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The Effect of Temperature on the Uropygial Gland Alkane Diol Diesters in the Kn Mutation of the Domestic Chicken1
The Effect of Temperature on the Uropygial Gland Alkane Diol Diesters in the Kn Mutation of the Domestic Chicken1 H. E. WALKER and R. G. SOMES, JR. Nutritional Sciences Department, University of Storrs, Connecticut 06268
Connecticut,
(Received for publication June 2, 1978)
1979 Poultry Science 58:998-1000 INTRODUCTION
tant chickens could be affected by raising these birds at a temperature which would cause their basal metabolic rate to be comparable to that of normal chickens.
The sex-linked k* locus of the domestic chicken which determines rate of feather growth consists of four alleles with the Kn allele being dominant to the other three (Somes, 1969 and McGibbon, 1977). Besides causing a delay in feather development and extreme nakedness in early life, the K11 gene has other pleiotropic effects. Chickens with this gene also have reduced comb development, are lighter in weight, have hypertrophied uropygial glands (Somes, 1975), and quantitative changes in the composition of the uropygial gland diesters (Walker and Somes, 1978). These mutant chickens have a diester composition that resembles that of older birds (Walker and Somes, 1978). Due to the decreased feather cover they may have an increased basal metabolic rate (Sturkie, 1976). According to Brody (1945), there is a theory which relates increased basal metabolic rates to an increased aging process. We have hypothesized that the previously observed compositional changes in the uropygial gland diesters of these birds may be due to this increased aging process (Walker and Somes, 1978). The work reported here was undertaken to see if a change in the composition of the diesters of the mu-
MATERIALS AND METHODS
1 Scientific Contribution No. 717, Storrs Agricultural Experiment Station, The University of Connecticut, Storrs, CT 06268.
In previous work with another naked mutant, the scaleless type, we found that at a temperature of about 34.4 C the C 0 2 output of the scaleless chicken was equal to that of normal chickens at 22.2 C (unpublished data). Based on this knowledge, six homozygous mutant male (Kn/Kn) chickens were raised intermingled from one day of age in a battery cage at 34.4 ± 2.2 C. Five homozygous mutant males and six normal males (k+/k+) were also raised under similar conditions but at 22.2 ± 2.2 C. All chickens were fed standard rations until 14 weeks of age when they were sacrificed. The combs and uropygial glands were removed at the time of death and weighed. Uropygial diesters were analyzed by a Hewlett-Packard 402 research gas chromatograph using columns containing Supelco 10% SP2330 on 100/120 mesh Supercoport at 200 C and SE 30 at 230 C, respectively, by the techniques previously described (Walker and Somes, 1978). The mole percentages of each carbon chain length fatty acid and diol were calculated and comparisons were made between the three test groups by analysis of variance and the Hartley sequential test of mean differences (Snedecor and Cochran, 1976).
998
Downloaded from http://ps.oxfordjournals.org/ at Monash University on April 12, 2015
ABSTRACT Lipids from the uropygial glands of Kn/Kn males raised at 34.4 C, and Kn/Kn and k+/k+ males raised at 22.2 C were quantitatively analyzed to determine if lowering the metabolic rate of this semi-naked mutant would alter the composition of its uropygial gland lipids. No significant differences were found between the two Kn/Kn groups in fatty acid or diol composition. Body weights also did not significantly differ nor did total gland weight as a percent of body weight or lipid weight as a percent of total gland weight. The only significant difference was in comb weight as a percent of body weight. The Kn/Ka males raised at 34.4 C had much larger combs as compared to the Kn/Kn males raised at 22.2 C.
999
RESEARCH NOTE TABLE 1. Temperature and genotype effects on body, uropygial gland, uropygial lipid, and comb weights
Pheno- Genotype type
Roomi temperature Body wt (C)
Total gland wt/body wt X 100 Lipid wt (%) (g)
Lipid wt/ total gland wtX 100
Comb wt
Comb wt/ body wt X 100
(%)
(g)
(%)
4.11 (1.45)
.29 a (.07)
.88 (.47)
20.6 a (7.3)
4.02 (2.36)
.27 a (.10)
Total gland wt
(g)
Kn/Kn 34.4
1415 a (331.9)'
Mutant
Kn/Kn 22.2
1384 a (173.9)
3.72 (1.36)
.28 a (.14)
.55 (.55)
13.7 a b (11.1)
1.53 (.69)
.llb (.04)
Normal
k+lk+
1956 b (186.7)
1.94 (.47)
.10° (.02)
.13 (.05)
6.6 b (1.6)
4.89 (1.84)
.25 a (.10)
22.2
a,b Means in each column with different superscripts are significantly different (P<.05). ( ) Represents the standard deviation.
RESULTS AND DISCUSSION Effects of genotype and temperature on uropygial lipid, uropygial gland, body and comb weights are shown in Table 1. The size of the uropygial glands of the two K^IK^ groups were unaffected by the change in temperature. As previously described (Somes, 1975 and Walker and Somes, 1978), the glands from mutant chickens were significantly larger than those of the non-mutants. The Kn/Kn males raised at 34.4 C had significantly greater amounts of lipid as percentage of gland weight than did the k+/k+ chickens. The amount of uropygial lipid from the Kn/Kn and k+/k+ chickens raised at 22.2 C were significantly different at the 10% level. We had previously observed that comb weights were reduced in the KnIKn chickens (Somes, 1975). In this study, the comb weights of the mutant birds raised at 34.4 C were no different than those of normal birds raised at a lower temperature. However, both of these groups had significantly larger combs than the Kn/Kn males raised at 22.2 C. Comb growth responds to a variety of hormonal and environmental factors and is usually a good indicator of gonadal development and testosterone secretion. In a previous study (Walker and Somes, 1978), we suggested that uropygial gland lipid production might be under testosterone control with testosterone having an inhibiting effect on lipid production. The results of this study, however, do not agree with that hypothesis if the comb size of the KnIKn males raised at 34.4 C was a true indication of their gonadal
development. It is also known that birds raised at higher temperatures have correspondingly larger combs than those raised at lower temperatures (Lamoreux, 1943). If the large comb size of the Kn/Kn males from the 34.4 C room is only due to a temperature effect, then the lipid production results are still consistent with previously reported results (Walker and Somes, 1978). No difference was found in the body weights between the two mutant male types raised at different temperatures. The normal feathering chickens had significantly greater body weights than did the other two groups. It has been suggested that without adequate feather cover, the chickens would use more energy for maintenance of body temperature and less would be available for growth. However, even when the Kn/Kn chickens were raised at warmer temperatures that would make their energy requirements for temperature maintenance less, no significant increase in growth occurred. It would appear that the KnIKn gene retards the growth of the whole chicken organism as well as affecting feather development. Although the two groups of Kn/Kn males were raised at two temperatures that differed by 12.2 C, a quantitative analysis of the uropygial gland lipids did not show any differences in their fatty acid or diol compositions. Differences similar to those previously described (Walker and Somes, 1978), occurred between the mutant and normal chickens raised at the same temperature. The results of this experiment verify those
Downloaded from http://ps.oxfordjournals.org/ at Monash University on April 12, 2015
Mutant
1000
WALKER AND SOMES, JR.
in our previous study (Walker and Somes, 1978), but they do not add any insight as to the cause of the uropygial lipid compositional changes that are characteristic of the Kn mutant. These data would seem not to substantiate the hypothesis that these changes are due t o an increased aging effect due to the increased metabolic rate which would be expected at moderate temperatures. REFERENCES
Downloaded from http://ps.oxfordjournals.org/ at Monash University on April 12, 2015
Brody, W., 1945. Bioenergetics and growth with special reference to the efficiency complex in domestic animals. Waverly Press, Baltimore, MD. Lamoreux, W. F., 1943. Effect of differences in light
and temperature upon the size of combs on White Leghorns. Endocrinology 32:497—504. McGibbon, W. H., 1977. A sex-linked mutation affecting rate of feathering in chickens. Poultry Sci. 56: 872-875. Snedecor, G., and W. Cochran, 1976. Statistical methods. The Iowa State University Press, Ames, IA. Somes, R. G., Jr., 1969. Delayed feathering, a third allele at the K locus of the domestic fowl. J. Hered. 60:281-286. Somes, R. G., Jr., 1975. Pleiotropic effects of the sexlinked delayed feathering gene, Kn, in the chicken. Poujtry Sci. 54:208-216. Sturkie, P., 1976. Avian physiology. 3rd Ed. SpringerVerlag, New York, NY. Walker, H. E., and R. G. Somes, Jr., 1978. Uropygial gland alkane diol diesters in the Kn mutation of the domestic chicken. Lipids 13:492—496.
Connecticut,
(Received for publication June 2, 1978)
1979 Poultry Science 58:998-1000 INTRODUCTION
tant chickens could be affected by raising these birds at a temperature which would cause their basal metabolic rate to be comparable to that of normal chickens.
The sex-linked k* locus of the domestic chicken which determines rate of feather growth consists of four alleles with the Kn allele being dominant to the other three (Somes, 1969 and McGibbon, 1977). Besides causing a delay in feather development and extreme nakedness in early life, the K11 gene has other pleiotropic effects. Chickens with this gene also have reduced comb development, are lighter in weight, have hypertrophied uropygial glands (Somes, 1975), and quantitative changes in the composition of the uropygial gland diesters (Walker and Somes, 1978). These mutant chickens have a diester composition that resembles that of older birds (Walker and Somes, 1978). Due to the decreased feather cover they may have an increased basal metabolic rate (Sturkie, 1976). According to Brody (1945), there is a theory which relates increased basal metabolic rates to an increased aging process. We have hypothesized that the previously observed compositional changes in the uropygial gland diesters of these birds may be due to this increased aging process (Walker and Somes, 1978). The work reported here was undertaken to see if a change in the composition of the diesters of the mu-
MATERIALS AND METHODS
1 Scientific Contribution No. 717, Storrs Agricultural Experiment Station, The University of Connecticut, Storrs, CT 06268.
In previous work with another naked mutant, the scaleless type, we found that at a temperature of about 34.4 C the C 0 2 output of the scaleless chicken was equal to that of normal chickens at 22.2 C (unpublished data). Based on this knowledge, six homozygous mutant male (Kn/Kn) chickens were raised intermingled from one day of age in a battery cage at 34.4 ± 2.2 C. Five homozygous mutant males and six normal males (k+/k+) were also raised under similar conditions but at 22.2 ± 2.2 C. All chickens were fed standard rations until 14 weeks of age when they were sacrificed. The combs and uropygial glands were removed at the time of death and weighed. Uropygial diesters were analyzed by a Hewlett-Packard 402 research gas chromatograph using columns containing Supelco 10% SP2330 on 100/120 mesh Supercoport at 200 C and SE 30 at 230 C, respectively, by the techniques previously described (Walker and Somes, 1978). The mole percentages of each carbon chain length fatty acid and diol were calculated and comparisons were made between the three test groups by analysis of variance and the Hartley sequential test of mean differences (Snedecor and Cochran, 1976).
998
Downloaded from http://ps.oxfordjournals.org/ at Monash University on April 12, 2015
ABSTRACT Lipids from the uropygial glands of Kn/Kn males raised at 34.4 C, and Kn/Kn and k+/k+ males raised at 22.2 C were quantitatively analyzed to determine if lowering the metabolic rate of this semi-naked mutant would alter the composition of its uropygial gland lipids. No significant differences were found between the two Kn/Kn groups in fatty acid or diol composition. Body weights also did not significantly differ nor did total gland weight as a percent of body weight or lipid weight as a percent of total gland weight. The only significant difference was in comb weight as a percent of body weight. The Kn/Ka males raised at 34.4 C had much larger combs as compared to the Kn/Kn males raised at 22.2 C.
999
RESEARCH NOTE TABLE 1. Temperature and genotype effects on body, uropygial gland, uropygial lipid, and comb weights
Pheno- Genotype type
Roomi temperature Body wt (C)
Total gland wt/body wt X 100 Lipid wt (%) (g)
Lipid wt/ total gland wtX 100
Comb wt
Comb wt/ body wt X 100
(%)
(g)
(%)
4.11 (1.45)
.29 a (.07)
.88 (.47)
20.6 a (7.3)
4.02 (2.36)
.27 a (.10)
Total gland wt
(g)
Kn/Kn 34.4
1415 a (331.9)'
Mutant
Kn/Kn 22.2
1384 a (173.9)
3.72 (1.36)
.28 a (.14)
.55 (.55)
13.7 a b (11.1)
1.53 (.69)
.llb (.04)
Normal
k+lk+
1956 b (186.7)
1.94 (.47)
.10° (.02)
.13 (.05)
6.6 b (1.6)
4.89 (1.84)
.25 a (.10)
22.2
a,b Means in each column with different superscripts are significantly different (P<.05). ( ) Represents the standard deviation.
RESULTS AND DISCUSSION Effects of genotype and temperature on uropygial lipid, uropygial gland, body and comb weights are shown in Table 1. The size of the uropygial glands of the two K^IK^ groups were unaffected by the change in temperature. As previously described (Somes, 1975 and Walker and Somes, 1978), the glands from mutant chickens were significantly larger than those of the non-mutants. The Kn/Kn males raised at 34.4 C had significantly greater amounts of lipid as percentage of gland weight than did the k+/k+ chickens. The amount of uropygial lipid from the Kn/Kn and k+/k+ chickens raised at 22.2 C were significantly different at the 10% level. We had previously observed that comb weights were reduced in the KnIKn chickens (Somes, 1975). In this study, the comb weights of the mutant birds raised at 34.4 C were no different than those of normal birds raised at a lower temperature. However, both of these groups had significantly larger combs than the Kn/Kn males raised at 22.2 C. Comb growth responds to a variety of hormonal and environmental factors and is usually a good indicator of gonadal development and testosterone secretion. In a previous study (Walker and Somes, 1978), we suggested that uropygial gland lipid production might be under testosterone control with testosterone having an inhibiting effect on lipid production. The results of this study, however, do not agree with that hypothesis if the comb size of the KnIKn males raised at 34.4 C was a true indication of their gonadal
development. It is also known that birds raised at higher temperatures have correspondingly larger combs than those raised at lower temperatures (Lamoreux, 1943). If the large comb size of the Kn/Kn males from the 34.4 C room is only due to a temperature effect, then the lipid production results are still consistent with previously reported results (Walker and Somes, 1978). No difference was found in the body weights between the two mutant male types raised at different temperatures. The normal feathering chickens had significantly greater body weights than did the other two groups. It has been suggested that without adequate feather cover, the chickens would use more energy for maintenance of body temperature and less would be available for growth. However, even when the Kn/Kn chickens were raised at warmer temperatures that would make their energy requirements for temperature maintenance less, no significant increase in growth occurred. It would appear that the KnIKn gene retards the growth of the whole chicken organism as well as affecting feather development. Although the two groups of Kn/Kn males were raised at two temperatures that differed by 12.2 C, a quantitative analysis of the uropygial gland lipids did not show any differences in their fatty acid or diol compositions. Differences similar to those previously described (Walker and Somes, 1978), occurred between the mutant and normal chickens raised at the same temperature. The results of this experiment verify those
Downloaded from http://ps.oxfordjournals.org/ at Monash University on April 12, 2015
Mutant
1000
WALKER AND SOMES, JR.
in our previous study (Walker and Somes, 1978), but they do not add any insight as to the cause of the uropygial lipid compositional changes that are characteristic of the Kn mutant. These data would seem not to substantiate the hypothesis that these changes are due t o an increased aging effect due to the increased metabolic rate which would be expected at moderate temperatures. REFERENCES
Downloaded from http://ps.oxfordjournals.org/ at Monash University on April 12, 2015
Brody, W., 1945. Bioenergetics and growth with special reference to the efficiency complex in domestic animals. Waverly Press, Baltimore, MD. Lamoreux, W. F., 1943. Effect of differences in light
and temperature upon the size of combs on White Leghorns. Endocrinology 32:497—504. McGibbon, W. H., 1977. A sex-linked mutation affecting rate of feathering in chickens. Poultry Sci. 56: 872-875. Snedecor, G., and W. Cochran, 1976. Statistical methods. The Iowa State University Press, Ames, IA. Somes, R. G., Jr., 1969. Delayed feathering, a third allele at the K locus of the domestic fowl. J. Hered. 60:281-286. Somes, R. G., Jr., 1975. Pleiotropic effects of the sexlinked delayed feathering gene, Kn, in the chicken. Poujtry Sci. 54:208-216. Sturkie, P., 1976. Avian physiology. 3rd Ed. SpringerVerlag, New York, NY. Walker, H. E., and R. G. Somes, Jr., 1978. Uropygial gland alkane diol diesters in the Kn mutation of the domestic chicken. Lipids 13:492—496.