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Use of Ascorbic Acid to Prevent the Decline in Eggshell Quality Observed with Saline Drinking Water
Use of Ascorbic Acid to Prevent the Decline in Eggshell Quality Observed with Saline Drinking Water D. BALNAVE,1 D. ZHANG, and R. E. MORENG2 Department of Animal Science, University of Sydney, Camden, New South Wales 2570, Australia (Received for publication July 24, 1990)
1991 Poultry Science 70:848-852 INTRODUCTION
Recent studies have shown that supplementing the drinking water of laying hens with between .2 and 2 g NaCl/L significantly reduces eggshell quality and significantly increases the incidence of eggshell defects (Balnave and Scott, 1986; Balnave and Yoselewitz, 1987; Yoselewitz et al., 1988; Yoselewitz and Balnave, 1989a). Concentrations of sodium and chloride as high as 570 and 2,000 mg/L, respectively, have been recorded in bore water in Australia. Both these ions contribute to the production of defective shells in eggs from hens receiving NaCl supplements in the drinking water (Yoselewitz et al, 1988). Past attempts to overcome this poor shell quality problem generally proved unsuccessful. Methods examined included replacing saline water with town drinking water, resting hens from lay, supplementing the diet with calcium carbonate, and removing the NaCl supplement from the diet. Recently Yoselewitz et al. (1991) reduced substantially, but not completely, the incidence of eggshell defects by simultaneous supplementation of saline drink-
ing water with either sodium or ammonium bicarbonate. However, these procedures have limitations because of problems with excess sodium in the drinking water and with reduced water intakes associated with ammonium bicarbonate supplements. Pullets in early lay (33 wk of age) show improvements when saline water is replaced by town water (Yoselewitz and Balnave, 1989b), but after 55 wk of age those hens previously receiving saline water produced eggs with a higher incidence of eggshell defects than hens receiving town water (unpublished data). Ascorbic acid is a vitamin reported to have beneficial effects in poultry exposed to environmental or nutritional stress (Thornton and Moreng, 1959; Pardue and Thaxton, 1986; Krautmann, 1988). Eggshell quality is one factor showing improvement, especially at high ambient temperatures, although the responses in individual experiments have been inconsistent (Pardue and Thaxton, 1986). Nevertheless, the continuing reports showing an involvement of ascorbic acid with eggshell quality have led the authors to evaluate the usefulness of this vitamin when hens are given saline drinking water. MATERIALS AND METHODS
To whom correspondence should be addressed. Present address: Animal Sciences Department, Colorado State University, Fort Collins, CO 80523.
Three experiments were conducted. In Experiment 1, two replicates of six individually
848
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
ABSTRACT Three experiments were carried out to determine the value of ascorbic acid in overcoming the poor eggshell quality problem associated with the use of saline drinking water. Laying hens were supplied with either town water or town water supplemented with NaCl, ascorbic acid, or a combination of NaCl and ascorbic acid. Supplementing the drinking water of laying hens with NaCl (2 g/L) significantly increased the incidence of eggshell defects and significantly decreased eggshell quality. Simultaneous supplementation of the saline drinking water with ascorbic acid (1 g/L) prevented these detrimental effects. This response to ascorbic acid was dependent upon concentration. Ascorbic acid acted as a preventive rather than a remedial treatment: hens producing eggs with defective shells as a result of receiving saline drinking water failed to show any improvement in eggshell quality or any reduction in the incidence of eggshell defects when the saline water was supplemented with ascorbic acid. (Key words: drinking water, sodium chloride, ascorbic acid, shell defects, shell quality)
EGGSHELL QUALITY AND SALINE DRINKING WATER
3
1 MJ = .239 Meal. A. A. Tegel Pty Ltd., Camden, New South Wales, Australia 2570. 4
Each treatment replicate was treated as an experimental unit with food and water intakes, egg production, and the number of eggshell defects being recorded each week for the complete group. The numbers of eggs with soft, broken, cracked, and deformed shells were determined once weekly after allowing the eggs from three consecutive days to accumulate on the cage fronts. Eggs were collected and inspected manually. All eggs were collected on the final 3 days of Experiment 1 and the final day of Experiments 2 and 3, and equal numbers of eggs were chosen at random from each water treatment for shell quality measurements (Curtis et al., 1985; Balnave and Yoselewitz, 1987). Thirty-two, 40, and 35 eggs per treatment were used, respectively, in Experiments 1, 2, and 3. One egg from each of 10 hens on each treatment was taken at the start of the final week in the case of the two groups of 12 hens selected from the saline water treatment at the end of Experiment 3. This corresponded with the maximum number of eggs obtained from the hens receiving the ascorbic acid supplement in the saline water. The use of a common water trough for both replicates of each treatment in Experiments 2 and 3 prevented statistical analyses of water intake data. However, the remaining data, other than shell quality, were analyzed by ANOVA using a completely randomized splitplot design with time as a repeat measure. In Experiments 1 and 2, the whole plot had a factorial NaCl by ascorbic acid treatment structure. Shell quality data were analyzed by one-way ANOVA. In each experiment, means were compared by least significant difference (Steel and Torrie, 1982). RESULTS AND DISCUSSION
The treatments had little effect on production parameters other than shell defects (Table 1) and the only significant NaCl by ascorbic acid interactions were observed with this measurement in Experiments 1 (P<.05) and 2 (P<.01). The increased food intakes and lowered water intakes observed in Experiment 3 reflect the lower temperatures to which the hens were exposed in this study. In all three experiments, eggshell defects were significantly increased (Table 1), and eggshell quality significantly decreased (Table 3), by the addition of 2 g NaCl/L to the town water. This response agrees with the results of
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
caged, 40-wk-old laying hens (White Leghorn x Australorp) were allocated at random to each of four treatments in a room maintained at a constant 30 C. The drinking water treatments consisted of 1) controls receiving town water (.3 mM Na and <1 mM CI), 2) town water supplemented with 2 g NaCl/L, 3) town water supplemented with 1 g ascorbic acid/L, and 4) town water supplemented with 2 g NaCl and 1 g ascorbic acid/L. The NaCl solution was prepared as required, and ascorbic acid was added to fresh supplies of drinking water daily at 1600 h, a time corresponding to the approximate initiation of eggshell formation in the shell gland. Birds were given free access to water and to a proprietary layer mash with a calculated composition (per kilogram) of 160 g crude protein, 11.0 MJ 3 of metabolizable energy, 1.6 g of sodium, 2.1 g of chloride, 5.2 g of available phosphorus and 34 g of calcium. A 16-h day length was provided over the 8-wk experiment. In Experiment 2, the same treatments were given to each of two replicates of 40 68-wk-old laying hens (Tegel Super Tint)4 maintained in a conventional layer shed in separate rows of individual single-deck cages with a common water trough. A day length of 16 h was again provided and the daily temperature range was 20 to 35 C over the 6-wk experiment. In Experiment 3, the five treatments given to each of two replicates of 24 76-wk-old laying hens of the same strain as used in Experiment 1 (White Leghorn x Australorp) consisted of town water or town water containing 2 g NaCl/L along with 0, .25, .5, or 1.0 g of ascorbic acid/L. The experimental conditions were similar to those of Experiment 2, and the daily temperature range was 18 to 30 C over the 6-wk experiment. At the conclusion of the experiment, 12 hens that had previously received only the saline drinking water and that were laying eggs with defective shells were transferred to alternative cages and given the saline water with ascorbic acid (1 g/ L) for 4 wk. Twelve hens from the same saline water treatment consistently laying eggs with visually normal shells were used as controls, and eggshell defects from all birds were measured daily.
849
850
BALNAVE ET AL. TABLE 1. Shell defects and production parameters from all experiments
Water supplement
Shell defects
Egg production MM
b
(^^
Water intake
Food intake
(
' Uyuuyj
•
2.3 13.4a 1.6b 4.9 b 1.16
72.9 77.5 75.4 72.5 4.10
56.6 57.9 58.3 57.9 .81
103 104 104 104 3.7
400 370 352 395 28.5
7.3 b 15.4a 6.0b 7.5b .60
74.2a 72.7* 72.3 b 72.6b .39
60.4 62.3 60.2 60.8 .85
107 107 107 107 .4
300 295 273 276
12.9b 27.0*
68.6 71.9
63.2 62.0
116b 120*
253 271
1 9 3 ab 8
71.6 72.6 72.8 1.83
62.9 61.6 63.4 .99
m* 116ab
252 279 255
lej * 13.4b 3.18
122" 1.5
1
1
a,b
Within experiments and columns, data with no common superscripts are significantly different (P<05). 'Common water troughs for each treatment, so data were not analyzed statistically.
many previous studies in Australia but contrasts with work in the United States reported by Maurice (1989). He failed to observe any detrimental effect of saline drinking water on shell strength, measured as shell weight per unit surface area and suggested that this contrasting response may reflect differences in the sensitivity of different strains of hen to saline water. Yoselewitz and Balnave (1990) have shown that such sensitivity exists among Australian layer strains. Although shell defects increased in all six strains given saline drinking water in this latter study, the strain used in Experiments 1 and 3 in the present work gave a 4.3-fold increase compared with between 2.3- and 2.6-fold increases with the other five strains examined, including that used in Experiment 2. The differing sensitivities observed between strains is also reflected within strains. Within any population not all hens are affected to the same degree by saline water, and although the ability of some hens to produce normal eggshells is adversely affected, others continue to lay eggs with good shell quality (Yoselewitz et al, 1988; Balnave et al, 1989; Yoselewitz and Balnave, 1989a). Li order to overcome this problem of differing sensitivities, it is essential
that relatively large numbers of hens be used in any comparison. In Experiments 1 and 2 introducing the 1 g/ L ascorbic acid supplement simultaneously with the NaCl to the town water significantly reduced the incidence of shell defects to values that were not significantly different to controls (Table 1). A reduction in shell defects was also observed when ascorbic acid was added to the town water, although these responses were not statistically significant. In the third experiment, the extent of the reduction in eggshell defects resulting from the use of ascorbic acid was dependent upon the concentration of the vitamin added to the saline water, with the incidence of shell defects from hens receiving the 1 g/L supplement again differing only slightly from that of hens receiving no added NaCl (Table 1). However, in Experiment 3, supplying ascorbic acid to hens already affected by the saline water had no beneficial effect on the incidence of shell defects (Table 2). Shell defects from hens already receiving saline water and producing eggs with defective shells varied from a mean of 39.2 to a mean of 37.1%, with little change in eggshell quality, over the 4-wk ascorbic acid-supplementation period. The mean change
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
Experiment 1 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 2 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 3 None NaCl NaCl plus ascorbic acid at .25 g/L .50g/L 1.00 g/L SEM
(•")
Egg weight
851
EGGSHELL QUALITY AND SALINE DRINKING WATER
TABLE 2. Effect of supplementing saline drinking water with ascorbic acid for 4 wk on eggshell defects and shell quality from hens previously receiving saline drinking water and laying eggs with defective shells (x ± SE) Water treatment
Measurement
Week
NaCl plus ascorbic acid (poor shells)1
Shell defects, %
1 4 1 4 1 4 1 4
39.2 37.1 298 294 6.86 6.78 57.8 58.6
Shell thickness, (lm Shell weightegg weight, g:g x 100 Shell weight per unit surface area, mg/cm2
± ± ± ± ± ± ± ±
10.79 13.63 11.63 10.30 .363 .284 3.60 2.49
NaCl (good shells)1 9.9 9.3 344 339 8.44 8.01 71.6 68.7
± ± ± ± ± ± ± ±
4.47 4.58 7.9 6.9 .205 .173 1.64 1.55
Initial shell quality.
in the saline controls over this time varied from 9.9 to 9.3%. Changes in the percentage of shell defects were reflected in the shell quality measurements (Table 3). Except for shell breaking strength in Experiment 1, the addition of NaCl to the town water significantly reduced eggshell quality in all experiments. Supplying ascorbic acid with the saline water maintained
eggshell quality measures close to control values. The data from Experiment 3 show that this effect of ascorbic acid was dependent on the concentration used with improvements in shell quality being observed with higher supplementation levels. In Experiment 3, hens producing eggs with defective shells as a result of receiving saline drinking water without the ascorbic acid
TABLE 3. Shell quality measurements from all experiments
Water supplement Experiment 1 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 2 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 3 None NaCl NaCl plus ascorbic acid at .25 g/L .50g/L 1.00 g/L SEM :
Shell breaking strength
Shell thickness
(g)
(urn)
l^S150 1,542° 2,144a l,857 b 83.7
Shell weight: egg we ght (g:g) x 100
Shell weight per unit surface area (mg/cm )
8.65a 8.22b 8.72a 8.50ab .134
72.0" 67.9 b 72.6 a 70.5 ab 1.11
2,187a l,805 b 2,141 a 2,057* 93.1
367a 342 b 363 a 358a 5.5
9.04" 8.26b 9.1 l a 8.88a .166
76.0" 70.0 b 76.4 a 74.7 a 1.37
2,062a l,823 b
341 a 323 b
8.28a 7.77°
70.5 a 65.7°
l,876 ab
330*0 330 s * 341 a 5.5
7.85bc 8.07abc 8.21 ab .152
66.7^ 68.1 abc 69.9 ab 1.29
1927ab
2,023" 77.5
Within experiments and columns, means with no common superscripts are significantly different (P<05).
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
1
852
BALNAVE ET AL.
ACKNOWLEDGMENTS
The present studies were supported by the Australian Egg Industry Research Council and the Poultry Research Foundation, University of Sydney. The Reserve Bank of Australia provided a Senior Research Fellowship to R. E. Moreng. REFERENCES Balnave, D., and T. Scott, 1986. The influence of minerals in drinking water on eggshell quality. Nutr. Rep. Int. 34:29-34. Balnave, D., and I. Yoselewitz, 1987. The relation between sodium chloride concentration in drinking
water and egg-shell damage. Br. J. Nutr. 58:503-509. Balnave, D., I. Yoselewitz, and R. J. Dixon, 1989. Physiological changes associated with the production of defective egg-shells by hens receiving sodium chloride in the drinking water. Br. J. Nutr. 61:35-4-3. Curtis, P. A., F. A. Gardner, and D. B. Mellor, 1985. A comparison of selected quality and compositional characteristics of brown and white shell eggs. 1. Shell quality. Poultry Sci. 64:297-301. Krautmann, B. A., 1988. Practical application of ascorbic acid in combating stress. Pages 48-67 in: The Role of Vitamin C in Poultry Stress Management. Hoffmann-La Roche, Inc., Nutley, NJ. Maurice, D. V., 1989. Salinity of drinking water and performance of chickens. Pages 140-144 in: Proceedings of the Georgia Nutrition Conference, University of Georgia, Athens, GA. Pardue, S. L., and J. P. Thaxton, 1986. Ascorbic acid in poultry: A review. World's Poult. Sci. J. 42:107-123. Steel, R.G.D., and J. H. Torrie, 1982. Principles and Procedures of Statistics. A Biometrical Approach. 2nd ed. McGraw-Hill, Kogakusha Ltd., Tokyo, Japan. Thornton, P. A., and R. E. Moreng, 1959. Further evidence on the value of ascorbic acid for maintenance of shell quality in warm environmental temperature. Poultry Sci. 38:594-599. Yoselewitz, I., and D. Balnave, 1989a. Responses in egg shell quality to sodium chloride supplementation of the diet and/or drinking water. Br. Poult. Sci. 30: 273-281. Yoselewitz, I., and D. Balnave, 1989b. Egg shell quality responses of pullets given saline drinking water at different ages. Br. Poult Sci. 30:715-718. Yoselewitz, I., and D. Balnave, 1989c. The influence of saline drinking water on the activity of carbonic anhydrase in the shell gland of laying hens. Aust J. Agric. Res. 40:1111-1115. Yoselewitz, I., and D. Balnave, 1990. Strain responses in egg shell quality to saline drinking water. Page 102 in: Proceedings of the Australian Poultry Science Symposium, University of Sydney, Camden, Australia. Yoselewitz, I., D. Balnave, and R. J. Dixon, 1988. Factors influencing the production of defective egg shells by laying hens receiving sodium chloride in the drinking water. Nutr. Rep. Int. 38:697-703. Yoselewitz, I., D. Zhang, and D. Balnave, 1991. The effect on egg shell quality of supplementing saline drinking water with sodium or ammonium bicarbonate. Aust J. Agric. Res. 41:1187-1192.
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
supplement failed to show any improvement in shell quality, or reduction in percentage of shell defects, when the saline water was supplemented with ascorbic acid. These data indicate that ascorbic acid acted as a preventive rather than a remedial treatment. It appears that saline water causes permanent damage to the shell gland of affected hens, a conclusion reached in previous studies (Balnave and Yoselewitz, 1987; Balnave et al., 1989; Yoselewitz and Balnave, 1989a). The inconsistent nature of the responses in eggshell quality to dietary ascorbic acid supplementation (Pardue and Thaxton, 1986) suggests that other factors may be affecting the response. These studies indicate that water quality may be one such factor, a possibility that has not previously been considered. The addition of NaCl to drinking water has been shown to reduce the activity of carbonic anhydrase in the shell gland mucosa (Yoselewitz and Balnave, 1989c). Therefore, the degree to which specific problems of shell quality respond to treatment with ascorbic acid may depend on whether or not the supply of bicarbonate is the limiting factor affecting eggshell formation in the shell gland.
1991 Poultry Science 70:848-852 INTRODUCTION
Recent studies have shown that supplementing the drinking water of laying hens with between .2 and 2 g NaCl/L significantly reduces eggshell quality and significantly increases the incidence of eggshell defects (Balnave and Scott, 1986; Balnave and Yoselewitz, 1987; Yoselewitz et al., 1988; Yoselewitz and Balnave, 1989a). Concentrations of sodium and chloride as high as 570 and 2,000 mg/L, respectively, have been recorded in bore water in Australia. Both these ions contribute to the production of defective shells in eggs from hens receiving NaCl supplements in the drinking water (Yoselewitz et al, 1988). Past attempts to overcome this poor shell quality problem generally proved unsuccessful. Methods examined included replacing saline water with town drinking water, resting hens from lay, supplementing the diet with calcium carbonate, and removing the NaCl supplement from the diet. Recently Yoselewitz et al. (1991) reduced substantially, but not completely, the incidence of eggshell defects by simultaneous supplementation of saline drink-
ing water with either sodium or ammonium bicarbonate. However, these procedures have limitations because of problems with excess sodium in the drinking water and with reduced water intakes associated with ammonium bicarbonate supplements. Pullets in early lay (33 wk of age) show improvements when saline water is replaced by town water (Yoselewitz and Balnave, 1989b), but after 55 wk of age those hens previously receiving saline water produced eggs with a higher incidence of eggshell defects than hens receiving town water (unpublished data). Ascorbic acid is a vitamin reported to have beneficial effects in poultry exposed to environmental or nutritional stress (Thornton and Moreng, 1959; Pardue and Thaxton, 1986; Krautmann, 1988). Eggshell quality is one factor showing improvement, especially at high ambient temperatures, although the responses in individual experiments have been inconsistent (Pardue and Thaxton, 1986). Nevertheless, the continuing reports showing an involvement of ascorbic acid with eggshell quality have led the authors to evaluate the usefulness of this vitamin when hens are given saline drinking water. MATERIALS AND METHODS
To whom correspondence should be addressed. Present address: Animal Sciences Department, Colorado State University, Fort Collins, CO 80523.
Three experiments were conducted. In Experiment 1, two replicates of six individually
848
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
ABSTRACT Three experiments were carried out to determine the value of ascorbic acid in overcoming the poor eggshell quality problem associated with the use of saline drinking water. Laying hens were supplied with either town water or town water supplemented with NaCl, ascorbic acid, or a combination of NaCl and ascorbic acid. Supplementing the drinking water of laying hens with NaCl (2 g/L) significantly increased the incidence of eggshell defects and significantly decreased eggshell quality. Simultaneous supplementation of the saline drinking water with ascorbic acid (1 g/L) prevented these detrimental effects. This response to ascorbic acid was dependent upon concentration. Ascorbic acid acted as a preventive rather than a remedial treatment: hens producing eggs with defective shells as a result of receiving saline drinking water failed to show any improvement in eggshell quality or any reduction in the incidence of eggshell defects when the saline water was supplemented with ascorbic acid. (Key words: drinking water, sodium chloride, ascorbic acid, shell defects, shell quality)
EGGSHELL QUALITY AND SALINE DRINKING WATER
3
1 MJ = .239 Meal. A. A. Tegel Pty Ltd., Camden, New South Wales, Australia 2570. 4
Each treatment replicate was treated as an experimental unit with food and water intakes, egg production, and the number of eggshell defects being recorded each week for the complete group. The numbers of eggs with soft, broken, cracked, and deformed shells were determined once weekly after allowing the eggs from three consecutive days to accumulate on the cage fronts. Eggs were collected and inspected manually. All eggs were collected on the final 3 days of Experiment 1 and the final day of Experiments 2 and 3, and equal numbers of eggs were chosen at random from each water treatment for shell quality measurements (Curtis et al., 1985; Balnave and Yoselewitz, 1987). Thirty-two, 40, and 35 eggs per treatment were used, respectively, in Experiments 1, 2, and 3. One egg from each of 10 hens on each treatment was taken at the start of the final week in the case of the two groups of 12 hens selected from the saline water treatment at the end of Experiment 3. This corresponded with the maximum number of eggs obtained from the hens receiving the ascorbic acid supplement in the saline water. The use of a common water trough for both replicates of each treatment in Experiments 2 and 3 prevented statistical analyses of water intake data. However, the remaining data, other than shell quality, were analyzed by ANOVA using a completely randomized splitplot design with time as a repeat measure. In Experiments 1 and 2, the whole plot had a factorial NaCl by ascorbic acid treatment structure. Shell quality data were analyzed by one-way ANOVA. In each experiment, means were compared by least significant difference (Steel and Torrie, 1982). RESULTS AND DISCUSSION
The treatments had little effect on production parameters other than shell defects (Table 1) and the only significant NaCl by ascorbic acid interactions were observed with this measurement in Experiments 1 (P<.05) and 2 (P<.01). The increased food intakes and lowered water intakes observed in Experiment 3 reflect the lower temperatures to which the hens were exposed in this study. In all three experiments, eggshell defects were significantly increased (Table 1), and eggshell quality significantly decreased (Table 3), by the addition of 2 g NaCl/L to the town water. This response agrees with the results of
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
caged, 40-wk-old laying hens (White Leghorn x Australorp) were allocated at random to each of four treatments in a room maintained at a constant 30 C. The drinking water treatments consisted of 1) controls receiving town water (.3 mM Na and <1 mM CI), 2) town water supplemented with 2 g NaCl/L, 3) town water supplemented with 1 g ascorbic acid/L, and 4) town water supplemented with 2 g NaCl and 1 g ascorbic acid/L. The NaCl solution was prepared as required, and ascorbic acid was added to fresh supplies of drinking water daily at 1600 h, a time corresponding to the approximate initiation of eggshell formation in the shell gland. Birds were given free access to water and to a proprietary layer mash with a calculated composition (per kilogram) of 160 g crude protein, 11.0 MJ 3 of metabolizable energy, 1.6 g of sodium, 2.1 g of chloride, 5.2 g of available phosphorus and 34 g of calcium. A 16-h day length was provided over the 8-wk experiment. In Experiment 2, the same treatments were given to each of two replicates of 40 68-wk-old laying hens (Tegel Super Tint)4 maintained in a conventional layer shed in separate rows of individual single-deck cages with a common water trough. A day length of 16 h was again provided and the daily temperature range was 20 to 35 C over the 6-wk experiment. In Experiment 3, the five treatments given to each of two replicates of 24 76-wk-old laying hens of the same strain as used in Experiment 1 (White Leghorn x Australorp) consisted of town water or town water containing 2 g NaCl/L along with 0, .25, .5, or 1.0 g of ascorbic acid/L. The experimental conditions were similar to those of Experiment 2, and the daily temperature range was 18 to 30 C over the 6-wk experiment. At the conclusion of the experiment, 12 hens that had previously received only the saline drinking water and that were laying eggs with defective shells were transferred to alternative cages and given the saline water with ascorbic acid (1 g/ L) for 4 wk. Twelve hens from the same saline water treatment consistently laying eggs with visually normal shells were used as controls, and eggshell defects from all birds were measured daily.
849
850
BALNAVE ET AL. TABLE 1. Shell defects and production parameters from all experiments
Water supplement
Shell defects
Egg production MM
b
(^^
Water intake
Food intake
(
' Uyuuyj
•
2.3 13.4a 1.6b 4.9 b 1.16
72.9 77.5 75.4 72.5 4.10
56.6 57.9 58.3 57.9 .81
103 104 104 104 3.7
400 370 352 395 28.5
7.3 b 15.4a 6.0b 7.5b .60
74.2a 72.7* 72.3 b 72.6b .39
60.4 62.3 60.2 60.8 .85
107 107 107 107 .4
300 295 273 276
12.9b 27.0*
68.6 71.9
63.2 62.0
116b 120*
253 271
1 9 3 ab 8
71.6 72.6 72.8 1.83
62.9 61.6 63.4 .99
m* 116ab
252 279 255
lej * 13.4b 3.18
122" 1.5
1
1
a,b
Within experiments and columns, data with no common superscripts are significantly different (P<05). 'Common water troughs for each treatment, so data were not analyzed statistically.
many previous studies in Australia but contrasts with work in the United States reported by Maurice (1989). He failed to observe any detrimental effect of saline drinking water on shell strength, measured as shell weight per unit surface area and suggested that this contrasting response may reflect differences in the sensitivity of different strains of hen to saline water. Yoselewitz and Balnave (1990) have shown that such sensitivity exists among Australian layer strains. Although shell defects increased in all six strains given saline drinking water in this latter study, the strain used in Experiments 1 and 3 in the present work gave a 4.3-fold increase compared with between 2.3- and 2.6-fold increases with the other five strains examined, including that used in Experiment 2. The differing sensitivities observed between strains is also reflected within strains. Within any population not all hens are affected to the same degree by saline water, and although the ability of some hens to produce normal eggshells is adversely affected, others continue to lay eggs with good shell quality (Yoselewitz et al, 1988; Balnave et al, 1989; Yoselewitz and Balnave, 1989a). Li order to overcome this problem of differing sensitivities, it is essential
that relatively large numbers of hens be used in any comparison. In Experiments 1 and 2 introducing the 1 g/ L ascorbic acid supplement simultaneously with the NaCl to the town water significantly reduced the incidence of shell defects to values that were not significantly different to controls (Table 1). A reduction in shell defects was also observed when ascorbic acid was added to the town water, although these responses were not statistically significant. In the third experiment, the extent of the reduction in eggshell defects resulting from the use of ascorbic acid was dependent upon the concentration of the vitamin added to the saline water, with the incidence of shell defects from hens receiving the 1 g/L supplement again differing only slightly from that of hens receiving no added NaCl (Table 1). However, in Experiment 3, supplying ascorbic acid to hens already affected by the saline water had no beneficial effect on the incidence of shell defects (Table 2). Shell defects from hens already receiving saline water and producing eggs with defective shells varied from a mean of 39.2 to a mean of 37.1%, with little change in eggshell quality, over the 4-wk ascorbic acid-supplementation period. The mean change
Downloaded from http://ps.oxfordjournals.org/ at Monash University on June 20, 2015
Experiment 1 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 2 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 3 None NaCl NaCl plus ascorbic acid at .25 g/L .50g/L 1.00 g/L SEM
(•")
Egg weight
851
EGGSHELL QUALITY AND SALINE DRINKING WATER
TABLE 2. Effect of supplementing saline drinking water with ascorbic acid for 4 wk on eggshell defects and shell quality from hens previously receiving saline drinking water and laying eggs with defective shells (x ± SE) Water treatment
Measurement
Week
NaCl plus ascorbic acid (poor shells)1
Shell defects, %
1 4 1 4 1 4 1 4
39.2 37.1 298 294 6.86 6.78 57.8 58.6
Shell thickness, (lm Shell weightegg weight, g:g x 100 Shell weight per unit surface area, mg/cm2
± ± ± ± ± ± ± ±
10.79 13.63 11.63 10.30 .363 .284 3.60 2.49
NaCl (good shells)1 9.9 9.3 344 339 8.44 8.01 71.6 68.7
± ± ± ± ± ± ± ±
4.47 4.58 7.9 6.9 .205 .173 1.64 1.55
Initial shell quality.
in the saline controls over this time varied from 9.9 to 9.3%. Changes in the percentage of shell defects were reflected in the shell quality measurements (Table 3). Except for shell breaking strength in Experiment 1, the addition of NaCl to the town water significantly reduced eggshell quality in all experiments. Supplying ascorbic acid with the saline water maintained
eggshell quality measures close to control values. The data from Experiment 3 show that this effect of ascorbic acid was dependent on the concentration used with improvements in shell quality being observed with higher supplementation levels. In Experiment 3, hens producing eggs with defective shells as a result of receiving saline drinking water without the ascorbic acid
TABLE 3. Shell quality measurements from all experiments
Water supplement Experiment 1 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 2 None NaCl Ascorbic acid NaCl plus ascorbic acid SEM Experiment 3 None NaCl NaCl plus ascorbic acid at .25 g/L .50g/L 1.00 g/L SEM :
Shell breaking strength
Shell thickness
(g)
(urn)
l^S150 1,542° 2,144a l,857 b 83.7
Shell weight: egg we ght (g:g) x 100
Shell weight per unit surface area (mg/cm )
8.65a 8.22b 8.72a 8.50ab .134
72.0" 67.9 b 72.6 a 70.5 ab 1.11
2,187a l,805 b 2,141 a 2,057* 93.1
367a 342 b 363 a 358a 5.5
9.04" 8.26b 9.1 l a 8.88a .166
76.0" 70.0 b 76.4 a 74.7 a 1.37
2,062a l,823 b
341 a 323 b
8.28a 7.77°
70.5 a 65.7°
l,876 ab
330*0 330 s * 341 a 5.5
7.85bc 8.07abc 8.21 ab .152
66.7^ 68.1 abc 69.9 ab 1.29
1927ab
2,023" 77.5
Within experiments and columns, means with no common superscripts are significantly different (P<05).
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ACKNOWLEDGMENTS
The present studies were supported by the Australian Egg Industry Research Council and the Poultry Research Foundation, University of Sydney. The Reserve Bank of Australia provided a Senior Research Fellowship to R. E. Moreng. REFERENCES Balnave, D., and T. Scott, 1986. The influence of minerals in drinking water on eggshell quality. Nutr. Rep. Int. 34:29-34. Balnave, D., and I. Yoselewitz, 1987. The relation between sodium chloride concentration in drinking
water and egg-shell damage. Br. J. Nutr. 58:503-509. Balnave, D., I. Yoselewitz, and R. J. Dixon, 1989. Physiological changes associated with the production of defective egg-shells by hens receiving sodium chloride in the drinking water. Br. J. Nutr. 61:35-4-3. Curtis, P. A., F. A. Gardner, and D. B. Mellor, 1985. A comparison of selected quality and compositional characteristics of brown and white shell eggs. 1. Shell quality. Poultry Sci. 64:297-301. Krautmann, B. A., 1988. Practical application of ascorbic acid in combating stress. Pages 48-67 in: The Role of Vitamin C in Poultry Stress Management. Hoffmann-La Roche, Inc., Nutley, NJ. Maurice, D. V., 1989. Salinity of drinking water and performance of chickens. Pages 140-144 in: Proceedings of the Georgia Nutrition Conference, University of Georgia, Athens, GA. Pardue, S. L., and J. P. Thaxton, 1986. Ascorbic acid in poultry: A review. World's Poult. Sci. J. 42:107-123. Steel, R.G.D., and J. H. Torrie, 1982. Principles and Procedures of Statistics. A Biometrical Approach. 2nd ed. McGraw-Hill, Kogakusha Ltd., Tokyo, Japan. Thornton, P. A., and R. E. Moreng, 1959. Further evidence on the value of ascorbic acid for maintenance of shell quality in warm environmental temperature. Poultry Sci. 38:594-599. Yoselewitz, I., and D. Balnave, 1989a. Responses in egg shell quality to sodium chloride supplementation of the diet and/or drinking water. Br. Poult. Sci. 30: 273-281. Yoselewitz, I., and D. Balnave, 1989b. Egg shell quality responses of pullets given saline drinking water at different ages. Br. Poult Sci. 30:715-718. Yoselewitz, I., and D. Balnave, 1989c. The influence of saline drinking water on the activity of carbonic anhydrase in the shell gland of laying hens. Aust J. Agric. Res. 40:1111-1115. Yoselewitz, I., and D. Balnave, 1990. Strain responses in egg shell quality to saline drinking water. Page 102 in: Proceedings of the Australian Poultry Science Symposium, University of Sydney, Camden, Australia. Yoselewitz, I., D. Balnave, and R. J. Dixon, 1988. Factors influencing the production of defective egg shells by laying hens receiving sodium chloride in the drinking water. Nutr. Rep. Int. 38:697-703. Yoselewitz, I., D. Zhang, and D. Balnave, 1991. The effect on egg shell quality of supplementing saline drinking water with sodium or ammonium bicarbonate. Aust J. Agric. Res. 41:1187-1192.
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supplement failed to show any improvement in shell quality, or reduction in percentage of shell defects, when the saline water was supplemented with ascorbic acid. These data indicate that ascorbic acid acted as a preventive rather than a remedial treatment. It appears that saline water causes permanent damage to the shell gland of affected hens, a conclusion reached in previous studies (Balnave and Yoselewitz, 1987; Balnave et al., 1989; Yoselewitz and Balnave, 1989a). The inconsistent nature of the responses in eggshell quality to dietary ascorbic acid supplementation (Pardue and Thaxton, 1986) suggests that other factors may be affecting the response. These studies indicate that water quality may be one such factor, a possibility that has not previously been considered. The addition of NaCl to drinking water has been shown to reduce the activity of carbonic anhydrase in the shell gland mucosa (Yoselewitz and Balnave, 1989c). Therefore, the degree to which specific problems of shell quality respond to treatment with ascorbic acid may depend on whether or not the supply of bicarbonate is the limiting factor affecting eggshell formation in the shell gland.