THE minimum requirement for sodium

Transcription

1 The Requirement of Breeding Hens for Sodium Chloride C. H. BURNS, W. W. CRAENS AND P. H. PHILLIPS Departments of Biochemistry and Poultry Husbandry, University of Wisconsin, Madison THE minimum requirement for sodium chloride for optimum performance by breeding hens fed purified diets has been investigated. In previous work (Barlow et ah, 1943; Halpin et ah, 1934; 1936; Prentice, 1933; Sjollema, 1935) with sodium chloride in the nutrition of poultry, optimum rather than minimum requirements were sought, and levels from to 1.0% were accepted as adequate. In the present investigation, the actual need with purified diets was found to be considerably lower. The data on the effect of sodium chloride deficient diets on the performance of breeding hens are also presented. EXPERIMENTAL Single-Comb White Leghorn pullets which had been reared to maturity on range and fed practical diets were placed in individual cages with raised screen bottoms and throughout the experiments were given water, oyster shell, and ration ad libitum. The purified basal ration used was complete in all known nutrients except the minerals; its composition in percent is as follows: Sucrose, (depending on level of NaCl used); alcohol-extracted casein, 18; crude gelatin, 5; soy- Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. Supported in part by a grant from the Salt Producers Association, Detroit, Michigan. We are indebted to Wilson and Company, Chicago, Illinois, for the gelatin; Merck and Company, Rahway, New Jersey and Lederle Laboratories, Pearl River, New York, for the crystalline vitamins. (Received for publication July 3, 19S1) 302 bean oil, 3; cod liver oil (2000-A, 400-D), 2. Crystalline vitamins were added in mgs. per kilo as follows: choline CI, 2000; Bi 2 adsorbate (Merck #3, 12.5 mg./lb.), 2000; i-inositol, 00; riboflavin, 6; thiamine HC1,4; Ca pantothenate, 15; niacin, 00; pyridoxine HC1, 4; 2-methyl-l,4-naphthoquinone, ; biotin, 0.2; alpha-tocopherol, 3; and folic acid, 2. The minerals were added in the form of salt mixtures: "Salts A" for diets without added sodium or potassium, and "Salts B" for diets without added sodium or chloride. The composition of these mixtures and the amounts fed are given in Table 1; for comparison, the complete "Salts I" mixture is also listed. When added to the ration in the specified amount, these salt mixtures supplied, with the intended exceptions, the following per- TABLE 1.Composition of salt mixtures CaC0 3 CaCl 2 2H 2 0 CaHP0 4 K 2 HP0 4 NaCl MgS0 4 7H 2 0 Ferric citrate 6H 2 0 MnS0 4 lh 2 0 KI CuS0 4 5H 2 0 ZnCl 2 Salts I Salts A Percent Added to Ration Salts B centages of the required minerals: calcium,.70; phosphorus,.36 (18% casein supplies an additional.14%); potassium,.73; sodium,.33; chloride,.51; magne-

2 SODIUM CHLORIDE REQUIREMENT OF HENS 303 sium,.; iron,.022; manganese,.009; iodine,.003; zinc,.0006; and copper, The basal diet was analyzed and found to contain.014% sodium, equivalent to.035% sodium chloride; no analyses were conducted for chloride alone. The minimum sodium chloride requirement was determined by adding sodium chloride at increasing levels to the basal diet supplemented with Salts B, and testing the effect of each level on a group of four birds. Body weight, egg production, and hatchability of fertile eggs were recorded weekly for each bird, and the lowest level of sodium chloride which afforded optimum performance was taken to be the minimum requirement- Analyses of the sodium and potassium content of the whites and yolks were carried out on eggs from hens which had received.035 and.89% sodium chloride for ten weeks. The method of analysis was that of Hald (1947) using the flame photometer. An experiment to compare the effect of deprivation of sodium alone, chloride alone, and sodium chloride on the breeding hen was conducted in a manner which, except for the dietary omissions, was identical with that described above. The chloride-restricted diet was made up by supplying Salts B plus 1.22% sodium bicarbonate (equivalent to.33% sodium) to the basal ration. The sodium-restricted ration was made up by substituting Salts A for Salts B and adding to this 1.87% potassium bicarbonate (equivalent to.73% potassium). The experimental period was five weeks. During the next four weeks, all but the chloride-restricted groups were placed on the control ration in order to determine the rate of recovery. RESULTS In Experiment 1, levels of.04,.14,.24,.44,.65,.89, 1.5, and 5.0% sodium chloride were tested for six weeks. The lowest level which supported body weight, egg production, and hatchability was.24%. Five% sodium chloride in the diet caused a marked depression as shown by all criteria while the effect of the 1.5% level was inconclusive. In Experiment 2, levels of.04,.14,.24,.34,.54, and.89% sodium chloride were tested for seven weeks. The.14% level was found to be nearly adequate for supporting body weight, egg production, and hatchability. The details of Experiments 1 and 2 have been presented by Burns (1950). The results of Experiment 3 are shown in Figure 1. Each graph represents the average performance of the four birds on each level of sodium chloride. Body weight, egg production, and hatchability each appear to be maintained by different levels of sodium chloride. Hatchability appears to be' unaffected in any of the groups, regardless of the decreases in egg production. The level of sodium chloride required to maintain the latter appears to be between.14 and.19%. Body weight decreases are noted, however, on all but the two highest levels of sodium chloride. Since.19% sodium chloride appears to be the lowest level at which all three of the performance criteria are maintained at normal levels, this level is taken as the minimum requirement for sodium chloride by breeding hens fed purified diets for the 14-week period. The results of the egg-content analyses for sodium and potassium are presented in Table 2. The two levels of dietary sodium chloride represent the lowest level used in these experiments and the optimum level commonly used with our purified diets. The.035% level of sodium chloride resulted in a decrease in the sodium content of the whites by about 20%, while the sodium content of the yolk was not changed. The level of potassium in the yolk appeared to be increased by

3 304 C. H. BURNS, W. W. CRAENS AND P. H. PHILLIPS about 15% by sodium chloride deficiency, but little if any change occurred in the potassium content of the whites. TABLE 2.Effect of NaCl level in diet of hens on sodium and potassium content of eggs Level of Sodium Potassium NaCl in diet of hens White Yolk White Yolk (all values in mgs. per 0 gms.).035% % An attempt was made to determine the effect of the sodium chloride level of the maternal diet on the sodium requirement «Body Weight, Jo of Initial... Egg Production, Percent oo Hatchability, Percent P^W 6o u u 8, * Group 3 NaCl =.135% i,..»., of the resulting chicks; but, owing to the small number of chicks available and to the incidence of mortality, the results are inconclusive. It appeared, however, that chicks from hens fed diets low in sodium chloride had a slightly higher requirement for sodium. If the chicks were supplied with adequate sodium (0.14%), the sodium chloride level of the maternal diet exerted no effect on the growth of the chicks. The effects of deprivation from the diet of the hen of sodium alone, chloride alone, and sodium chloride are shown in Figure 2. The performance of the three groups is distinguished mainly by the differences in egg production. With birds on a diet inadequate in sodium chloride, production fell to about 20% in five weeks. When sodium alone was restricted from the diet, however, production fell to zero in three weeks. When sodium was supplied but chloride omitted, little if any change occurred after nine weeks. When the groups.r^:r^ Group 1 ';... NaCl=.035% a s Week = u r-vvw Group 4 NaCl =.185% l.^-- 20 Group 2 NaCl=.085% O 8 / 0 to. i Week "Ttfxc "X - * ' vy Group 5 NaCl = -235% to 12. I* 0 /O IZ /4 Week Week Week FIG. 1. ariation of body weight, egg production, and hatchability with level of dietary NaCl. on low sodium and low sodium chloride were placed on the control diet, recovery from the deficiencies began immediately. Complete recovery was evident within three weeks. DISCUSSION The level of sodium chloride (0.19% of the diet) established in this study as the \;

4 SODIUM CHLORIDE REQUIREMENT, OF HENS 305 minimum requirement for maintenance of body weight and satisfactory egg production is considerably lower than the requirement (-1.0% of the diet) set by earlier workers as a supplement to natural rations. Hence the % level recommended by the National Research Council (1944) should provide an adequate allowance of sodium chloride provided that the nature of the diet does not interfere with the utilization of the salt. In one case, Slinger et al. (1950) have shown that 2% or more sodium chloride is required with high-fiber, low energy diets. On the other hand, Sjollema (1935) found this same level injurious. In view of the notable susceptibility of avian species to sodium chloride toxicity as discussed by Selye (1943) and others, it would appear advisable to consider the nature of the ration in determining the level of sodium chloride supplementation. For example, large portions of animal products in the diet may reduce considerably the amount of sodium chloride which should be added. The principal reaction of the breeding hen to the lowest level of sodium chloride (.04%) attained with the purified diet used was a marked decrease in egg production. In none of the experiments, however, did this level of sodium chloride restrict egg production altogether, and in those experiments continued beyond six or seven weeks, egg production tended to recover from the initial drop. It is interesting to note that despite these decreases, the eggs produced appeared normal as indicated by the normal yolk content of sodium (if not of the whites), by sustained liatchability, and by the good growth of the chicks hatched when provided with adequate sodium. This is in contrast to the results of restricted potassium intake (unpublished results) in which egg production is likewise decreased but with severe impairment of hatchability. The ef * - Body Weight, % of Initial Egg Production, Percent..o«. Hatchability, Percent Group 1 Adequate NaCl (Control) n t ' ' i ' i ' i ' i :. \ X \ j N! /'"^ i /!/ 1/ i/ N.'/,PLACED M. Group 2 j CIET Low NaCl _/\»»' Weeks Group 4 Low CI. /vy; FIG. 2. Comparative effect of low Na, low CI, and low NaCl on body weight, egg production, and hatchability. feet of sodium chloride restriction in the maternal diet on the sodium content of the egg white may be the cause of the slightly higher sodium requirement of chicks hatched from such eggs. The manner in which dietary salt restriction interferes with egg production but not with hatchability cannot be explained. The greater reduction in egg production caused by omitting sodium alone from the diet than by omitting sodium chloride may be considered in terms of an ion imbalance. Thus a sodium deficient diet is equivalent to one deficient in sodium chloride to which chloride has been added, suggesting that chloride exerts a toxic effect when supplied in excess of sodium. When sodium was added to such a diet, on the other hand, the effect of sodium chloride deficiency on egg production dis-

5 306 NEWS AND NOTES appeared. There is a, direct relation between the chloride-to-sodium ratio in these three diets and the degree to which egg production was decreased. Since the excretion of chloride must be accompanied by cations, and that of sodium by anions, it is possible that anions other than chloride, for example bicarbonate, can be mobilized to accompany the excretion of sodium, but that the excretion of a relatively high amount of chloride may aggravate a sodium deficiency by drawing upon the limited amount of sodium available, if not of other essential cations; the alternative would be a positive chloride balance with the possible consequence of acidosis. SUMMARY The minimum requirement for sodium chloride by breeding hens fed purified diets has been investigated and found to be approximately.19% of the diet. In a sodium chloride deficiency, the sodium appeared to be the limiting factor, and that chloride in considerable excess of sodium- may have had adverse effects. The chief effect of sodium chloride restriction from the diet of the breeding hen was a lowering of egg production. Body weight was only slightly decreased and hatchability was not affected. The sodium content of eggs produced by sodium chloride deficient hens was not appreciably Boardman, Texas, (4) P. Seigel, Connecticut, (5) P. Griminger, Illinois, (6) G. Townsen, Texas, (7) J. F. Greer, Missouri, (8) C. E, Broadus, Kentucky, (9) G. E. Masters, Arkansas, and () M. S. Fry, Kentucky. The individual placings were: in exhibition judging, (1) G. E. Masters, Arkansas, (2) G. B. Carey, Nebraska, and (3) M. Battig, Minnesota; in production judging, (1) G. M. Balstad, Minnesota, (2) P. Griminger, Illinois,, and (3) J. J, Morrow, lowered, and chicks hatched from such eggs were unaffected by deficiencies of sodium chloride in the maternal diet provided the chicks received adequate sodium. NEWS AND NOTES {Continued from page 301) {Continued on page 315) REFERENCES Barlow, J. S., S. J. Slinger and R. P. Zimmer, The reaction of growing chicks to diets varying in sodium chloride content. Poultry Sci. 27: 542- SS2. Burns, C. H., Some studies on sodium and potassium in the nutrition of poultry. M. S. Thesis, University of Wisconsin. Hald, P. M., The flame photometer for the measurement of sodium and potassium in biological fluids. J. Biol. Chem. 167: Halpin, J. G., C. E. Holmes and E. B. Hart, Salt requirements of growing chicks. Poultry Sci. 13: 308. Halpin, J. G., C. E. Holmes and E. B. Hart, Salt requirements of poultry. Poultry Sci. 15: National Research Council, Recommended nutrient allowances for poultry. Committee on Animal Nutrition, N.R.C., Washington, D. C. Prentice, J. H., Role of salt in poultry nutrition. J. Minist. Agr. No. Ireland, 4: and Selye, H., Production of nephrosclerosis in fowl by.nacl. J. Am. et. Med. Assoc. 3: Sjollema, B., Studies on sodium requirements of chickens and on consequences of a diet almost free of sodium. Biedermann's Zentralb. B. Tierernahrung 7: Slinger, S. J., W. F. Pepper and I. Motzok, Factors affecting the salt requirements of chickens. Poultry Sci. 29: Missouri; in market products judging, (1) W. Boardman, Texas, (2) J. Wendt, Wisconsin and (3) J. M. Jones, Arkansas. The trophies, medals, cash and merchandise prizes were provided by 34 companies associated with the poultry industry. Kansas State College won permanent possession of the first Institute of American Poultry Industries Trophy in 1933, winning the required three times in five attempts. They took permanent possession of