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The Mineral Concentration Change of Turkey Eggshell Membranes During Incubation1,2
PHYSIOLOGY AND REPRODUCTION The Mineral Concentration Change of Turkey Eggshell Membranes During Incubation1-2 V. L. CHRISTENSEN Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 (Received for publication April 27, 1989)
1990 Poultry Science 69:992-998 INTRODUCTION
The path a gas must travel from the outside to the inside of an egg or the reverse can be viewed as a series of resistances to flow. There are six structures that offer resistance to the flow of oxygen, carbon dioxide, or water vapor (Tranter et al, 1983). These are from the outside of the egg to the inside: the boundary layer, the cuticle, pore canal, outer shell membrane, inner shell membrane, and the limiting membrane. Several studies have shown that a 10-fold increase in oxygen permeability of the integument (the porous calcific shell lined on its inner surface with fibrous membranes) occurs 22% of the way through incubation of several species of birds (Tullett and Board, 1976; Kayar et al., 1981; Seymour and Piiper, 1988). Attempts to interpret this observation have caused questions about the role of water, either in or between fibers of the shell membranes, on the diffusion of oxygen through the interstitial spaces. Kayar et al. (1981) and Robel et al. (1986) proposed the theory that the increased oxygen permeability
'Paper Number 12146 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7643. T h e use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service nor criticism of similar ones not mentioned. 3 Jamesway 252B, Ft. Atkinson, WI 53538.
was due to increased inner membrane permeability. The increased permeability was thought to be due to evaporation causing a layer of water in the inner membrane to be reduced in thickness from about 63 to .6 urn. It is notable that a narrow band of electrondense material separating the main membrane and the chorioallantois has been observed repeatedly (Tranter et al., 1983). Before using any hypothesis that attempts to explain changes in oxygen permeability of shell membranes in terms of water content, the fine structure and chemical composition of die shell membranes must be considered. Tranter et al. (1983) have previously examined the mineral composition of fertile and infertile chicken eggshell membranes during incubation. The experiments reported here were undertaken to determine the mineral content of shell membranes of fertile and infertile turkey eggs at different times during incubation. MATERIALS AND METHODS
Fertile and infertile turkey eggs were collected from Large White turkey hens. All eggs were collected on the same day, washed, and stored at 15.5 C and 75% relative humidity for 2 days before setting in Jamesway 252B incubators.3 The eggs were incubated using standard procedures (37.5 C drybulb temperature and 29.4 C wet-bulb temperature). Eight fertile and 8 infertile eggs were selected randomly and removed from the
992
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
ABSTRACT Membranes from fertile and infertile turkey eggs were examined during incubation to determine the content of Ca, Mg, Na, and K. The Ca concentration in shell membranes of fertile eggs increased (K.05) as compared with that in infertile eggs, but concentrations of Mg, Na, and K in shell membranes of fertile eggs declined (P£.05) as compared with those in infertile eggshell membranes. The data suggest a possible role for some minerals in regulating functional eggshell properties. (Key words: eggshell membranes, minerals, function, fertility, incubation)
993
MINERALS AND EGGSHELL MEMBRANES
INFERTILE FERTILE
FERTILE = 8.334 + .137x a R = .20
30
25"
20
c o
o
to
o
10
5-.
12
1 6
2 0
24
Day of Incubation FIGURE 1. Milligrams of calcium per gram of dried membrane weight found in fertile and infertile turkey during incubation. Slopes are significantly different (PS.0001).
incubator on Days 0, 4, 8, 12, 16, 20, 24, 25, 26, 27, and 28. The inner eggshell membrane and part of the outer shell membrane, which may have adhered to the inner membrane, were removed from both groups of eggs, washed three times in deionized water, and dried (Tranter et al., 1983). The dried membranes were weighed to the nearest .01 mg and wet-ashed in 8 mL of 1
4 5
Fisher Scientific Co., Raleigh, NC 27629. Model 403, Perkin-Elmer, Silver Springs, MD 20907.
N hydrochloric acid plus 12 mL of methanol for 4 days at room temperature. An aliquot of the resulting mineral solution was placed in a .5% lanthanum chloride solution4 in deionized water. The aliquot was diluted appropriately to determine Ca, Mg, Na, or K concentration using atomic-absorption spectrophotometry.5 The relative mineral concentration of each eggshell membrane was computed by dividing the observed concentration of each mineral by the dried membrane weight (milligrams of mineral per gram of dried membrane weight). The mineral concentrations of the fertile and infertile eggs were compared using regression analysis. Mineral concentrations of fertile or infertile eggs were regressed on the days of incubation, and the slopes of the lines were tested for significance at P<.05.
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
S 15 o c o
994
CHRISTENSEN
The chorioallantoic membrane, with its active transport of Na from other fluids to The present study examined the mineral blood and associated movement of water, is composition of fertile and infertile turkey currently thought to be a major osmoregulatory eggshell membranes. The results suggest that mechanism of developing embryos (Davis and mineral flux to and from turkey eggshell Ackerman, 1987; Davis et al., 1988; Seymour membranes was very similar to that of chicken and Piiper, 1988). Although osmotic regulation eggshell membranes (Tranter et al., 1983). The of fluids has been observed many times concentration of individual minerals may also (Adolph, 1967; Hoyt, 1979; Davis et al, be related to the eggshell water vapor conduc- 1988), the regulation of fluid balance in tance. Water vapor conductance is thought to incubating eggs is not well understood. Addibe regulated by the osmotic or evaporative loss tionally, the role of shell membranes in of water from the keratin fibers constituting osmotic balance of incubating eggs has not the inner shell membrane (Robel et al., 1986; been thoroughly examined. This may be a Davis et al, 1988; Seymour and Piiper, 1988). mechanism to conserve water (Hoyt, 1979), to RESULTS AND DISCUSSION
2.0-
INFERTILE = .802 + .003x b R '=.15
INFERTILE FERTILE
FERTILE = .912- .027x a R 2 = .70
• 1.5-
c o
•
• D
c a> u c o
1.0-
o
O)
I
S
Ul
•
i
K* 5
B
a
•
D
9
B
R
1—
B
D B
• • •
I
•
D
a g
B
•
i
•
D
D
•
El
• D
D
•
/ • ••«••
•
• ••
2 0
24
O
• 1
1 2
16 I
'
Day of Incubation HGURE 2. Milligrams of magnesium per gram of dried membrane weight found in fertile and infertile turkey eggs during incubation. Slopes are significantly different (P^.0001).
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
B •
MINERALS AND EGGSHELL MEMBRANES D •
INFERTILE = 2.674 + Ox
INFERTILE FERTILE
FERTILE = 2.666 - .11x
995
R = .01 R 2 = .88
0)
u c o
o
(0
z
Day of Incubation FIGURE 3. Milligrams of sodium per gram of dried membrane weight found in fertile and infertile turkey eggs during incubation. Slopes are significantly different (P£.002).
prevent excessive carbon dioxide loss (Windle and Barcroft, 1938), or to influence some other respiratory mechanism to enhance survival. In the present study, Ca was unique among the minerals studied because the Ca concentrations of fertile turkey eggshell membranes increased as embryos developed (Figure 1). However, the R 2 value for the Ca concentration of fertile eggs over time of incubation was low, thus indicating a poor fit. This may be due to the large variation in Ca values due to differences in Ca metabolism among embryos. Magnesium, Na, and K concentrations of eggshell membranes of fertile eggs declined during incubation compared to infertile egg
membranes (Figures 2, 3, and 4). Taken together, these results may indicate mobilization of Ca reserves for embryonic growth rather than changes associated with an active transport system affecting osmotic balance (Hoyt, 1979). Magnesium flux away from the membrane may have more physiological significance than the presence of Ca. The possibility exists that excessive Mg at the level of the inner membrane may interact with water, the fibrous proteins of the membrane, or the narrow band of electron-dense material to increase their resistance to gas flow. Such a hypothesis would explain why embryonic deaths occur
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
c
996
CHRISTENSEN
a •
INFERTILE = .695 + .018x
INFERTILE FERTILE
FERTILE s .791 - .030x
R = .36 R s .65
c o
2 4
Day of Incubation
FIGURE 4. Milligrams of potassium per gram of dried membrane weight found in fertile and infertile turkey during incubation. Slopes are significantly different (P£.05).
late in the incubation period in experiments creating a nutritional Mg deficiency in hens (Sell et al., 1967). Previous data indicated that shells from nonhatching turkey eggs had reduced Mg concentrations as compared with that of shells from eggs that hatched; however, no differences were seen between hatching and nonhatching eggshell Ca concentrations (Christensen and Edens, 1985). Christensen and Edens (1985) also observed that injecting 1 mg of Ca into incubating turkey eggs improved hatchability whereas injecting 1 mg of Mg decreased hatchability. These observations sug-
gest that too much or too little Mg or both in turkey eggshells may be associated with decreased hatchability. Romanoff (1929) demonstrated a connection between high incubational humidity, increased Ca metabolism, and increased embryonic mortality during pipping. Potassium concentrations in the turkey eggshell membranes declined as development occurred, and almost no K was found in the membranes by Days 20 and 24 of incubation (Figure 4). Reductions in Na concentrations to near nondetectable levels were also observed at Days 20 and 24 of incubation (Figure 3). This suggests a vital role for membrane Na or K in
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
I
997
MINERALS AND EGGSHELL MEMBRANES
12 Q •
INFERTILE FERTILE
INFERTILE = 4.596 - .1 OOx FERTILE = 4.493 - .179x
R = .51 R = .74
10
c o c 0)
6-,
o
"S
z
1 2
16
2 0
2 4
Day of Incubation FIGURE 5. Ratio of sodium to potassium (mg per g of dried membrane) found in fertile and infertile turkey during incubation. Slopes are significantly different (P<0001).
determining eggshell water vapor conductance at the plateau stage of incubation and supports previous observations of a Na-K-dependent active transport system (Hoyt, 1979; Davis et al, 1988). If active transport of minerals exists in the inner membrane or if an electrical gradient exists across the membrane, the ratios of Na to K or Ca to Mg may be physiologically important to maintain osmotic balance. When the data for fertile and infertile eggs were
plotted as Na to K ratios or Ca to Mg ratios (Figures 5 and 6), Na to K ratios of fertile eggs declined (P<.05) more rapidly than that of infertile eggs during incubation, whereas Ca to Mg ratios increased (R£.05) compared with those ratios in infertile controls. If the total amount of the four minerals in the membranes was considered, the total did not change. Consequently, the density of the membranes may not have changed, but the types of minerals were exchanged.
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
u c o
998
CHRISTENSEN 80• •
INFERTILE = 7.524 + .017x
INFERTILE FERTILE
FERTILE = 1.552 + 1.991X
R = .02 R 2 = .76
• • •
•
60-
•
•
• c o
• •
•
c 0)
40"
•
o
••
O)
s ^a o
o-
K
is 8
V
D
•
EI
0 EI
B
t B
1
e
§ |
• 0
• •
El
i i
D
•
•
20-
•
1
1
1
1—
12
8
D
•
•
1 1
16
1
I r—
1
20
Q 1
1
24
Day of Incubation
FIGURE 6. Ratio of calcium to magnesium (mg per g of dried membrane) found in fertile and infertile turkey eggs during incubation. Slopes are significantly different (PS.0001).
ACKNOWLEDGMENTS
The author thanks Debbie Ort and Pamela Jenkins for excellent technical assistance and Andrea Free-Kwiatkowski for preparation of the manuscript. REFERENCES Adolph, E. F., 1967. Ontogeny of volume regulations in embryonic extracellular fluids. Q. Rev. Biol. 42:1-39. Christensen, V. L., and F. W. Edens, 1985. Magnesium, calcium, and phosphorus content of shells from hatching and nonhatching turkey eggs. Poultry Sci. 64: 1020-1027. Davis, T. A., and R. A. Ackerman, 1987. Effects of increased water loss on growth and water content of the chick embryo. J. Exp. Zool. 244(Suppl. l):357-364. Davis, T. A., S. S. Shen, and R. A. Ackerman, 1988. Embryonic osmoregulation: consequences of high and low water loss during incubation of the chicken egg. J. Exp. Zool. 245:144-156. Hoyt, D. F., 1979. Osmoregulation by avian embryos: the allantois functions like a toad's bladder. Physiol. Zool. 52:354-362.
Kayar, S. R., G. K. Snyder, G. F. Birchard, and C. P. Black, 1981. Oxygen permeability of the shell and membranes of chicken eggs during development Respir. Physiol. 46:209-221. Robel, E. J., C. C. Lai, and S. G. Gilbert, 1986. Permeability of turkey eggs from hens with different hatchability rates. Comp. Biochem. Physiol. 84A:633-636. Romanoff, A. L., 1929. Effect of humidity on the growth, calcium metabolism and mortality of the chick embryo. J. Exp. Zool. 54:343-384. Sell, J. L., R. Hajj, A. Cox, and W. Guenter, 1967. Effect of magnesium deficiency in the hen on egg production and hatchability of eggs. Br. Poult Sci. 8:55-63. Seymour, R. J., and J. Piiper, 1988. Aeration of the shell membranes of avian eggs. Respir. Physiol. 71: 101-116. Tullett, S. G., and R. G. Board, 1976. Oxygenfluxacross the integument of the avian egg during incubation. Br. Poult Sci. 17:441-450. Tranter, H. S., N.H.C. Sparks, and R. G. Board, 1983. Changes in the structure of the limiting membrane and in oxygen permeability of the chicken egg integument during incubation. Br. Poult. Sci. 24:537-547. Windle, W. F., and J. Barcroft, 1938. Some factors governing the initiation of respiration in the chick. Am. J. Physiol. 121:684-691.
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
o c o
1990 Poultry Science 69:992-998 INTRODUCTION
The path a gas must travel from the outside to the inside of an egg or the reverse can be viewed as a series of resistances to flow. There are six structures that offer resistance to the flow of oxygen, carbon dioxide, or water vapor (Tranter et al, 1983). These are from the outside of the egg to the inside: the boundary layer, the cuticle, pore canal, outer shell membrane, inner shell membrane, and the limiting membrane. Several studies have shown that a 10-fold increase in oxygen permeability of the integument (the porous calcific shell lined on its inner surface with fibrous membranes) occurs 22% of the way through incubation of several species of birds (Tullett and Board, 1976; Kayar et al., 1981; Seymour and Piiper, 1988). Attempts to interpret this observation have caused questions about the role of water, either in or between fibers of the shell membranes, on the diffusion of oxygen through the interstitial spaces. Kayar et al. (1981) and Robel et al. (1986) proposed the theory that the increased oxygen permeability
'Paper Number 12146 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7643. T h e use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service nor criticism of similar ones not mentioned. 3 Jamesway 252B, Ft. Atkinson, WI 53538.
was due to increased inner membrane permeability. The increased permeability was thought to be due to evaporation causing a layer of water in the inner membrane to be reduced in thickness from about 63 to .6 urn. It is notable that a narrow band of electrondense material separating the main membrane and the chorioallantois has been observed repeatedly (Tranter et al., 1983). Before using any hypothesis that attempts to explain changes in oxygen permeability of shell membranes in terms of water content, the fine structure and chemical composition of die shell membranes must be considered. Tranter et al. (1983) have previously examined the mineral composition of fertile and infertile chicken eggshell membranes during incubation. The experiments reported here were undertaken to determine the mineral content of shell membranes of fertile and infertile turkey eggs at different times during incubation. MATERIALS AND METHODS
Fertile and infertile turkey eggs were collected from Large White turkey hens. All eggs were collected on the same day, washed, and stored at 15.5 C and 75% relative humidity for 2 days before setting in Jamesway 252B incubators.3 The eggs were incubated using standard procedures (37.5 C drybulb temperature and 29.4 C wet-bulb temperature). Eight fertile and 8 infertile eggs were selected randomly and removed from the
992
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
ABSTRACT Membranes from fertile and infertile turkey eggs were examined during incubation to determine the content of Ca, Mg, Na, and K. The Ca concentration in shell membranes of fertile eggs increased (K.05) as compared with that in infertile eggs, but concentrations of Mg, Na, and K in shell membranes of fertile eggs declined (P£.05) as compared with those in infertile eggshell membranes. The data suggest a possible role for some minerals in regulating functional eggshell properties. (Key words: eggshell membranes, minerals, function, fertility, incubation)
993
MINERALS AND EGGSHELL MEMBRANES
INFERTILE FERTILE
FERTILE = 8.334 + .137x a R = .20
30
25"
20
c o
o
to
o
10
5-.
12
1 6
2 0
24
Day of Incubation FIGURE 1. Milligrams of calcium per gram of dried membrane weight found in fertile and infertile turkey during incubation. Slopes are significantly different (PS.0001).
incubator on Days 0, 4, 8, 12, 16, 20, 24, 25, 26, 27, and 28. The inner eggshell membrane and part of the outer shell membrane, which may have adhered to the inner membrane, were removed from both groups of eggs, washed three times in deionized water, and dried (Tranter et al., 1983). The dried membranes were weighed to the nearest .01 mg and wet-ashed in 8 mL of 1
4 5
Fisher Scientific Co., Raleigh, NC 27629. Model 403, Perkin-Elmer, Silver Springs, MD 20907.
N hydrochloric acid plus 12 mL of methanol for 4 days at room temperature. An aliquot of the resulting mineral solution was placed in a .5% lanthanum chloride solution4 in deionized water. The aliquot was diluted appropriately to determine Ca, Mg, Na, or K concentration using atomic-absorption spectrophotometry.5 The relative mineral concentration of each eggshell membrane was computed by dividing the observed concentration of each mineral by the dried membrane weight (milligrams of mineral per gram of dried membrane weight). The mineral concentrations of the fertile and infertile eggs were compared using regression analysis. Mineral concentrations of fertile or infertile eggs were regressed on the days of incubation, and the slopes of the lines were tested for significance at P<.05.
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
S 15 o c o
994
CHRISTENSEN
The chorioallantoic membrane, with its active transport of Na from other fluids to The present study examined the mineral blood and associated movement of water, is composition of fertile and infertile turkey currently thought to be a major osmoregulatory eggshell membranes. The results suggest that mechanism of developing embryos (Davis and mineral flux to and from turkey eggshell Ackerman, 1987; Davis et al., 1988; Seymour membranes was very similar to that of chicken and Piiper, 1988). Although osmotic regulation eggshell membranes (Tranter et al., 1983). The of fluids has been observed many times concentration of individual minerals may also (Adolph, 1967; Hoyt, 1979; Davis et al, be related to the eggshell water vapor conduc- 1988), the regulation of fluid balance in tance. Water vapor conductance is thought to incubating eggs is not well understood. Addibe regulated by the osmotic or evaporative loss tionally, the role of shell membranes in of water from the keratin fibers constituting osmotic balance of incubating eggs has not the inner shell membrane (Robel et al., 1986; been thoroughly examined. This may be a Davis et al, 1988; Seymour and Piiper, 1988). mechanism to conserve water (Hoyt, 1979), to RESULTS AND DISCUSSION
2.0-
INFERTILE = .802 + .003x b R '=.15
INFERTILE FERTILE
FERTILE = .912- .027x a R 2 = .70
• 1.5-
c o
•
• D
c a> u c o
1.0-
o
O)
I
S
Ul
•
i
K* 5
B
a
•
D
9
B
R
1—
B
D B
• • •
I
•
D
a g
B
•
i
•
D
D
•
El
• D
D
•
/ • ••«••
•
• ••
2 0
24
O
• 1
1 2
16 I
'
Day of Incubation HGURE 2. Milligrams of magnesium per gram of dried membrane weight found in fertile and infertile turkey eggs during incubation. Slopes are significantly different (P^.0001).
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
B •
MINERALS AND EGGSHELL MEMBRANES D •
INFERTILE = 2.674 + Ox
INFERTILE FERTILE
FERTILE = 2.666 - .11x
995
R = .01 R 2 = .88
0)
u c o
o
(0
z
Day of Incubation FIGURE 3. Milligrams of sodium per gram of dried membrane weight found in fertile and infertile turkey eggs during incubation. Slopes are significantly different (P£.002).
prevent excessive carbon dioxide loss (Windle and Barcroft, 1938), or to influence some other respiratory mechanism to enhance survival. In the present study, Ca was unique among the minerals studied because the Ca concentrations of fertile turkey eggshell membranes increased as embryos developed (Figure 1). However, the R 2 value for the Ca concentration of fertile eggs over time of incubation was low, thus indicating a poor fit. This may be due to the large variation in Ca values due to differences in Ca metabolism among embryos. Magnesium, Na, and K concentrations of eggshell membranes of fertile eggs declined during incubation compared to infertile egg
membranes (Figures 2, 3, and 4). Taken together, these results may indicate mobilization of Ca reserves for embryonic growth rather than changes associated with an active transport system affecting osmotic balance (Hoyt, 1979). Magnesium flux away from the membrane may have more physiological significance than the presence of Ca. The possibility exists that excessive Mg at the level of the inner membrane may interact with water, the fibrous proteins of the membrane, or the narrow band of electron-dense material to increase their resistance to gas flow. Such a hypothesis would explain why embryonic deaths occur
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
c
996
CHRISTENSEN
a •
INFERTILE = .695 + .018x
INFERTILE FERTILE
FERTILE s .791 - .030x
R = .36 R s .65
c o
2 4
Day of Incubation
FIGURE 4. Milligrams of potassium per gram of dried membrane weight found in fertile and infertile turkey during incubation. Slopes are significantly different (P£.05).
late in the incubation period in experiments creating a nutritional Mg deficiency in hens (Sell et al., 1967). Previous data indicated that shells from nonhatching turkey eggs had reduced Mg concentrations as compared with that of shells from eggs that hatched; however, no differences were seen between hatching and nonhatching eggshell Ca concentrations (Christensen and Edens, 1985). Christensen and Edens (1985) also observed that injecting 1 mg of Ca into incubating turkey eggs improved hatchability whereas injecting 1 mg of Mg decreased hatchability. These observations sug-
gest that too much or too little Mg or both in turkey eggshells may be associated with decreased hatchability. Romanoff (1929) demonstrated a connection between high incubational humidity, increased Ca metabolism, and increased embryonic mortality during pipping. Potassium concentrations in the turkey eggshell membranes declined as development occurred, and almost no K was found in the membranes by Days 20 and 24 of incubation (Figure 4). Reductions in Na concentrations to near nondetectable levels were also observed at Days 20 and 24 of incubation (Figure 3). This suggests a vital role for membrane Na or K in
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
I
997
MINERALS AND EGGSHELL MEMBRANES
12 Q •
INFERTILE FERTILE
INFERTILE = 4.596 - .1 OOx FERTILE = 4.493 - .179x
R = .51 R = .74
10
c o c 0)
6-,
o
"S
z
1 2
16
2 0
2 4
Day of Incubation FIGURE 5. Ratio of sodium to potassium (mg per g of dried membrane) found in fertile and infertile turkey during incubation. Slopes are significantly different (P<0001).
determining eggshell water vapor conductance at the plateau stage of incubation and supports previous observations of a Na-K-dependent active transport system (Hoyt, 1979; Davis et al, 1988). If active transport of minerals exists in the inner membrane or if an electrical gradient exists across the membrane, the ratios of Na to K or Ca to Mg may be physiologically important to maintain osmotic balance. When the data for fertile and infertile eggs were
plotted as Na to K ratios or Ca to Mg ratios (Figures 5 and 6), Na to K ratios of fertile eggs declined (P<.05) more rapidly than that of infertile eggs during incubation, whereas Ca to Mg ratios increased (R£.05) compared with those ratios in infertile controls. If the total amount of the four minerals in the membranes was considered, the total did not change. Consequently, the density of the membranes may not have changed, but the types of minerals were exchanged.
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
u c o
998
CHRISTENSEN 80• •
INFERTILE = 7.524 + .017x
INFERTILE FERTILE
FERTILE = 1.552 + 1.991X
R = .02 R 2 = .76
• • •
•
60-
•
•
• c o
• •
•
c 0)
40"
•
o
••
O)
s ^a o
o-
K
is 8
V
D
•
EI
0 EI
B
t B
1
e
§ |
• 0
• •
El
i i
D
•
•
20-
•
1
1
1
1—
12
8
D
•
•
1 1
16
1
I r—
1
20
Q 1
1
24
Day of Incubation
FIGURE 6. Ratio of calcium to magnesium (mg per g of dried membrane) found in fertile and infertile turkey eggs during incubation. Slopes are significantly different (PS.0001).
ACKNOWLEDGMENTS
The author thanks Debbie Ort and Pamela Jenkins for excellent technical assistance and Andrea Free-Kwiatkowski for preparation of the manuscript. REFERENCES Adolph, E. F., 1967. Ontogeny of volume regulations in embryonic extracellular fluids. Q. Rev. Biol. 42:1-39. Christensen, V. L., and F. W. Edens, 1985. Magnesium, calcium, and phosphorus content of shells from hatching and nonhatching turkey eggs. Poultry Sci. 64: 1020-1027. Davis, T. A., and R. A. Ackerman, 1987. Effects of increased water loss on growth and water content of the chick embryo. J. Exp. Zool. 244(Suppl. l):357-364. Davis, T. A., S. S. Shen, and R. A. Ackerman, 1988. Embryonic osmoregulation: consequences of high and low water loss during incubation of the chicken egg. J. Exp. Zool. 245:144-156. Hoyt, D. F., 1979. Osmoregulation by avian embryos: the allantois functions like a toad's bladder. Physiol. Zool. 52:354-362.
Kayar, S. R., G. K. Snyder, G. F. Birchard, and C. P. Black, 1981. Oxygen permeability of the shell and membranes of chicken eggs during development Respir. Physiol. 46:209-221. Robel, E. J., C. C. Lai, and S. G. Gilbert, 1986. Permeability of turkey eggs from hens with different hatchability rates. Comp. Biochem. Physiol. 84A:633-636. Romanoff, A. L., 1929. Effect of humidity on the growth, calcium metabolism and mortality of the chick embryo. J. Exp. Zool. 54:343-384. Sell, J. L., R. Hajj, A. Cox, and W. Guenter, 1967. Effect of magnesium deficiency in the hen on egg production and hatchability of eggs. Br. Poult Sci. 8:55-63. Seymour, R. J., and J. Piiper, 1988. Aeration of the shell membranes of avian eggs. Respir. Physiol. 71: 101-116. Tullett, S. G., and R. G. Board, 1976. Oxygenfluxacross the integument of the avian egg during incubation. Br. Poult Sci. 17:441-450. Tranter, H. S., N.H.C. Sparks, and R. G. Board, 1983. Changes in the structure of the limiting membrane and in oxygen permeability of the chicken egg integument during incubation. Br. Poult. Sci. 24:537-547. Windle, W. F., and J. Barcroft, 1938. Some factors governing the initiation of respiration in the chick. Am. J. Physiol. 121:684-691.
Downloaded from http://ps.oxfordjournals.org/ at Mount Royal College on June 14, 2015
o c o