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Sodium Chloride in the Feed and Drinking Water of Chicks
YOLK COLOR colored yolks. Poultry Sci. 21: 497-499. Marusich, W., E. DeRitter and J. C. Bauernfeind, 1960. Evaluation of carotenoid pigments for coloring egg yolks. Poultry Sci. 39: 1338-1345. Parkhurst, R. T., 1937. Producing light yolks and its effect on flock health. Flour and Feed, 12(5): 10, 1937. Peterson, W. J., J. S. Hughes and L. F. Payne, 1939. The carotenoid pigments. Agricultural Experi-
541
ment Station College, Kansas State of Agriculture Technical Bulletin #46. Rubin, M., and H. R. Bird, 1946. The apparent antagonism between vitamin A and carotenoids in the fowl. Science, 103: 584-586. Sunde, M. L., and G. Madiedo, 1960. Influencia del maiz, del millo y de un pigmento carotenol en el color de la yema del huevo. Agricultural Tropical, 16: 725-730.
I. R. SIBBALD, W. F. PEPPER AND S. J. SLINGER Departments of Nutrition and Poultry Science, Ontario Agricultural College, Guelph, Ontario, Canada (Received for publication July 7, 1961)
and chlorine are essential SODIUM nutrients for the chick; however, high intakes of sodium chloride may prove toxic. Barlow et al. (1948) and Kare and Biely (1948) have reviewed much of the early literature concerning this subject. Barlow et al. (1948) observed that young chicks were more susceptible to the toxic effects of salt than were older birds; further, it was reported that the addition of 1% of salt to a practical type starter diet was optimal whereas the minimum toxic salt level was found to be 3 percent. Kare and Biely (1948) stressed the wide variation in salt tolerance between chicks within treatments; a diet containing 5.18% of sodium chloride proved lethal to some birds and harmless to others. When rations containing more than 4% of salt were fed, some birds in every group exhibited symptoms of oedema. There was no significant variation in feed efficiencies of chicks fed diets ranging in salt content from 1.08 to 3.18 percent. Slinger et al. (1950) observed that the level of fibre in the ration influenced the responses of chicks to variations in sodium chloride levels. When a low fibre-
high energy diet was employed 0.25% of added salt proved adequate; however, with high fibre-low energy diets the optimal salt level was not less than 2 percent. These findings help explain some of the variations in reported salt requirements. The report provides a rare example of a requirement for an inverse variation between the dietary concentrations of energy and a nutrient. As feed intake is largely controlled by the available energy concentration thereof it is usual to vary nutrient concentration in direct proportion to changes in energy density. The minimum dietary salt concentration for chicks was reported by Heuser (1952) to be 0.65%. Feed efficiency was found to improve with salt additions but it was indicated that this might be solely due to increased water retention. The addition of 4% of sodium chloride to the ration was insufficient to cause toxicity. This latter finding does not agree with the work of Barlow et al. (1948) previously mentioned. Working with purified rations, McWard and Scott (1960) observed that a dietary sodium concentration of 0.06% (0.15%
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
Sodium Chloride in the Feed and Drinking Water of Chicks
542
I. R. SIBBALD, W. F. PEPPER AND S. J. SLINGER
MATERIALS AND METHODS
Each experiment was of a randomized block design and involved 4 replicates. The criteria measured were weight changes of the birds, feed consumption and mortality. As mortality among birds on some treatments was quite high it was necessary to make allowance for this factor in the weight change and feed efficiency data. The use of the statistic "gain per chick started", which may be defined as the final weight of the chicks surviving minus the initial weight of the chicks started divided by the number of chicks started, circumvented many problems and made it possible to present change in weight data corrected for mortality. Similarly the "gain per 100 gm. feed" was estimated by subtracting the initial weight of the chicks started from the final weight of the chicks surviving and dividing the result by the total amount of feed consumed by the pen of birds during the course of the experiment. The birds were housed in electrically heated, wire-floored pens in battery brooders where they were offered feed and water or salt solutions ad libitum.
Water and salt solutions were changed daily, the troughs being cleaned to prevent an accumulation of salt. Experiment 1. Day-old, male chicks of the Ames 415b strain were randomly distributed between 32 pens until each pen contained 20 birds. Four replicated pens were allotted to each of 8 treatments for the 4 week experimental period. The treatments consisted of two basal diets (Table 1) containing respectively 0 and 0.5% of added sodium chloride fed in combination with salt solutions of different concentrations as shown in Table 2. Experiment 2. Day-old, male, strain cross White Leghorn chicks were randomly distributed between 32 pens until each pen contained 20 birds. The 4 week experiment involved the feeding of a basal diet (Table 1) to which was added, at the expense of the basal, 0.0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0 or 16.0 percent of sodium chloride. Fresh water was available to the birds at all times. TABLE 1.—Compositions of the basal diets Exp. I1 Exp. 2 and 3 Ground wheat Ground corn Soybean oil meal (44% protein) Soybean oil meal (50% protein) Dehydrated alfalfa meal (17% protein) Fish meal (65% protein) Meat meal (50% protein) Dried whey (65% lactose) Distillers dried solubles Ground limestone Dicalcium phosphate Tallow (stabilized) Vitamin A (10,000 I.U./gm.) Vitamin Da (1,650 I.C.U./gm.) DL methionine (feed grade) Riboflavin (24 gm./lb.) Riboflavin (1 gm./oz.) d-calcium pantothenate (2 gm./oz.) Niacin Procaine penicillin G (10 gm./oz.) ' Vitamin B12 (9 mg./lb.) Choline chloride (25%) 3-nitro, 4-hydroxy phenylarsonic acid (10%) Manganese sulphate (75%) Calcium iodate Potassium iodide Zinc oxide (80% Zn) Butylated hydroxy toluene (25%)
lb. 20.0 32.35 34.75
lb. 29.0 29.15
—
—
29.0 2.0
— — 1.65
2.5 1.5 1.5 1.0 1.5 2.5
2.0 2.5 2.5
1.0 3.0 gm. 22.7 22.7 11.4
—
6.0 0.15 0.80 0.20 30.3 22.7
22.7 10.0
— — 22.7
0.15
—
gm. 22.7 22.7 22.7 1.33
—
3.0 0.8 0.2 30.3 22.7
22.7 6.0 3.0
— —
0.2
1 The other basal employed in Experiment 1 contained 0.5 lb. of sodium chloride included at the expense of an equal weight of
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
NaCl) was adequate for chick survival; unfortunately no data were presented concerning weight gains or feed utilization. The National Research Council (1960) indicate a sodium requirement for the chick equivalent to 0.37% of sodium chloride in the ration. The present report concerns 3 experiments designed to obtain further information about effects of sodium chloride upon the weight gains, feed efficiencies and survivals of chicks. Feed and excreta samples collected during two of the experiments were assayed to determine the effect of salt on energy utilization; the resulting information will form the subject of a later report.
SALT L E V E L S
TABLE 2.—The eject of level of sodium chloride in the feed and water on chick performance1 Sodium chloride in:
Gain/
Water
started
gm. feed
tality
%
%
gm.
gm.
%
0 0 0 0
0.25 0.50 0.75 1.00
329 345 161 -28
47.2 49.4 41.6
—
1.2 0.0 46.2 96.2
0.5 0.5 0.5 0.5
0.00 0.25 0.50 0.75
327 337 328 70
47.8 48.3 47.1 27.1
3.8 1.2 3.8 71.2
1 Experiment conducted with chicks from hatching to 4 weeks of age.
Experiment 3. Ten, 5-week old, male White Leghorn chicks were randomly assigned to each of 16 pens. T h e birds were offered a basal diet (Table 1) containing no added salt. During the two weeks of the experiment the birds were given water containing 0.0, 0.2, 0.4 or 0 . 8 % of sodium choride; these constituted the 4 treatments. RESULTS AND DISCUSSION
Experiment 1. A description of the 8 treatments involved in this experiment, together with the mean chick response data, are presented in Table 2. When the feed contained no added salt the greatest gains were made b y the birds receiving water containing 0 . 5 % of sodium chloride. Because they had the greatest gains these chicks also had the best feed efficiency for they gained faster and required proportionately less feed for maintenance t h a n did the chicks of the other treatment groups. The birds receiving 0.25% of salt in the drinking water were only slightly inferior to those receiving the 0 . 5 % solution; however, those receiving 0.75% were grossly inferior. This suggests t h a t the optimal salt level lay between 0.25 and 0.50 percent. The lethal
nature of the 1 % salt solution is immediately apparent. When the feed contained 0 . 5 % of added salt the best overall results, in terms of the criteria measured, were demonstrated by the birds receiving water containing 0.25% of sodium chloride. The birds receiving water containing 0.0 or 0 . 5 % of salt performed almost as well, their slight inferiority being explainable on the basis of the slightly higher mortality among these groups. I t is doubtful if the mortality can be a t t r i b u t e d entirely to the sodium chloride, consequently the d a t a suggest t h a t when the diet contains 0 . 5 % of added salt the chick can perform equally well on water containing from 0.0 to 0 . 5 % of sodium chloride. I t is again a p p a r e n t t h a t a solution containing 0.75% of salt was toxic. The tolerance of individual chicks to the different t r e a t m e n t s was highly variable, this supports the findings of Kare and Biely (1948). T h e experimental results suggest t h a t 0 . 5 % of added salt in the feed is sufficient to maintain satisfactory weight gains, feed efficiencies and survival among young chicks. Even in the presence of this q u a n t i t y of dietary salt the young chick appears to be capable of performing satisfactorily when the only free water available is in the form of a 0 . 5 % sodium chloride solution. Experiment Z. T h e treatments, and mean responses of the chicks exposed to the treatments, are described in Table 3. T h e need for added salt in a chick starter diet is immediately apparent. Although the mortality rate among the birds receiving no added salt was low their weight gains and efficiency of feed utilization were considerably poorer t h a n the groups receiving sodium chloride at levels of 0.25, 0.50, 1.00 and 2.00 percent. T h e minimum q u a n t i t y of added salt required to allow maximum weight gains
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
Feed
543
544
I. R. SIBBALD, W. F. PEPPER AND S. J. SLINGER
TABLE 3.—The responses of chicks to rations containing various levels of added sodium chloride1 Gain/chick started
Gain/100 gm. feed
%
gm. 268 318 317 317 315 277 108 44
gm. 45.1 50.7 50.8 50.8 49.8 49.2 36.9 21.4
0.00 0.25 0.50 1.00 2.00 4.00 8.00 16.00
Mortality
% 2.5 0.0 0.0 0.0 0.0 10.0 49.0 55.0
1 Experiment conducted with chicks from hatching to 4 weeks of age.
and high feed efficiencies was not more than 0.25%; this is considerably lower than the value of 1% reported by Barlow et al. (1948) but agrees with the value reported by Slinger et al. (1950) for low fibre-high energy diets. Heuser (1952) found the addition of 0.25% of salt to a basal diet, containing 0.41% of sodium chloride, was satisfactory. The chicks could apparently tolerate a wide range of dietary salt levels since weight gains and efficiency of feed utilization were relatively constant between levels of 0.25 and 2.0 percent. At salt levels of 4, 8 and 16% mortality occurred and in consequence weight gains and feed efficiencies were greatly depressed. The weight gain data for the birds receiving the three highest salt levels are misleading since some of the surviving birds were oedematous; the over-estimation of true weight gain, by the methods of calculation employed, would introduce similar faults into the feed efficiency data. Perhaps the most striking feature of the data of Table 3 is the demonstration that young chicks can survive for 4 weeks when fed rations containing as much as 16% of salt. Most of the mortality occurred during the second week of the experiment there being relatively few deaths during the final week. This again
TABLE 4.—The effect of level of sodium chloride in the drinking water on chick performance1^ NaCI in water
Gain/chick started
Gain/100 gm. feed
%
gm. 249 262 269 213
gm. 30.8 35.3 34.2 28.7
0.0 0.2 0.4 0.8 1
Mortality
% 0.0 0.0 0.0 0.0
The feed contained no added sodium chloride. Experiment conducted with chicks from 5 to 7 weeks of age. 2
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
NaCI in feed
demonstrates the considerable variation in salt tolerance between chicks. Heuser (1952) found that the addition of 4% of salt to a ration was insufficient to cause toxicity. Kare and Biely (1948) suggested that diets ranging in salt content from 1.08 to 3.18% were satisfactory whereas more than 4% caused some oedema. Barlow et al. (1948) claimed that the minimum toxic salt level was 3 percent. The data of Table 3 demonstrate that the maximum tolerance level was between 2 and 4 percent. At the latter level weight gains were depressed, oedema occurred and mortality was assuming economic importance. Experiment 3. The treatments employed in this experiment, together with the mean chick response data, are described in Table 4. The need of the chicks for added salt was again demonstrated since the birds receiving salt-free water made poorer weight gains and were less efficient than those receiving either 0.2 or 0.4% saline solutions. A solution containing 0.8% of salt, though causing no mortality during the two weeks of the experiment, did inhibit weight gains and feed efficiency. The data suggest that when the diet contains no added salt a 0.2% saline solution will allow satisfactory production. This level is somewhat lower than that found in experiment 1 but may be explained by the differences in the basal
545
SALT LEVELS
diets and in the ages of the chicks involved. The maximum concentration of salt in the water, which could be tolerated, was not less than 0.4 percent. It is of interest to note that whereas a solution containing 0.75% of salt proved quite lethal to young chicks during a 4 week period (Table 2) 0.8% of salt caused no mortality among older birds during a 2 week period.
Three randomized block design experiments, each involving 4 replications, were conducted to study the salt tolerances of chicks. Three criteria were used to evaluate the experimental findings, these were: "gain per chick started" which was denned as the final pen weight minus the initial pen weight divided by the number of birds started, "gain per 100 gm. of feed" which was defined as the final pen weight minus the initial pen weight divided by the feed consumed during the experimental period, and "mortality". When the feed contained no added salt, chicks aged 0 to 4 weeks required saline solutions containing between 0.25 and 0.5% of sodium chloride to perform satisfactorily; 0.2% of salt in the drinking
REFERENCES Barlow, J. S., S. J. Slinger and R. P. Zimmer, 1948. The reaction of growing chicks to diets varying in sodium chloride content. Poultry Sci. 27: 542552. Heuser, G. F., 1952. Salt additions to chick rations. Poultry Sci. 31:85-88. Kare, M. R., and J. Biely, 1948. The toxicity of sodium chloride and its relation to water intake in baby chicks. Poultry Sci. 27: 751-758. McWard, G. W., and H. M. Scott, 1960. The potassium and sodium requirements of the young chick fed a purified diet. Poultry Sci. 39: 1274. Slinger, S. J., W. F. Pepper and I. Motzok, 1950. Factors affecting the salt requirements of chickens. Poultry Sci. 29: 780-781.
NEWS AND NOTES (Continued from page 512) mental Design, and Sampling Designs; 4 courses in Theory, including the Basic Year Sequence, Introduction to Theory of Statistics, Statistical Models, and Advanced Experimental Designs; and 5 courses in Mathematics, including Probability, Theory of Games, Linear and Dynamic Programming, Matrix Algebra, and Advanced Calculus. Since the session runs concurrently with the regular summer session, other advanced courses in mathematics and highspeed computing will be available. Applications. Inquiries and requests for application blanks for the summer school should be directed to Dr. Carl E. Marshall, Department of Mathematics
and Statistics, Statistical Laboratory, Oklahoma State University, Stillwater, Oklahoma. PENB NOTES Dr. R. H. Forsythe, Head of the Department of Poultry Husbandry and Professor of Biochemistry and Biophysics, Iowa State University of Science and Technology, Ames, has been elected Chairman of the Technical Research Advisory Committee for 1962 of the Poultry and Egg National Board. He succeeds Dr. L. E. Dawson, Associate Professor of Food Sciences, Michigan State University. Dr. Dawson continues as a Committee Member.
(Continued on page 555)
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
SUMMARY
water was sufficient for birds aged 5 to 7 weeks. Chicks could tolerate water containing as much as 0.5% of salt even when the feed contained 0.5% of added sodium chloride. When the drinking water contained no sodium chloride, salt levels of 0.25 to 2.0% in the feed allowed satisfactory production. Mortality and oedema, together with depressed weight gains, occurred when the diet contained 4, 8 or 16% of salt; however, even at the latter level 45% of the birds started were still alive at the end of 4 weeks. Individual variation in salt tolerance was remarkable.
541
ment Station College, Kansas State of Agriculture Technical Bulletin #46. Rubin, M., and H. R. Bird, 1946. The apparent antagonism between vitamin A and carotenoids in the fowl. Science, 103: 584-586. Sunde, M. L., and G. Madiedo, 1960. Influencia del maiz, del millo y de un pigmento carotenol en el color de la yema del huevo. Agricultural Tropical, 16: 725-730.
I. R. SIBBALD, W. F. PEPPER AND S. J. SLINGER Departments of Nutrition and Poultry Science, Ontario Agricultural College, Guelph, Ontario, Canada (Received for publication July 7, 1961)
and chlorine are essential SODIUM nutrients for the chick; however, high intakes of sodium chloride may prove toxic. Barlow et al. (1948) and Kare and Biely (1948) have reviewed much of the early literature concerning this subject. Barlow et al. (1948) observed that young chicks were more susceptible to the toxic effects of salt than were older birds; further, it was reported that the addition of 1% of salt to a practical type starter diet was optimal whereas the minimum toxic salt level was found to be 3 percent. Kare and Biely (1948) stressed the wide variation in salt tolerance between chicks within treatments; a diet containing 5.18% of sodium chloride proved lethal to some birds and harmless to others. When rations containing more than 4% of salt were fed, some birds in every group exhibited symptoms of oedema. There was no significant variation in feed efficiencies of chicks fed diets ranging in salt content from 1.08 to 3.18 percent. Slinger et al. (1950) observed that the level of fibre in the ration influenced the responses of chicks to variations in sodium chloride levels. When a low fibre-
high energy diet was employed 0.25% of added salt proved adequate; however, with high fibre-low energy diets the optimal salt level was not less than 2 percent. These findings help explain some of the variations in reported salt requirements. The report provides a rare example of a requirement for an inverse variation between the dietary concentrations of energy and a nutrient. As feed intake is largely controlled by the available energy concentration thereof it is usual to vary nutrient concentration in direct proportion to changes in energy density. The minimum dietary salt concentration for chicks was reported by Heuser (1952) to be 0.65%. Feed efficiency was found to improve with salt additions but it was indicated that this might be solely due to increased water retention. The addition of 4% of sodium chloride to the ration was insufficient to cause toxicity. This latter finding does not agree with the work of Barlow et al. (1948) previously mentioned. Working with purified rations, McWard and Scott (1960) observed that a dietary sodium concentration of 0.06% (0.15%
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
Sodium Chloride in the Feed and Drinking Water of Chicks
542
I. R. SIBBALD, W. F. PEPPER AND S. J. SLINGER
MATERIALS AND METHODS
Each experiment was of a randomized block design and involved 4 replicates. The criteria measured were weight changes of the birds, feed consumption and mortality. As mortality among birds on some treatments was quite high it was necessary to make allowance for this factor in the weight change and feed efficiency data. The use of the statistic "gain per chick started", which may be defined as the final weight of the chicks surviving minus the initial weight of the chicks started divided by the number of chicks started, circumvented many problems and made it possible to present change in weight data corrected for mortality. Similarly the "gain per 100 gm. feed" was estimated by subtracting the initial weight of the chicks started from the final weight of the chicks surviving and dividing the result by the total amount of feed consumed by the pen of birds during the course of the experiment. The birds were housed in electrically heated, wire-floored pens in battery brooders where they were offered feed and water or salt solutions ad libitum.
Water and salt solutions were changed daily, the troughs being cleaned to prevent an accumulation of salt. Experiment 1. Day-old, male chicks of the Ames 415b strain were randomly distributed between 32 pens until each pen contained 20 birds. Four replicated pens were allotted to each of 8 treatments for the 4 week experimental period. The treatments consisted of two basal diets (Table 1) containing respectively 0 and 0.5% of added sodium chloride fed in combination with salt solutions of different concentrations as shown in Table 2. Experiment 2. Day-old, male, strain cross White Leghorn chicks were randomly distributed between 32 pens until each pen contained 20 birds. The 4 week experiment involved the feeding of a basal diet (Table 1) to which was added, at the expense of the basal, 0.0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0 or 16.0 percent of sodium chloride. Fresh water was available to the birds at all times. TABLE 1.—Compositions of the basal diets Exp. I1 Exp. 2 and 3 Ground wheat Ground corn Soybean oil meal (44% protein) Soybean oil meal (50% protein) Dehydrated alfalfa meal (17% protein) Fish meal (65% protein) Meat meal (50% protein) Dried whey (65% lactose) Distillers dried solubles Ground limestone Dicalcium phosphate Tallow (stabilized) Vitamin A (10,000 I.U./gm.) Vitamin Da (1,650 I.C.U./gm.) DL methionine (feed grade) Riboflavin (24 gm./lb.) Riboflavin (1 gm./oz.) d-calcium pantothenate (2 gm./oz.) Niacin Procaine penicillin G (10 gm./oz.) ' Vitamin B12 (9 mg./lb.) Choline chloride (25%) 3-nitro, 4-hydroxy phenylarsonic acid (10%) Manganese sulphate (75%) Calcium iodate Potassium iodide Zinc oxide (80% Zn) Butylated hydroxy toluene (25%)
lb. 20.0 32.35 34.75
lb. 29.0 29.15
—
—
29.0 2.0
— — 1.65
2.5 1.5 1.5 1.0 1.5 2.5
2.0 2.5 2.5
1.0 3.0 gm. 22.7 22.7 11.4
—
6.0 0.15 0.80 0.20 30.3 22.7
22.7 10.0
— — 22.7
0.15
—
gm. 22.7 22.7 22.7 1.33
—
3.0 0.8 0.2 30.3 22.7
22.7 6.0 3.0
— —
0.2
1 The other basal employed in Experiment 1 contained 0.5 lb. of sodium chloride included at the expense of an equal weight of
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
NaCl) was adequate for chick survival; unfortunately no data were presented concerning weight gains or feed utilization. The National Research Council (1960) indicate a sodium requirement for the chick equivalent to 0.37% of sodium chloride in the ration. The present report concerns 3 experiments designed to obtain further information about effects of sodium chloride upon the weight gains, feed efficiencies and survivals of chicks. Feed and excreta samples collected during two of the experiments were assayed to determine the effect of salt on energy utilization; the resulting information will form the subject of a later report.
SALT L E V E L S
TABLE 2.—The eject of level of sodium chloride in the feed and water on chick performance1 Sodium chloride in:
Gain/
Water
started
gm. feed
tality
%
%
gm.
gm.
%
0 0 0 0
0.25 0.50 0.75 1.00
329 345 161 -28
47.2 49.4 41.6
—
1.2 0.0 46.2 96.2
0.5 0.5 0.5 0.5
0.00 0.25 0.50 0.75
327 337 328 70
47.8 48.3 47.1 27.1
3.8 1.2 3.8 71.2
1 Experiment conducted with chicks from hatching to 4 weeks of age.
Experiment 3. Ten, 5-week old, male White Leghorn chicks were randomly assigned to each of 16 pens. T h e birds were offered a basal diet (Table 1) containing no added salt. During the two weeks of the experiment the birds were given water containing 0.0, 0.2, 0.4 or 0 . 8 % of sodium choride; these constituted the 4 treatments. RESULTS AND DISCUSSION
Experiment 1. A description of the 8 treatments involved in this experiment, together with the mean chick response data, are presented in Table 2. When the feed contained no added salt the greatest gains were made b y the birds receiving water containing 0 . 5 % of sodium chloride. Because they had the greatest gains these chicks also had the best feed efficiency for they gained faster and required proportionately less feed for maintenance t h a n did the chicks of the other treatment groups. The birds receiving 0.25% of salt in the drinking water were only slightly inferior to those receiving the 0 . 5 % solution; however, those receiving 0.75% were grossly inferior. This suggests t h a t the optimal salt level lay between 0.25 and 0.50 percent. The lethal
nature of the 1 % salt solution is immediately apparent. When the feed contained 0 . 5 % of added salt the best overall results, in terms of the criteria measured, were demonstrated by the birds receiving water containing 0.25% of sodium chloride. The birds receiving water containing 0.0 or 0 . 5 % of salt performed almost as well, their slight inferiority being explainable on the basis of the slightly higher mortality among these groups. I t is doubtful if the mortality can be a t t r i b u t e d entirely to the sodium chloride, consequently the d a t a suggest t h a t when the diet contains 0 . 5 % of added salt the chick can perform equally well on water containing from 0.0 to 0 . 5 % of sodium chloride. I t is again a p p a r e n t t h a t a solution containing 0.75% of salt was toxic. The tolerance of individual chicks to the different t r e a t m e n t s was highly variable, this supports the findings of Kare and Biely (1948). T h e experimental results suggest t h a t 0 . 5 % of added salt in the feed is sufficient to maintain satisfactory weight gains, feed efficiencies and survival among young chicks. Even in the presence of this q u a n t i t y of dietary salt the young chick appears to be capable of performing satisfactorily when the only free water available is in the form of a 0 . 5 % sodium chloride solution. Experiment Z. T h e treatments, and mean responses of the chicks exposed to the treatments, are described in Table 3. T h e need for added salt in a chick starter diet is immediately apparent. Although the mortality rate among the birds receiving no added salt was low their weight gains and efficiency of feed utilization were considerably poorer t h a n the groups receiving sodium chloride at levels of 0.25, 0.50, 1.00 and 2.00 percent. T h e minimum q u a n t i t y of added salt required to allow maximum weight gains
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
Feed
543
544
I. R. SIBBALD, W. F. PEPPER AND S. J. SLINGER
TABLE 3.—The responses of chicks to rations containing various levels of added sodium chloride1 Gain/chick started
Gain/100 gm. feed
%
gm. 268 318 317 317 315 277 108 44
gm. 45.1 50.7 50.8 50.8 49.8 49.2 36.9 21.4
0.00 0.25 0.50 1.00 2.00 4.00 8.00 16.00
Mortality
% 2.5 0.0 0.0 0.0 0.0 10.0 49.0 55.0
1 Experiment conducted with chicks from hatching to 4 weeks of age.
and high feed efficiencies was not more than 0.25%; this is considerably lower than the value of 1% reported by Barlow et al. (1948) but agrees with the value reported by Slinger et al. (1950) for low fibre-high energy diets. Heuser (1952) found the addition of 0.25% of salt to a basal diet, containing 0.41% of sodium chloride, was satisfactory. The chicks could apparently tolerate a wide range of dietary salt levels since weight gains and efficiency of feed utilization were relatively constant between levels of 0.25 and 2.0 percent. At salt levels of 4, 8 and 16% mortality occurred and in consequence weight gains and feed efficiencies were greatly depressed. The weight gain data for the birds receiving the three highest salt levels are misleading since some of the surviving birds were oedematous; the over-estimation of true weight gain, by the methods of calculation employed, would introduce similar faults into the feed efficiency data. Perhaps the most striking feature of the data of Table 3 is the demonstration that young chicks can survive for 4 weeks when fed rations containing as much as 16% of salt. Most of the mortality occurred during the second week of the experiment there being relatively few deaths during the final week. This again
TABLE 4.—The effect of level of sodium chloride in the drinking water on chick performance1^ NaCI in water
Gain/chick started
Gain/100 gm. feed
%
gm. 249 262 269 213
gm. 30.8 35.3 34.2 28.7
0.0 0.2 0.4 0.8 1
Mortality
% 0.0 0.0 0.0 0.0
The feed contained no added sodium chloride. Experiment conducted with chicks from 5 to 7 weeks of age. 2
Downloaded from http://ps.oxfordjournals.org/ at University of British Columbia on June 21, 2015
NaCI in feed
demonstrates the considerable variation in salt tolerance between chicks. Heuser (1952) found that the addition of 4% of salt to a ration was insufficient to cause toxicity. Kare and Biely (1948) suggested that diets ranging in salt content from 1.08 to 3.18% were satisfactory whereas more than 4% caused some oedema. Barlow et al. (1948) claimed that the minimum toxic salt level was 3 percent. The data of Table 3 demonstrate that the maximum tolerance level was between 2 and 4 percent. At the latter level weight gains were depressed, oedema occurred and mortality was assuming economic importance. Experiment 3. The treatments employed in this experiment, together with the mean chick response data, are described in Table 4. The need of the chicks for added salt was again demonstrated since the birds receiving salt-free water made poorer weight gains and were less efficient than those receiving either 0.2 or 0.4% saline solutions. A solution containing 0.8% of salt, though causing no mortality during the two weeks of the experiment, did inhibit weight gains and feed efficiency. The data suggest that when the diet contains no added salt a 0.2% saline solution will allow satisfactory production. This level is somewhat lower than that found in experiment 1 but may be explained by the differences in the basal
545
SALT LEVELS
diets and in the ages of the chicks involved. The maximum concentration of salt in the water, which could be tolerated, was not less than 0.4 percent. It is of interest to note that whereas a solution containing 0.75% of salt proved quite lethal to young chicks during a 4 week period (Table 2) 0.8% of salt caused no mortality among older birds during a 2 week period.
Three randomized block design experiments, each involving 4 replications, were conducted to study the salt tolerances of chicks. Three criteria were used to evaluate the experimental findings, these were: "gain per chick started" which was denned as the final pen weight minus the initial pen weight divided by the number of birds started, "gain per 100 gm. of feed" which was defined as the final pen weight minus the initial pen weight divided by the feed consumed during the experimental period, and "mortality". When the feed contained no added salt, chicks aged 0 to 4 weeks required saline solutions containing between 0.25 and 0.5% of sodium chloride to perform satisfactorily; 0.2% of salt in the drinking
REFERENCES Barlow, J. S., S. J. Slinger and R. P. Zimmer, 1948. The reaction of growing chicks to diets varying in sodium chloride content. Poultry Sci. 27: 542552. Heuser, G. F., 1952. Salt additions to chick rations. Poultry Sci. 31:85-88. Kare, M. R., and J. Biely, 1948. The toxicity of sodium chloride and its relation to water intake in baby chicks. Poultry Sci. 27: 751-758. McWard, G. W., and H. M. Scott, 1960. The potassium and sodium requirements of the young chick fed a purified diet. Poultry Sci. 39: 1274. Slinger, S. J., W. F. Pepper and I. Motzok, 1950. Factors affecting the salt requirements of chickens. Poultry Sci. 29: 780-781.
NEWS AND NOTES (Continued from page 512) mental Design, and Sampling Designs; 4 courses in Theory, including the Basic Year Sequence, Introduction to Theory of Statistics, Statistical Models, and Advanced Experimental Designs; and 5 courses in Mathematics, including Probability, Theory of Games, Linear and Dynamic Programming, Matrix Algebra, and Advanced Calculus. Since the session runs concurrently with the regular summer session, other advanced courses in mathematics and highspeed computing will be available. Applications. Inquiries and requests for application blanks for the summer school should be directed to Dr. Carl E. Marshall, Department of Mathematics
and Statistics, Statistical Laboratory, Oklahoma State University, Stillwater, Oklahoma. PENB NOTES Dr. R. H. Forsythe, Head of the Department of Poultry Husbandry and Professor of Biochemistry and Biophysics, Iowa State University of Science and Technology, Ames, has been elected Chairman of the Technical Research Advisory Committee for 1962 of the Poultry and Egg National Board. He succeeds Dr. L. E. Dawson, Associate Professor of Food Sciences, Michigan State University. Dr. Dawson continues as a Committee Member.
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SUMMARY
water was sufficient for birds aged 5 to 7 weeks. Chicks could tolerate water containing as much as 0.5% of salt even when the feed contained 0.5% of added sodium chloride. When the drinking water contained no sodium chloride, salt levels of 0.25 to 2.0% in the feed allowed satisfactory production. Mortality and oedema, together with depressed weight gains, occurred when the diet contained 4, 8 or 16% of salt; however, even at the latter level 45% of the birds started were still alive at the end of 4 weeks. Individual variation in salt tolerance was remarkable.