Estrous cycle synchronization in dairy heifers with the prostaglandin analog alfaprostol (II)

THERIOGENOLOGY

ESTROUS WITH

CYCLE

SYNCHRONIZATION

THE PROSTAGLANDIN Schilling,

E.,

ANALOG

IN DAIRY

HEIFERS

ALFAPROSTOL

+I).

W. JClchle* and D. Smidt

Federal Research Institutes for Agriculture, Institute for Animal Science and Animal Behavior, Marlensee, D-3057 Neustadt 1, F.R. of Germany. * Wolfgang Jdchle Associates, Inc. 10 Old Boonton Road, Denville, NJ 07834,

USA.

Received for Publication: April 20, 1982 Accepted: July 29, 1982

ABSTRACT Over a two year period, 276 dairy heifers (German Black Pied x Holstein Friesian) received one or two injections i.m. of 1.5 mg/lOO kg body weight of the PGF analog alfaprostol.Only animals not showing heat after the first injection were treated twice, with the same dose, 11 days apart. Before treatment, 71% of the heifers were cycling regularly, 12% were cycling irregularly and 17% were not observed in heat prior to treatment. Animals in heat were inseminated once or twice, 18 to 24 h apart. In response to the first injection, 60.5% of all treated animals came into heat: 38% showed heat after the 2nd treatment. Three of the six non-responding animals were later diagnosed as freemartins. Heat was well synchronized. Twenty seven percent, 60% and 9% of all first inseminations occurred respectively; on days two, three and four after treatment(s), 65% of all heifers conceived from the first insemination. Pregnancy rates after one or two inseminations were 66.0% and 63.8%, respectively. At the second a.i., 45% of all animals had already ovulated. Pregnancy rates from first a.i. after one or two treatments with alfaprostol were 60.1% and 72.2%, respectively. Years had no influence on any of the parameters Stage of cycle in which the first treatment occurred observed. had a strong influence on the occurrence of heat and on conceptions as well. Of the animals treated between days 6 and 18% of their cycles, 92.6% responded with heat to the first When animals were treated for the treatment and 79% conceived. first time between days 19 and 5 of their cycles, only 28.8% came into heat and only 23.8% conceived. After the 2nd treatment,71.2% of the latter group came into heat and 73.1% conceived. ')Alfaprostol (K 11941): 18,19,20-trinor-17-cyclohexyl-13,14 didehydro-PGF2,-methylester: VETEMS.p.A., Milan, Italy.

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INTRODUCTION effect of prostaglandin Over the last decade, the luteolytic (PG)F2c( and Its analogs (PGAs) has been used successfully to synchronize estrus and ovulation in beef and dairy cattle (For reviews, see l-7). Under Central European dairy cattle cycle synchronization with PGAs is of interest in management, took on the responsibility dairy heifers only. This institute to evaluate several of these PGAs for their effectiveness, for the fertility observed after several differing treatment after insemination at predetermined intervals from schedules, or after one or two inseminations when animals treatment, were observed in heat (8,9). Animals were either treated twice in ll+l-day intervals (schedule I) or once with only those animals not coming into heat treated twice llfl days later rates were higher (schedule II). In these trials, conception (72%) with schedule II compared to ca 50% with schedule I (8,9), using the PGAs Iliren (Hoechst) and Prostianol(INTERVET; E.Merck/Darmstadt), respectively. Results with one or two inseminations at synchronized heat were ambiguous(9). In the trials reported here, the PGA alfaprostol was evaluated by the above characterized treatment schedule II forestrous cycle synchronization. Earlier studies had confirmed alfaprostolls effectiveness as a luteolytic agent in the bovine (10, 111 and as a tool for cycle control in dairy cattle (12). In these studies, including dose titration trials using clinical parameters and monitoring of luteolysis, a dose/body weightrelationship had emerged (13). Hence, heifers in our studies were dosed accordingly (See Material and Methods). Animals were inseminated once or twice at the first heat after to contribute to the current discussion about treatment(s), the most effective and economic schedule for a.i. after synchronization (9). The ovarian status was determined at each Correlations between theday insemination by rectal palpation. of the cycle, at which the first treatment occurred, and heat and conceptions were subsequently recorded. MATERIAL

AND METHODS

These trials were conducted during the winter breedrng seasons of 1979/80 and 1980/81 in two farms which belong to the institute and are located 200 km apart in Northern Germany. Since management, climatic and geographic conditions, and results between farms were similar, data were pooled. A total of 276 German Black Pied and F Crossbred heifers (German Black Pied x Holstein-Friesian;) were used, that is, 111 in 1979/80 and 165 in 1980/81. In each breeding season 5 to 7 groups of 15 to 20 equally old heifers were formed and admitted to treatment. The majority of these heifers weighed 350 to 450 kg; two groups weighed only 300 to 350 kg, and the heifers of the two groups treated first at each season were 22 to 26 months old and weighed 450 to 520 kg.

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Animals were kept indoors in free-stalls and received a diet of grass, or maize silage and hay. Commencing 4 to 6 weeks before the start of the season, they were fed 1 kg concentrate daily. Untreated, contemporary controls were not available. Before treatment, animals were observed by trained personnel once daily; after treatment, heat was observed twice daily until 10 days after the 2nd inJection. In accordance with instructions given by the drug's sponsor, animals received 1.5 ml alfaprostol (1.5 mg) per 100 kg body weight. Accordingly, most animals received 6 mg; the two groups deviating in body weight, as described above, received 5 and 7 mg alfaprostol, respectively. All treatments were administered between 11.00 and 13.00 hours. Only animals not responding with heat within 10 days were treated again with the same dose at day llfl. All animals coming into clinical heat, were alternately inseminated once or twice. The second insemination came 18 to 24 h after the first. At each a.i., the ovarian status was examined by rectal palpation about 60 days after service and calvings were recorded. Before treatment, 181 (71%) of the heifers had shown at least two regular cycles; 32 (12%) of the heifers had cycled irregularly and had shown, in most instances, prolonged heat periods while 43 (17%) had not shown heat symptoms prior to treatment. RESULTS As shown in table 1, 96% and 99% of the heifers treated with alfaprostol during 1979/80 and 1980/81 responded with synchronized heat. Three of the six non-responding animals were belatedly diagnosed as freemartins. Sixty percent of all animals showed synchronized heat after the first treatment; 38% had to be treated twice. The difference between the two years in this regard was insignificant. The degree of synchronization, as expressed by the days at which insemination occurred, was satisfactory. On days 2, 3 and 4 after the 1st or the 2nd injection with alfaprostol 27%, 60% and 2% of the animals came into heat and were inseminated (Table 1). No differences were seen in the occurrence of heat on day 2, 3 and 4 between animals treated with alfaprostol once or twice. The duration of the synchronized heat was 24 h in 72%, and longer than 24 h (up to 36 h) in 28% of the treated heifers. heat Pregnancy rates recorded after a.i. at the synchronized are summarized in table 2. More animals conceived after the second injection (72.2%) than after the first injection (60%). The same trend was observed in both years. The generally lower conception rates during the 1979/80 season were, in the related to managerial factors judgement of the investigators, and were not a drug related effect. Two inseminations were not more efficacious than one insemiI;ation (Table 2). The ovarian status obtained at the first

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and second insemination indicated, as shown in table 3, that, at the 2nd insemination, 45% of all synchronized heifers had already- ovulated. Hence, estrus and ovulations were well synwhich may explain the short duration of heat as chronized, mentioned above. Small preovulatory follicles had entirely disappeared at the second a.i. Animals not observed in heat before treatment or animals with prevl.ously irregular cycles responded to treatment in a very simi:.ar fashion, with about 60% responding to one treatment and about 40% responding to two treatments, respectively. Heifers which had not conceived returned to heat in a high percentage in a regular interval of 18 to 23 days (64 and 61%): in 36 and 39%, this interval was irregular and was in most instances >24 days (Table 4). All animals coming into heat were inseminated; with a.i. at the first and second heat after the synchronized heat, the overall pregnancy rate was elevated to 83 and 91%, respectively. At each of these subsequent heat periods, about two thirds of the animals bred did conceive (Tabie 4). In animals with one or two regular cycles before alfaprostol treadlments, occurrence of heat after one or two treatments and conceptions were correlated with the day of the cycle at which the first inJection was administered (Table 5). Of the heifers treated between days 6 to 18, 92% responded to the firs: treatment and 81% conceived; while, in this group, only 8% responded to the 2nd treatment, and of those only 28% conceived. Of the heifers treated between days 19 and 4 of their respective cycles, 27% responded to the first injection, but only 28% of those became pregnant. All others (73%) reacted to and 74% of those became pregthe 2nd injection of alfaprostol nant. Animals treated on day 5 reacted with synchronized heat 64% responded to the second injecin 3lj%, but none conceived; tion and 12% of those became pregnant (Table 5). Differences in age and body weight, and the fact that heifers cyclcad before treatment regularly or irregularly, or showed on the response to treatanestrus, had nosignificantinfluence and on pregnancy rate. ment, i.e., on synchronization DISCUSSIOL The results reported here indicate that alfaprostol, at the dosasge used, acted as a reliable luteolysin and, hence, a highly satisfactory degree of estrus synchronization and ovulations could be compared was recorded. In this respect, alfaprostol favorably ,dith the other PG analogs previously tested in dairy heifers at this institution (8,9) or elsewhere (14-17). In a'ddition, alfaprostol must have induced heat and ovulation in 43 animals which previously had not shown cyclic activity. We do not know to which extent these animals may have cycled silently or may have been acyclic. Treatment with PGF gRe(;;121J and with alfaprostol as well (221, is known to cause lease of LH and androgens in bulls. The assumption is made by

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Table

Pregnancy rates in herfers inseminated once or twice at the synchronized heat, and bred after the frrst, or the second treatment with alfaprostol (%).

2.

Year

Number

n

of 1

1979/80

Number

treatments 2

of 1

insemrnations 2

1980/81

107 163

48.5 67.6

67.5 75.3

58.1 71.4

54.0 70.0

Total

270

60.1

72.2

66.0

63.8

Table

Status small

Ovarian status 18 to 24 hours

3.

of

the

and

normal

Year

follicle:

fluctuating had

4.

first

firm

and

ovulation

Table

ovulatory

at the apart.

already

occurred

Cyclic patterns in zation and pregnancy chronized heat and

n

Repeat with normal cycle length

at

and

second

first

a.i.

rnsemlnation,

at second

19%

0%

75%

55%

6%

45%

repeat breeders after synchronirates from a-1. at the synof the next two heat periods.

breeders with abnormal cycle length*

Pregnancy rates from a.i. in all animals at the synat the next two chronized heat oeriods heat (cumuiative)

1979/80

47

64%

36%

56.2%

84%

93%

1980/81

48

61%

39%

70.6%

82%

89%

Total

9,

62%

38%

65.0%

83%

91%

* mostly

prolonged

418

intervals,>24

a.i.

days.

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Table

between the day of the cycle in which 5. Relationship the first injection of alfaprostol was given and the occurrence of heat and conception, in animals which cycled regularly prior to treatment.

n

Day of the cycle when the first injection of alfaprostol was given. 5 6-18 79-4

In heat after the first treatment (%)

168

88/95 (92.6)

Pregnancy rate, %

109

73

In heat treatment after the (%) second

168

Pregnancy rate, %

59

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7/95 (7.4) 28

17,'62 (27.4)

4/11 (36.4)

28

0

45/62 (72.6)

7/1t (63.63

74

72

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THERIOGENOLOGY

effect us that in acyclic animals this gonadotropin-releasing of alfaprostol may have initiated follicular growth and ovulation. Since a high percentage of animals came into heat within 48 and 72 h after treatments, blind a-i. at these intervals should be highly effective, as shown before (12). A similar recommendation had been made previously for the PGF analog Prostianol (9), while the optimal time table for fixed-time after treatment with the PGF analogs Iliren and Estrumate strongly indiFsidifferent (8 14 15 16). These observations cate that schedile; f;r fixed-time inseminations after cycle control with,PGF analogs cannot be transposed from one analog to the other, but have to be establrshed for each analog separately. Conception rates from a.i. at the synchronized estrus was highly satisfactory. Claims made that young age may impair the chance to conceive after synchronization with a PGF analog were not confirmed (14,15). The pregnancy rate was higher after the 2nd treatment (Table 2). Two inseminations at the same heat were not more effective than one insemination; the short duration of heat observed and the high rate of ovulations which had occurred at the 2nd insemination explain why, after the use of alfaprostol, only one insemination is sufficient. The high rate of heifers which returned in a normal interval and the high conception rate at the next two inseminations are indicative of undisturbed cyclic functions and normal fertility after the use of alfaprostol as a luteolysin, as well as a "cycle starter"; this was seen also in previous studies with this PGF analog (11,12). A correlation was observed between heat response, as well as conception, and the time when the first treatment occurred during the individual cycles of normally cycling heifers (TableS). The high rate of heat response and conceptions when animals were treated between (and including) days 6 to 18 only confirms that alfaprostol is a reliable luteolysin and that fertility at the induced and synchronized heat is not impaired. The small percentage of animals responding between days 19 and 4 (27%) reflects approximately the percentage of animals one would expect to come into heat spontaneously during this time period (3). Unexpected was the low percentage of animals which became pregnant (28%) in this subgroup; but the percentages of animals showing heat after the 2nd treatment were high (74%). Day 5, as has (73%), as were those becoming pregnant been shown before (1,2,3), is on the transition of corpus luteum responsiveness to the luteolytic effects of PGF analogs. The majority of animals responded to the 2nd injection when the corpora lutea were fully matured (Table 5). The data presented here confirm the effectiveness of the treatment schedule (II) used in these trials, which is economically more attractive than the dual-injection schedule (I), provided

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heat observations timed a.i. could

are acceptable. be used.

After

the 2nd treatment,

A third technique for estrous cycle synchronization with prostaglandin analogs (Schedule III) involves heat observations for five days and rnsemination of all animals coming intoheat. Provided a sufficiently high percentage of animals shows heat during this period, the remainder of the herd is treated siis used with this method, multaneously (2,3). If alfaprostol timed inseminations at 48 and 72 h after treatment could beused. REFERENCES 1.

Hafs, H.D., Manns, J.G., Lamming, G.E. Synchronisation of of Cattle oestrus and ovulation rn cattle. 1n"Principles of NotProduction", Proc. 23rd Easter School, University tingham, 1975. Eds. H. Swan, W.H. Broster, Butterworths. PP. 45-48 (1976).

of ovulation 2. Hansel, W., Fortune, J.E. The applications control, In "Control of Ovulation", Proc. 26th Easter of Nottingham, 1977. Eds. D.B. Crighton, School, University G.R. Foxcroft, N.B. Haynes, G.E. Lamming, Butterworths. PP. 237-263 (1978). Ovulation control in cattle. In 3. Hansel, W. & Beal, W.E. "Animals Reproduction", Beltsville Symposia in Agricultural Research; 3, 1978. Halsted Press, pp.91-110 (1979). control in the cow. In "Control of 4. Cooper, M.J. Ovulation of NottinqOvulation",Proc. 26th Easter School, University ham, 1977. Eds. D.B. Crighton, G.R. Foxcroft, N.B. Haynes, pp.413-420 (1978). G.E. Lamming, Butterworths. functions 5. Jt)chle, W. & Lamond, D.R. Control of reproductive Medicine in domestic animals. Current Topics in Veterinary and Animal Science, 7. Martinus Nilhoff Publ., Boston & The Hague; 1980, 248 pp. ISBN 90-247-2400-7. 6. Jnchle, W. Review: Progress Anim. Reprod. Rep.(Therioq. 7. Jbchle, W. Review: Anim. Reprod. Rep.

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E. & Smidt, D. Zyklussynchronisation 8. Petac, D., Schilling von Faersen mit Prostaglandinanalogen. Berl. Munch. Tier(1978). aerztl. Wschr. -91:473-475 von Faerscn E. & Smidt, D. Zyklussynchronisation 9. Schilling, mit dem Prostaglandln-Analog "Prostianol". Berl. Munch. Tieraerztl. Wschr. 93: 30-33 (1980). 10 .Schams, D. & Karg, H. Hormonal response following treatment with different luteolytic acting PG analogs for cycle regulation in cattle. Internat.. Symp. Steroids in Anim. Production. Ed.: Henryk Jasiorowski; p.95, Warsaw 1981. Roussel-Uclaf/Warsaw Agric. IJniv., SGGW/AR.

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11.

of the clinical and luteolytic efGtlnzler, 0. Evaluation fects of the prostaglandin analog K 11941 In dairy cattle. Personal communication (1980).

12. JUchle,

W., Kusmanov, D. & Vujosevic, synchronization in dairy heifers with analog alfaprostol (I). Theriogenology

J. Estrous cycle the prostaglandin (In press).

13. Maffeo,

G., Dagnino, G., Olgiati, V., Guidobono, F.& Ballabio, R. Luteolytic activity of a new analogue of in cows. Proc. V. Intern. Ej;;:aglandin F2a (Alfaprostol) Florence, 1982 (in press). . on Prostaglandins,

H. & Pedersen, H. Investigations on oestrus 14. Philipsen, synchronization by means of prostaglandin in Danishcattle herds. Arsberetning, Inst. for Sterilitetsforskning, Kongelige Veterinaerog Landbohdjskole, -21: 165-170 (1978).

15. Swensson,

T., Astrom, G.& Andersson, U. Conception rates in dairy heifers following insemination at a predetermined time. Svensk Veterindrtidning, (1978). -30:623-626

16. Roche,

J.F. & Prendiville, D.J. Control of estrus in dairy cows with a synthetic analoque of prostaglandin F2alpha. Theriogenology, 11: 153-162 (1979). -

Andresen, P., Grunert! G. 6 Schulte, 0. Untersuchungen zur Zyklusynchronisation mit dem Prostaglandin-Analog HR-837V. Zuchthygiene, -13: 89 (1978). H.D. Prostaglandins and the control of anterior 18. Hafs pituitary hormone secretion. In: Hypothalamic Hormones, Eds. M. Motta, P.G. Crosignani & L. Martini, Academic Press, New York, 1975, pp, 183-193.

17.

19.

Hafs, H.D., Kiser, T.E., Haynes, N.B., Kesner, J.S. & Stellflug, J.N. Release of pituitary hormones, cortisol, testosterone and insulin in response to prostaglandin F20( given during intracarotid infusion of somatostatin in bulls. J. Anim. Sci., -44: 1061-1066 (1977).

20. Haynes, N.B., Kiser, T.E., Hafs, H.D., Carruthers, T.D., Oxender, W.D. & McCarthy, M.S. Effect of intracarotid infusion of prostaglandin F on plasma luteinizing hormone, testosterone and glucocor t* icoid concentrations in bulls. J. Anim. Sci., -45: 1102-1107 (1977). 21. Kiser, T.E., Milvae, R.A., Hafs, H.D., Oxender, W.D. & Louis, T.M. Comparison of estosterone and androstenedione secretion in bulls given prostaglandin F or luteinizing hormone. J. Anim. Sci., -46: 436-442 (19767. 22. MUller, U.M. Die Testosteronsekretion des zuchtreifen Stieres unter verschiedenen Bedingungen. Vet. Med. Dissertation, Universitaet Zurich, Switzerland, 1980.

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