Thesis (MScAgric)--Stellenbosch University, 1978. / In title Greek letter 'alpha' is in subscript. / ENGLISH ABSTRACT: 1. Preliminary observations proved that an intramuscular injection
of 62,5pg Cloprostenol terminates the oestrus cycle of ewes.
Higher dosages (1251jg, 250pg and 500pg) caused a more abrupt
termination of the cycle and more synchronised occurrence of
oestrus. However, 125pg was only effective in terminating
the oestrus cycle when injected between days 4 and 14.
2. In order to overcome this refractory period to Cloprostenol
treatment, (days 15 through oestrus to day 4 of the oestrus
cycle) ewes were treated with intravaginal progestogen
sponges for 8 - 9 days and injected with Cloprostenol on the
day of sponge withdrawal. A dosage of 31,251ig proved
adequate, but conception rates were significantly lower at
the first post treatment oestrus (mean 63,7%) as compared
to the second post treatment oestrus (mean 81,9%). The change
in the serum progesterone concentration following the cessation of treatment was not affected by the dosage of Cloprostenol (31,251g; 62,5pg and 125pg), but the position of the
LH peak relative to the onset of oestrus varied markedly.
The stage of the cycle when the intravaginal sponge treatment
started had a significant affect on the interval between the
cessation of treatment, the onset of oestrus and the LH peak.
3. The time of Cloprostenol administration relative to intravaginal sponge withdrawal (-48, -24 and 0h) showed no significant effect on either the oestrus response or the duration
of oestrus. However, for the group receiving the prostaglandin injection at sponge withdrawal (Oh) the interval
between cessation of treatment and oestrus showed a marked
decrease as the onset of the progestogen treatment progressed from day 2 to day 17 of the oestrus cycle. The reproductive efficiencies of the three respective treatment groups
did not differ significantly from each other, neither was
there a significant difference between the reproductive performances at the first and the second post treatment oestrus.
4. An alternative method of bypassing the refractory period of
the corpus luteum to prostaglandin is by giving two injections of prostaglandin 8 to 14 days apart. In this experiment different dosages (31,25pg; 62,5pg; 125pg and 250pg)
of Cloprostenol were injected at a 10 day interval. Mn
increase in the dosage was followed by a significant increase
in the oestrus response (50,0%; 56,3%; 81,3% and 100,0%
respectively). The higher dosages (250pg) of Cloprostenol
cause more rapid and complete luteolysis as is reflected in
the decrease in plasma progesterone concentration, while
lower dosages (31,25pg and 62,5pg) often fail.
5. The reproductive efficiencies of ewes treated with the intravaginal progestogen sponge (MAP), an intravaginal progestogen
sponge (MAP) followed by an injection of Cloprostenol (125pg),
a double injection of 250pg Cloprostenol at a 9 day interval
and a control groupwere compared. The oestrus response, the
interval from cessation of treatment to the onset of oestrus
and the duration of oestrus did not differ significantly for
the respective groups. The mean conception rate of ewes
treated with a double injection of Cloprostenol at a 9 day
interval was significantly lower (36%) than that of the other
groups (mean of 71,9%).
G. In a 2 x 2 factorial experiment the reproductive efficiency
of ewes treated with a double injection of prostaglandin at
a 10 day interval and of a group of progestogen sponge (MAP)
treated ewes were compared following insemination at observed
oestrus and insemination at a predetermined time. The prostaglandin treated group was inseminated at 60 and 72 hours
following the last injection of Cloprostenol and the sponge
treated group at 48 and 60 hours following sponge withdrawal.
Although the conception rates of the ewes were about 10% lower
following fixed time A.I. as compared to A.I. at obs'arved
oestrus, these differences were not significant.
7. The reproductive efficiencies of ewes treated with two
injections of prostaglandin (Cloprostenol) administered at
intervals of 9, 10 and 11 days, were compared. The conception rates of ewes in these treatment groups were 11,1%;
40,0% and 70,0% respectively and that of the control group
82,4%. These differences indicate the importance of injecting Cloprostenol at an interval of at least 11 days. / AFRIKAANSE OPSOMMING: 1. Voorlopige waarnemings bewys dat intramuskulere inspuiting van
62,5pg Cloprostenol die estrus siklus van ooie beeindig.
Hoer dosisse (125pg, 2501jg en 500pg) veroorsaak 'n meer
effektiewe en meer gesinkroniseerde estrus reaksie.
Die gebruik van 124ig Cloprostenol is gevind om voldoende
te wees om effektiewe luteoliese te veroorsaak vanaf dag
4 tot 14 van die estrus siklus.
2. Die sinkronisasie van die estrus periode met Cloprostenol
is gedoen met 'n voorafbehandeling van intravaginale sponse,
bevattende medroksie-progesteroon asetaat vir 8 - 9 dae, om
die refraktoriese periode te oorbrug (dag 15 - 3).
Die aanteeldoeltreffendheid van die verskillende behandelde
groepe het geen noemenswaardige patroon gevolg nie, alhoewel
die vrugbaarheid betekenisvol verskil het vir die eerste nabehandelings estrus (gemid. 63,7%) en die tweede (normals)
na-behandelings estrus (gemid. 81,9%). Aangaande die serum
progesteroon konsentrasies is gevind dat die tempo van .afname
in progesteroon konsentrasie na begindiging van behandeling,
nie betekenisvol beinvloed is deur die verskillende dosisse
(31,2514; 62,5pg en 125pg) van prostaglandien nie— Heelwat
variasie in die posisie van die LH piek t.o.v. die begin van
estrus is gevind en dit was duidelik dat die stadium van die
estrus siklus betekenisvolle effek op die interval tussen
die beeindiging van behandeling en die voorkoms van die LH
piek het.
3. Dit is gevind dat die tyd (-48, -24 en Oh) van Cloprostenol
toediening relatief tot intravaginale spans onttrekking geen
betekenisvolle effek op beide die estrus reaksie of die lengte
van die estrus periode het nie. Alhoewel, vir die groep
wat 'n prostaalandien inspuiting by spans onttrekking ontvang
het (Oh), is 'n duidelike afname in die interval tussen die
beeindiging van behandeling en estrus waargeneem soos die
- stadium van progesteroon behandeling gewissel het van dag
2 tot dag 17 van die estrus siklus. Die aanteeldoeltreffendheid vir die onderskeie behandelings groepe het nie betekenisvol verskil van mekaar nie en oak was dear geen betekenisvoile verskil in die aanteeldoeltreffendheid by die eerste
en tweede (normale) na-behandelings estrus nie.
4. 'n Alternatiewe metode am die refraktoriese periode van die
corpus luteum tot prostaglandien te oorbrug, is deur die
toediening van twee inspuitings prostaglandien 8 tot 14 dae
uitmekaar. Verskillende dosisse (31,25pg; 62,5pg: 125pg
en 250/4) Cloprostenol is gegee met 'n 10 dae interval tussen
die inspuitings. Vermeerdering van die dosis is gevolg
deur 'n betekenisvolle verhoging in die estrus reaksie (50,0%;
56,3%; 81,3% en 100,0% respektiewelik). Die hoer dosisse
(2501jg) Cloprostenol veroorsaak meer vinnige en doeltreffende luteoliese terwyl die laer dosiese (31,25pg en 62,5pg)
dikwels ondoeltreffend is. Die 250pg Cloprostenol groep
het die vinnigste afname in die gemiddelde serum progesteroon
konsentrasie getoon.
5. Die aanteeldoeltreffendheid tussen intravaginaleprogesteroon
sponse (MAP) gevolg deur 'n inspuiting van Cloprostenol (125pg),
'n dubbele inspuiting Cloprostenol met 'n 9 dae interval en 'n
kontrole groep is vergelyk. Die estrus reaksie, die interval vanaf beeindiging van behandelino tot begin van estrus
en die lengte van die estrus periode het nie betekenisvol
verskil vir die verskillende groepe nie. Die gemiddelde
konsepsie syfer van ooie behandel met 'n dubbele inspuiting
Cloprostenol met 'n 9 dae interval, was betekenisvol laer
(36%) as die ender groepe (gemid. 71,9%).
6. In 'n 2 x 2 faktoriale eksperiment is vrugbaarheid, na inseminasie op waargeneemde estrus en inseminasie wat op 'n
tydsbasis uitgevoer is, tussen dubbele inspuiting prostaglandien groep met 'n 10 dae interval en 'n intravaginale
MAP) spons groep vergelyk. Die dubbel inspuiting groep is
geinsemineer 60 en 72 uur na die laaste inspuiting en die
spons groep is geinsemineer 48 en 60 uur na spons onttrekking. Alhoewel die konsepsie syfers van ooie ongeveer
10% leer was na inseminasie op 'n vasgestelde tyd teenoor
inseminasie na waargeneemde estrus, was die verskil nie
betekenisvol nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/68025 |
| Date | 12 1900 |
| Creators | Greyling, Johannes Petrus Carl |
| Contributors | Van der Westhuysen, J. M., Stellenbosch University. Faculty of AgricSciences. Dept. of Animal Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 68 pages : illustrations |
| Rights | Stellenbosch University |
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