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The Effect of Dietary Lysine upon the Free Lysine Content of Egg Yolks
THE EFFECT OF DIETARY LYSINE UPON THE FREE LYSINE CONTENT OF EGG YOLKS D. J. BRAY AND M. KELLY Department of Animal Science, University of Illinois, Vrbana (Received for publication July 14, 1966)
Egg yolks have been shown to contain amino acids in the chemically free state by Lea and Rhodes (1953) and Ducay et al. (1960). The present report deals with (1) the quantitative content of free lysine in egg yolk substance and (2) the effect of the level of dietary lysine upon the free lysine content of egg yolk. Diets containing the levels of lysine indicated in Figure 1 were each fed to 13 individually-caged pullets (Bray, 1966). Six eggs produced on the 53rd day of the assay were randomly chosen from each dietary regimen for microbiological determination of free lysine in egg yolk material. After each yolk was wiped free of albumen, the
vitelline membrane was ruptured and removed and an aliquot of blended yolk material was dialyzed across % 2 dialysis tubing* against distilled water for 24 hours. The lysine content of the dialyzate was determined as described by Difco Laboratories (1963). The dietary levels of lysine had a highly significant linear effect upon the concentration of free lysine in egg yolks, Table 1. As shown in Figure 1, the concentration of free lysine in egg yolk was approximately 550 micrograms per milliliter at the accepted dietary requirement level of 0.5 per* Visking Division, Union Carbide Corp., Chicago, Illinois.
650 0
600 CD O
550
UJ
co >-
500
_i UJ
uj
0
0
0
y=306 + 482X
450 40C_ .30
.40 .50 .60 LYSINE, % OF DIET
.70
FIG. 1. The effect of increasing levels of dietary lysine upon the free lysine content of egg yolks.
1425
1426
RESEARCH NOTES
TABLE 1.—Analysis of variance of free lysine content of egg yolk as influenced by the level of dietary lysine
Source
Degrees of freedom
Lysine levels 8 Linear (1) Residual (7) Error 45 Total 53
Sum of squares
Mean squares
189,563 179,231 10,332 215,925 405,488
23,695*** 179,231*** 1,476 4,798
*** P (<.001).
cent of the diet (National Research Council, 1960). As the level of dietary lysine was increased from below to above the requirement, there did not appear to be an inflection in the rate of increase in the yolk content of free lysine as occurs in the plasma free lysine in the chick when the dietary level of lysine is increased beyond the need of maximum growth (Zimmerman and Scott, 1965). The narrow range of levels of lysine fed in the present study may have precluded the detection of such an effect. The fact that the free amino acid content of egg yolk can be influenced by the level
of dietary amino acids, at least for lysine, indicates another criterion for measuring the effect of amino acid balance of the diet upon laying pullets. The pullet has the capacity to deliver a daily sample of egg yolk material that can be assayed to detect progressive changes in free amino acid content which may occur in conjunction with manipulations in the amino acid balance of the diet. REFERENCES Bray, D. J., 1966. Unpublished data. Difco Laboratories, 1963. Difco Manual, Ninth Edition. Difco Laboratories, Detroit, Michigan. Ducay, E. D., L. Kline and S. Mandeles, 1960. Free amino acid content of infertile chicken eggs. Poultry Sci. 39: 831-835. Lea, C. H., and D. N. Rhodes, 1953. Phospholi p i d . I. Partition chromatography of egg-yolk phospholipins on cellulose. Biochem. J. 54: 467-469. National Research Council, 1960. Nutrient requirements of domestic animals. No. 1. Nutrient requirements of poultry. Publication 827. Zimmerman, R. A., and H. M. Scott, 1965. Interrelationship of plasma amino acid levels and weight gain in the chick as influenced by suboptimal and superoptimal dietary concentrations of single amino acids. J. Nutrition, 87: 13-18.
OVIDUCAL IRRITANTS AND OVULATION IN THE DOMESTIC FOWL1 A. J. FARRINGTON, R. T. DUBY AND W. J. MELLEN Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst,
Massachusetts
(Received for publication August 1, 1966)
A key paper in the literature on neurohumoral control of ovulation in the domestic hen is that by Huston and Nalbandov (1953). According to these authors, "the presence of an irritant, such as a loop of thread, in the magnum portion of the oviduct of laying hens, completely suppresses 1 Contribution from the Massachusetts Experiment Station.
ovulation in the great majority of treated animals." The irritant was thought to prevent release of sufficient LH to cause ovulation ("ovulatory peaks"), but apparently did not prevent secretion of basal amounts of LH or secretion of FSH. Confirmation and extension of this work was reported by vanTienhoven (1953). Both of the reports cited have become widely quoted in the literature on avian re-
Egg yolks have been shown to contain amino acids in the chemically free state by Lea and Rhodes (1953) and Ducay et al. (1960). The present report deals with (1) the quantitative content of free lysine in egg yolk substance and (2) the effect of the level of dietary lysine upon the free lysine content of egg yolk. Diets containing the levels of lysine indicated in Figure 1 were each fed to 13 individually-caged pullets (Bray, 1966). Six eggs produced on the 53rd day of the assay were randomly chosen from each dietary regimen for microbiological determination of free lysine in egg yolk material. After each yolk was wiped free of albumen, the
vitelline membrane was ruptured and removed and an aliquot of blended yolk material was dialyzed across % 2 dialysis tubing* against distilled water for 24 hours. The lysine content of the dialyzate was determined as described by Difco Laboratories (1963). The dietary levels of lysine had a highly significant linear effect upon the concentration of free lysine in egg yolks, Table 1. As shown in Figure 1, the concentration of free lysine in egg yolk was approximately 550 micrograms per milliliter at the accepted dietary requirement level of 0.5 per* Visking Division, Union Carbide Corp., Chicago, Illinois.
650 0
600 CD O
550
UJ
co >-
500
_i UJ
uj
0
0
0
y=306 + 482X
450 40C_ .30
.40 .50 .60 LYSINE, % OF DIET
.70
FIG. 1. The effect of increasing levels of dietary lysine upon the free lysine content of egg yolks.
1425
1426
RESEARCH NOTES
TABLE 1.—Analysis of variance of free lysine content of egg yolk as influenced by the level of dietary lysine
Source
Degrees of freedom
Lysine levels 8 Linear (1) Residual (7) Error 45 Total 53
Sum of squares
Mean squares
189,563 179,231 10,332 215,925 405,488
23,695*** 179,231*** 1,476 4,798
*** P (<.001).
cent of the diet (National Research Council, 1960). As the level of dietary lysine was increased from below to above the requirement, there did not appear to be an inflection in the rate of increase in the yolk content of free lysine as occurs in the plasma free lysine in the chick when the dietary level of lysine is increased beyond the need of maximum growth (Zimmerman and Scott, 1965). The narrow range of levels of lysine fed in the present study may have precluded the detection of such an effect. The fact that the free amino acid content of egg yolk can be influenced by the level
of dietary amino acids, at least for lysine, indicates another criterion for measuring the effect of amino acid balance of the diet upon laying pullets. The pullet has the capacity to deliver a daily sample of egg yolk material that can be assayed to detect progressive changes in free amino acid content which may occur in conjunction with manipulations in the amino acid balance of the diet. REFERENCES Bray, D. J., 1966. Unpublished data. Difco Laboratories, 1963. Difco Manual, Ninth Edition. Difco Laboratories, Detroit, Michigan. Ducay, E. D., L. Kline and S. Mandeles, 1960. Free amino acid content of infertile chicken eggs. Poultry Sci. 39: 831-835. Lea, C. H., and D. N. Rhodes, 1953. Phospholi p i d . I. Partition chromatography of egg-yolk phospholipins on cellulose. Biochem. J. 54: 467-469. National Research Council, 1960. Nutrient requirements of domestic animals. No. 1. Nutrient requirements of poultry. Publication 827. Zimmerman, R. A., and H. M. Scott, 1965. Interrelationship of plasma amino acid levels and weight gain in the chick as influenced by suboptimal and superoptimal dietary concentrations of single amino acids. J. Nutrition, 87: 13-18.
OVIDUCAL IRRITANTS AND OVULATION IN THE DOMESTIC FOWL1 A. J. FARRINGTON, R. T. DUBY AND W. J. MELLEN Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst,
Massachusetts
(Received for publication August 1, 1966)
A key paper in the literature on neurohumoral control of ovulation in the domestic hen is that by Huston and Nalbandov (1953). According to these authors, "the presence of an irritant, such as a loop of thread, in the magnum portion of the oviduct of laying hens, completely suppresses 1 Contribution from the Massachusetts Experiment Station.
ovulation in the great majority of treated animals." The irritant was thought to prevent release of sufficient LH to cause ovulation ("ovulatory peaks"), but apparently did not prevent secretion of basal amounts of LH or secretion of FSH. Confirmation and extension of this work was reported by vanTienhoven (1953). Both of the reports cited have become widely quoted in the literature on avian re-