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Research Note: The Effect of Tamoxifen on Semen Fertilization Capacity in White Leghorn Male Chicks
RESEARCH NOTES Research Note: The Effect of Tamoxifen on Semen Fertilization Capacity in White Leghorn Male Chicks B. ROBINZON, I. ROZENBOIM, E. ARNON, and N. SNAPTR Department of Animal Science, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel (Received for publication August 28, 1989) ABSTRACT Tamoxifen (TAM) is an antiestrogen that advances sexual puberty in cockerels, turkey toms, and Muscovy drakes. The effect of TAM on semen-fertilization capacity in White Leghorn (WL) male chicks was assayed in the present study. Sixty, 2-wk-old, male chicks were divided into two equal groups. The chicks from one group were injected im with 1 mgof TAM per kg of BW every other day, those from the second group were vehicle-treated (with corn oil) and served as controls. Bach chick was paired with a virgin, WL laying hen. When semen was produced, the paired female was inseminated twice a week. The results revealed that TAM administration caused the early production of fertile semen, which resulted in the first normal descendants as early as 8 wk of age arid brought about 100% of parenthood by the age of 88 days. (Key words: tamoxifen, semen, sexual maturity, fertility) 1990 Poultry Science 69:1220-1222
administration of TAM advanced semen production to the age of 13.5 wk in turkey toms Tamoxifen (TAM) is a nonsteroidal, anties- and 17.5 wk in Muscovy drakes (Rozenboim et trogen that binds to estrogen binding sites and al., 1989b). Although precocious semen prois routinely used to treat patients with estro- duction, as a result of TAM administration, has gen-responsive breast cancer (Patterson, 1981). been reported previously (Rozenboim et al., Therefore, TAM probably reduces the ability 1986, 1988, 1989a), the fertilization capacity of the sex steroids to activate negative of this semen has not been assayed systematifeedback on gonadotropin secretion in the hypothalamus and the pituitary glands. Thus, cally until the present study. TAM should increase gonadotropin release and should enhance gonadal activity (Patterson, MATERIALS AND METHODS 1981; Willis et al, 1986). Sixty, 2-wk-old, WL male chicks were When studied further, TAM was found to divided into two equal groups. The chicks have a wider spectrum of activities in animals, from one group were injected im with 1 mg of from a pure estrogen antagonist to a sole TAM per kg of BW (1 mg of TAM per 1 mL agonist, depending on which species was being of com oil) every other day. Those from the assayed (Patterson, 1981). However, in a previous study of White Leghorn (WL) cocker- second group were vehicle-treated and served els, Rozenboim et al. (1989a) found that even as controls. Using the abdominal massage within the same species, TAM has many procedure (Burrows and Quinn, 1939), ejaculafunctions, some antagonistic and others agonis- tion was attempted with the chicks twice a week, starting as early as 40 days of age and tic, depending on the dose administered. continuing until the end of the experimental Precocious sexual puberty and an increase in the ejaculate's sperm count are of great period, at 170 days of age. The response to the economic value in poultry farming. The TAM massage procedure was graded from 0 to 8 as administration to juvenile broiler males (White follows: 0 equals no erection; 1 equals erection Rock by White Cornish) enhanced both the with nofluid;2 equals erection withfluid;3 to growth of the testes and the spermatogenesis 8 equals secretion of semen with an increasing process (Rozenboim et al, 1986). White amount of spermatozoa (Rozenboim et al, Leghorn male chicks treated similarly 1989a). produced fertile semen at 9 wk of age, which Assays of the semen's fertilization capacity following insemination resulted in normal were carried out using 60, virgin, WL hens descendants (Rozenboim et al., 1988). The during the 2nd mo of their first laying period. INTRODUCTION
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90 100 110 120 130 140 150 160 170 AGE (days)
FIGURE 1. Mean response to abdominal-massage procedure, from 40 days of age and on in the tamoxifen (TAM)-treated and the control chicks, a = significantly different from control (P<05; Mann-Whitney U-test).
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AGE (days)
FIGURE 2. Percentage of chicks that produced semen in the tamoxifen (TAM)-treated group and the control group.
days of age. At that age, 55% (16 chicks) of Each cockerel was paired with a specific the TAM-treated birds were producing semen. testing female. The insemination regimen was The controls reached the same level of semen commenced twice a week with each pair, as production 21 days later. All the TAM-treated scon as the ejaculate was graded at a 3 or chicks produced semen by the age of 80 days, higher. For the hens being tested, all eggs were whereas the control chicks did not attain 100% collected daily, numbered, and then stored at semen production until 101 days of age. 15 C. Once a week, all of the collected eggs In the insemination test, first descendants were placed in an incubator (38 C, 65% were produced by a TAM-treated chick when relative humidity). On the 10th day of incuba- it was 58 days old (Figures 3 and 4). Fifty tion, the eggs were transilluminated in order to percent of the TAM-treated chicks produced test fertility rate. On the 18th day of incuba- normal descendants by 72 days of age, and tion, the eggs were removed individually to the 100% by 88 days of age. For the control hatchery, where the hatching rate was record- chicks, however,firstparenthood was observed ed. A statistical evaluation of data was made at 70 days of age, 50% at 83 days of age, and using Mann-Whitney U test and the Chi-square 100% at 101 days of age. test (Siegel, 1956; Brownlee, 1965). RESULTS AND DISCUSSION
The effect of TAM treatment on ejaculate grade is presented in Figure 1. A significant increase in semen production was measured from 50 to 97 days of age in the TAM-treated chicks, compared with controls. Chicks from me TAM-treated group reached a maximum grade of ejaculation by 97 days of age; the control group did not reach the same level until 130 days of age. Figure 2 shows the percentage of chicks from each treated group that produced semen containing variable numbers of spermatozoa (ejaculate, grades 3 to 8). One of the TAM-treated chicks produced semen with live spermatozoa at the age of 50 days, while the first production of similar semen by a control chick was measured at 63
100
110
120
130
AGE (days)
FIGURE 3. Percentage of chicks that achieved parenthood in the tamoxifen (TAM)-treated group and the control group, a = significantly different from control (P<05; Chi-square test).
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The administration of TAM to juvenile cockerels caused an early rise in hypothalamic gonadotrophin-releasing hormone and plasma luteinizing hormone (Rozenboim et al., unpublished data). Thus, the hypothalamic and pituitary organs seem to be the target sites for the induction of precocious puberty by the TAM antiestrogen. REFERENCES
FIGURE 4. Average daily fertile egg produced by tamoxifen (TAM>treated chicks and the control chicks, a = significantly different from control (P<05; Chi square test).
The present data are in agreement with previous studies (Rozenboim et al., 1986, 1988,1989a). Again, the authors found that the administration of TAM to juvenile, male, WL chicks caused precocious puberty, including early semen production. In the present study, this semen was found to be fertile; and if inseminated, to result in normal descendants with 100% parenthood by 88 days of age. The commercial use of TAM in poultry breeding should be evaluated according to the specific needs of each division of the industry. However, the effect of early TAM administration on fertility over the whole reproductive period needs to be assayed before any recommendations can be made.
Brownlee, K. A., 1965. Statistical Theory and Methodology in Science and Engineering. 2nd ed. John Wiley, Inc., New York, NY. Burrows, W. H., and J. P. Quinn, 1939. Pages 525-529 in: Artificial insemination of chickens and turkeys. USDA Circ. 525, USDA, Washington, DC. Patterson, J. S., 1981. Clinical aspects and development of antiestrogen therapy: a review of the endocrine effects of tamoxifen in animals and man. J. Endocrinol. 89: 67-75. Rozenboim, I., O. Dgany, B. Robinzon, E. Anion, and N. Snapir, 1989a. The effect of tamoxifen on the reproductive traits in White Leghorn cockerels. Pharmacol. Biochem. Behav. 32:377-381. Rozenboim, I., G. Gvaryahu, B. Robinzon, N. Sayag, and N. Snapir, 1986. The induction of precocious development of reproductive function in cockerels by tamoxifen administration. Poultry Sci. 65:1980-1983. Rozenboim, I., G. Gvaryahu, B. Robinzon, N. Sayag, and N. Snapir, 1988. Fertile semen from 9-week-old chicks treated with tamoxifen. Poultry Sci. 67:1642-1643. Rozenboim, I., A. Meltzer, B. Robinzon, S. Gahaly, E. Anion, and N. Snapir, 1989b. The effect of tamoxifen on sexual development of turkeys and Muscovy drakes. Poultry Sci. 69:176-178. Siegel, S., 1956. Nonparametric Statistics for the Behavioral Sciences. McGraw-Hill Book Co., New York, NY. Willis, K. L., D. R. London, M. A. Bevis, W. R. Butt, S. S. Lynch, and G. Holder, 1986. Hormonal effects of tamoxifen in oligospermic men. J. Endocrinol. 73: 171-178.
administration of TAM advanced semen production to the age of 13.5 wk in turkey toms Tamoxifen (TAM) is a nonsteroidal, anties- and 17.5 wk in Muscovy drakes (Rozenboim et trogen that binds to estrogen binding sites and al., 1989b). Although precocious semen prois routinely used to treat patients with estro- duction, as a result of TAM administration, has gen-responsive breast cancer (Patterson, 1981). been reported previously (Rozenboim et al., Therefore, TAM probably reduces the ability 1986, 1988, 1989a), the fertilization capacity of the sex steroids to activate negative of this semen has not been assayed systematifeedback on gonadotropin secretion in the hypothalamus and the pituitary glands. Thus, cally until the present study. TAM should increase gonadotropin release and should enhance gonadal activity (Patterson, MATERIALS AND METHODS 1981; Willis et al, 1986). Sixty, 2-wk-old, WL male chicks were When studied further, TAM was found to divided into two equal groups. The chicks have a wider spectrum of activities in animals, from one group were injected im with 1 mg of from a pure estrogen antagonist to a sole TAM per kg of BW (1 mg of TAM per 1 mL agonist, depending on which species was being of com oil) every other day. Those from the assayed (Patterson, 1981). However, in a previous study of White Leghorn (WL) cocker- second group were vehicle-treated and served els, Rozenboim et al. (1989a) found that even as controls. Using the abdominal massage within the same species, TAM has many procedure (Burrows and Quinn, 1939), ejaculafunctions, some antagonistic and others agonis- tion was attempted with the chicks twice a week, starting as early as 40 days of age and tic, depending on the dose administered. continuing until the end of the experimental Precocious sexual puberty and an increase in the ejaculate's sperm count are of great period, at 170 days of age. The response to the economic value in poultry farming. The TAM massage procedure was graded from 0 to 8 as administration to juvenile broiler males (White follows: 0 equals no erection; 1 equals erection Rock by White Cornish) enhanced both the with nofluid;2 equals erection withfluid;3 to growth of the testes and the spermatogenesis 8 equals secretion of semen with an increasing process (Rozenboim et al, 1986). White amount of spermatozoa (Rozenboim et al, Leghorn male chicks treated similarly 1989a). produced fertile semen at 9 wk of age, which Assays of the semen's fertilization capacity following insemination resulted in normal were carried out using 60, virgin, WL hens descendants (Rozenboim et al., 1988). The during the 2nd mo of their first laying period. INTRODUCTION
1220
1221
RESEARCH NOTE
-v --•? - v- — -•:' —s?
40
50
60
70
80
90 100 110 120 130 140 150 160 170 AGE (days)
FIGURE 1. Mean response to abdominal-massage procedure, from 40 days of age and on in the tamoxifen (TAM)-treated and the control chicks, a = significantly different from control (P<05; Mann-Whitney U-test).
45
50
55
60
65
70
75
80
85
90
95 100 105 110
AGE (days)
FIGURE 2. Percentage of chicks that produced semen in the tamoxifen (TAM)-treated group and the control group.
days of age. At that age, 55% (16 chicks) of Each cockerel was paired with a specific the TAM-treated birds were producing semen. testing female. The insemination regimen was The controls reached the same level of semen commenced twice a week with each pair, as production 21 days later. All the TAM-treated scon as the ejaculate was graded at a 3 or chicks produced semen by the age of 80 days, higher. For the hens being tested, all eggs were whereas the control chicks did not attain 100% collected daily, numbered, and then stored at semen production until 101 days of age. 15 C. Once a week, all of the collected eggs In the insemination test, first descendants were placed in an incubator (38 C, 65% were produced by a TAM-treated chick when relative humidity). On the 10th day of incuba- it was 58 days old (Figures 3 and 4). Fifty tion, the eggs were transilluminated in order to percent of the TAM-treated chicks produced test fertility rate. On the 18th day of incuba- normal descendants by 72 days of age, and tion, the eggs were removed individually to the 100% by 88 days of age. For the control hatchery, where the hatching rate was record- chicks, however,firstparenthood was observed ed. A statistical evaluation of data was made at 70 days of age, 50% at 83 days of age, and using Mann-Whitney U test and the Chi-square 100% at 101 days of age. test (Siegel, 1956; Brownlee, 1965). RESULTS AND DISCUSSION
The effect of TAM treatment on ejaculate grade is presented in Figure 1. A significant increase in semen production was measured from 50 to 97 days of age in the TAM-treated chicks, compared with controls. Chicks from me TAM-treated group reached a maximum grade of ejaculation by 97 days of age; the control group did not reach the same level until 130 days of age. Figure 2 shows the percentage of chicks from each treated group that produced semen containing variable numbers of spermatozoa (ejaculate, grades 3 to 8). One of the TAM-treated chicks produced semen with live spermatozoa at the age of 50 days, while the first production of similar semen by a control chick was measured at 63
100
110
120
130
AGE (days)
FIGURE 3. Percentage of chicks that achieved parenthood in the tamoxifen (TAM)-treated group and the control group, a = significantly different from control (P<05; Chi-square test).
1222
R O B I N Z O N ET AL.
m en w o O o to
a a
The administration of TAM to juvenile cockerels caused an early rise in hypothalamic gonadotrophin-releasing hormone and plasma luteinizing hormone (Rozenboim et al., unpublished data). Thus, the hypothalamic and pituitary organs seem to be the target sites for the induction of precocious puberty by the TAM antiestrogen. REFERENCES
FIGURE 4. Average daily fertile egg produced by tamoxifen (TAM>treated chicks and the control chicks, a = significantly different from control (P<05; Chi square test).
The present data are in agreement with previous studies (Rozenboim et al., 1986, 1988,1989a). Again, the authors found that the administration of TAM to juvenile, male, WL chicks caused precocious puberty, including early semen production. In the present study, this semen was found to be fertile; and if inseminated, to result in normal descendants with 100% parenthood by 88 days of age. The commercial use of TAM in poultry breeding should be evaluated according to the specific needs of each division of the industry. However, the effect of early TAM administration on fertility over the whole reproductive period needs to be assayed before any recommendations can be made.
Brownlee, K. A., 1965. Statistical Theory and Methodology in Science and Engineering. 2nd ed. John Wiley, Inc., New York, NY. Burrows, W. H., and J. P. Quinn, 1939. Pages 525-529 in: Artificial insemination of chickens and turkeys. USDA Circ. 525, USDA, Washington, DC. Patterson, J. S., 1981. Clinical aspects and development of antiestrogen therapy: a review of the endocrine effects of tamoxifen in animals and man. J. Endocrinol. 89: 67-75. Rozenboim, I., O. Dgany, B. Robinzon, E. Anion, and N. Snapir, 1989a. The effect of tamoxifen on the reproductive traits in White Leghorn cockerels. Pharmacol. Biochem. Behav. 32:377-381. Rozenboim, I., G. Gvaryahu, B. Robinzon, N. Sayag, and N. Snapir, 1986. The induction of precocious development of reproductive function in cockerels by tamoxifen administration. Poultry Sci. 65:1980-1983. Rozenboim, I., G. Gvaryahu, B. Robinzon, N. Sayag, and N. Snapir, 1988. Fertile semen from 9-week-old chicks treated with tamoxifen. Poultry Sci. 67:1642-1643. Rozenboim, I., A. Meltzer, B. Robinzon, S. Gahaly, E. Anion, and N. Snapir, 1989b. The effect of tamoxifen on sexual development of turkeys and Muscovy drakes. Poultry Sci. 69:176-178. Siegel, S., 1956. Nonparametric Statistics for the Behavioral Sciences. McGraw-Hill Book Co., New York, NY. Willis, K. L., D. R. London, M. A. Bevis, W. R. Butt, S. S. Lynch, and G. Holder, 1986. Hormonal effects of tamoxifen in oligospermic men. J. Endocrinol. 73: 171-178.