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Dietary Zinc Methionine Effect on Eggshell Quality of Hens Drinking Saline Water
Dietary Zinc Methionine Effect on Eggshell Quality of Hens Drinking Saline Water R. E. MORENG,1 D. BALNAVE,2 and D. ZHANG2 Department of Animal Sciences, Colorado State University, Fort Collins, Colorado 80523 and
ABSTRACT In two experiments individually caged 60-wk-old laying hens were exposed to daily temperatures ranging between 18 and 35 C and given various dietary and drinking water treatments. In Experiment 1 these were: 1) basal diet and town water; 2) basal diet and town water supplemented with 2 g NaCl/L; 3) basal diet supplemented with .2 g zinc methionine (Zinpro-200)/kg diet and town water; or 4) basal diet supplemented with .2 g zinc methionine/ kg and town water supplemented with 2 g NaCl/L. In Experiment 2, Treatments 1 and 2 were the same as in Experiment 1. Birds on Treatments 3 and 4 received the town water supplemented with 2 g NaCl/L and the basal diet supplemented with either .5 g zinc methionine/kg (Treatment 3) or .28 g ZnS04H20/kg to approximate the same dietary zinc concentration in Treatment 3 (Treatment 4). In both experiments, dietary zinc methionine plus 2 g NaCl/L in the drinking water significantly improved shell breaking strength over those birds on the 2 g NaCl/L with no zinc methionine supplementation. This same pattern occurred for shell weight, shell weight per unit of surface area, and percentage of shell defects. There were no improvements in the parameters measured from the supplementation of Z11SO4. The zinc methionine compound apparently was effective in overcoming the negative influence of the added 2 g NaQ/L of town water. (Key words: eggshell, zinc methionine, saline drinking water, laying hens, stress) 1992 Poultry Science 71:1163-1167
INTRODUCTION Recent studies have shown that supplementing the drinking water of laying hens with between .2 and 2 g NaQ/L significantly reduces eggshell quality and significantly increases the incidence of eggshell defects (Balnave et ah, 1991). Attempts to
Received for publication November 27, 1991. Accepted for publication March 16, 1992. TV) whom correspondence should be addressed: R. E. Moreng, Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523. Department of Animal Science, University of Sydney, Werombi Road, Camden, New South Wales 2570, Australia.
overcome this poor shell quality problem have generally had limited success; however, ascorbic acid has recently been shown to exert a beneficial influence (Balnave, 1991; Balnave et ah, 1991). Ascorbic acid appears to act as a preventive rather than a remedial treatment and proves beneficial if the ascorbic acid is administered in the diet or drinking water from the first time mature hens receive saline drinking water. Increased rate of hen-housed egg production was reported by Harbaugh and Sanford (1970) when optimum levels of zinc methionine supplemented the layer diet. Further studies reported by Magruder (1979) found that the addition
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Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
Department of Animal Science, University of Sydney, Werombi Road, Camden, New South Wales 2570, Australia
1164
MORENG ET AL.
MATERIALS AND METHODS Two experiments were conducted. In Experiment 1, two replicates of 40 individually caged, 68-wk-old laying hens 3 were allocated at random to each experimental treatment. They were maintained in a conventional layer shed in separate rows of individual single-deck cages with a common water trough. A daylength of 16 h was provided and the daily temperature range in this study was 20 to 35 C over the 6-wk experiment. In Experiment 2, two replicates of 25 individually caged, 60-wk-old laying hens (White Leghorn x Australorp) were allocated to each experimental treatment under experimental conditions similar to those of Experiment 1. In this study, the daily temperature range was 18 to 30 C over the 6-wk experiment. In each study, the hens were selected from
^egel Supertint; A. A. Tegel Pty. Ltd., Camden, New South Wales 2570, Australia. 4 Zuipro Corp., Edina, MN 55439-2441.
larger populations on the basis of egg production and good eggshell quality as evidenced by lack of production of softshelled, broken, cracked, or deformed eggshells. During the experiments, all hens were given free access to drinking water and to a mash diet. The basal diet used in both experiments was a commercial layer mash with a calculated composition (per kilogram of diet) of 160 g crude protein, 2,650 kcal of metabolizable energy, 1.6 g sodium, 2.1 g chloride, 5.2 g of available phosphorus, and 35 g of calcium. This diet was supplemented with zinc methionine and Z11SO4 to obtain the desired concentrations; methionine, 3.6 g/kg; zinc, 50 m g / k g . The source of drinking water was town municipal water (.3 mM Na and <1 mM Q ) to which NaCl was added to obtain the desired concentrations. The ZnSO^HaO was laboratory grade and the NaCl was analytical grade. In Experiment 1, the treatments used were: 1) diet and town water; 2) diet and town water supplemented with 2 g NaCl/ L; 3) diet supplemented with .2 g zinc methionine/kg (Zinpro-200) 4 and town water; and 4) diet supplemented with .2 g zinc methionine/kg and town water supplemented with 2 g NaCl/L. In Experiment 2, the treatments used were: 1) diet and town water; 2) diet and town water supplemented with 2 g NaCl/L; 3) diet supplemented with .5 g zinc methionine/ kg and town water supplemented with 2 g NaCl/L; and 4) diet supplemented with .28 g ZnS04-H20/kg, to approximate the same dietary zinc supplement as in Treatment 3, and town water supplemented with 2 g NaCl/L. Each replicate was treated as an experimental unit and the measurements of the various production parameters were carried out as described previously (Balnave et ah, 1991). Production parameters were measured weekly in both experiments except for feed intake in Experiment 2, which was measured over the complete experimental period. All eggs were collected at random from each treatment (40 eggs for Experiment 1; 30 eggs for Experiment 2) for shell quality measurements (Balnave et ah, 1991) in both experiments. The data were analyzed by a two-way
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
of this compound also reduced the cost of producing a dozen eggs by between 2 and 12C by reducing feed intake without affecting egg production, egg size, or body weight of the hens. However, more recent studies (Kienholz et ah, 1990) demonstrated that laying hens subjected to various forms of environmental stresses were better enabled to recover from each stress when they had 2 g / k g of zinc methionine in the diet than were hens receiving only the basic diet. Yoselewitz and Balnave (1989) reported reduced activity of carbonic anhydrase in the shell gland mucosa of laying hens receiving saline drinking water and related this to other evidence suggesting that the supply of bicarbonate to the lumen of the shell gland may be a major factor limiting eggshell quality u n d e r these circumstances. Because zinc is an integral component of this enzyme, it is possible that supplying zinc methionine to the diet may have a direct effect on eggshell quality as well as modifying any stress associated with the use of saline drinking water. This possibility was examined in the present study.
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ZINC METHIONINE AND EGGSHELL TABLE 1. Effects of dietary zinc methionine (Zn-Met) supplementation1 on eggshell characteristics, feed and water intake, and egg production of laying hens receiving saline drinking water,2 Experiment 1
Variable
Control
Zn-Met (•2 g/kg diet)
Zn-Met + NaQ
SEM
Least significant difference
62.3 1,806B 342 B 8.3 B
61.1 1,961*° 361 A 9.0*
60.6 2,072 A 356 A B 8.8 A
.86 912 5.4 .15
2.4 255 15 .4
126 .45 .54
33 1.8 2.1
70.0 B 15.4 A 107.0 295 .727
75.4 A 7.8 C 107.2 277 .737
74.4 A 10.0B 106.8 271 .741
.0085
.033
Means within each row with no common superscripts are significantly different (P < .01). Diet contained added .2 g Zn-Met/kg diet from Zinpro 200; Zinpro Corp., Edina, MN 55439-2441. 2 Drinking water contained 2 g NaCl/L added. T'orty eggs collected at random from each treatment. 1
(Experiment 1) or one-way (Experiment 2) ANOVA and means were compared by least significant difference (Steel and Torrie, 1982). The use of a common water trough prevented statistical analysis of water intake data. RESULTS AND DISCUSSION Table 1 contains the data summarized from Experiment 1 and presents a comparison of the performance of hens in terms of eggshell characteristics as influenced by the various treatments. As can be seen from these data, statistically significant differences in all eggshell quality measures were recorded between those eggs produced by the control birds and those produced by birds drinking water containing 2 g / L of added N a Q . In the case of birds receiving the salt water, all eggshell quality measures, other than shell thickness, were significantly improved when the zinc methionine was added to the diet. There were no significant differences in eggshell quality measures for birds on the town water with or without the dietary zinc methionine. In support of earlier observations of Balnave and Yoselewitz (1987), there was a significant increase in
percentage of shell defects in the presence of saline drinking water and these defects were significantly reduced when birds receiving salt water had zinc methionine included in the diet. Significant zinc methionine by N a Q interactions were obtained for shell breaking strength, shell weight percentage, and percentage shell defects. No statistical differences among treatments were observed in either feed intake, egg production, or egg weight. The second experiment was designed to approximate the same dietary zinc supplement as that received from the zinc methionine through the inclusion of ZnSC>4, as shown in Table 2. In this study, the significant increase in the numbers of shell defects that resulted from the use of saline water was not reflected in significant reductions in the various shell quality measures. However, although there were again no significant differences in egg weight between treatments, all eggshell quality measures, other than shell thickness, were significantly improved when zinc methionine was added to the feed of hens receiving saline drinking water. N o beneficial effects were recorded when birds on the salt water received ZnSC>4. The only significant difference in the shell
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
Egg weight, g 60.4 Shell breaking strength, g 2,187 A Shell thickness, um 367 A Shell weight:egg weight, % 9.0* Shell weight per unit surface area, 2 mg/cm 76.0* Shell defects, % 73c Feed intake, g per hen per day 107.3 Water intake, mL per hen per day 300 Hen-day egg production, % .742
NaQ (2 g/L)
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MORENG ET AL. TABLE 2. Effects of dietary zinc methionine (Zn-Met) or zinc sulfate supplementation on eggshell characteristics, feed and water intake, and egg production of laying hens receiving saline drinking water,2 Experiment 2^
Variable
Control
NaCl
NaQ + ZnS0 4 (•28 g/kg diet)
SEM
Least significant difference
63.8 2,004b 8.0 b
63.1 2,267* 8.5 a
62.8 2,029b 8.2 ab
.96 72.3 .16
2.7 203 .4
69.8 ab 348 15.0 ab 119.6 234 .743
1.25 5.4 1.41 2.93
3.5 15 55 115
68.4 b 335 18.5a 120.8 231 .715
72.2 a 349 11.O^ 122.3 229 .727
.0090
.036
a_c
Means within each row with no common superscripts are significantly different (P < .05). Diet contained added .2 g Zn-Met/kg diet from Zinpro 200; Zinpro Corp., Edina, MN 55439-2441. 2 Drinking water contained 2 g NaCl/L added. ^Thirty eggs collected at random from each treatment.
quality measures between the Z11SO4 and zinc methionine treatments was the improved shell breaking strength of eggs from hens receiving the zinc methionine. A significant reduction in shell defects was recorded when zinc methionine was added to the diet of birds drinking salt water but the use of dietary Z11SO4 with birds receiving the salt water failed to reduce significantly the incidence of shell defects. No significant differences in feed intake, egg production, or egg weight were recorded (Table 2). The consistency of these results suggests a possible physiological action of the zinc methionine compound on eggshell formation that prevents the production of the minute cracks in the eggshell as observed by Balnave and Yoselewitz (1987). The absence of a response to ZnSC>4 may reflect differences in zinc availability between the two sources of zinc (Wedekind et al., 1990). It is unknown whether the beneficial responses to zinc methionine reflect zinc availability or some other physiological action of this organic trace mineral supplement following absorption.
ACKNOWLEDGMENTS The studies carried out in Australia were supported by the Australian Egg Industry Research and Development Council, the Poultry Research Foundation, University of Sydney and the Reserve Bank of Australia. Zinc methionine (Zinpro 200) was provided by the Zinpro Corporation, Edina, MN 55439-2441. REFERENCES Balnave, D., 1991. Prevention of saline water-induced increases in egg shell defects. Pages 56-59 in: Proceedings of the Australian Poultry Science Symposium 1991. D. Balnave, ed. University of Sydney Printing Service, New South Wales, Australia. 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., D. Zhang, and R. E. Moreng, 1991. Use of ascorbic acid to prevent the decline in eggshell quality observed with saline drinking water. Poultry Sci. 70:848-852. Harbaugh, D. D., and P. E. Sanford, 1970. The effect of various levels of zinc-methiomne supplement on flock performance, egg size and shell quality. Poultry Sci. 49:1393.(Abstr.) Kienholz, E. W., J. L. Flinchum, W. P. Pfaff, and R. E.
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
Egg weight, g 64.2 Shell breaking strength, g 2,108 ab Shell weight:egg weight, % 8.2 ab Shell weight per unit surface area, m g / c m 2 70.3 ab Shell thickness, urn 345 SheU defects, % 9.3C Feed intake, g per hen per day 122.6 Water intake, mL per hen per day 227 Hen-day egg production, % .744
NaQ + Zn-Met (-5 g / k g diet)
ZINC METHIONINE AND EGGSHELL Moreng, 1990. Effect of zinc-methionine on stressed laying hens. Poultry Sci. 69(Suppl. 1): 72.(Abstr.) Magruder, N., 1979. Cargill develops new poultry laying hen feed. Feedstuffs 51(41):6. SteeL R.G.D., and J. H. Torrie, 1982. Principles and Procedures of Statistics. A Biometrical Approach. 2nd ed. McGraw-Hill Publishing Co.,
1167
Kogakusha Ltd., Tokyo, Japan. Wedekind, K. J., A. E. Hortin, and D. H. Baker, 1990. Bioavailability of zinc in a zinc-methionine chelate. J. Anim. Sci. 68(Suppl. l):394.(Abstr.) Yoselewitz, I., and D. Balnave, 1989. 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.
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
ABSTRACT In two experiments individually caged 60-wk-old laying hens were exposed to daily temperatures ranging between 18 and 35 C and given various dietary and drinking water treatments. In Experiment 1 these were: 1) basal diet and town water; 2) basal diet and town water supplemented with 2 g NaCl/L; 3) basal diet supplemented with .2 g zinc methionine (Zinpro-200)/kg diet and town water; or 4) basal diet supplemented with .2 g zinc methionine/ kg and town water supplemented with 2 g NaCl/L. In Experiment 2, Treatments 1 and 2 were the same as in Experiment 1. Birds on Treatments 3 and 4 received the town water supplemented with 2 g NaCl/L and the basal diet supplemented with either .5 g zinc methionine/kg (Treatment 3) or .28 g ZnS04H20/kg to approximate the same dietary zinc concentration in Treatment 3 (Treatment 4). In both experiments, dietary zinc methionine plus 2 g NaCl/L in the drinking water significantly improved shell breaking strength over those birds on the 2 g NaCl/L with no zinc methionine supplementation. This same pattern occurred for shell weight, shell weight per unit of surface area, and percentage of shell defects. There were no improvements in the parameters measured from the supplementation of Z11SO4. The zinc methionine compound apparently was effective in overcoming the negative influence of the added 2 g NaQ/L of town water. (Key words: eggshell, zinc methionine, saline drinking water, laying hens, stress) 1992 Poultry Science 71:1163-1167
INTRODUCTION Recent studies have shown that supplementing the drinking water of laying hens with between .2 and 2 g NaQ/L significantly reduces eggshell quality and significantly increases the incidence of eggshell defects (Balnave et ah, 1991). Attempts to
Received for publication November 27, 1991. Accepted for publication March 16, 1992. TV) whom correspondence should be addressed: R. E. Moreng, Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523. Department of Animal Science, University of Sydney, Werombi Road, Camden, New South Wales 2570, Australia.
overcome this poor shell quality problem have generally had limited success; however, ascorbic acid has recently been shown to exert a beneficial influence (Balnave, 1991; Balnave et ah, 1991). Ascorbic acid appears to act as a preventive rather than a remedial treatment and proves beneficial if the ascorbic acid is administered in the diet or drinking water from the first time mature hens receive saline drinking water. Increased rate of hen-housed egg production was reported by Harbaugh and Sanford (1970) when optimum levels of zinc methionine supplemented the layer diet. Further studies reported by Magruder (1979) found that the addition
1163
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
Department of Animal Science, University of Sydney, Werombi Road, Camden, New South Wales 2570, Australia
1164
MORENG ET AL.
MATERIALS AND METHODS Two experiments were conducted. In Experiment 1, two replicates of 40 individually caged, 68-wk-old laying hens 3 were allocated at random to each experimental treatment. They were maintained in a conventional layer shed in separate rows of individual single-deck cages with a common water trough. A daylength of 16 h was provided and the daily temperature range in this study was 20 to 35 C over the 6-wk experiment. In Experiment 2, two replicates of 25 individually caged, 60-wk-old laying hens (White Leghorn x Australorp) were allocated to each experimental treatment under experimental conditions similar to those of Experiment 1. In this study, the daily temperature range was 18 to 30 C over the 6-wk experiment. In each study, the hens were selected from
^egel Supertint; A. A. Tegel Pty. Ltd., Camden, New South Wales 2570, Australia. 4 Zuipro Corp., Edina, MN 55439-2441.
larger populations on the basis of egg production and good eggshell quality as evidenced by lack of production of softshelled, broken, cracked, or deformed eggshells. During the experiments, all hens were given free access to drinking water and to a mash diet. The basal diet used in both experiments was a commercial layer mash with a calculated composition (per kilogram of diet) of 160 g crude protein, 2,650 kcal of metabolizable energy, 1.6 g sodium, 2.1 g chloride, 5.2 g of available phosphorus, and 35 g of calcium. This diet was supplemented with zinc methionine and Z11SO4 to obtain the desired concentrations; methionine, 3.6 g/kg; zinc, 50 m g / k g . The source of drinking water was town municipal water (.3 mM Na and <1 mM Q ) to which NaCl was added to obtain the desired concentrations. The ZnSO^HaO was laboratory grade and the NaCl was analytical grade. In Experiment 1, the treatments used were: 1) diet and town water; 2) diet and town water supplemented with 2 g NaCl/ L; 3) diet supplemented with .2 g zinc methionine/kg (Zinpro-200) 4 and town water; and 4) diet supplemented with .2 g zinc methionine/kg and town water supplemented with 2 g NaCl/L. In Experiment 2, the treatments used were: 1) diet and town water; 2) diet and town water supplemented with 2 g NaCl/L; 3) diet supplemented with .5 g zinc methionine/ kg and town water supplemented with 2 g NaCl/L; and 4) diet supplemented with .28 g ZnS04-H20/kg, to approximate the same dietary zinc supplement as in Treatment 3, and town water supplemented with 2 g NaCl/L. Each replicate was treated as an experimental unit and the measurements of the various production parameters were carried out as described previously (Balnave et ah, 1991). Production parameters were measured weekly in both experiments except for feed intake in Experiment 2, which was measured over the complete experimental period. All eggs were collected at random from each treatment (40 eggs for Experiment 1; 30 eggs for Experiment 2) for shell quality measurements (Balnave et ah, 1991) in both experiments. The data were analyzed by a two-way
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
of this compound also reduced the cost of producing a dozen eggs by between 2 and 12C by reducing feed intake without affecting egg production, egg size, or body weight of the hens. However, more recent studies (Kienholz et ah, 1990) demonstrated that laying hens subjected to various forms of environmental stresses were better enabled to recover from each stress when they had 2 g / k g of zinc methionine in the diet than were hens receiving only the basic diet. Yoselewitz and Balnave (1989) reported reduced activity of carbonic anhydrase in the shell gland mucosa of laying hens receiving saline drinking water and related this to other evidence suggesting that the supply of bicarbonate to the lumen of the shell gland may be a major factor limiting eggshell quality u n d e r these circumstances. Because zinc is an integral component of this enzyme, it is possible that supplying zinc methionine to the diet may have a direct effect on eggshell quality as well as modifying any stress associated with the use of saline drinking water. This possibility was examined in the present study.
1165
ZINC METHIONINE AND EGGSHELL TABLE 1. Effects of dietary zinc methionine (Zn-Met) supplementation1 on eggshell characteristics, feed and water intake, and egg production of laying hens receiving saline drinking water,2 Experiment 1
Variable
Control
Zn-Met (•2 g/kg diet)
Zn-Met + NaQ
SEM
Least significant difference
62.3 1,806B 342 B 8.3 B
61.1 1,961*° 361 A 9.0*
60.6 2,072 A 356 A B 8.8 A
.86 912 5.4 .15
2.4 255 15 .4
126 .45 .54
33 1.8 2.1
70.0 B 15.4 A 107.0 295 .727
75.4 A 7.8 C 107.2 277 .737
74.4 A 10.0B 106.8 271 .741
.0085
.033
Means within each row with no common superscripts are significantly different (P < .01). Diet contained added .2 g Zn-Met/kg diet from Zinpro 200; Zinpro Corp., Edina, MN 55439-2441. 2 Drinking water contained 2 g NaCl/L added. T'orty eggs collected at random from each treatment. 1
(Experiment 1) or one-way (Experiment 2) ANOVA and means were compared by least significant difference (Steel and Torrie, 1982). The use of a common water trough prevented statistical analysis of water intake data. RESULTS AND DISCUSSION Table 1 contains the data summarized from Experiment 1 and presents a comparison of the performance of hens in terms of eggshell characteristics as influenced by the various treatments. As can be seen from these data, statistically significant differences in all eggshell quality measures were recorded between those eggs produced by the control birds and those produced by birds drinking water containing 2 g / L of added N a Q . In the case of birds receiving the salt water, all eggshell quality measures, other than shell thickness, were significantly improved when the zinc methionine was added to the diet. There were no significant differences in eggshell quality measures for birds on the town water with or without the dietary zinc methionine. In support of earlier observations of Balnave and Yoselewitz (1987), there was a significant increase in
percentage of shell defects in the presence of saline drinking water and these defects were significantly reduced when birds receiving salt water had zinc methionine included in the diet. Significant zinc methionine by N a Q interactions were obtained for shell breaking strength, shell weight percentage, and percentage shell defects. No statistical differences among treatments were observed in either feed intake, egg production, or egg weight. The second experiment was designed to approximate the same dietary zinc supplement as that received from the zinc methionine through the inclusion of ZnSC>4, as shown in Table 2. In this study, the significant increase in the numbers of shell defects that resulted from the use of saline water was not reflected in significant reductions in the various shell quality measures. However, although there were again no significant differences in egg weight between treatments, all eggshell quality measures, other than shell thickness, were significantly improved when zinc methionine was added to the feed of hens receiving saline drinking water. N o beneficial effects were recorded when birds on the salt water received ZnSC>4. The only significant difference in the shell
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
Egg weight, g 60.4 Shell breaking strength, g 2,187 A Shell thickness, um 367 A Shell weight:egg weight, % 9.0* Shell weight per unit surface area, 2 mg/cm 76.0* Shell defects, % 73c Feed intake, g per hen per day 107.3 Water intake, mL per hen per day 300 Hen-day egg production, % .742
NaQ (2 g/L)
1166
MORENG ET AL. TABLE 2. Effects of dietary zinc methionine (Zn-Met) or zinc sulfate supplementation on eggshell characteristics, feed and water intake, and egg production of laying hens receiving saline drinking water,2 Experiment 2^
Variable
Control
NaCl
NaQ + ZnS0 4 (•28 g/kg diet)
SEM
Least significant difference
63.8 2,004b 8.0 b
63.1 2,267* 8.5 a
62.8 2,029b 8.2 ab
.96 72.3 .16
2.7 203 .4
69.8 ab 348 15.0 ab 119.6 234 .743
1.25 5.4 1.41 2.93
3.5 15 55 115
68.4 b 335 18.5a 120.8 231 .715
72.2 a 349 11.O^ 122.3 229 .727
.0090
.036
a_c
Means within each row with no common superscripts are significantly different (P < .05). Diet contained added .2 g Zn-Met/kg diet from Zinpro 200; Zinpro Corp., Edina, MN 55439-2441. 2 Drinking water contained 2 g NaCl/L added. ^Thirty eggs collected at random from each treatment.
quality measures between the Z11SO4 and zinc methionine treatments was the improved shell breaking strength of eggs from hens receiving the zinc methionine. A significant reduction in shell defects was recorded when zinc methionine was added to the diet of birds drinking salt water but the use of dietary Z11SO4 with birds receiving the salt water failed to reduce significantly the incidence of shell defects. No significant differences in feed intake, egg production, or egg weight were recorded (Table 2). The consistency of these results suggests a possible physiological action of the zinc methionine compound on eggshell formation that prevents the production of the minute cracks in the eggshell as observed by Balnave and Yoselewitz (1987). The absence of a response to ZnSC>4 may reflect differences in zinc availability between the two sources of zinc (Wedekind et al., 1990). It is unknown whether the beneficial responses to zinc methionine reflect zinc availability or some other physiological action of this organic trace mineral supplement following absorption.
ACKNOWLEDGMENTS The studies carried out in Australia were supported by the Australian Egg Industry Research and Development Council, the Poultry Research Foundation, University of Sydney and the Reserve Bank of Australia. Zinc methionine (Zinpro 200) was provided by the Zinpro Corporation, Edina, MN 55439-2441. REFERENCES Balnave, D., 1991. Prevention of saline water-induced increases in egg shell defects. Pages 56-59 in: Proceedings of the Australian Poultry Science Symposium 1991. D. Balnave, ed. University of Sydney Printing Service, New South Wales, Australia. 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., D. Zhang, and R. E. Moreng, 1991. Use of ascorbic acid to prevent the decline in eggshell quality observed with saline drinking water. Poultry Sci. 70:848-852. Harbaugh, D. D., and P. E. Sanford, 1970. The effect of various levels of zinc-methiomne supplement on flock performance, egg size and shell quality. Poultry Sci. 49:1393.(Abstr.) Kienholz, E. W., J. L. Flinchum, W. P. Pfaff, and R. E.
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015
Egg weight, g 64.2 Shell breaking strength, g 2,108 ab Shell weight:egg weight, % 8.2 ab Shell weight per unit surface area, m g / c m 2 70.3 ab Shell thickness, urn 345 SheU defects, % 9.3C Feed intake, g per hen per day 122.6 Water intake, mL per hen per day 227 Hen-day egg production, % .744
NaQ + Zn-Met (-5 g / k g diet)
ZINC METHIONINE AND EGGSHELL Moreng, 1990. Effect of zinc-methionine on stressed laying hens. Poultry Sci. 69(Suppl. 1): 72.(Abstr.) Magruder, N., 1979. Cargill develops new poultry laying hen feed. Feedstuffs 51(41):6. SteeL R.G.D., and J. H. Torrie, 1982. Principles and Procedures of Statistics. A Biometrical Approach. 2nd ed. McGraw-Hill Publishing Co.,
1167
Kogakusha Ltd., Tokyo, Japan. Wedekind, K. J., A. E. Hortin, and D. H. Baker, 1990. Bioavailability of zinc in a zinc-methionine chelate. J. Anim. Sci. 68(Suppl. l):394.(Abstr.) Yoselewitz, I., and D. Balnave, 1989. 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.
Downloaded from http://ps.oxfordjournals.org/ at New York University on February 6, 2015