Different synchronization techniques in Boer goat does outside the normal breeding season

Small Ruminant Research, 5 ( 1991 ) 233-243

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Elsevier Science Publishers B.V., Amsterdam

Different synchronization techniques in Boer goat does outside the normal breeding season J.P.C. Greylinga and C.H. Van Niekerkb aDepartment of Animal Science, Faculty of Agriculture, University of Orange Free State, P.O. Box 339, Bloemfontein 9300, South Africa hDepartment of Human and Animal Physiology, University of Stellenbosch, Stellenbosch, 7600 South Africa (Accepted 14 July 1990)

ABSTRACT Greyling, J.P.C. and Van Niekerk, C.H., 1991. Different synchronization techniques in Boer goat does outside the normal breeding season. Small Rumin. Res., 5: 233-243. Synchronization techniques outside the normal breeding season were evaluated on 85 Boer goats with intravaginal progestagen sponges, sponges plus prostaglandin, and two injections of prostaglandin, with or without 500 IU PMSG. Oestrous response following the double prostaglandin injection regime was significantly (P < 0.01 ) lower than in the intravaginal sponge and sponge plus prostaglandin groups (with and without exogenous PMSG). The PMSG led to a higher (P<0.01) oestrous response in goats treated with intravaginal sponges only ( 100.0% vs. 53.3%). Administration of 500 IU PMSG led to a shorter time interval (P< 0.01 ) from cessation of treatment to the onset ofoestrus in the intravaginal sponge and sponge plus prostaglandin groups (40.0 vs. 72. lhr and 39.3 vs. 71.3hr, respectively). Time interval from treatment to the LH peak was shorter (P<0.01) in the groups (excluding the double injection prostaglandin groups) receiving 500 IU PMSG, with no significant difference between the two intravaginal sponge treated groups. No significant differences in the time interval between LH peak and onset of the oestrous period was recorded between treatment groups. There was no significant difference in fertility between the intravaginal sponge and sponge plus prostaglandin groups ( 73.3 vs. 66.7% with PMSG and 53.3 vs. 60.0% without PMSG). Intravaginal sponge and sponge plus prostaglandin techniques (with PMSG) are effective as synchronizing agents outside the breeding season in Boer goat does. The double prostaglandin injection regime on the other hand proved ineffective outside the breeding season.

INTRODUCTION

Synchronization of oestrus remains a tool with great potential in controlled breeding of small stock (Haresign, 1978 ). A variety of synchronization techniques have been used to induce oestrus in the ewe (Cumming, 1979; Greyling and Van der Westhuysen, 1980) and to a lesser extent in the doe, especially outside the normal breeding season (Bosu, et al., 1978; Greyling, et al., 1985; Greyling and Van Niekerk, 1986). However, oestrus synchronization 0921-4488/91/$03.50

© 1991 - - Elsevier Science Publishers B.V.

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J.P.C. GREYLING AND C.H. VAN NIEKERK

with progestagens has been associated with reduced fertility during the induced oestrous period, which has been shown to be associated with impeded sperm transport (Robertson, 1977) and a disturbed temporal relationship between the onset of oestrus and the pre-ovulatory LH surge (Gordon, 1975 ). The Boer goat doe has been shown to have an extended breeding season with periods of complete anoestrous being absent (Greyling and Van Niekerk, 1987 ). This study was initiated to compare the effectiveness of different synchronization techniques outside the normal breeding season, in the Boer goat doe. MATERIAL AND METHODS

Eighty-five Boer goat does, nulliparous (n = 7 ) to multiparous (n = 78 ) were randomly allocated to six treatment groups, outside the normal breeding season (November): (1) intravaginal sponges (MAP, 60 mg; Upjohn) for 14 days plus 500 IU PMSG administered subcutaneously at sponge withdrawal ( n = 1 5 ) ; (2) intravaginal sponges (MAP, 60 mg; Upjohn) for 14 days ( n = 15); (3) intravaginal sponges (MAP, 60 rag; Upjohn) for 8 days followed by 62.5 ag prostaglandin F2, (PGF) (Estrumate, ICI 80996) administered intramuscularly, and 500 IU PMSG subcutaneously, at sponge withdrawal (n = 15 ); (4) intravaginal sponges (MAP, 60 mg; Upjohn) for 8 days followed by 62.5 pg prostaglandin F2, (PGF) (Estrumate; ICI 80996) administered intramuscularly at sponge withdrawal (n = 15 ); (5) two 62.5 #g intramuscular prostaglandin F2, (PGF) (Estrumate; ICI 80996) injections 14 days apart plus 500 IU PMSG subcutaneously at second injection (n = 10); (6) two 62.5 pg intramuscular prostaglandin F2a (PGF) (Estrumate; ICI 80996) injections, 14 days apart ( n = 15). All animals were housed in well sheltered and ventilated pens by night and fed a pelleted high energy diet (ME = 9.6 MJ/kg DM) ad libitum. By day the goats were allowed to browse in grass camps ( 10 000 m 2 ), with water always freely available. From four does out of each group, venous blood was sampled at eight hour intervals, starting at sponge withdrawal or the second prostaglandin injection, until the end of the induced oestrus. Oestrus observations, with the aid of vasectomised bucks, were carried out concurrently with the blood sampling at 8-hour intervals, 7.00 h, 15.00 h and 23.00 h and additionally at 9.00 h, 11.00 h, 13.00 h and 18.00 h. Does were tested for oestrus for a maximum observation period of 120 h following the cessation of treatment. Does were inseminated (0.05 ml fresh undiluted semen per insemination) 12 h after the detection of oestrus for the first time, and again at 12-hourly intervals for the duration of oestrus. Fertility was monitored in terms of conception rate (percentage does kidding/does inseminated), kidding rate (percentage kids born/ does inseminated) and fecundity (number of kids born/does kidding). Serum

SYNCHRONIZATION TECHNIQUES IN BOER GOATS DOES

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was recovered and stored ( - 20 ° C) until assayed for serum progesterone and LH concentrations.

Progesterone assay Serum 9rogesterone concentrations were determined by the RIA technique ofYousefnajadian, et al., ( 1972 ), as modified by Faure ( 1975 ) and validated for goats by Van der Westhuysen (1979). The assay entailed progesterone extraction from unknown serum samples with the aid of diethyl ether. Antisera with a working dilution of 1 : 12500 in buffer were used in the assays, together with a progesterone isotope (progesterone-1,2,6,73H (N) ). With every series of unknown samples, a standard curve (progesterone standards of 10.0; 5.0; 2.5; 1.25; 0.6125; 0.3062; 0.1531 and 0 ng/ml) was concurrently set up. Separation of the bound and free isotope was performed with the aid of dextran-coated charcoal. Values for each serum sample were determined as a percentage of zero standard and serum progesterone concentrations were read off the standard curve. Intra- and inter-assay coefficients of variation were 8.5% and 15.2%, respectively. Luteinizing hormone assay Serum LH levels were determined according to the RIA double-antibody technique of Niswender, et al., ( 1969 ) and Miller and Aehnelt ( 1977 ). Iodination (1::51) was by modification of the method by Hunter and Greenwood (1962). A series of NIH-LH-17 standards between 0 and 100 ng/ml were prepared by dilutio:a with 0.1% BSA/PBS buffer. Anti-ovine LH was diluted with 1:400 NRS to give a final working solution of 1:30 000. Following the addition of the isotope (125I) and an incubation period, the antibody-bound LH complexes we:re precipitated using a second antibody (anti-rabbit gamma globulin, donkey; from Wellcome Co., Beckenham, England). After incubation, the supernatant was removed and the precipitate radiation counted in a gamma spectrophotometer, and LH concentrations expressed in terms of ng/ NIH.LH/ml. Inter- and intra-assay coefficients of variation for serum LH were 15.8'% and 9.0%, respectively. All datz were statistically analysed by means of analysis of variance at the 1% and 5% level of significance. The chi-square test was implemented to compare reproductive responses between groups (Snedecor and Cochran, 1980 ). RESULTS

Oestrus response, mean intervals from the cessation of treatment to oestrus, changes in the serum progesterone and LH concentrations are in Table 1 and 2. Oestrous response following double prostaglandin injections was lower ( P < 0.01 ') than that in the intravaginal sponge and sponge plus prostaglandin

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J.P.C. G R E Y L I N G A N D C . H . V A N N I E K E R K

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TABLE 1 Oestrous response, interval after treatment to oestrus and the duration of the induced oestrous period following different synchronization techniques. Item

500IU PMSG

Sponges Number of does 15 OestrousResponse (%) 100.0 a Intervaltooestrus2(h) 40.0_+ 9.7 a Range (h) 31-54 D u r a t i o n o f o e s t r u s ( h ) 40.7+14.5 a

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15 13.3c 45.5+24.7 b 28-63 39.0+22.6 a

~PGF = Prostaglandin F2a 2Values in the body of the Table are m e a n _ S.D. abCMeans in the same row, with the same superscript indicate no significant difference

groups (with and without exogenous PMSG). PMSG led to a higher ( P < 0 . 0 1 ) oestrous response (Fig. 1) in goats treated with intravaginal sponges. Due to a poor oestrus response from the double prostaglandin injections (only 2 animals per group responding), they were excluded from Fig. 1. Similarly, the administration of 500 IU PMSG led to a significantly ( P < 0.01 ) shorter interval from cessation of treatment to the onset of oestrus in both the

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intravaginal sponge and sponge plus prostaglandin groups. Duration of the induced oestrous periods showed no significant difference between the different treatment groups (Table 1 ). Considerable standard deviation in the peak LH concentration (Table 2) existed within the different treatment groups (Fig. 2). Interval from cessation of treatment to serum LH peak was significantly ( P < 0.01 ) shorter in the groups (excluding the double injection prostaglandin groups) receiving 500 IU PMSG, with no significant difference between the intravaginal sponge group and sponge plus prostaglandin synchronization groups. Peak LH level was taken as the highest measured LH (which varied between 7.2 ng/ml and 49.5 n g / m l ) for individual animals in the different treatment groups. PMSG had no significant effect on the peak values recorded. In the double prostag-

239

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landin injection groups, only one animal (in the group receiving no PMSG) of the does from which blood was sampled, exhibited a LH peak value. Interval of the ~erum LH peak to onset of oestrus was not significantly different between the different progestagen treatments, with PMSG having no significant influence. In the single doe exhibited a LH peak in the double prostaglandin injection group, this interval from prostaglandin administration to the LH peak was considerably shorter than in the other treatment groups. No significant differences in interval from LH peak to the end of the oestrous period were recorded. Mean serum progesterone concentrations (Table 2) remained low following treatment, with no significant difference in progesterone concentration at the onset of the induced oestrous period. Regarding fertility (Table 3 ), there was no significant difference between the intravaginal sponge and sponge plus prostaglandin treatment. Double prostaglan,lin injections had lower ( P < 0 . 0 1 ) fertility (with and without

240

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TABLE 3 Effect of synchronization techniques on reproductive performance of Boer goat does. Item

N u m b e r of does Conception rate % Kidding rate % Fecundity

5001U P M S G

N o P,SG

Sponges

Sponges plus PGF

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15 53.3 a 106.7 a 2.0 a

15 60.0 a 126.7 a 2.11 a

15 6.7 b 13.3 b 2.0 a

abMeans in the same row, with the same superscript indicate no significant difference

PMSG) than other treatment groups. Administration of 500 IU PMSG showed no significant effect on conception, kidding rate and fecundity following different synchronizations.

SYNCHRONIZATION TECHNIQUES IN BOER GOATS DOES

241

DISCUSSION Synchronization with two injections of prostaglandin in the Boer goat outside the normal breeding season (November) led to poor oestrous responses which indicates that prostaglandin as a synchronizing agent is only effective in the active breeding season by causing luteolysis of the corpus luteum (Greyling, 1978 ). Stimulation of follicular growth in the ovary by exogenous PMSG led to higher ( P < 0.01 ) oestrous response by anoestrous goats only in the intrawaginal sponge group. First ovulation in sheep during the non-breeding season will not be associated with overt oestrus, except if the ewe has been exposed to progesterone/progestagen treatment shortly before ovulation (Cumming, 1979 ). Whether this is true for goats, is speculative. The requirement for ;prior exposure to progestagen in order for oestrous behaviour to occur, may be dependent on the intensity of the subsequent oestrogen stimulus (Armstrong, et al., 1982). PMSG injection required to induce oestrus in females during the non-breeding season, decreases time interval between the end of progestagen and onset of oestrus (Cognie, et al., 1970), as was seen in this experiiment. Absence of oestrus/ovulation may result from either insufficient go~adotrophic hormones liberated by the hypophysis, from a poor response by ovary to the exogenous PMSG (Mauleon, 1979) or, great variation in responsiveness of animals to PMSG (Armstrong, et al., 1982). The inverse relationship found between changes in progesterone and tonic LH secret;ion during the follicular phase of the oestrous cycle agrees with Karsch, et al. (1977), Goodman and Karsch (1980), with progesterone and oestradiol being the major components of the negative feedback system regulating tonic LH secretion (Goodman and Karsch, 1980; Haresign, 1985). The precise mechanisms through which oestradiol and progesterone suppress LH secretion is still unclear. Peak serum LH levels recorded during the preovulatory I_,H surge occurred 4.3 to 14.0 h (double prostaglandin injection groups excluded) after the onset of oestrus, which is in line with Cognie and Pelletier (1976), who also found the duration of increased LH release and value of the peak are higher in dry than in lactating ewes. Baumgartner, et al., ( 1974 ) postulated that concentrations of LH in the plasma are lower during LH surges which occur after the administration of progesterone than during LH surges in unsynchronized sheep. The present results could not indicate subnormal levels of LH, but then the intersampling intervals (8 h) were too long for the determination of reliable peak LH values - - due to the pulsatile nature of LH. Synchronization of oestrus progestagens commonly results in a reduced conception rate (Baumgartner, et al., 1974), having detrimental effects on sperm transport and sperm survival in the female reproductive tract (Hawk and Conley 1971 ; Pearce and Robinson, 1985 ). The conception rate achieved in this trial (double prostaglandin regime excluded) was acceptable (Hunter, 1980). Alt;aough there was not a significant difference in fertility following PMSG administration, the treatment with PMSG had a beneficial effect. The

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J.P.C. GREYLING AND C.H. VAN NIEKERK

m a i n a i m w i t h a single i n j e c t i o n o f 350 to 750 I U P M S G at sponge withd r a w a l is t h a t it i m p r o v e s the degree o f s y n c h r o n i s a t i o n a n d slightly hastens the o n s e t o f oestrus ( G o r d o n , 1975 ). F r o m the o e s t r o u s r e s p o n s e a n d fertility results o b t a i n e d , the c o n v e n t i o n a l i n t r a v a g i n a l p r o g e s t a g e n a n d 500 I U P M S G m e t h o d is the m o s t suitable (especially i f cost is also t a k e n into a c c o u n t ) for s y n c h r o n i z a t i o n in B o e r goat does, o u t s i d e the b r e e d i n g season, a l t h o u g h the i n t r a v a g i n a l sponge plus prost a g l a n d i n t r e a t m e n t also gave c o m p a r a b l e results. T h e d o u b l e p r o s t a g l a n d i n i n j e c t i o n was n o t r e c o m m e n d a b l e as a s y n c h r o n i z a t i o n t e c h n i q u e in B o e r goats, o u t s i d e the n o r m a l b r e e d i n g season. ACKNOWLEDGEMENT A n t i s e r a for p r o g e s t e r o n e a n d L H d e t e r m i n a t i o n s were m a d e available b y Prof. J.C. M o r g e n t h a l , U n i v e r s i t y o f Stellenbosch, S o u t h Africa.

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Greyling, J.P.C. van Niekerk, C.H. and Grobbelaar, J.A.N., 1985. Synchronization of oestrus in the Boer goat doe: the response to the use of intravaginal progestagen and PMSG. S. Afr. J. Anim. Sci., 15: 52-55. Greyling, J.P.C. and van Niekerk, C.H., 1986. Synchronization ofoestrus in the Boer goat doe: Dose effect of prostaglandin in the double injection regime. S. Afr. J. Anim. Sci., 16 146150. Greyling, J.P.C. and van Niekerk, C.H., 1987. Occurrence of oestrus in the Boer goat doe. S. Afr. J. Anim. Sci., 17: 147-149. Haresign, V¢., 1978. Ovulation control in sheep. In: D.B. Crighton, N.B. Haynes, G.R. Foxcroft and G.E. Lamming (Editors), Control of ovulation. 1st Edn. Butterworths, London, 435451. Haresign, W., 1985. Comparison of the rate of decline in plasma progesterone concentrations at a natural and progesterone - - synchronized oestrus and its effect on tonic LH secretion in the ewe..l. Reprod. Fert., 75:231-236. Hawk, H.W and Conley, H.H., 1971. Sperm transport in ewes administered synthetic progestagen. J. Anim. Sci., 33: 255-256. Hunter, R.H.F., 1980. Physiology and technology of reproduction in female domestic animals. Academic Press, London. Hunter, W.M. and Greenwood, F.C., 1962. Preparation of iodine-131 labelled growth hormone of high specific activity. Nature, 194: 495-498. Karsch, F.J., Legan, S.J., Hauger, R.L. and Foster, D.L., 1977. Negative feedback action of progesterone on tonic luteinizing hormone secretion in the ewe: Dependence on the ovaries. Endocrinology. 101: 800-806. Mauleon, P.~ 1979. Manipulation of the breeding season. In: G.J. Tomes, D.E. Robertson and R.J. Lightfoot (Editors), 2nd Edn. Butterworths, London, 439-449. Millar, R.P. and Aehnelt, C., 1977. Application of ovine luteinizing hormone (LH) radioimmunoass~ty in the quantification of LH in different mammalian species. Endocrinology 101: 760-768. Niswender, H.D., Reichert, L.E.J.R., Midgley, A.R. and Nalbandov, A.V., 1969. Radioimmunoassay figr bovine and ovine luteinizing hormone. Endocrinology, 84:1166-1173. Pearce, D.T. and Robinson, T.J., 1985. Plasma progesterone concentrations, ovarian and endocrinological responses and sperm transport in ewes with synchronised oestrus. J. Reprod. Fert. 75: ,19-62. Robertson, I-LA., 1977. Reproduction in the ewe and goat. In: H.H. Cole and P.T. Cupps (Editors), Reproduction in domestic animals, 3rd Edn. Academic Press, New York, 475-498. Snedecor, G.W. and Cochran, W.G., 1980. Statistical Methods, 7th Edition. Iowa State University Press, Ames, Iowa, USA, 215-233. Van der Westhuysen, J.M., 1979. The oestrous response and changes in plasma progesterone concentrations of Angora and Boer goat does following injection of a GnRH analogue. S. Afr. J. Anim. Sci., 9: 17-19. Yousefnajadian, E., Florensa, E., Collins, W.P. and Sommerville, I.F., 1972. Radio-immunoassay of plasma progesterone. J. Steroid. Biochem., 3: 893-896.