OESTRUS INDUCTION ANDSYNCHRONISATION IN CASHMERE GOATS Oestrus induction and synchronisation during anoestrus in cashmere goats using hormonal treatment in association with "male effect" Fiorella Carnevali*, Gabriele Schino*, Silvana Diverio** * ENEA Centro Ricerche Casaccia, Divisione Miglioramento Produzioni Animali, Via
Anguillarese 301, 00060 S.M. Galeria, ROME ITALY **Istituto di Fisiologia Veterinaria e Chimica Biologica, Facoltà di Medicina
Veterinaria, Via S. Costanzo, 4, 06126 Perugia. Italy During the anoestrous period, induction and synchronisation of oestrous was obtained in30 cashmere goats at 54±5 days after kidding. A treatment for 11 days with vaginal spongescontaining FGA (Fluorogestone-acetate) 45 mg and an injection of 400 I.U. of PMSG and125 mg of PGF i.m. two days before sponge removal, was used. Goats were equally divided into two groups: A and B. In order to verify the effect of male introduction on the resumptionof sexual activity and on oestrous fertility, males were introduced three days before spongeinsertion into group A and 24 hours after sponge removal into group B. Males wereequipped with a ram-harness carring a coloured crayons. Before their utilization, eachbuck had been housed for one week in a small pen with an estradiol injected female. Aftermale introduction, oestrous was checked daily looking to the colored signs on the femaleback. Blood samples from each goat starting from delivery until the 35th day after maleintroduction were collected and plasma progesterone profiles by RIA method weredetermined. Pregnancy diagnosis by ultrasonography was performed at on the 35th dayafter male introduction. The precocious introduction of males exerted no influence on theresumption of female sexual activity. Plasma progesterone before sponge removal wasalways less than 1.5 ng/ml indicating the absence of luteal activity in all goats After spongeremoval, progesterone profiles indicated luteal activity in 82.8% of the goats in bothgroups. Though 68.9% of the goats were mated, fertility was very low: only one goat of groupA and one of group B became pregnant. Oestrous induction schedule was effective ininducing a normal luteal cycle in 45% of goats but males were not active and their spermprobably not sufficiently fertile. F.CARNEVALI, G.SCHINO, S. DIVERIO & S.MISITI Cashmere goats, as well as most other goats, present sexual activity during thefall, while kidding occurs between the end of winter and the early spring.
Reproductive performance may be improved by induction and synchronisa-tion of oestrous during the anoestrous period, but fertility of induced oestrousis generally low. This is due to sexual inactivity of both males and femalesduring spring, but also to lactating post-partum anoestrous after delivery (fora review see: Malpaux et al., 1994, Thimonier 1981). Several authors haveshown that it is possible to induce the resumption of the sexual activity inanovulatory lactating goats out-of season using the “male effect” in associationwith different hormonal treatments or artificial light regimen (Ott et al., 1980;Pearce, 1985; Claus, 1990; Chemineaux, 1985, 1986b, 1987).
In this work, we verified the possibility of inducing oestrus in out-of-seasonlactating cashmere goats by the association of hormonal treatment with maleeffect, which is considered a natural method for oestrous synchronisation(Chemineau, 1987; Walkden-Brown et al., 1993 a, b, c).
Pregnancy diagnosis by ultrasonography, performed on February 1st, 1995showed that more than 90% of the goats were pregnant. Deliveries weredistributed as follows: 60% (25/42) during the second part of March, 16% (7/42) during April and 23% (10/42) during May. For the present experiment wechose 30 goats which delivered before April 20. One of them died during theexperiment. Non-pregnant goats were not choosen because they were tooyoung in relation to the adult goats.
At the time of oestrous synchronisation, goats the average time since lastkidding was 54±5 (mean ± standard deviation) days , although someindividuals were no more than 40 days. Experimental goats were separatedfrom the rest of the herd but, since they were lactating, kids were not removed.
Adult males had been kept isolated for almost four months. Goats were housedand fed with hay and alfalfa concentrate. A week before the beginning of theexperiment, females were divided into two groups, A and B, balancedaccording to date of delivery. Hormonal treatments for oestrous induction werethe same for both groups, while time of exposure to males was different. Theexperimental schedule is summarized in Table 1.
OESTRUS INDUCTION ANDSYNCHRONISATION IN CASHMERE GOATS Oestrous induction and synchronisation: Vaginal sponges containing 45mgof FGA (Fluorogestone acetate, Crono-gest, Intervet, Italy) were inserted for11 days by vaginal way. Two days before sponge removal, each goat wasinjected with 400 I.U. of PMSG (Pregnant Mare Serum Gonadotropin, Crono-gest, Intervet Italy) and mg125 of synthetic PGF (Cloprostenol, Estrumate, Male preparation: In order to stimulate sexual activity, each male was housedwith a female in oestrus the week before its introduction into the experimentalgroup. Oestrus was induced in the stimulus females by administration of 10 mgi.m of estradiol benzoate (Progynon Depot, Schering).
Exposure to the male: Groups A and B were divided into two subgroups (A , A , B and B each with 7-8 females. In each subgroup, A and A one male was introduced to the females three days before the insertion of vaginalsponges. In subgroups B and B one male was introduced to the females 24 hour after sponge removal - i.e., 15 days later than in subgroups A and A . All males carried a “Ram-harness” with a coloured crayon. Sexual activity wasregistered by daily observations looking for the coloured marks on the female'sbacks. Males were left into the mating groups for 35 days after sponge removal.
Blood sample collection: Blood samples were collected weekly from kiddingto the beginning of hormonal treatment, and twice weekly until the 35th dayafter sponge removal. Plasma progesterone was assayed by RIA method.
F.CARNEVALI, G.SCHINO, S. DIVERIO & S.MISITI Pregnancy diagnosis: Fertility was evaluated by plasma progesterone assaysand by ultrasonography performed on the 35th day from male introductionusing a Toshiba Sonolayer B with 5MHtz probe.
During the preparation phase, males did not mate the estradiol-injected femalesand did not show the characteristic ircin odour. Similarly, the precociousintroduction of males into the group A, 3 days before sponge insertion did notlead to any mating, neither before vaginal sponge insertion nor duringhormonal treatment.
Plasma progesterone concentrations between delivery and the fourth day aftersponge removal were always lower than 1.5 ng/ml in all goats.
One day after vaginal sponge removal, 68.97% of females (10/14=71% ingroup A and 10/15=66.7% in group B) showed oestrus. These animals weremated within three days after sponge removal. All males but one (the male ofgroup A ) showed normal sexual behaviour. 24 hours after his introduction, the inactive male was removed and the females were introduced with the activemale of group A .
Plasma progesterone concentrations between the 2nd and 9th day after spongeremoval showed that 89.6% of goats (12/14=86.7% in group A and 14/15=93.3% in group B) presented luteal activity, with a mean progesteronelevel of 3.3±1.3 ng/ml at the 8th day (see Table 2).
TABLE 2Oestrous behaviour and luteal activity after sponge removal luteal activity between 2nd and 9th day after sponge removal OESTRUS INDUCTION ANDSYNCHRONISATION IN CASHMERE GOATS According to the progesterone profiles of the 20 mated goats, 3 were pregnant,7 showed a normal luteal cycle at the sponge removal but did not becomepregnant, 8 showed a short luteal cycle (plasma progesterone fell to levels lessthan 1.5 ng/ml before the 21th day after oestrous) and 2 never showedprogesterone level higher than 1.5 ng/ml, although they were regularly mated.
According to the progesterone profiles of the 9 non-mated goats, 6 showed anormal luteal cycle, 2 showed a short luteal cycle and 1 never achieved aplasma progesterone level higher than 1.5 ng/ml, and did not show oestrousbehaviour. Data are summarized in Table 3. Progesterone profiles are shownin Fig. 1.
Pregnancy diagnosis performed by ultrasonography on the 35th day after maleintroduction showed that only one goat of group A and one of group B werepregnant, while the third goat which had shown high progesterone concentra-tions on the 27th day after sponge removal, did not become pregnant.
This experiment confirms that cashmere goats, as most other goats (MalpauxB. et al. 1994), are in deep seasonal anoestrous during springtime. Plasmaprogesterone profiles showed that before, and until four days after spongeremoval, 100% of the goats were in deep seasonal and lactational post-partumanoestrous since none of them presented progesterone levels higher than 1.5ng/ml.
F.CARNEVALI, G.SCHINO, S. DIVERIO & S.MISITI Males too showed deep anoestrous since they did not present the typical ircinodour of the active male (Claus et al., 1986; Over et al., 1990) and did not matethe estradiol-injected females during the preparation phase. The failure of thistreatment may be due to the stimulus females being too young, and thus failingto respond to estradiol, consequently not adequately stimulating the males.
Contrary to reports by several other authors (Chemineaux 1986a, 1986b,1987,Walkden-Brown et al., 1993a, 1993b, 1993c), the introduction of males didnot induce ovarian activity: Group A females showed the same low levels ofplasma progesterone as those in group B and no goat was mated until spongeremoval.
Ten goats (34.4% of total, 8 of them mated) had low progesterone concentra-tions on the 8th day after sponge removal (see fig. 1). Such abnormal durationof luteal activity is generally due to a short life of the corpora lutea and isusually called “Short Luteal Phase” (SLP). SLP has been reported to occur onthe introduction of males into female flocks in both goats and ewes as the veryfirst ovarian activity (Chemineaux 1983, 1985, 1986a, 1986b, 1987, 1989; Ottet al. 1980 in goats; Pearce et al. 1985 in ewes). However, in the presentexperiment the male introduction before hormonal treatments failed to induceeither short or normal duration ovarian activity. We observed ovarian activityin both experimental groups only after hormonal treatment, and the observed34.4% of SLP of the present experiment is much higher than the 5% reportedby Chemineaux (1985) after both long or short duration FGA-treatment. Ourresults demonstrated that the hormonal treatment (either in association withexposure to the males or not) failed to induce a complete luteal activity.
Moreover, none of the SLP goats presented a second oestrous, as normallyhappens after the male effect (Chemineaux, 1985, 1987, 1989, Carnevali et al.,1994), demonstrating that male introduction and hormonal treatment were notable to completely overcome the out-of season and lactational post-partumanoestrous and to restore cyclicity of sexual activity (see Pearce G.P. andOldham C.M., 1988 and Malpaux et al., 1994 in the ewe). In fact, even in thosegoats in which the hormonal treatment induced a normal luteal activity,cyclicity was not induced and progesterone concentrations returned to typicalout-of-season values (less than 1.5 ng/ml). Furthermore, about half of theselatter goats were not mated and probably had silent ovulations without sexualbehaviour (Thimonier, 1981, Chemineaux, 1985, 1987, 1989, Carnevali et al.,1994), further supporting the hypothesis that the hormonal treatment was notable to completely overcome the post-partum anoestrous.
OESTRUS INDUCTION ANDSYNCHRONISATION IN CASHMERE GOATS The low overall fertility we observed was mostly due to those females thateither did not mate or showed a short luteal phase, or had progesteroneconcentrations always lower than 1.5 ng/ml (19/29). Of the remaining tenfemales, in which hormonal treatment was effective and that were regularlymated, only three become pregnant. In our opinion, this low fertility might bedue to the anoestrous of the male. In fact, male cashmere goats show acircannual cycle of LH and testosterone production associated with theseasonal sexual activity (Walkden et al., 1993a, 1983b, 1983c, 1994). Ovineand caprine males showing a normal sexual behaviour during the anoestrousseason, present low sperm fertility because of a poor quality and quantity ofsperm production (Dacheux et al., 1981; Grasselli et al., 1992, Susha et al.,1992), therefore the observed low fertility in this experiment may also beattributed to poor sperm quality.
In conclusion, the schedule of oestrous induction and synchronization wasonly moderately effective in inducing oestrous in female cashmere goats andwas not able to restore normal cyclicity. Males also presented a deep seasonalanoestrous and their fertility was probably low.
Future studies will evaluate whether artificial insemination with frozen semencould partially overcome these problems and to improve fertility of cashmeregoats during the lactational post-partum anoestrous.
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