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Plasma concentration of progesterone during normal estrous cycles and following prostaglandin F2α treatment of Bos indicus and tropic-adapted Bos taurus heifers
THERIOGENOLOGY
PLASMA CONCENTRATION OF PROGESTERONE DURING NORMAL ESTROUS CYCLES AND FOLLOWING PROSTAGLANDIN FM TREATMENT OF BOS INDICUS AND TROPIC-ADAPTED -~ BOS TAURUS HEIFERS
Oyewole Adeyemo Department of Veterinary Anatomy University of Ibadan Ibadan, Nigeria
Received for publication: September 27, 1985 Accepted: March 18, 1987
ABSTRACT The introduction of the use of prostaglandin FZoc (PGF2%) to synchronize estrus in cattle adapted to the tropics suggests a need to investigate the endocrine response to this treatment. Progesterone (P) concentrations in blood plasma of Bos indicus and tropic-adapted Bos taurus heifers during normal estrous cycles and folloXgestrus synchronization were administration, the heifers were compared. After PGF divided into two gro@ps on the basis of response to treatment. Mean P levels in heifers showing estrus after the first injection ranged from l-O-3.0 ng/ml, decreasing to 0.2-0.4 ng/ml 24 to 48 hr after treatment. The second group exhibited estrus injection and had low P (0.2-0.9 only after the second PGF a. ng/ml) in plasma before the first injection. Mean peak P after the first injection levels in both groups 8 to 12 d in the periestrous period were not different from values in the same heifers at similar periods of the preceding control estrous cycle. Neither the tropical location nor breed affected the luteolytic effect of PGFM Key words:
Prostaglandin Fs, progesterone
estrus
synchronization,
Acknowledgements I wish to acknowledge the gift of Lutaiyse from Upjohn, the gift of antisera from the Department of Steroid Biochemistry, University of Glasgow,and the assistance of the staff of the University of Ibadan Teaching and Research Farm.
MAY
1987 VOL.
27 NO. 5
759
THERIOGENOLOGY
INTRODUCTION PGF2, and its analogues are being used in the managecycles of cattle. Early reports on the ment of estrous in cattie (1, 2) stimulated luteolytic effects of PGF (3, 4) and its analonumerous studies on the & of PGF gues (5) in the control of estrous?ycles in cattle. Administration of PGF& intravenously, subcutaneously, intrauterinely or intramuscularly into cattle with corpora lutea (CL) developed up to 5 d or more following estrus is effective in causing corpus luteum regression followed by expression of estrus. PGFti is a very potent drug and there were fears following its introduction that its use in controlled breeding programs might cause some unwanted side effects including hormonal imbalance. Some investigators have determined hormonal levels in -Bos taurus cattle during PGF -synchronized estrus (4, 5). The introduction of the use of $GF& to estrus in the tropical environment makes it synchronize desirable to investigate endocrine responses to the treatment. This shall complement the general studies comparing ovarian physiology and fertility in PGFX -treated and control cows in temperate climates (1, 2, 6). sterone indicus estrus during
The objectives of this study were to determine progeconcentrations in plasma of tropic-adapted Bos and Bos taurus heifers after synchronization of with PGF,JTto compare with values measured normal ez?rous cycles. MATERIALS AND METHODS
Nineteen postpubertal nulliparous heifers consisting seven Holstein Friesian and six of six German Brown Swiss. They were kept together White Fuiani heifers were’used. on the University of Ibadan Teaching and Research Farm (3O 54’ east long., 7’ 26’ north lat.). All heifers were exhibiting estrus every 16 to 23 d. The management procedures The applied were as explained in a previous report (7). heifers grazed from 0600 to 1100 h in paddocks planted with They spent the remaining giant star grass (Cynodon sp.). hours of the day in shaded concrete-floored pens where they were fed cut grass and concentrate at 1 kg/l1 kn bodv weight The c&rand 1 kg/123 kg body weight per day, respectively. 15% palm kernel centrate was composed of 65% guinea corn, and 20% groundnut cake.
760
MAY 1987 VOL. 27 NO. 5
THERIOGENOLOGY
Two vasectomised bulls kept with the heifers were The time when a hiefer stayed to used to detect estrus. be mounted by a bull or another heifer was regarded as the The heifers were bled daily commencement of estrus. between 0800 and 0900 h for 30 consecutive days by jugular the plasma samples obtained were stored at venipuncture; - 2OoC until assayed for progesterone. At the end of the 30 d, all the animals were injected with Lutalyse (Upjohn), a commercial preparation of prostaInjections were given intramuscularly at a glandin F2&. dose of 25 mg PGF,, per animal at an interval of 12 d. The animals were inseminated 80 h after the second injection. Blood samoles were obtained twice daily (0800 h and 1600 h) for 5 d starting from each day of injection and once daily (0800 h) on other days between the injections. Progesterone levels in the plasma samples were determined by radioimmunoassay (RIA). The method of Abraham et al. (8), modified as previously described (9),was adopted using the antiserum (Y29/6B) raised in sheep against BSAThe sensitivity ll-hemisuccinate conjugated to progesterone. of the assay was between 10 - 20 pg/ml. Intra-assay and inter-assay co-efficients of variation were 6 and lo%, respectively. The mean values of daily plasma hormonal levels were calculated and used to draw line graphs. The values during estrous cycles before PGFti injection served as control. Ilean peak The statistical analysis is as follows. values of P measured at mid-cycle were compared between the regulated and control estrous cycles by the two-factor PGF@ ysis ana : of variance (10). Values obtained from six heifers in each breed with complete hormonal data during the period under consideration were used for analysis of variance. Mean plasma P values (from Days 8 to 12 after PGFM injection and during asimilar period of normal estrous cycles)were taken as peak values. RESULTS The estrous behaviour and ovarian morphological changes during normal cycles and following PGFx treatment in the heifers under study have been described (11). The profile of P during normal estrous cycles in the heifers is presented (Figure 1). Eight of 19 animals were in estrus 2 to 3 d after the first PGF2d injection, but all the heifers were in estrus 2 to 3 d after the second PGF s%,tFj;c;;;;als The eight heifers in estrus are referred to as and the remaining 11 heifers in estrus only after the second i;jection of PGFZd are referred to as Group 2 animals. In Group 1 heifers, P levels in plasma decreased from an average of 2 ng/ml 1 h before the injection of PGFm to 0.7 ng/ml 24 h after the injection and to 0.2 ng/ml on Day 3 (Figure 2). Thereafter, the level of P increased
MAY
1987 VOL.
27 NO. 5
THERIOGENOLOGY
Figure 1.
762
Blood plasma was collected daily from heifers of Bos indicus and Bos taurus cattle during normal estrous cycles pi%TXTng treatment with PGFz4., Progesterone levels in plasma were determined by RIA. Each point represents the mean of 18 yalues.
MAY 1987 VOL. 27 NO. 5
THERIOGENOLOGY
:-=
t
Figure
2.
Days (pro- and
Day
of
Period
injection of estrus
post-ln.jection)
Heifers were injected with 25 mg (Lutalyse, Upjohn) twice at 12-d Concentrations of progesterone in were determined by RIA. Heifers group responded to injections by estrus 2 to3 d after the injection. point on the graph represents the values from eight heifers.
MAY 1987 VOL. 27 NO. 5
PGF2, intervals. plasma in this showing Each mean of
763
THERIOGENOLOGY
sharply to a peak ranging between 1.0 and 3.0 ng/ml at Day 6 post-injection and remained elevated until about injection. Following the second injection the second PGF the $&level of PGF decreased sharply to an average of 0.7 ng?& at 24 h. In Group 2 heifers, before the first injection of PGFa the level of P ranged between 0.2 and 0.9 ng/ml (Figure 3). After the injection the level increased,reaching a mean The elevated level of P persisted until value of 3.3 ng/ml. of P dropped. the second injection of PGF$% when the level e second injection of PGF2, The hormonal profile after was similar to that observed in Group 1 heifers. The patterns immediately after
of the
change in P levels first injection of
in Group PGF& is
2 heifers similar
to that observed from 1 or 2 d after estrus in normal estrous cycles. A comparison of the P profiles following the first PGF injection in Groups 1 and 2 heifers reveals that the was attained sooner (4 to 5 d) in Group 2 heifers pea Izdlevel than in Group 1 heifers (6 to 7 d post-injection). No differences in values of P between normal estrous cycles (control) and those following PGFZd treatment were detected (Table 1). Table
1.
Analysis of variance of progesterone concentrations during control estrous cycles in heifers and following PGFzq injection
Progesterone df
S.V.
MS
F-ratio
Breed
(B)
2
Animal
1.49
15
0.87
1
2.17
1.89
2
2.06
1.79
Residual
20
1.15
Total
35
Treatment BXT
764
1.3
S.V.
=
df MS
= =
(T)
Sources of variation degree of freedom The analysis shows no significant mean square. (p>O.O5) difference in progesterone levels between normal estrous cycles of heifers The differences treatment. and during PGF and tropic-adapted between the Ze iYu cattle Bos taurus heifers were also not significant 00.05).
MAY
1987 VOL.
27 NO. 5
THERIOGENOLOGY
Days
Figure
3.
Heifers
(pre-and
were
post-lnjectlon)
injected
with
25 mg PGFZ6
Concentrations twice at 12-d intervals. of progesterone in plasma were determined Heifers in this group responded by RIA. injection. only to the second PGF the Each point on the grap p represents mean of values from 11 heifers.
MAY
1987 VOL.
27 NO. 5
765
THERIOGENOLOGY
DISCUSSION The results indicated similar mean peak values and profiles for P during control and PGFX-regulated estrous cycles. This suggests that the development of CL and hormonal synthesis and secretion by this structure are not influenced or altered by PGFZd treatment. These results are similar to results previously reported (4, 5). PGF% causes regression of the CL (4). As for the causes mechanism of action it is believed that PGF luteolysis by inhibjting gonadotropin recept?? rs on the CL (12) or by reducing blood flow through the CL (13) due to the vasoconstrictive properties of PGI&(l4). Bovine CL are refractory to PGFZo( during the first 5 d of the cycle (15, 16). The differences in the stage of growth of CL in heifers before the first PGF treatment explains the differences in hormonal profi 3 es between heifers in Groups 1 and 2 during the experiment. Animais in Group 2 either showed estrus or ovulated shortly before the first PGF% treatment. The hormonal profiles in Group 2 heifers treatment did during the period following the first PGF not differ from those in control estrous $? ycles. Since newly formed CL were insensitive to PGFW at the time, CL growth in Group 2 followed a normal course of development until the second PGF administration. The fact that CL development in this Boup of heifers was unaffected by the first PGF treatment explains the faster rate of increase to peak p rasma P level in Group 2 heifers after the first injection of PGF CL had matured in all heifers (Groups 1 and 2) by 10 d2clfollowing the first injection of PGF and allowed a uniform response by all heifers to the %cond PGFZti injection on Day 12. In conclusion, P profiles were detected for Bos indicus and Bos taurus heifers both before and after PGFti treatment, and these profiles indicated that a tropical location did not affect ovarian response to PGF effectiveness of PGFH in achieving estrus syncal( and the ronization.
766
MAY
1987 VOL.
27 NO. 5
THERIOGENOLOGY
REFERENCES 1.
Louis, T. M., Hafs, H. D. and Morrow, Il. A. Estrus and J. Anim. Sci. ovulation after uterine PGFZA in cows. 35: 247-248 (1972).
2.
Lauderdale, J. W. Effects estrous cycles of cattle. abstr. (1972).
3.
of PGF J . An%
on pregnancy
and
. Sci. 35~246
Elsden, R. P., Lewis, S., Cumming, T. A. and Lawson, Superovulation in the cow following treatment R.A.S. with PMSG and prostaglandin FZM J. Reprod. Fertil. 36:455-456 (1974).
4.
Louis, T. M., Hafs, H. D. and Seguin, B. E. Progesterone, LH, estrus and ovulation after prostaglandin Proc. Sot. Exp. Biol. Med. 143:152-155 FZtnin heifers. (1973).
5.
Dobson, H., Cooper M. J. and Furr, J. A. Synchronization of estrus with ICI 79339, an analogue of PGF 201 and associated changes in plasma progesterone, and LH in heifers. J. Reprod. Fertil. estradiol-17 42:141-144 B1975).
6.
of estrus and fertility Roche, J. F. Synchronization following artificial insemination in heifers given prostaglandin F20,.J. Reprod. Fertil. -37:419-425 (1975).
7.
Adeyemo, O., Akpokodje, J. U. and Odili, P. I. Synchronization of Bos indicus and -~ Bos taurus heifers with prostaglandin F@. Theriogenology -12:255-292 (1980).
8.
Abraham, G. E., Serdloff, R., Tulchinsky, 11. and Odell, W. D. Radioimmunoassay of plasma progesterone. Endocr. 32:619-624 (1971).
9.
Adeyemo, 0. and Heath, E. Plasma progesterone concentration in Bos taurus and Bos indicus heifers. TheriogenologyT:411-420 (1981).
10.
Campbell, R. C. Statistics for Biologists. University Press, 1974.~. 177-237.
11.
Adeyemo, O., Heath, E., B. K. Estrous cycles in heifers acclimatized to climate. Zbl. Vet. Med.
12.
Grinwich, D. D., Ham, E. A. Hichens M. and Behrman, H. R. Binding of human chorionic gon;dotropin and response of cyclic nucleotides to luteinizing hormones in luteal tissue from rats treated with prostaglandin
MAY 1987 VOL. 27 NO. 5
Cambridge
Steinbach, J. and Adadevoh, Bos indicus and ~~ Bos taurus ~-the hot humid seasonal equatorial A. 26:788-799 (1979).
767
THERIOGENOLOGY
Endocrinology -98:146-150 (1976). 13. Navy, M. J., and Cook, M. J. Redistribution of blood _. flow by prostaglandin F2& in the ovary. Am. J. Obst. Gynecol. 117:381-385 (1978). 14. Ducharme, D. W., Weeks, J. R. and Montgomery, R. G. Studies on the mechanism of the hypertensive effect of prostaglandin Fzd. J. Pharmacol. Exp. Ther. 160: l-10 (1968). 15. Cooper, M. J., and Fur-r,B. J. A. prostaglandin in animal breeding. 161-163 (1974).
The role of Vet. Rec. _* 94.
16. Lamming, G. E., Hafs, W. D. and Manns, J. G. Hormonal control of reproduction in cattle. Proc. Brit. Sot. Anim. Prod. -4:71-78 (1975).
768
MAY 1987 VOL. 27 NO. 5
PLASMA CONCENTRATION OF PROGESTERONE DURING NORMAL ESTROUS CYCLES AND FOLLOWING PROSTAGLANDIN FM TREATMENT OF BOS INDICUS AND TROPIC-ADAPTED -~ BOS TAURUS HEIFERS
Oyewole Adeyemo Department of Veterinary Anatomy University of Ibadan Ibadan, Nigeria
Received for publication: September 27, 1985 Accepted: March 18, 1987
ABSTRACT The introduction of the use of prostaglandin FZoc (PGF2%) to synchronize estrus in cattle adapted to the tropics suggests a need to investigate the endocrine response to this treatment. Progesterone (P) concentrations in blood plasma of Bos indicus and tropic-adapted Bos taurus heifers during normal estrous cycles and folloXgestrus synchronization were administration, the heifers were compared. After PGF divided into two gro@ps on the basis of response to treatment. Mean P levels in heifers showing estrus after the first injection ranged from l-O-3.0 ng/ml, decreasing to 0.2-0.4 ng/ml 24 to 48 hr after treatment. The second group exhibited estrus injection and had low P (0.2-0.9 only after the second PGF a. ng/ml) in plasma before the first injection. Mean peak P after the first injection levels in both groups 8 to 12 d in the periestrous period were not different from values in the same heifers at similar periods of the preceding control estrous cycle. Neither the tropical location nor breed affected the luteolytic effect of PGFM Key words:
Prostaglandin Fs, progesterone
estrus
synchronization,
Acknowledgements I wish to acknowledge the gift of Lutaiyse from Upjohn, the gift of antisera from the Department of Steroid Biochemistry, University of Glasgow,and the assistance of the staff of the University of Ibadan Teaching and Research Farm.
MAY
1987 VOL.
27 NO. 5
759
THERIOGENOLOGY
INTRODUCTION PGF2, and its analogues are being used in the managecycles of cattle. Early reports on the ment of estrous in cattie (1, 2) stimulated luteolytic effects of PGF (3, 4) and its analonumerous studies on the & of PGF gues (5) in the control of estrous?ycles in cattle. Administration of PGF& intravenously, subcutaneously, intrauterinely or intramuscularly into cattle with corpora lutea (CL) developed up to 5 d or more following estrus is effective in causing corpus luteum regression followed by expression of estrus. PGFti is a very potent drug and there were fears following its introduction that its use in controlled breeding programs might cause some unwanted side effects including hormonal imbalance. Some investigators have determined hormonal levels in -Bos taurus cattle during PGF -synchronized estrus (4, 5). The introduction of the use of $GF& to estrus in the tropical environment makes it synchronize desirable to investigate endocrine responses to the treatment. This shall complement the general studies comparing ovarian physiology and fertility in PGFX -treated and control cows in temperate climates (1, 2, 6). sterone indicus estrus during
The objectives of this study were to determine progeconcentrations in plasma of tropic-adapted Bos and Bos taurus heifers after synchronization of with PGF,JTto compare with values measured normal ez?rous cycles. MATERIALS AND METHODS
Nineteen postpubertal nulliparous heifers consisting seven Holstein Friesian and six of six German Brown Swiss. They were kept together White Fuiani heifers were’used. on the University of Ibadan Teaching and Research Farm (3O 54’ east long., 7’ 26’ north lat.). All heifers were exhibiting estrus every 16 to 23 d. The management procedures The applied were as explained in a previous report (7). heifers grazed from 0600 to 1100 h in paddocks planted with They spent the remaining giant star grass (Cynodon sp.). hours of the day in shaded concrete-floored pens where they were fed cut grass and concentrate at 1 kg/l1 kn bodv weight The c&rand 1 kg/123 kg body weight per day, respectively. 15% palm kernel centrate was composed of 65% guinea corn, and 20% groundnut cake.
760
MAY 1987 VOL. 27 NO. 5
THERIOGENOLOGY
Two vasectomised bulls kept with the heifers were The time when a hiefer stayed to used to detect estrus. be mounted by a bull or another heifer was regarded as the The heifers were bled daily commencement of estrus. between 0800 and 0900 h for 30 consecutive days by jugular the plasma samples obtained were stored at venipuncture; - 2OoC until assayed for progesterone. At the end of the 30 d, all the animals were injected with Lutalyse (Upjohn), a commercial preparation of prostaInjections were given intramuscularly at a glandin F2&. dose of 25 mg PGF,, per animal at an interval of 12 d. The animals were inseminated 80 h after the second injection. Blood samoles were obtained twice daily (0800 h and 1600 h) for 5 d starting from each day of injection and once daily (0800 h) on other days between the injections. Progesterone levels in the plasma samples were determined by radioimmunoassay (RIA). The method of Abraham et al. (8), modified as previously described (9),was adopted using the antiserum (Y29/6B) raised in sheep against BSAThe sensitivity ll-hemisuccinate conjugated to progesterone. of the assay was between 10 - 20 pg/ml. Intra-assay and inter-assay co-efficients of variation were 6 and lo%, respectively. The mean values of daily plasma hormonal levels were calculated and used to draw line graphs. The values during estrous cycles before PGFti injection served as control. Ilean peak The statistical analysis is as follows. values of P measured at mid-cycle were compared between the regulated and control estrous cycles by the two-factor PGF@ ysis ana : of variance (10). Values obtained from six heifers in each breed with complete hormonal data during the period under consideration were used for analysis of variance. Mean plasma P values (from Days 8 to 12 after PGFM injection and during asimilar period of normal estrous cycles)were taken as peak values. RESULTS The estrous behaviour and ovarian morphological changes during normal cycles and following PGFx treatment in the heifers under study have been described (11). The profile of P during normal estrous cycles in the heifers is presented (Figure 1). Eight of 19 animals were in estrus 2 to 3 d after the first PGF2d injection, but all the heifers were in estrus 2 to 3 d after the second PGF s%,tFj;c;;;;als The eight heifers in estrus are referred to as and the remaining 11 heifers in estrus only after the second i;jection of PGFZd are referred to as Group 2 animals. In Group 1 heifers, P levels in plasma decreased from an average of 2 ng/ml 1 h before the injection of PGFm to 0.7 ng/ml 24 h after the injection and to 0.2 ng/ml on Day 3 (Figure 2). Thereafter, the level of P increased
MAY
1987 VOL.
27 NO. 5
THERIOGENOLOGY
Figure 1.
762
Blood plasma was collected daily from heifers of Bos indicus and Bos taurus cattle during normal estrous cycles pi%TXTng treatment with PGFz4., Progesterone levels in plasma were determined by RIA. Each point represents the mean of 18 yalues.
MAY 1987 VOL. 27 NO. 5
THERIOGENOLOGY
:-=
t
Figure
2.
Days (pro- and
Day
of
Period
injection of estrus
post-ln.jection)
Heifers were injected with 25 mg (Lutalyse, Upjohn) twice at 12-d Concentrations of progesterone in were determined by RIA. Heifers group responded to injections by estrus 2 to3 d after the injection. point on the graph represents the values from eight heifers.
MAY 1987 VOL. 27 NO. 5
PGF2, intervals. plasma in this showing Each mean of
763
THERIOGENOLOGY
sharply to a peak ranging between 1.0 and 3.0 ng/ml at Day 6 post-injection and remained elevated until about injection. Following the second injection the second PGF the $&level of PGF decreased sharply to an average of 0.7 ng?& at 24 h. In Group 2 heifers, before the first injection of PGFa the level of P ranged between 0.2 and 0.9 ng/ml (Figure 3). After the injection the level increased,reaching a mean The elevated level of P persisted until value of 3.3 ng/ml. of P dropped. the second injection of PGF$% when the level e second injection of PGF2, The hormonal profile after was similar to that observed in Group 1 heifers. The patterns immediately after
of the
change in P levels first injection of
in Group PGF& is
2 heifers similar
to that observed from 1 or 2 d after estrus in normal estrous cycles. A comparison of the P profiles following the first PGF injection in Groups 1 and 2 heifers reveals that the was attained sooner (4 to 5 d) in Group 2 heifers pea Izdlevel than in Group 1 heifers (6 to 7 d post-injection). No differences in values of P between normal estrous cycles (control) and those following PGFZd treatment were detected (Table 1). Table
1.
Analysis of variance of progesterone concentrations during control estrous cycles in heifers and following PGFzq injection
Progesterone df
S.V.
MS
F-ratio
Breed
(B)
2
Animal
1.49
15
0.87
1
2.17
1.89
2
2.06
1.79
Residual
20
1.15
Total
35
Treatment BXT
764
1.3
S.V.
=
df MS
= =
(T)
Sources of variation degree of freedom The analysis shows no significant mean square. (p>O.O5) difference in progesterone levels between normal estrous cycles of heifers The differences treatment. and during PGF and tropic-adapted between the Ze iYu cattle Bos taurus heifers were also not significant 00.05).
MAY
1987 VOL.
27 NO. 5
THERIOGENOLOGY
Days
Figure
3.
Heifers
(pre-and
were
post-lnjectlon)
injected
with
25 mg PGFZ6
Concentrations twice at 12-d intervals. of progesterone in plasma were determined Heifers in this group responded by RIA. injection. only to the second PGF the Each point on the grap p represents mean of values from 11 heifers.
MAY
1987 VOL.
27 NO. 5
765
THERIOGENOLOGY
DISCUSSION The results indicated similar mean peak values and profiles for P during control and PGFX-regulated estrous cycles. This suggests that the development of CL and hormonal synthesis and secretion by this structure are not influenced or altered by PGFZd treatment. These results are similar to results previously reported (4, 5). PGF% causes regression of the CL (4). As for the causes mechanism of action it is believed that PGF luteolysis by inhibjting gonadotropin recept?? rs on the CL (12) or by reducing blood flow through the CL (13) due to the vasoconstrictive properties of PGI&(l4). Bovine CL are refractory to PGFZo( during the first 5 d of the cycle (15, 16). The differences in the stage of growth of CL in heifers before the first PGF treatment explains the differences in hormonal profi 3 es between heifers in Groups 1 and 2 during the experiment. Animais in Group 2 either showed estrus or ovulated shortly before the first PGF% treatment. The hormonal profiles in Group 2 heifers treatment did during the period following the first PGF not differ from those in control estrous $? ycles. Since newly formed CL were insensitive to PGFW at the time, CL growth in Group 2 followed a normal course of development until the second PGF administration. The fact that CL development in this Boup of heifers was unaffected by the first PGF treatment explains the faster rate of increase to peak p rasma P level in Group 2 heifers after the first injection of PGF CL had matured in all heifers (Groups 1 and 2) by 10 d2clfollowing the first injection of PGF and allowed a uniform response by all heifers to the %cond PGFZti injection on Day 12. In conclusion, P profiles were detected for Bos indicus and Bos taurus heifers both before and after PGFti treatment, and these profiles indicated that a tropical location did not affect ovarian response to PGF effectiveness of PGFH in achieving estrus syncal( and the ronization.
766
MAY
1987 VOL.
27 NO. 5
THERIOGENOLOGY
REFERENCES 1.
Louis, T. M., Hafs, H. D. and Morrow, Il. A. Estrus and J. Anim. Sci. ovulation after uterine PGFZA in cows. 35: 247-248 (1972).
2.
Lauderdale, J. W. Effects estrous cycles of cattle. abstr. (1972).
3.
of PGF J . An%
on pregnancy
and
. Sci. 35~246
Elsden, R. P., Lewis, S., Cumming, T. A. and Lawson, Superovulation in the cow following treatment R.A.S. with PMSG and prostaglandin FZM J. Reprod. Fertil. 36:455-456 (1974).
4.
Louis, T. M., Hafs, H. D. and Seguin, B. E. Progesterone, LH, estrus and ovulation after prostaglandin Proc. Sot. Exp. Biol. Med. 143:152-155 FZtnin heifers. (1973).
5.
Dobson, H., Cooper M. J. and Furr, J. A. Synchronization of estrus with ICI 79339, an analogue of PGF 201 and associated changes in plasma progesterone, and LH in heifers. J. Reprod. Fertil. estradiol-17 42:141-144 B1975).
6.
of estrus and fertility Roche, J. F. Synchronization following artificial insemination in heifers given prostaglandin F20,.J. Reprod. Fertil. -37:419-425 (1975).
7.
Adeyemo, O., Akpokodje, J. U. and Odili, P. I. Synchronization of Bos indicus and -~ Bos taurus heifers with prostaglandin F@. Theriogenology -12:255-292 (1980).
8.
Abraham, G. E., Serdloff, R., Tulchinsky, 11. and Odell, W. D. Radioimmunoassay of plasma progesterone. Endocr. 32:619-624 (1971).
9.
Adeyemo, 0. and Heath, E. Plasma progesterone concentration in Bos taurus and Bos indicus heifers. TheriogenologyT:411-420 (1981).
10.
Campbell, R. C. Statistics for Biologists. University Press, 1974.~. 177-237.
11.
Adeyemo, O., Heath, E., B. K. Estrous cycles in heifers acclimatized to climate. Zbl. Vet. Med.
12.
Grinwich, D. D., Ham, E. A. Hichens M. and Behrman, H. R. Binding of human chorionic gon;dotropin and response of cyclic nucleotides to luteinizing hormones in luteal tissue from rats treated with prostaglandin
MAY 1987 VOL. 27 NO. 5
Cambridge
Steinbach, J. and Adadevoh, Bos indicus and ~~ Bos taurus ~-the hot humid seasonal equatorial A. 26:788-799 (1979).
767
THERIOGENOLOGY
Endocrinology -98:146-150 (1976). 13. Navy, M. J., and Cook, M. J. Redistribution of blood _. flow by prostaglandin F2& in the ovary. Am. J. Obst. Gynecol. 117:381-385 (1978). 14. Ducharme, D. W., Weeks, J. R. and Montgomery, R. G. Studies on the mechanism of the hypertensive effect of prostaglandin Fzd. J. Pharmacol. Exp. Ther. 160: l-10 (1968). 15. Cooper, M. J., and Fur-r,B. J. A. prostaglandin in animal breeding. 161-163 (1974).
The role of Vet. Rec. _* 94.
16. Lamming, G. E., Hafs, W. D. and Manns, J. G. Hormonal control of reproduction in cattle. Proc. Brit. Sot. Anim. Prod. -4:71-78 (1975).
768
MAY 1987 VOL. 27 NO. 5