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A Study of the Effects of Gonadal Hormones on the Phosphorus Balance of the Domestic Fowl
A Study of the Effects of Gonadal Hormones on the Phosphorus Balance of the Domestic Fowl ALAN THOMPSON AND R. C. NOBLE* King's College, Newcastle upon Tyne, England (Received for publication May 10, 1961)
ALNAN (1925) suggested that gonadal hormones played an important role in calcium and phosphorus retention by the domestic fowl. A considerable literature has subsequently been published on the subject, although calcium appears to have received much more attention than has phosphorus. Common el al. (1947, 1948), using several hormonal treatments showed that both calcium and phosphorus retentions could be significantly increased by the administration of oestrogen and androgen together but not separately. All such findings have been based largely upon data obtained from conventional balance studies in which distinction cannot readily be made between the nonabsorbed faecal excretion of an element and that of endogenous origin excreted into the gastro-intestinal tract. As a result, the data obtained only provide a measure of overall net retention and allow of no assessment of true absorption and true excretion rates. It has been adequately shown that by means of radiochemical procedures utilising the principle of isotopic dilution, the amount of faecal endogenous excretion of an element can be measured (Hansard et al., 1951, 1954; Kleiber et al., 1951; Lofgreen and Kleiber, 1953; Visek et al., 1953). These procedures involve the use of a conventional balance experiment, together with a study of the distribution of * Recipient of a British Egg Marketing Board Studentship.
injected isotope between blood, faeces and urine. The resulting data make possible the calculation of the partition of the faecal excretion into non-absorbed dietary element and that of body origin secreted into the gastro-intestinal tract (the endogenous faecal excretion). This enables any change in the net balance of an element to be attributed to a change in (a) faecal endogenous excretion, (b) urinary excretion (c) true absorption, (d) a combination of the above. In the domestic fowl the situation is complicated by the excretion of combined urine and faeces. However evidence exists that once the injected radio-nuclide has attained equilibrium between the body tissues, the specific activities of the plasma, urine and faecal endogenous excretions should be equal (Kjerulf-Jensen, 1941; Thompson, 1960, unpublished). If certain minor assumptions are allowed, it appears permissible to apply the isotope dilution principle to the fowl, using the data to calculate the 'combined metabolic excretion,' a term used in the present work to cover the combined urinary and faecal endogenous excretions. Any change in the net balance of an element may then be considered to be the result of a change in (a) combined metabolic excretion, (b) true absorption, or (c) both. Although this suggested application is not so satisfactory as when applied to mammals, it provides more useful data than does the normal conventional balance procedure.
347
Techniques involving the use of phos-
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H
348
A. THOMPSON AND R. C. NOBLE
EXPERIMENTAL
Sixteen 10 week-old Rhode Island Red X Light Sussex pullets were kept in individual metabolism cages and fed commercial growers pellets. After a preliminary period of 12 days during which the diet was reduced to a rate of 80 g. per day, the birds were randomised into 4 blocks, each block containing 4 treatments which were as follows: (1) Control, no hormones, but injections of the same quantity of carrier oil as used in the other treatments, were given. (2) 1.0 mg. oestradiol dipropionate (O.D.P.) given each day for 9 days. (3) 0.5 mg. testosterone propionate (T.S.T.) given each day for 9 days. (4) 1.0 mg. oestradiol dipropionate plus 0.5 mg. testosterone propionate given each day for 9 days. Each bird received 80 g. of food daily, being given 50 g. in the morning and 30 g. in the afternoon. At the beginning of the experimental period the birds were weighed after which 0.25 mc. of phosphorus-32 was injected intramuscularly. Droppings for each 24-hour period were homogenised and aliquots were ovendried, ashed and finally taken up in 20% hydrochloric acid. At the commencement of days 8, 9 and 10, blood samples were taken from each bird and were obtained from the subclavian vein on days 8 and 9 and by slaughter and exsanguination on day 10. Final body-weights were taken prior to slaughter. The heparinised blood samples were centrifuged and the plasma withdrawn. Aliquots were dried, ashed and taken up in 20% hydrochloric acid. The acid extracts of excreta and blood were radio-assayed for P-32 content, using an end-window GM. counter, against standards prepared at the time of dosing. The total phosphorus content of samples
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phorus-32 in balance trials have been successfully applied to mammals (Kleiber el al., 1951; Lofgreen and Kleiber, 1953) but do not appear to have been used with birds. However, calcium-45 has been used in avian balance studies, several of which involved varying hormonal treatments, and these are of considerable interest here in view of the relationship between calcium and phosphorus metabolism. Govaerts et al. (1951), using pigeons, showed that oestrogen reduced- the excretion rate of injected Ca-45, while Common et al. (1953) and Jowsey et al. (1953), repeating part of a balance trial carried out five years earlier, introduced into it a radiochemical Ca-45 balance. Their experiment was divided into two parts, the first being a conventional balance trial lasting for ten days (Common et al., 1953) in which significant increases in retention of calcium were obtained not only with oestrogen and androgen together but also with each hormone separately. On the eleventh day Ca-45 was fed to the birds and a one day radio-chemical balance was performed (Jowsey et al., 1953), this forming the basis of the second part of the work. By this means it was possible to provide an estimate of excretory body loss of the element (called by the authors 'presumptive loss') and to calculate a value for true absorption of calcium. The latter was only increased by oestrogen plus androgen together, while 'presumptive loss' was found to be less in control birds than with any other treatment. The net calcium gain was only significantly increased by the double treatment, while in the case of oestrogen alone a loss was noted. Jowsey attempted to explain this result by suggesting that the body had become refractory to the female hormone by the eleventh day after an initial positive response, a suggestion which has been questioned recently (Common et al., 1956).
349
GONADAL HORMONES AND PHOSPHORUS
TABLE 1.—Ejfect of gonadal hormones on live-weight gain, serum dry-matter and crude protein contents, and oviduct weights (Means + Standard Error)
Live-weight gain g. Serum dry matter % Serum crude protein % Oviduct weights g.
Control
Oestrogen (O.D.P.)
Androgen (T.S.T.)
Oestrogen plus androgen (O.D.P.+T.S.T.)
148 + 2.9 5.92 + 0.14 4.35 + 0.10 0.25
167 + 14.6 12.67 + 1.08*** 5.82 + 0.21*** 13.73
176+12.3 5.40 + 0.05* 3.90 + 0.09* 0.18
181±17.4 11.59 + 0.52*** 5.81 + 0.14*** 20.54
was determined by the method of Fiske and Subbarow (1925), with slight modification. The nitrogen content of the plasma was determined by a micro-Kjeldahl procedure. RESULTS AND DISCUSSION
Table 1 shows the liveweight gains, the dry-matter and protein contents of the blood plasma; oviduct weights are also given. Although all treatments produced increases in liveweight gains over the control, such increases were not significant. Dry-matter and protein contents of the plasma were increased by oestrogen alone and by the double treatment, such increases being very highly significant (P<.001). These effects may be expected in birds treated with O.D.P. and O.D.P.
-I-T.S.T. (Jackson and Brown, 1957) and this together with the large increase in oviduct weights establishes the degree of response of the pullets to the hormonal treatments. Androgen alone, produced a significant decrease (P<.05) in both drymatter and protein contents of the plasma. The balance data may be divided into two sections; (1) data for the period, days 7-9 (2) data for the total balance period, days 1-9. (1) Data for days 7-9. (Table 2). In addition to the results of the conventional balance trial over this period, the radiochemical data for the plasma and excreta have provided the estimate of the combined metabolic excretory phosphorus (urinary+faecal endogenous excretions), using the isotope dilution principle. As a result, it has been possible to calculate the
TABLE 2.—Ejfect of gonadal hormones on phosphorus absorption and excretion during a 3-day period {Days 7, 8 and 9) (Means + Standard Error)
Control Phosphorus intake mg. daily 576.5 Total phosphorus excreted mg. daily 419.5 + 6.3 Net phosphorus retention mg. daily 157.0 + 6.3 Combined metabolic phosphorus excretion mg. daily 65.5 + 7.3 mg.Ag- body-weight 47.4 + 4.9 True absorbed phosphorus mg. daily 222.5 + 6.1 Significant at the 1 percent level. Significant at the 0.1 percent level.
k
Oestrogen (O.D.P.)
Androgen (T.S.T.)
Oestrogen plus androgen (O.D.P.+T.S.T.)
576.5 419.9 + 6.7 156.6 + 6.7
576.5 404.0+15.5 172.5 + 15.5
575.5 336.5 + 9.9*** 240.0 + 9.9***
75.1 + 6.1 53.7 + 4.4 231.7 + 8.8
52.3 + 7.2 37.3 + 5.2 224.8+17.1
34.3 + 3.0** 23.7 + 2.2** 274.3 + 10.1**
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' Significant at the 5 percent level. : ** Significant at the 0.1 percent level.
350 TABLE 3.—Effect
A. THOMPSON AND R. C. NOBLE of gonadal hormones on phosphorus absorption and excretion during a 9-day period {Days 1-9) (Means + Standard Error)
Control Phosphorus intake rag. daily Total phosphorus excreted mg. daily Net phosphorus retention mg. daily Combined metabolic phosphorus excretion mg. daily
576.5 435.1±6.7 141.4 + 6.7 67.7±7.0
Oestrogen (O.D.P.)
Androgen (T.S.T.)
Oestrogen plus androgen (O.D.P.+T.S.T.)
576.5 576.5 576.5 408.2 + 8.8* 400.5+14.4 346.1 + 12.2*** 168.3 + 8.8* 176.0 + 14.4 230.4 + 12.2*** 73.1 + 6.1
52.4±7.8
35.4+3.6**
true absorption of phosphorus. Birds receiving T.S.T. and T.S.T. + O.D.P. showed reduced total phosphorus excretion and consequently increased net phosphorus retention. The effect of the double treatment as compared with the controls was very highly significant (P<.001) but no significance could be shown in the case of the T.S.T. treatment. That some of the increase in phosphorus retention was the result of lowered excretion may be seen from the combined metabolic excretion data; the lowest values being found in the O.D.P.+T.S.T. treated birds (P<0.01). The significance of this result was not affected by correction for differences in body-weight. In fact the combined metabolic phosphorus excretion in the birds receiving the combined treatment was less than half that of the control birds. True absorbed phosphorus was determined by difference; again only the O.D.P. + T.S.T. treatment produced any increase in phosphorus absorption, a result which was highly significant (P<0.01). It would appear that in addition to decreased metabolic+urinary excretion, increased abosrption results from the double hormone treatment. While the work of Jowsey et al. (1953)
dealt only with calcium, some of the results are of interest in the present context. True absorbed calcium was found to be highest with the double hormonal treatment, although a definite decrease in calcium absorption in birds receiving O.D.P. alone was noted; no similar decrease was found in phosphorus absorption. In so far as 'presumptive loss' as calculated by the above authors may be equated with 'combined metabolic excretion' in the present work, differences in the excretion of calcium and phosphorus occasioned by hormonal treatments obviously exist. Jowsey et al. found the lowest presumptive loss of calcium in the control birds and highest in those receiving O.D.P. + T.S.T., whereas with phosphorus in the present work, the reverse appears to be true. (2) Data for days 1-9. (Table 3). The data for the complete 9-day balance trial show that all treatments reduced the total phosphorus excretion and consequently increased the net retention of phosphorus. The increased retention brought about by O.D.P. alone, proved to be significant (P<0.05) while that produced by O.D.P. + T.S.T. was very highly significant (P<0.001). Owing to the greater variation in the results from the group of birds receiving T.S.T. alone, the increase due to
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" Significant at the 5 percent level. ** Significant at the 1 percent level. "** Significant at the 0.1 percent level.
GONADAL H O R M O N E S AND P H O S P H O R U S 300
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351
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FIG. 1. The effects of gonadal hormones on the daily phosphorus retention in immature pullets. this treatment just failed to attain significance at the 5 percent level. Also shown in Table 3 are the estimates of the combined metabolic excretions of phosphorus calculated from the radiochemical data obtained during days 7-9 and the chemical d a t a for the 9-day balance period. These estimates agree very closely with those derived from the 3-day balance period and indicate the consistency of the daily balance data. The effects of the double hormonal t r e a t m e n t over the 9-day period is essentially the same as t h a t shown for the 3-day trial, namely, the increase in the true absorption and decrease in the excretion of phosphorus resulting in a large positive net retention of the element. Common et al. (1947, 1948) recorded a similar effect of the double hormonal t r e a t m e n t . On first sight T.S.T. would appear to have produced a similar, though smaller effect upon true absorption, excretion and net retention, b u t , in fact, the differences failed to be significant. T h e effect of O.D.P. alone is of particular interest; net retention during days
7-9 was not increased, although over the 9-day period a significant increase was found. This result is similar to t h a t observed b y Common et al. (1953) a n d Jowsey et al. (1953) in their studies on calcium retention in oestrogen treated birds. These workers found a significant increase in retention over a 10-day balance trial, while on the 11th day a single d a y balance trial indicated a negative retention. Common and Jowsey have suggested t h a t oestrogen had an initial positive effect upon retention, reaching a maximum about the 4th day, followed by a definite decrease in retention as the b o d y became refractory to the hormone, finally resulting in a negative retention. Later work (Common et al., 1956) suggests t h a t the transient positive effect m a y not always occur, a consistent decline being more probable. Whether, in the present work, the positive increase in net retention of phosphorus during the first few days in birds receiving O.D.P. alone is due to a change in absorption, excretion, or both is impossible to determine from the results
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CE
352
A. THOMPSON AND R. C. NOBLE
obtained. Further work is in progress which may help to clear up this point. The daily mean net retentions of phosphorus under all treatments are shown graphically in Figure 1, and clearly show the large positive effect of the O.D.P. +T.S.T. treatment. SUMMARY AND CONCLUSIONS
Finally, the refractory nature of the body towards oestrogen treatment with time has been shown.
The authors wish to acknowledge the help given by Ciba Laboratories Limited, Horsham, England, in the supply of hormones and other materials. REFERENCES Common, R. H., W. A. Maw and J. R. Jowsey, 1953. Observations on the mineral metabolism of pullets. IX. The effects of oestrogen and androgen administered separately on the retention of calcium by the sexually immature pullet. Can. J. Agric. Sci. 33: 172-177. Common, R. H., K. A. McCully, H. A. Steppler and W. A. Maw, 1956. Observations on the mineral metabolism of pullets. XI. The effects of protracted treatment with oestrogen and with oestrogen plus androgen on retention of calcium by the sexually immature pullet. Can. J. Agric. Sci. 36: 166-173. Common, R. H., W. A. Rutledge and R. W. Hale, 1947. Gonadal hormones and mineral balance in the domestic fowl. Nature, 160: 541-542. Common, R. H., W. A. Rutledge and R. W. Hale, 1948. Observations on the mineral metabolism of pullets. VIII. The influence of gonadal hormones on retention of calcium and phosphorus. J. Agric. Sci. 38: 64-80. Fiske, C. H., and Y. Subbarow, 1925. The colorimetric determination of phosphorus. J. Biol. Chem. 66: 375. Govaerts, J., M. J. Dallemagne and J. Melon, 1951. Radiocalcium as an indicator in the study of the action of oestradiol on calcium metabolism. Endocrinology, 48: 443-452. Hainan, E. T., 1925. The calcium, phosphorus and nitrogen balance of the non-laying and laying pullet. J. Nat. Poultry Inst. 10:410-416. Hansard, S. L., C. L. Comar and M. P. Plumlee, 1951. The integration of concurrent chemical and radioisotope balance trials for the interpretation of calcium metabolism studies. J. Dairy Sci. 34: 508. Hansard, S. L., and M. P. Plumlee, 1954. Effects of dietary calcium and phosphorus levels upon the physiological behavior of calcium and phosphorus in the rat. J. Nutrition, 54: 17-31. Jackson, N., and W. 0. Brown, 1958. The effect of gonadal hormones on nitrogen retention in the immature fowl. Poultry Sci. 37: 886-889. Jowsey, J. R., W. F. Oliver, W. A. Maw and R. H. Common, 1953. Observations on the mineral
Downloaded from http://ps.oxfordjournals.org/ at Florida International University on May 30, 2015
A 9-day phosphorus balance trial was carried out on immature pullets to which had been administered oestradiol dipropionate, testosterone propionate, and oestradiol plus testosterone. Dry-matter and protein contents of the blood plasma, together with oviduct weights showed that the treatments had had the desired effect. Each bird received an intramuscular injection of phosphorus32 at the beginning of the experimental period to allow of the calculation of the 'combined metabolic excretory phosphorus' and the true phosphorus absorption during days 7, 8 and 9; these data being calculated using the isotope dilution procedure. Evidence is provided for a positive interaction of oestrogen and androgen upon the phosphorus balance. During days 7, 8 and 9, net retention and true absorbed phosphorus were increased while the combined metabolic excretory phosphorus was decreased by the administration of oestrogen and androgen together; all these results being significant. Significance could not be attached to the effects of the hormones administered separately. Over the complete 9-day trial, net retention was increased to a significant degree by both the double hormone treatment and the oestrogen alone. Significance for the increase produced with androgen alone could not be shown.
ACKNOWLEDGMENT
GONADAL HORMONES AND PHOSPHORUS metabolism of pullets. X. The effects of gonadal hormones on retention and turnover of calcium by the skeleton. Can. J. Agric. Sci. 33: 216-224. Kjerulf-Jensen, K., 1941. Excretion of phosphorus by the bowel. Acta. Physiol. Scand. 3: 1-27. Kleiber, M., A. H. Smith, N. B. Ralston and A. L. Black, 1951. Radiophosphorus P32 as tracer for measuring endogenous phosphorus in cow faeces.
353
J. Nutrition, 35: 253:263. Lofgreen, G. P., and M. Kleiber, 1953. The availability of phosphorus in alfalfa hay. J. Animal Sci. 12: 366-371. Visek, W. J., R. A. Monroe, E. W. Swanson and C. L. Comar, 1953. Determination of endogenous faecal calcium in cattle by a simple isotope dilution method. J. Nutrition, 50: 23-33.
W. E. DONALDSON AND R. I. MILLAR 2 Poultry Science Department, University of Rhode Island, Kingston, Rhode Island (Received for publication May 10. 1961)
INTRODUCTION
B
ECAUSE high feed consumption, obesity and relatively low egg production are characteristic of heavy meattype laying hens, interest has developed in attempting to improve the performance of this type of hen by restriction of feed intake. Numerous reports dealing with the effects of feed restriction during the growing period on subsequent egg production have been published, but there are few reports available on restriction during the laying period. Heywang (1940) observed drastic reductions in egg production but no effect on body weight or egg size by restricting the feed intake of Leghorn hens to 87J and 75% of ad libitum intake. Singsen et al. (1959) used body weight, egg production and environmental temperature to predict feed consumption of White Rock laying hens. Controlled feeding (based on predicted consumption) of high and low energy rations was compared with ad libitum feeding of the same rations. Al1
Contribution No. 1025 of the Rhode Island Agricultural Experiment Station. 2 Present address: Beacon Milling Company, Cayuga, New York.
though intake of the high energy ration was only 84.3% of ad libitum, production was not affected. Production was reduced when the low energy ration was controlfed (77% of ad libitum) even though digestible nutrient intake was calculated to be the same as the intake of the birds control-fed the high energy rations. Combs et al. (1961) reported that restriction of energy intake of heavy-type hens to 81 and 87% of ad libitum intake did not affect egg production, Haugh unit scores or mortality. Reductions in body weight gain and rate of increase in egg size were observed with energy restriction. The purpose of the experiments reported herein was to determine the effects of energy restriction on productive traits of meat-type laying hens. PROCEDURE
Two experiments were conducted in each of which April hatched pullets were placed on experiment on the succeeding January 21st and continued for 36 weeks All birds were reared on an ad libitumieeding system. In experiment 1, 29 White Plymouth Rock pullets were randomly assigned to
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Effects of Energy Restriction on Laying Hens 1
ALNAN (1925) suggested that gonadal hormones played an important role in calcium and phosphorus retention by the domestic fowl. A considerable literature has subsequently been published on the subject, although calcium appears to have received much more attention than has phosphorus. Common el al. (1947, 1948), using several hormonal treatments showed that both calcium and phosphorus retentions could be significantly increased by the administration of oestrogen and androgen together but not separately. All such findings have been based largely upon data obtained from conventional balance studies in which distinction cannot readily be made between the nonabsorbed faecal excretion of an element and that of endogenous origin excreted into the gastro-intestinal tract. As a result, the data obtained only provide a measure of overall net retention and allow of no assessment of true absorption and true excretion rates. It has been adequately shown that by means of radiochemical procedures utilising the principle of isotopic dilution, the amount of faecal endogenous excretion of an element can be measured (Hansard et al., 1951, 1954; Kleiber et al., 1951; Lofgreen and Kleiber, 1953; Visek et al., 1953). These procedures involve the use of a conventional balance experiment, together with a study of the distribution of * Recipient of a British Egg Marketing Board Studentship.
injected isotope between blood, faeces and urine. The resulting data make possible the calculation of the partition of the faecal excretion into non-absorbed dietary element and that of body origin secreted into the gastro-intestinal tract (the endogenous faecal excretion). This enables any change in the net balance of an element to be attributed to a change in (a) faecal endogenous excretion, (b) urinary excretion (c) true absorption, (d) a combination of the above. In the domestic fowl the situation is complicated by the excretion of combined urine and faeces. However evidence exists that once the injected radio-nuclide has attained equilibrium between the body tissues, the specific activities of the plasma, urine and faecal endogenous excretions should be equal (Kjerulf-Jensen, 1941; Thompson, 1960, unpublished). If certain minor assumptions are allowed, it appears permissible to apply the isotope dilution principle to the fowl, using the data to calculate the 'combined metabolic excretion,' a term used in the present work to cover the combined urinary and faecal endogenous excretions. Any change in the net balance of an element may then be considered to be the result of a change in (a) combined metabolic excretion, (b) true absorption, or (c) both. Although this suggested application is not so satisfactory as when applied to mammals, it provides more useful data than does the normal conventional balance procedure.
347
Techniques involving the use of phos-
Downloaded from http://ps.oxfordjournals.org/ at Florida International University on May 30, 2015
H
348
A. THOMPSON AND R. C. NOBLE
EXPERIMENTAL
Sixteen 10 week-old Rhode Island Red X Light Sussex pullets were kept in individual metabolism cages and fed commercial growers pellets. After a preliminary period of 12 days during which the diet was reduced to a rate of 80 g. per day, the birds were randomised into 4 blocks, each block containing 4 treatments which were as follows: (1) Control, no hormones, but injections of the same quantity of carrier oil as used in the other treatments, were given. (2) 1.0 mg. oestradiol dipropionate (O.D.P.) given each day for 9 days. (3) 0.5 mg. testosterone propionate (T.S.T.) given each day for 9 days. (4) 1.0 mg. oestradiol dipropionate plus 0.5 mg. testosterone propionate given each day for 9 days. Each bird received 80 g. of food daily, being given 50 g. in the morning and 30 g. in the afternoon. At the beginning of the experimental period the birds were weighed after which 0.25 mc. of phosphorus-32 was injected intramuscularly. Droppings for each 24-hour period were homogenised and aliquots were ovendried, ashed and finally taken up in 20% hydrochloric acid. At the commencement of days 8, 9 and 10, blood samples were taken from each bird and were obtained from the subclavian vein on days 8 and 9 and by slaughter and exsanguination on day 10. Final body-weights were taken prior to slaughter. The heparinised blood samples were centrifuged and the plasma withdrawn. Aliquots were dried, ashed and taken up in 20% hydrochloric acid. The acid extracts of excreta and blood were radio-assayed for P-32 content, using an end-window GM. counter, against standards prepared at the time of dosing. The total phosphorus content of samples
Downloaded from http://ps.oxfordjournals.org/ at Florida International University on May 30, 2015
phorus-32 in balance trials have been successfully applied to mammals (Kleiber el al., 1951; Lofgreen and Kleiber, 1953) but do not appear to have been used with birds. However, calcium-45 has been used in avian balance studies, several of which involved varying hormonal treatments, and these are of considerable interest here in view of the relationship between calcium and phosphorus metabolism. Govaerts et al. (1951), using pigeons, showed that oestrogen reduced- the excretion rate of injected Ca-45, while Common et al. (1953) and Jowsey et al. (1953), repeating part of a balance trial carried out five years earlier, introduced into it a radiochemical Ca-45 balance. Their experiment was divided into two parts, the first being a conventional balance trial lasting for ten days (Common et al., 1953) in which significant increases in retention of calcium were obtained not only with oestrogen and androgen together but also with each hormone separately. On the eleventh day Ca-45 was fed to the birds and a one day radio-chemical balance was performed (Jowsey et al., 1953), this forming the basis of the second part of the work. By this means it was possible to provide an estimate of excretory body loss of the element (called by the authors 'presumptive loss') and to calculate a value for true absorption of calcium. The latter was only increased by oestrogen plus androgen together, while 'presumptive loss' was found to be less in control birds than with any other treatment. The net calcium gain was only significantly increased by the double treatment, while in the case of oestrogen alone a loss was noted. Jowsey attempted to explain this result by suggesting that the body had become refractory to the female hormone by the eleventh day after an initial positive response, a suggestion which has been questioned recently (Common et al., 1956).
349
GONADAL HORMONES AND PHOSPHORUS
TABLE 1.—Ejfect of gonadal hormones on live-weight gain, serum dry-matter and crude protein contents, and oviduct weights (Means + Standard Error)
Live-weight gain g. Serum dry matter % Serum crude protein % Oviduct weights g.
Control
Oestrogen (O.D.P.)
Androgen (T.S.T.)
Oestrogen plus androgen (O.D.P.+T.S.T.)
148 + 2.9 5.92 + 0.14 4.35 + 0.10 0.25
167 + 14.6 12.67 + 1.08*** 5.82 + 0.21*** 13.73
176+12.3 5.40 + 0.05* 3.90 + 0.09* 0.18
181±17.4 11.59 + 0.52*** 5.81 + 0.14*** 20.54
was determined by the method of Fiske and Subbarow (1925), with slight modification. The nitrogen content of the plasma was determined by a micro-Kjeldahl procedure. RESULTS AND DISCUSSION
Table 1 shows the liveweight gains, the dry-matter and protein contents of the blood plasma; oviduct weights are also given. Although all treatments produced increases in liveweight gains over the control, such increases were not significant. Dry-matter and protein contents of the plasma were increased by oestrogen alone and by the double treatment, such increases being very highly significant (P<.001). These effects may be expected in birds treated with O.D.P. and O.D.P.
-I-T.S.T. (Jackson and Brown, 1957) and this together with the large increase in oviduct weights establishes the degree of response of the pullets to the hormonal treatments. Androgen alone, produced a significant decrease (P<.05) in both drymatter and protein contents of the plasma. The balance data may be divided into two sections; (1) data for the period, days 7-9 (2) data for the total balance period, days 1-9. (1) Data for days 7-9. (Table 2). In addition to the results of the conventional balance trial over this period, the radiochemical data for the plasma and excreta have provided the estimate of the combined metabolic excretory phosphorus (urinary+faecal endogenous excretions), using the isotope dilution principle. As a result, it has been possible to calculate the
TABLE 2.—Ejfect of gonadal hormones on phosphorus absorption and excretion during a 3-day period {Days 7, 8 and 9) (Means + Standard Error)
Control Phosphorus intake mg. daily 576.5 Total phosphorus excreted mg. daily 419.5 + 6.3 Net phosphorus retention mg. daily 157.0 + 6.3 Combined metabolic phosphorus excretion mg. daily 65.5 + 7.3 mg.Ag- body-weight 47.4 + 4.9 True absorbed phosphorus mg. daily 222.5 + 6.1 Significant at the 1 percent level. Significant at the 0.1 percent level.
k
Oestrogen (O.D.P.)
Androgen (T.S.T.)
Oestrogen plus androgen (O.D.P.+T.S.T.)
576.5 419.9 + 6.7 156.6 + 6.7
576.5 404.0+15.5 172.5 + 15.5
575.5 336.5 + 9.9*** 240.0 + 9.9***
75.1 + 6.1 53.7 + 4.4 231.7 + 8.8
52.3 + 7.2 37.3 + 5.2 224.8+17.1
34.3 + 3.0** 23.7 + 2.2** 274.3 + 10.1**
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' Significant at the 5 percent level. : ** Significant at the 0.1 percent level.
350 TABLE 3.—Effect
A. THOMPSON AND R. C. NOBLE of gonadal hormones on phosphorus absorption and excretion during a 9-day period {Days 1-9) (Means + Standard Error)
Control Phosphorus intake rag. daily Total phosphorus excreted mg. daily Net phosphorus retention mg. daily Combined metabolic phosphorus excretion mg. daily
576.5 435.1±6.7 141.4 + 6.7 67.7±7.0
Oestrogen (O.D.P.)
Androgen (T.S.T.)
Oestrogen plus androgen (O.D.P.+T.S.T.)
576.5 576.5 576.5 408.2 + 8.8* 400.5+14.4 346.1 + 12.2*** 168.3 + 8.8* 176.0 + 14.4 230.4 + 12.2*** 73.1 + 6.1
52.4±7.8
35.4+3.6**
true absorption of phosphorus. Birds receiving T.S.T. and T.S.T. + O.D.P. showed reduced total phosphorus excretion and consequently increased net phosphorus retention. The effect of the double treatment as compared with the controls was very highly significant (P<.001) but no significance could be shown in the case of the T.S.T. treatment. That some of the increase in phosphorus retention was the result of lowered excretion may be seen from the combined metabolic excretion data; the lowest values being found in the O.D.P.+T.S.T. treated birds (P<0.01). The significance of this result was not affected by correction for differences in body-weight. In fact the combined metabolic phosphorus excretion in the birds receiving the combined treatment was less than half that of the control birds. True absorbed phosphorus was determined by difference; again only the O.D.P. + T.S.T. treatment produced any increase in phosphorus absorption, a result which was highly significant (P<0.01). It would appear that in addition to decreased metabolic+urinary excretion, increased abosrption results from the double hormone treatment. While the work of Jowsey et al. (1953)
dealt only with calcium, some of the results are of interest in the present context. True absorbed calcium was found to be highest with the double hormonal treatment, although a definite decrease in calcium absorption in birds receiving O.D.P. alone was noted; no similar decrease was found in phosphorus absorption. In so far as 'presumptive loss' as calculated by the above authors may be equated with 'combined metabolic excretion' in the present work, differences in the excretion of calcium and phosphorus occasioned by hormonal treatments obviously exist. Jowsey et al. found the lowest presumptive loss of calcium in the control birds and highest in those receiving O.D.P. + T.S.T., whereas with phosphorus in the present work, the reverse appears to be true. (2) Data for days 1-9. (Table 3). The data for the complete 9-day balance trial show that all treatments reduced the total phosphorus excretion and consequently increased the net retention of phosphorus. The increased retention brought about by O.D.P. alone, proved to be significant (P<0.05) while that produced by O.D.P. + T.S.T. was very highly significant (P<0.001). Owing to the greater variation in the results from the group of birds receiving T.S.T. alone, the increase due to
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" Significant at the 5 percent level. ** Significant at the 1 percent level. "** Significant at the 0.1 percent level.
GONADAL H O R M O N E S AND P H O S P H O R U S 300
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351
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FIG. 1. The effects of gonadal hormones on the daily phosphorus retention in immature pullets. this treatment just failed to attain significance at the 5 percent level. Also shown in Table 3 are the estimates of the combined metabolic excretions of phosphorus calculated from the radiochemical data obtained during days 7-9 and the chemical d a t a for the 9-day balance period. These estimates agree very closely with those derived from the 3-day balance period and indicate the consistency of the daily balance data. The effects of the double hormonal t r e a t m e n t over the 9-day period is essentially the same as t h a t shown for the 3-day trial, namely, the increase in the true absorption and decrease in the excretion of phosphorus resulting in a large positive net retention of the element. Common et al. (1947, 1948) recorded a similar effect of the double hormonal t r e a t m e n t . On first sight T.S.T. would appear to have produced a similar, though smaller effect upon true absorption, excretion and net retention, b u t , in fact, the differences failed to be significant. T h e effect of O.D.P. alone is of particular interest; net retention during days
7-9 was not increased, although over the 9-day period a significant increase was found. This result is similar to t h a t observed b y Common et al. (1953) a n d Jowsey et al. (1953) in their studies on calcium retention in oestrogen treated birds. These workers found a significant increase in retention over a 10-day balance trial, while on the 11th day a single d a y balance trial indicated a negative retention. Common and Jowsey have suggested t h a t oestrogen had an initial positive effect upon retention, reaching a maximum about the 4th day, followed by a definite decrease in retention as the b o d y became refractory to the hormone, finally resulting in a negative retention. Later work (Common et al., 1956) suggests t h a t the transient positive effect m a y not always occur, a consistent decline being more probable. Whether, in the present work, the positive increase in net retention of phosphorus during the first few days in birds receiving O.D.P. alone is due to a change in absorption, excretion, or both is impossible to determine from the results
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CE
352
A. THOMPSON AND R. C. NOBLE
obtained. Further work is in progress which may help to clear up this point. The daily mean net retentions of phosphorus under all treatments are shown graphically in Figure 1, and clearly show the large positive effect of the O.D.P. +T.S.T. treatment. SUMMARY AND CONCLUSIONS
Finally, the refractory nature of the body towards oestrogen treatment with time has been shown.
The authors wish to acknowledge the help given by Ciba Laboratories Limited, Horsham, England, in the supply of hormones and other materials. REFERENCES Common, R. H., W. A. Maw and J. R. Jowsey, 1953. Observations on the mineral metabolism of pullets. IX. The effects of oestrogen and androgen administered separately on the retention of calcium by the sexually immature pullet. Can. J. Agric. Sci. 33: 172-177. Common, R. H., K. A. McCully, H. A. Steppler and W. A. Maw, 1956. Observations on the mineral metabolism of pullets. XI. The effects of protracted treatment with oestrogen and with oestrogen plus androgen on retention of calcium by the sexually immature pullet. Can. J. Agric. Sci. 36: 166-173. Common, R. H., W. A. Rutledge and R. W. Hale, 1947. Gonadal hormones and mineral balance in the domestic fowl. Nature, 160: 541-542. Common, R. H., W. A. Rutledge and R. W. Hale, 1948. Observations on the mineral metabolism of pullets. VIII. The influence of gonadal hormones on retention of calcium and phosphorus. J. Agric. Sci. 38: 64-80. Fiske, C. H., and Y. Subbarow, 1925. The colorimetric determination of phosphorus. J. Biol. Chem. 66: 375. Govaerts, J., M. J. Dallemagne and J. Melon, 1951. Radiocalcium as an indicator in the study of the action of oestradiol on calcium metabolism. Endocrinology, 48: 443-452. Hainan, E. T., 1925. The calcium, phosphorus and nitrogen balance of the non-laying and laying pullet. J. Nat. Poultry Inst. 10:410-416. Hansard, S. L., C. L. Comar and M. P. Plumlee, 1951. The integration of concurrent chemical and radioisotope balance trials for the interpretation of calcium metabolism studies. J. Dairy Sci. 34: 508. Hansard, S. L., and M. P. Plumlee, 1954. Effects of dietary calcium and phosphorus levels upon the physiological behavior of calcium and phosphorus in the rat. J. Nutrition, 54: 17-31. Jackson, N., and W. 0. Brown, 1958. The effect of gonadal hormones on nitrogen retention in the immature fowl. Poultry Sci. 37: 886-889. Jowsey, J. R., W. F. Oliver, W. A. Maw and R. H. Common, 1953. Observations on the mineral
Downloaded from http://ps.oxfordjournals.org/ at Florida International University on May 30, 2015
A 9-day phosphorus balance trial was carried out on immature pullets to which had been administered oestradiol dipropionate, testosterone propionate, and oestradiol plus testosterone. Dry-matter and protein contents of the blood plasma, together with oviduct weights showed that the treatments had had the desired effect. Each bird received an intramuscular injection of phosphorus32 at the beginning of the experimental period to allow of the calculation of the 'combined metabolic excretory phosphorus' and the true phosphorus absorption during days 7, 8 and 9; these data being calculated using the isotope dilution procedure. Evidence is provided for a positive interaction of oestrogen and androgen upon the phosphorus balance. During days 7, 8 and 9, net retention and true absorbed phosphorus were increased while the combined metabolic excretory phosphorus was decreased by the administration of oestrogen and androgen together; all these results being significant. Significance could not be attached to the effects of the hormones administered separately. Over the complete 9-day trial, net retention was increased to a significant degree by both the double hormone treatment and the oestrogen alone. Significance for the increase produced with androgen alone could not be shown.
ACKNOWLEDGMENT
GONADAL HORMONES AND PHOSPHORUS metabolism of pullets. X. The effects of gonadal hormones on retention and turnover of calcium by the skeleton. Can. J. Agric. Sci. 33: 216-224. Kjerulf-Jensen, K., 1941. Excretion of phosphorus by the bowel. Acta. Physiol. Scand. 3: 1-27. Kleiber, M., A. H. Smith, N. B. Ralston and A. L. Black, 1951. Radiophosphorus P32 as tracer for measuring endogenous phosphorus in cow faeces.
353
J. Nutrition, 35: 253:263. Lofgreen, G. P., and M. Kleiber, 1953. The availability of phosphorus in alfalfa hay. J. Animal Sci. 12: 366-371. Visek, W. J., R. A. Monroe, E. W. Swanson and C. L. Comar, 1953. Determination of endogenous faecal calcium in cattle by a simple isotope dilution method. J. Nutrition, 50: 23-33.
W. E. DONALDSON AND R. I. MILLAR 2 Poultry Science Department, University of Rhode Island, Kingston, Rhode Island (Received for publication May 10. 1961)
INTRODUCTION
B
ECAUSE high feed consumption, obesity and relatively low egg production are characteristic of heavy meattype laying hens, interest has developed in attempting to improve the performance of this type of hen by restriction of feed intake. Numerous reports dealing with the effects of feed restriction during the growing period on subsequent egg production have been published, but there are few reports available on restriction during the laying period. Heywang (1940) observed drastic reductions in egg production but no effect on body weight or egg size by restricting the feed intake of Leghorn hens to 87J and 75% of ad libitum intake. Singsen et al. (1959) used body weight, egg production and environmental temperature to predict feed consumption of White Rock laying hens. Controlled feeding (based on predicted consumption) of high and low energy rations was compared with ad libitum feeding of the same rations. Al1
Contribution No. 1025 of the Rhode Island Agricultural Experiment Station. 2 Present address: Beacon Milling Company, Cayuga, New York.
though intake of the high energy ration was only 84.3% of ad libitum, production was not affected. Production was reduced when the low energy ration was controlfed (77% of ad libitum) even though digestible nutrient intake was calculated to be the same as the intake of the birds control-fed the high energy rations. Combs et al. (1961) reported that restriction of energy intake of heavy-type hens to 81 and 87% of ad libitum intake did not affect egg production, Haugh unit scores or mortality. Reductions in body weight gain and rate of increase in egg size were observed with energy restriction. The purpose of the experiments reported herein was to determine the effects of energy restriction on productive traits of meat-type laying hens. PROCEDURE
Two experiments were conducted in each of which April hatched pullets were placed on experiment on the succeeding January 21st and continued for 36 weeks All birds were reared on an ad libitumieeding system. In experiment 1, 29 White Plymouth Rock pullets were randomly assigned to
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Effects of Energy Restriction on Laying Hens 1