ACIDULATED SOAPSTOCK
DISCUSSION
A comparison between the results obtained from supplementing broiler diets with ASS or with ACS containing nontoxic concentrations of gossypol indicates that, generally speaking and in terms of weight gain and feed/gain ratio, there is no difference between these two types of soapstocks. In trial 1, at the 10% supplementation level, ASS tended to improve growth rate to a greater extent than the better samples of ACS, but this insignificant trend is hardly recognizable in trial 2, and is completely absent at the 3 % level in both of these trials and at all supplementation levels in trial 3. In an indirect way this may be interpreted as meaning that ACS of low gossypol content is comparable to tallow, since previous publications of this division (Bornstein and Lipstein, 1961, 1963) and a report by Sibbald et al. (1962) show similar effects of ASS and tallow on chick
growth and feed utilization. In trial 1 (Table 3) only 0.16% gossypol in the diet significantly affected broiler performance, with some indication of slightly less beneficial effects from the supplementation with ACS which raises the dietary gossypol content to 0.11%. In trial 2, the lowest concentration of gossypol in the diet which depressed growth significantly was 0.20%, whereas 0.18% retarded growth only slightly and only at 5 weeks of age (Table 4). In trial 3, 0.22% and 0.28% gossypol inhibited weight gains significantly (Table 5), whereas a concentration of 0.16% gossypol in the diet caused a slight and insignificant depression of growth, feed consumption and feed utilization, and also increased mortality. On the other hand, concentrations of 0.11% and 0.10% gossypol, due to 14% ACS-1 and 5% ACS-9, respectively, did not diminish the beneficial effects of ACS supplementation on chick performance, which were very similar to those of parallel levels of ASS. Trials 1 and 3 were performed with January- and November-hatched chicks, respectively, while the chicks used in trial 2 were hatched in July. Experience at this station has shown that summer heat decreases weight gains while improving feed utilization, and these factors may have influenced the results of trial 2. In trial 2 (Table 4) chicks fed the control or 3 % supplementation diets possessed lower body weights than did those in trials 1 and 3, and they responded less to the growth-promoting effect of fat supplementation. This lowered responsiveness of their growth rate may also have affected their reaction to gossypol, and therefore the effect of the diet containing 0.18% gossypol was less severe than might have been expected on the basis of the data for 0.16% gossypol in trial 1 (Table 3).
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that in trial 3 gossypol levels up to and including 0.11% of the diet had no adverse effect: (a) there is no difference at 5% soapstock supplementation between 0.04% and 0.10% gossypol with regard to growth rate, feed consumption and feed utilization; and (b) the growth curve shows the expected slight irregular increase with increasing fat supplement up to 0.11% gossypol, but above this concentration and up to 0.28% the weights decline sharply in a linear fashion. Feed consumption declines slightly with increasing fat level, as expected, but beginning with the 0.16% gossypol concentration it decreases parallel to the decrease in growth rate. Feed utilization improves linearly with soapstock supplementation from 2% to 14% levels, up to 0.11% gossypol concentration, after which it worsens rapidly.
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B . LlPSTEIN AND S. BORNSTEIN
The results obtained in this study also indicate the mode of action of gossypol with regard to growth retardation in broilers. They show that the inhibition of growth is primarily the result of depressed feed intake, with little effect on feed utilization. The latter usually does not decrease significantly beyond that for diets containing no or 2% fat supplement. Hill and Totsuka (1963) report that a
toxic level of gossypol depressed feed consumption twice as much as it did growth rate. Moreover, the data of Heywang and Bird (1955) seem to indicate a greater effect on weight gains than on feed utilization. Lyman (1959) postulated that gossypol acts by blocking the epsilon amino groups of lysine, thus reducing its availability. Under the conditions of trial 3 supplementing the high-gossypol diet with lysine (on a mole per mole basis) did not reduce the very high mortality during the first 4 days of the experiment, nor did it improve the depressed growth fate of the survivors. This is in accordance with Heywang and Bird (1950) and Couch el al. (1955), who found that adding lysine did not change the gossypol tolerance level. The effect of gossypol on mortality was not very consistent. In trial 1, 0.16% gossypol tripled the mortality as compared to the other diets; in trial 3, 0.16% gossypol approximately doubled the mortality, 0.22% increased mortality about 7-fold and 0.28% over 10-fold as compared to the other diets; on the other hand, in trial 2 neither 0.18% nor 0.20% gossypol increased mortality. SUMMARY
The value of acidulated cottonseed-oil soapstock and the tolerance level of gossypol, in diets of broilers, were tested in one 5-week and two 10-week battery trials involving 2,314 chicks. The results obtained in these trials indicate that 0.10% dietary gossypol (supplied by this soapstock) is the safe upper tolerance level. Up to this limit there is no difference between acidulated cottonseed- and acidulated soybean-oil soapstock in terms of chick weight gains and feed/gain ratio. Levels of gossypol above 0.10% depress growth rate by means of reduced feed
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The toxicity of 0.16% gossypol in the diet of chicks has been demonstrated in trials 1 and 3, whereas only in trial 1 an indication was obtained that 0.11%, too, might be slightly toxic. Nevertheless, and for safety's sake, it may be advisable to accept the latter concentration as exceeding the safe upper tolerance level of chicks. The data of the 3 trials together seem, therefore, to justify the conclusion that chicks and broilers are not adversely affected by gossypol concentrations up to 0.1% of their diet, as long as this gossypol is contributed by ACS. The conclusion of the foregoing paragraph differs from the accepted toxicity levels of gossypol for chicks, when the gossypol is found in cottonseed meal, which have been reported as 0.02% (Heywang and Bird, 1955), 0.06% (Couch el ah, 1955) and 0.04% (Hill and Totsuka, 1963). The data of the present paper agree with those of Curtin and Raper (1956), who reported that gossypol in ACS is less harmful than that in cottonseed meal. The difference in toxicity between these two sources of gossypol may be the result of the treatments with alkali, acids and especially heat which ACS undergoes during its production process. In other words, the assay employed may not be specific for gossypol, but probably also determines gossypol derivatives and closely related compounds, which may represent less toxic forms resulting from these treatments.
ACIDULATED SOAPSTOCK
consumption, with a relatively smaller effect on the feed/gain ratio. At concentrations which exceed 0.20%, gossypol causes high mortality. In one trial, lysine supplementation did not affect the gossypol tolerance level.
This study was supported by a grant from the Food Branch of the Israel Ministry of Commerce and Industry. The authors are indebted to the managing directors of "Etz-Hazaith" Oil and Soap Industry, "Izhar" Oil Industry of Israel Ltd., and "Shemen" Israel Oil Industry Ltd. for supplying the cotton-seed-oil soapstocks used in this study. Appreciation is also expressed to Dr. R. Larisch of Agrochemiya Ltd., for providing the lysine. REFERENCES Altschul, A. M., 1960. Report to the Government of Israel on protein from oilseeds and oilseed processing. F.A.O. Rpt. No. 1245. Bornstein, S., and B. Lipstein, 1961. By-products of soybean oil as fat supplements in practical broiler rations. World's Poultry Sci. J. 17: 167-178. Bornstein, S., and B. Lipstein, 1963. Some unusual waste vegetable oils as fat supplements in practical broiler rations. World's Poultry Sci. J. 19: 172-184. Combs, G. F., 1961. Maryland broiler nutrition studies. Proc. Maryland Nutrit. Conf. p. 51-65. Couch, J. R., 1953. The use of waste fats in poultry feeds. Proc. 3rd Conf. on Processing Cottonseed Meal. U.S.D.A., A.R.S. South Util. Res. Branch, p. 3 8 ^ 0 .
Couch, J. R., W. Y. Chang and C. M. Lyman, 1955, The effect of free gossypol on chick growth. Poultry Sci. 34:178-183. Curtin, L. V., and J. T. Raper 1956. Feeding value of hydrolyzed vegetable fats in broiler rations. Poultry Sci. 35: 273-278. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11:1-42. Heywang, B. W., and H. R. Bird, 1950. Supplements for cottonseed meal in diets for chickens. Poultry Sci. 29:486-495. Heywang. B. W., and H. R. Bird, 1955. Relationship between the weight of chicks and levels of dietary free gossypol supplied by different cottonseed products. Poultry Sci. 34: 1239-1247. Hill, F. W., and K. Totsuka, 1963. Metabolizable energy of cottonseed meals for chicks with particular reference to the effects of gossypol. Fed. Proc. 22: 200. Lyman, C. M., 1959. Gossypol reactions with proteins. Proc. of the Conf. on the Chemical Structure and Reactions of Gossypol and Nongossypol Pigments of Cottonseed. National Cottonseed Products Assn., p. 61-70. Naber, E. C , and C. L. Morgan, 1957. Fat supplementation of chick starting rations containing cottonseed meal. Poultry Sci. 36: 721-732. Pepper, W. F., E. S. Snyder, I. R. Sibbald and S. J. Slinger, 1962. The effects of cottonseed oil and cottonseed oil derivatives on the quality of eggs stored at 30° and 60°F. for varying periods of time. Poultry Sci. 41:1943-1946. Pons, W. A., D. J. Mitcham, T. R. O'Connor and M. F. Stansbury, 1956. Improved method for determining gossypol in crude cottonseed oils. J. Am. Oil Chem. Soc. 33:324-330. Sibbald, I. R., W. F. Pepper and S. J. Slinger, 1962. A comparison of feed grade tallow and acidulated soapstocks in practical starter rations. Poultry Sci. 41:120-124. Snedecor, G. W., 1956. Statistical Methods, 5th ed., Iowa State College Press. Ames, Iowa.
NEWS AND NOTES {Continued from page 685) ture, University of California, Davis. This Department succeeds the "Group in Animal Physiology," a less formal interdepartmental organization of physiologists, established in 1953, which offered some course work, and supervised an undergraduate major in Animal Physiology leading to the B.S. degree. Initially, the Department will consist of four
full-time faculty. There are 24 additional faculty members on the campus with physiological interests (12 of whom are members of the American Physiological Society) who will cooperate in teaching and in curricular methods. The objectives of the new Department are to lead and coordinate academic activities in Animal
(Continued on page 775)
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ACKNOWLEDGMENTS
693
(Received for publication November 20, 1963)
P
REVIOUS reports from this Division have described the use of acidulated soybean-oil soapstock (Bornstein and Lipstein, 1961) and of acidulated sunflower-oil soapstock (Bornstein and Lipstein, 1963) in chick rations. These fat supplements were found to compare with tallow in terms of chick growth and feed/gain ratio. Cottonseed-oil soapstock has been used commercially in the United States as fatty acid methyl esters, but regular acidulated cottonseed-oil soapstock (ACS) has not been accepted for general use because of the possible toxicity of gossypol. An extensive literature exists on the use of cottonseed meal and on its gossypol content, but little information is available on ACS or its gossypol. Couch (1953), Naber and Morgan (1957) and Combs (1961) mention ACS in a rather incidental manner, whereas to the best of our knowledge only Curtin and Raper (1956) investigated it systematically in broilers, and Pepper et al. (1962) in laying hens. The former workers showed that gossypol found in ACS is much less toxic than that found in cottonseed meal, but they did not estimate the maximal tolerance levels. The purpose of the present study was to test a number of different local samples of ACS of various sources and to try to establish the highest permissible levels 1
Contribution from the National and University Institute of Agriculture, Rehovot, Israel. 1963 Series. No. 628-E.
of gossypol of ACS in practical broiler rations. GENERAL PROCEDURE Two 10-week and one 5-week battery trials were conducted during 1961. Commerical, day-old sexed CornishX White Rock crossbred chicks were randomly (except for sex) allocated to compartments (2 compartments per story) of either two or three-story (depending on trial) electric battery brooders with raised wire floors. Each compartment received an equal number of male and female chicks. The rations were also assigned at random to the various compartments. At 5 weeks of age, the chicks were transferred to a shed containing two-story wire cages, each cage capable of holding 7 to 8 full-grown broilers. Feed and water were supplied ad libitum at all times. Body weights and feed consumption were recorded at 3, 5, 8 and 10 weeks of age, on a group basis. At the latter two ages, the cockerels and pullets of each group were weighed separately. Up to six weeks the chicks were fed starter diets the composition of which is shown in Tables 1 and 2. The gossypol content mentioned in the latter table were determined by the method of Pons et al. (1956). From 6 to 10 weeks of age the birds were given finishing rations, which differed from the former in that 9% or 10% (diets containing 10% and more added fat) soybean meal was replaced by an equal amount of sorghum
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BlANKA LlPSTEIN AND S. BORNSTEIN Division of Poultry Husbandry, The National and University Institute of Agriculture, Rehovot, Israel
687
ACIDULATED SOAPSTOCK TABLE 1.—Composition of diets Ingredients
Calculated analysis: Crude protein (%) Prod, energy (Cal./lOO gm.) 4 Cal./lOO gm. ratio % protein
%
%
%
%
%
%
%
%
0.0 28.0 62.8 0.06 9.15 —
2.0 28.0 60.8 0.06 9.15 —
3.0 29.0 57.8 0.06 9.15 —
5.0 31.0 54.8 0.07 9.15
8.0 34.0 48.8 0.08 9.15
10.0 36.0 44.5 0.09
11.0 37.0 42.5 0.10
14.0 40.0 36.5 0.12
9.4
9.4
9.4
22.7 203
22.5 209
22.6 211
23.3 217
24.2 224
24.5 228
25.0 231
25.9 238
8.9
9.3
9.3
9.3
9.3
9.3
9.2
9.2
1
Variable with regard to source of soapstock and gossypol content, see Table 2. Fish meal, 3 % ; alfalfa meal (dehyr.), 2.5%; ground oyster shells, 1.5%; D.C.P., 1.5%;mineral mix, 0.3%; vitamin mix, 0.25%; coccidiostat, 0.1%. 3 Fish meal, 3 % ; alfalfa meal (dehyr.), 2.5%; gr. oyster shells, 1.4%; D.C.P., 1.6%; mineral mix, 0.35%; coccidiostat 0.1%. The composition of the mineral and vitamin mixes and of coccidiostat has been given in a previous report (Bornstein and Lipstein, 1963). 4 Based on the assumption that acidulated soapstocks contain 560 Cal. (P.E.)/100 gm., and that soybean meal of 49% protein content contains 160 Cal./lOO gm. 2
grain in order to widen the C/P ratio (Calories of productive energy per 100 gm./percentage protein) from 9.3 to 11.4, and in that the methionine supplement was decreased by 20%. The results were subjected to an analysis of variance according to Snedecor (1956), and when significant differences were obtained Duncan's multiple range test (1955) was used to compare means. All interpretations of data are based on the 1% level of probability. EXPERIMENTAL AND RESULTS
Trial 1. The purpose of the first and preliminary experiment was to test the effect of 3 sources of crude oil obtained from 2 plants, and in one case from the production of 2 different years (Table 2), on the gossypol content of the soapstock produced from them and on the performance of broilers fed these ACS. Accordingly, 4 samples of ACS were used at 3 % and 10% levels each, and were compared with a sample of acidulated soybean-oil soapstock (ASS) employed at the same levels
and with a control diet. These 11 diets (Table 3) were fed to 616 chicks divided into 44 groups of 14 chicks each. The gossypol content of the 4 samples of ACS is given in Table 2, and the results obtained from the feeding experiment are summarized in Table 3. According to the TABLE 2.—Types of acidulated cottonseed soapstock employed in different trials Soapstock No.
Source of crude oil1
Producer2
Gossypol content, %
1 2 3 4 5 6 7 8 9
Extraction Mixed Mixed Pressing Pressing Extraction Mixed Extraction Pressing
B C C B A A C B B
0.79 1.10 1.10 1.60 0.32 0.51 0.84 1.84 2.02
1 The plants in Israel which process cottonseed use two-stage screw pressing, followed by solvent extraction (Altschul, 1960). Some refine separately the crude oil derived from pressing and that from extraction, while others mix the oils before refining; soapstock being the by-product obtained from refining any vegetable oil. 2 All soapstocks were produced during I960, except No. 2 which was the product of 1959.
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Acidulated soapstock1 Soybean meal (49% protein) Ground sorghum (milo) DL-Methionine Constant ingredients l 2 Constant ingredients 2 3
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B . L l P S T E I N AND S . B O R N S T E I N
T A B L E 3.—Effect of acidulated soybean-oil soapstock and 4 kinds of acidulated cottonseed soapstock, fed at 2 levels, on the performance of broilers {Trial i ) 1 ' 2 Soap- Gossypol 3 stock in diet none
ASS 1 2 3 4 S.E.
—
0.02 0.03 0.03 0.05
— 0.08 0.11 0.11 0.16
(gm.) 599 c
(gm.j 1,717 b
Feed/gain ratio, at age 5 weeks 1.93 c
10 weeks 2.62 c
3% Supplementary 632 b 1,740 1,797 656 ab 659 ab 1,763 1,767 637 b 642 b 1,727
soapstock 1.82 be b ab 1.82 be b 1.84c b 1.81 be b 1.86 c
2.60 2.56 2.61 2.55 2.62
be be c be c
10% Supplementary 713 a 1,906 671 a b 1,823 652 ab 1,764 637 b 1,723 410 d 1,012
soapstock 1.65 a a 1.68a ab 1.71 a b b b 1.71 ab c 1.89 c
2.37 2.43 2.43 2.52 3.11
a ab ab abc d
12.3
25.9
0.22
0.031
1 2
Averages of 4 replicates of 14 birds each. Any 2 mean values within a column not having one letter in common differ significantly (P<0.01). s Calculated on the basis of Table 2. * Mean value of the separate averages for males and females. 6 Acidulated soybean-oil soapstock. ' See Table 2.
latter, at the 3 % supplementation level of soapstock there were no significant differences in growth and feed/gain ratio at 5 and 10 weeks of age among the various soapstocks. At 5 weeks of age body weights were significantly higher in the soapstock-supplemented groups than in the control (improvements of 5.5% to 10.0%), whereas this supplementation level did not have a significant effect on weight gains at 10 weeks of age or on feed utilization at either age. At the 10% supplementation level ASS tended to improve growth to a greater extent than the 4 samples of ACS, ACS-3 tended to be inferior to ACS-1 and 2, and ACS-4 was significantly inferior to the other three ACS's. Comparing the results of the diet containing 10% ACS-4 with those of the ASS diet it becomes obvious that the toxic level of gossypol (0.16% of the diet) affected growth rate much more than it did feed/gain ratio. According to feed consumption data obtained (but not presented in Table 3) the average feed
Trial 2. The purpose of this experiment was to compare the performance of broilers fed 5 samples of ACS, chosen on the basis of their gossypol content and also of their variability in source. These samples were each used at 2 supplementation levels (3% and 10%), in comparison with parallel levels of a sample of ASS and with a control diet. These 13 diets (Table 4) were fed to 546 chicks divided into 39 groups of 14 chicks each. In accordance with the results of the previous trial, the data presented in Table 4 for the 3 % supplementation level T A B L E 4.—Performance of broilers fed either acidulated soybean-oil soapstock or 5 kinds of acidulated cottonseed soapstock, at two levels (Trial 2 ) 1 ' 2 Gossypol Soap- • j : - f 3 stock (m) {'°'
B o d y wei
S nts > a t a B e
5 weeks 10 weeks4 (
1,624 a
Feed/gain ratio, at age 5 weeks 1.78 <
10 weeks 2.45 e
3% Supplementary soapstock ASS* S« 6 7 8 9 ASS 5 6 7 8 9
—
0.01 0.02 0.03 0.06 0.06
— 0.03 0.05 0.08 0.18 0.20
574 580 598 600 567 557 10% 611 585 583 605 549 515
1.68 1.66 1.65 1.69 1.70 1.70
d cd bed d d d
2.36 2.38 2.32 2.36 2.31 2.35
cd d bed cd abed cd
Supplementary.soapstock a 1,667 a 1.55 a 1,601a 1.57 a 1,646 a 1.59 a 1,624 a 1.57 a 1,593 a 1.57 b 1,450 b 1.66
a ab abc ab ab cd
2.13 2.21 2.19 2.21 2.12 2.37
ab abed abc abed a cd
a a a a a a
1,609 1,625 1,661 1,604 1,593 1,570
a a a a a a
S.E. 1
Averages of 3 replicates of 14 birds each. J-6 See corresponding footnotes to Table 3.
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ASS' 16 2 3 4
(%) —
Body weights, a t age
intake per chick during the first 5 weeks for the 10%, ASS diet was 1,179 gm., while for the diet containing 10% ACS-4 it was 775 gm., and the respective figures up to 10 weeks of age were 4.484 kg. and 3.152 kg. The toxicity of gossypol also caused an increased mortality. Whereas the average mortality of the groups of chicks fed the other 10 diets amounted to 2.9%, 10% ACS-4 in the diet caused a mortality of 8.9% during the first 5 weeks.
689
ACIDULATED SOAPSTOCK
Trial 3. The purpose of this experiment was to determine the tolerance level of chicks to gossypol, by using 2 samples of ACS containing very different gossypol concentrations. Thus, for instance, 5% ACS-9 and 14% ACS-1 supplied similar amounts of gossypol to the diet. Moreover, the opportunity was utilized to test the effects of lysine supplementation on gossypol toxicity. Accordingly, 2 samples of ACS and one of ASS were each used at 5 levels of supplementation (Table 5) in a factorial design. As an additional experimental treatment a diet containing 14% ACS-9 was supplemented with 0.16% lysine. These 16 diets were fed for 5 weeks to 1152 chicks divided into 48 groups of 24 chicks each. In this trial there was high mortality during the first 4 days of the experiment (and almost none during the period of 1
TABLE 5.—Effect of 3 acidulated soapstocks fed at 5 levels on the performance of chicks at 5 weeks of age. {Trial 3)1-2 Gossypol in diet3 (%)
Body weight (gm.)
ASS« I* 9
Feed consumption (kg.) 2% supplementary soapstock — 658a 1.140a 0.02 648 a 1.147 a 0.04 636 a 1.110 ab
ASS 1 9
— 0.04 0.10
5% supplementary soapstock 650 a 1.103 ab 676 a 1.152 a 667 a 1.153 a
1.70 cdef 1.69 cde 1.73 def
ASS 1 9
— 0.06 0.16
8% supplementary soapstock 693 a 1.139 a 683 a 1.135 a 641a 1.097 ab
1.63 abed 1.66 bed 1.70 cdef
ASS 1 9»
— 0.09 0.22
11% supplementary soapstock 675 a 1.090 abc 677 a 1.090 abc 595 b 1.036 be
1.61 abc 1.61 abc 1.74 def
ASS 1 9' 98
14% supplementary soapstock — 666 a 1.006 c 0.11 695 a 1.088 abc 0.28 506 c 0.906 d 0.28 474 c 0.862 d
Soapstock
S.E.
0.016
Feed/gain ratio 1.73 def 1.75 def 1.76 ef
1.51a 1.56 ab 1.79 f 1.82 f 0.02
1
Averages of 3 replicates of 24 chicks each. V See corresponding footnotes to Table 3. * See footnote 5 to Table 3. « See footnote 6 to Table 3. 6 Averages of 2 replicates of 18 chicks each. 7 One replicate of 8 chicks. 8 One replicate of 8 chicks supplemented with lysine.
to 5 weeks of age), due to two reasons: (a) a marked general and non-specific mortality, apparently the fault of the hatchery, which amounted to an average of 7% (maximum of 9%) per treatment for the chicks fed the 5 levels of ASS and ACS-1 and 2% and 5% levels of ACS-9; (b) a mortality due to high concentrations of gossypol: the 3 groups fed 8% ACS-9 (0.16% dietary gossypol) lost up to 15% of their chicks, those fed 11% ACS-9 (0.22% gossypol) lost 5 1 % , and the 6 groups fed 0.28% gossypol (with and without lysine supplementation) had a mortality of 89%. At 1 week of age the survivors among the chicks fed 1 1 % ACS9 were rearranged into 2 groups of 18 chicks each, and those of the last 6 groups into 2 groups (of 8 chicks each), one with and one without lysine supplement. The growth results of this trial are summarized in Table 5 and Figure 1.
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show an absence of significant effect of type of soapstock on broiler performance at 5 and 10 weeks of age. In contrast to trial 1, growth rate up to 5 weeks of age was not accelerated by this soapstock level, but feed/gain ratio was significantly improved at both ages (by 4.7% to 7.9%). At the 10% level of supplementation with soapstock there were no significant differences between ASS and ACS-5-8, nor did these 4 samples of ACS differ among themselves. However, ACS-9 significantly reduced weight gains, and in some cases also feed utilization, in comparison with other ACS's. The S-week results indicate a greater depression on growth rate than in feed utilization due to 10% ACS-9 (0.20% gossypol) in the diet, as pointed out for ACS-4 in trial 1. At that age average feed consumption per chick fed 10% ASS was 947 gm., whereas the corresponding figure for 10% ACS-9 was 855 gm. Mortality in this trial was low and appeared accidental.
690
B . LlPSTEIN AND S. BORNSTEIN
1.80
2 S \ Q UJ
1.60
1.50
-o BODY WEIGHT o FEED CONSUMPTION o FEED/GAIN RATIO
o o
0.04
0.06 0.12 0.16 0.20 % GOSSYPOL IN DIETS
0.24
0.28
FIG. 1. The effect of gossypol on body weight, feed consumption and feed/gain ratio of S-week old chicks. The percentages designate levels of soapstock in the diet.
With regard to ASS, the best weight gain response of the chicks was obtained with an 8% supplement, while additional ASS tended to decrease growth rate, to an insignificant extent, apparently due to decreased feed intake. On the other hand, there was a significant improvement in feed utilization with increasing supplementation, which reached 14.5%. As far as ACS-1 is concerned, there was a slight, insignificant trend for a steady increase in growth rate with increasing level of supplementation, and this trend
was pronounced and significant for feed utilization. On the other hand, supplementations with ACS-9 quickly caused toxic concentrations of gossypol, the first, and yet insignificant, indication appearing in the diet containing 8% of this soapstock (0.16% gossypol). Again, as in previous trials, the detrimental effect of gossypol was stronger on growth rate than on feed utilization. Figure 1, presenting the effects of dietary gossypol concentration on chick performance, demonstrates in two ways
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1.70
ACIDULATED SOAPSTOCK
DISCUSSION
A comparison between the results obtained from supplementing broiler diets with ASS or with ACS containing nontoxic concentrations of gossypol indicates that, generally speaking and in terms of weight gain and feed/gain ratio, there is no difference between these two types of soapstocks. In trial 1, at the 10% supplementation level, ASS tended to improve growth rate to a greater extent than the better samples of ACS, but this insignificant trend is hardly recognizable in trial 2, and is completely absent at the 3 % level in both of these trials and at all supplementation levels in trial 3. In an indirect way this may be interpreted as meaning that ACS of low gossypol content is comparable to tallow, since previous publications of this division (Bornstein and Lipstein, 1961, 1963) and a report by Sibbald et al. (1962) show similar effects of ASS and tallow on chick
growth and feed utilization. In trial 1 (Table 3) only 0.16% gossypol in the diet significantly affected broiler performance, with some indication of slightly less beneficial effects from the supplementation with ACS which raises the dietary gossypol content to 0.11%. In trial 2, the lowest concentration of gossypol in the diet which depressed growth significantly was 0.20%, whereas 0.18% retarded growth only slightly and only at 5 weeks of age (Table 4). In trial 3, 0.22% and 0.28% gossypol inhibited weight gains significantly (Table 5), whereas a concentration of 0.16% gossypol in the diet caused a slight and insignificant depression of growth, feed consumption and feed utilization, and also increased mortality. On the other hand, concentrations of 0.11% and 0.10% gossypol, due to 14% ACS-1 and 5% ACS-9, respectively, did not diminish the beneficial effects of ACS supplementation on chick performance, which were very similar to those of parallel levels of ASS. Trials 1 and 3 were performed with January- and November-hatched chicks, respectively, while the chicks used in trial 2 were hatched in July. Experience at this station has shown that summer heat decreases weight gains while improving feed utilization, and these factors may have influenced the results of trial 2. In trial 2 (Table 4) chicks fed the control or 3 % supplementation diets possessed lower body weights than did those in trials 1 and 3, and they responded less to the growth-promoting effect of fat supplementation. This lowered responsiveness of their growth rate may also have affected their reaction to gossypol, and therefore the effect of the diet containing 0.18% gossypol was less severe than might have been expected on the basis of the data for 0.16% gossypol in trial 1 (Table 3).
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that in trial 3 gossypol levels up to and including 0.11% of the diet had no adverse effect: (a) there is no difference at 5% soapstock supplementation between 0.04% and 0.10% gossypol with regard to growth rate, feed consumption and feed utilization; and (b) the growth curve shows the expected slight irregular increase with increasing fat supplement up to 0.11% gossypol, but above this concentration and up to 0.28% the weights decline sharply in a linear fashion. Feed consumption declines slightly with increasing fat level, as expected, but beginning with the 0.16% gossypol concentration it decreases parallel to the decrease in growth rate. Feed utilization improves linearly with soapstock supplementation from 2% to 14% levels, up to 0.11% gossypol concentration, after which it worsens rapidly.
691
692
B . LlPSTEIN AND S. BORNSTEIN
The results obtained in this study also indicate the mode of action of gossypol with regard to growth retardation in broilers. They show that the inhibition of growth is primarily the result of depressed feed intake, with little effect on feed utilization. The latter usually does not decrease significantly beyond that for diets containing no or 2% fat supplement. Hill and Totsuka (1963) report that a
toxic level of gossypol depressed feed consumption twice as much as it did growth rate. Moreover, the data of Heywang and Bird (1955) seem to indicate a greater effect on weight gains than on feed utilization. Lyman (1959) postulated that gossypol acts by blocking the epsilon amino groups of lysine, thus reducing its availability. Under the conditions of trial 3 supplementing the high-gossypol diet with lysine (on a mole per mole basis) did not reduce the very high mortality during the first 4 days of the experiment, nor did it improve the depressed growth fate of the survivors. This is in accordance with Heywang and Bird (1950) and Couch el al. (1955), who found that adding lysine did not change the gossypol tolerance level. The effect of gossypol on mortality was not very consistent. In trial 1, 0.16% gossypol tripled the mortality as compared to the other diets; in trial 3, 0.16% gossypol approximately doubled the mortality, 0.22% increased mortality about 7-fold and 0.28% over 10-fold as compared to the other diets; on the other hand, in trial 2 neither 0.18% nor 0.20% gossypol increased mortality. SUMMARY
The value of acidulated cottonseed-oil soapstock and the tolerance level of gossypol, in diets of broilers, were tested in one 5-week and two 10-week battery trials involving 2,314 chicks. The results obtained in these trials indicate that 0.10% dietary gossypol (supplied by this soapstock) is the safe upper tolerance level. Up to this limit there is no difference between acidulated cottonseed- and acidulated soybean-oil soapstock in terms of chick weight gains and feed/gain ratio. Levels of gossypol above 0.10% depress growth rate by means of reduced feed
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The toxicity of 0.16% gossypol in the diet of chicks has been demonstrated in trials 1 and 3, whereas only in trial 1 an indication was obtained that 0.11%, too, might be slightly toxic. Nevertheless, and for safety's sake, it may be advisable to accept the latter concentration as exceeding the safe upper tolerance level of chicks. The data of the 3 trials together seem, therefore, to justify the conclusion that chicks and broilers are not adversely affected by gossypol concentrations up to 0.1% of their diet, as long as this gossypol is contributed by ACS. The conclusion of the foregoing paragraph differs from the accepted toxicity levels of gossypol for chicks, when the gossypol is found in cottonseed meal, which have been reported as 0.02% (Heywang and Bird, 1955), 0.06% (Couch el ah, 1955) and 0.04% (Hill and Totsuka, 1963). The data of the present paper agree with those of Curtin and Raper (1956), who reported that gossypol in ACS is less harmful than that in cottonseed meal. The difference in toxicity between these two sources of gossypol may be the result of the treatments with alkali, acids and especially heat which ACS undergoes during its production process. In other words, the assay employed may not be specific for gossypol, but probably also determines gossypol derivatives and closely related compounds, which may represent less toxic forms resulting from these treatments.
ACIDULATED SOAPSTOCK
consumption, with a relatively smaller effect on the feed/gain ratio. At concentrations which exceed 0.20%, gossypol causes high mortality. In one trial, lysine supplementation did not affect the gossypol tolerance level.
This study was supported by a grant from the Food Branch of the Israel Ministry of Commerce and Industry. The authors are indebted to the managing directors of "Etz-Hazaith" Oil and Soap Industry, "Izhar" Oil Industry of Israel Ltd., and "Shemen" Israel Oil Industry Ltd. for supplying the cotton-seed-oil soapstocks used in this study. Appreciation is also expressed to Dr. R. Larisch of Agrochemiya Ltd., for providing the lysine. REFERENCES Altschul, A. M., 1960. Report to the Government of Israel on protein from oilseeds and oilseed processing. F.A.O. Rpt. No. 1245. Bornstein, S., and B. Lipstein, 1961. By-products of soybean oil as fat supplements in practical broiler rations. World's Poultry Sci. J. 17: 167-178. Bornstein, S., and B. Lipstein, 1963. Some unusual waste vegetable oils as fat supplements in practical broiler rations. World's Poultry Sci. J. 19: 172-184. Combs, G. F., 1961. Maryland broiler nutrition studies. Proc. Maryland Nutrit. Conf. p. 51-65. Couch, J. R., 1953. The use of waste fats in poultry feeds. Proc. 3rd Conf. on Processing Cottonseed Meal. U.S.D.A., A.R.S. South Util. Res. Branch, p. 3 8 ^ 0 .
Couch, J. R., W. Y. Chang and C. M. Lyman, 1955, The effect of free gossypol on chick growth. Poultry Sci. 34:178-183. Curtin, L. V., and J. T. Raper 1956. Feeding value of hydrolyzed vegetable fats in broiler rations. Poultry Sci. 35: 273-278. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11:1-42. Heywang, B. W., and H. R. Bird, 1950. Supplements for cottonseed meal in diets for chickens. Poultry Sci. 29:486-495. Heywang. B. W., and H. R. Bird, 1955. Relationship between the weight of chicks and levels of dietary free gossypol supplied by different cottonseed products. Poultry Sci. 34: 1239-1247. Hill, F. W., and K. Totsuka, 1963. Metabolizable energy of cottonseed meals for chicks with particular reference to the effects of gossypol. Fed. Proc. 22: 200. Lyman, C. M., 1959. Gossypol reactions with proteins. Proc. of the Conf. on the Chemical Structure and Reactions of Gossypol and Nongossypol Pigments of Cottonseed. National Cottonseed Products Assn., p. 61-70. Naber, E. C , and C. L. Morgan, 1957. Fat supplementation of chick starting rations containing cottonseed meal. Poultry Sci. 36: 721-732. Pepper, W. F., E. S. Snyder, I. R. Sibbald and S. J. Slinger, 1962. The effects of cottonseed oil and cottonseed oil derivatives on the quality of eggs stored at 30° and 60°F. for varying periods of time. Poultry Sci. 41:1943-1946. Pons, W. A., D. J. Mitcham, T. R. O'Connor and M. F. Stansbury, 1956. Improved method for determining gossypol in crude cottonseed oils. J. Am. Oil Chem. Soc. 33:324-330. Sibbald, I. R., W. F. Pepper and S. J. Slinger, 1962. A comparison of feed grade tallow and acidulated soapstocks in practical starter rations. Poultry Sci. 41:120-124. Snedecor, G. W., 1956. Statistical Methods, 5th ed., Iowa State College Press. Ames, Iowa.
NEWS AND NOTES {Continued from page 685) ture, University of California, Davis. This Department succeeds the "Group in Animal Physiology," a less formal interdepartmental organization of physiologists, established in 1953, which offered some course work, and supervised an undergraduate major in Animal Physiology leading to the B.S. degree. Initially, the Department will consist of four
full-time faculty. There are 24 additional faculty members on the campus with physiological interests (12 of whom are members of the American Physiological Society) who will cooperate in teaching and in curricular methods. The objectives of the new Department are to lead and coordinate academic activities in Animal
(Continued on page 775)
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ACKNOWLEDGMENTS
693