Microsoft word - summary of the findings of the sfindings_laparoscopic_insemination_2013.doc

Summary of the findings of the survey conducted on laparoscopic insemination programs
associated with the 2011 and 2012 lambings
The SA Stud Merino Breeders Association surveyed members in late 2012 to determine the extent ofa perceived failure in many laparoscopic insemination programs and to identify factors that may havebeen responsible. There were 32 respondents and information was provided on 54 flocks. Twelverespondents reported pregnancy rates (and/or lambing rates) below 50% in at least one year includingsix who reported rates below 30 - 35%. The remainder reported figures that ranged from 55% to 97%in both years although the higher figures are almost certainly lambing percentages rather thanpregnancy percentages. Never-the-less, adequate bona fide information was provided to comparemost aspects of the insemination programs and to assess factors that may have affected performance.
There was a tendency for more good performing flocks than poor performing flocks to be inseminatedin Spring than Autumn and for poor flocks to have higher body condition scores than good flocks (allflocks were in good condition). Essential components of the synchronisation protocol that did notcontribute to the between-flock variability included the type of pessary (68% CIDR vs 32% spongeusage), dose of PMSG (range 1.0 - 2.0 ml) and duration of pessary treatment (range 12 - 14 days).
Teaser rams were used in only 50% of flocks and they were not used properly, being introduced toewes the day after pessary removal rather than at the time of removal. Their use did not appear toinfluence flock performance which, under the circumstances, is not surprising. Insufficientinformation was provided to associate flock performance with either pasture status or weatherconditions although some respondents stated that a rising plane of nutrition prior to insemination wasessential.
The survey results indicate that a poor synchrony of oestrus was the likely cause of poor flockperformance. In some flocks, ewes came into oestrus over an extended 4 – 5 day period (as observedusing harnessed/painted teasers up to and after AI) rather than the conventional 24 – 30h period. Theextent of this problem is difficult to assess because harnessed/painted teasers were not always usednor run with the flock after AI. However, the phenomenon was not related to any particular protocolor operator and was most likely related to (1) the treatment of large framed and/or overweight ewes,(2) the use of pessaries with inadequate progesterone and/or (3) the incorrect use of teasers. Fatnessper se suppresses fertility but body fat can also absorb progesterone from pessaries making asynchronised oestrus less likely as this progesterone can be released back into the circulatory systemafter pessary removal. Teasers are important during times of the year (mainly Spring) when mostewes are not cycling spontaneously – they elicit a hormonal response in the ewe that assists in ovarianfunction and onset of oestrus. This response should occur at the time of pessary removal. That goodresults were obtained in Spring without the use of teasers indicates that many ewes were cyclingspontaneously – perhaps further evidence that 2011 and 2012 were unusual years.
The 2012 year was particularly unusual with pregnancy rates of some flocks declining inexplicably.
That a significant number of non-pregnant ewes failed to get pregnant following natural mating afterAI is further evidence of the complexity of the situation. The survey’s results highlight the need forresearch to be conducted, in the first instance, on factors that are believed to influence the synchronyof oestrus including live-weight/condition score, the concentration of progesterone in pessaries andthe use of teasers. The need for this research is further apparent when it is considered that (1) thesuccess of laparoscopic insemination has not improved during the last three decades and (2) treatmentprotocols have remained largely unchanged despite substantial potential for improvement. Attachedare suggested protocols and recommendations that may influence the success of an inseminationprogram but successful treatment protocols/management strategies should not be changed.
Protocol for the synchronisation of ewes using CIDRs
This table outlines the timings for a protocol that aims to commence insemination 45h afterCIDR removal. Starting time for insemination is partly determined by number of sheep to beinseminated, availability of vet etc – this time can vary provided time of pessary removal isadjusted. This information is provided as a guide and is not, in itself, a recommendation.
Time relative to
Activity
Comments
pessaryremoval
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
CIDRs out by this Teasers (10%) to betime; 2ml PMSG; marked; don’t inseminateunmarked ewes; minimisestress (no dogs) Do maidens first if in aseparate flock but don’tdraft off if in main flock Post-AI period - Put back-up rams in 12 days after AI. Maintain ewe condition during the
first week after AI (to maximise embryo survival) followed by conventional management as
pregnancy progresses.
Protocol for the synchronisation of ewes using sponges
This table outlines the timings for a protocol that aims to commence insemination 51h aftersponge removal. Starting time for insemination is partly determined by number of sheep tobe inseminated, availability of vet etc – this time can vary provided time of pessary removalis adjusted. This information is provided as a guide and is not, in itself, a recommendation.
Time relative to
Activity
Comments
pessaryremoval
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
marked; don’t inseminateunmarked ewes; minimisestress (no dogs) Do maidens first if in aseparate flock but don’tdraft off if in main flock Post-AI period – Put back-up rams in 12 days after AI. Maintain ewe condition during the
first week after AI (to maximise embryo survival) followed by conventional management as
pregnancy progresses.
General recommendations
Below is a list of factors that are likely to influence the success of a laparoscopicinsemination program and should be considered when planning a program. However,successful treatment protocols/management strategies should not be changed.
Nutrition
1. Aim to have ewes in condition scores 3.0 – 3.5 at the time of AI.
2. Use the “flushing effect” to have ewes on a rising plane of nutrition (e.g. using lupins) from one month before AI. Evidence indicates that intake of high protein feedsshould be gradually reduced to maintain body condition score one week before AI.
This facilitates an increase in ovulation rate without high ammonia concentrations inthe circulatory system adversely affecting egg/embryo quality.
3. Maintain ewe live-weight in the week following AI. It is generally believed that a maintenance diet in this week helps rates of embryo survival.
Choice of pessaries
1. Both the CIDR and sponge are effective in synchronising oestrus with limited evidence indicating that a better synchrony is obtained with the CIDR. Thisinformation was generated when the sponge contained 60 mg synthetic progesterone(progestagen) compared with current levels of 20 – 40mg.
2. It is generally considered that concentrations of progesterone/progestagen in both the CIDR and sponge are barely adequate to effect optimal synchronisation.
a. This is particularly the case in large framed and/or over-weight ewes. This problem is more serious in fat ewes where fat is able to absorb theprogesterone/progestagen only to have it released back into circulation afterpessary removal.
b. Such release is likely to cause delays in the onset of oestrus.
3. Choice of pessary can influence the timing of oestrus/ovulation and this should be taken into account when determining the time of insemination (see below).
4. If the sponge is to be used, endeavour to obtain the most concentrated – 40mg Use of teasers
1. Teasers need to be used in AI programs for the following reasons: a. They assist in stimulating ovarian function and aid in the onset of oestrus i. Allow an assessment of the degree of synchrony.
ii. Provide the option of drafting off marked ewes for AI (unmarked ewes seldom produce results that justify the cost of AI).
2. Teasers can be either vasectomised rams or treated wethers but avoid using treated ewes. Anecdotal evidence indicates that the use of vasectomised rams is the preferredoption.
3. It is important that teasers are introduced to the flock at the time of CIDR/sponge
removal. The hormonal stimulation that they elicit in the ewes needs to occur at this
time. The benefits of using teasers are likely to be negated by delaying their
introduction.
Observing onset and pattern of oestrus
1. Observing the time of onset of oestrus and, more generally, the overall pattern of oestrus provides valuable information on the success of synchrony. Poor synchrony isthe major cause of AI failure.
2. Time of onset can be established by observing teaser mating activity 24h after CIDR/sponge removal. This should be done from the fence-line to avoid yarding theflock. Another observation at 32h or thereabouts is worthwhile particularly whenthere is little or no activity at 24h.
3. A final determination of the number of marked ewes immediately before AI is important. Unmarked ewes should not be inseminated. However, adequate teasersmust be used (e.g. 10%) and unmarked ewes should be checked for oestrus usinghand/finger pressure on either side of the tail. Ewes in oestrus will respond withobvious tail movement. Ewes that are detected in oestrus using this method should beincluded in the AI program.
4. Whilst there is large variation between flocks and breeds, the following is a guide to the percentage of ewes in oestrus at various times after CIDR/sponge removal: Time after CIDR/sponge
Ewes in oestrus
removal (h)
(approx.)
5. On occasions, onset of oestrus will not be observed until after 24h. This doesn’t necessarily indicate that the synchrony will be poor but it does make the observationat about 32h more important.
6. Even in flocks with good synchrony, approximately 15% of the ewes will fail to come into oestrus by the time AI commences. The reasons are not known. Conceptionrates in these ewes are invariably low if inseminated but they retain their ability to getpregnant at following natural cycles.
Options to minimise loss from a poor or delayed synchrony
1. There are very few options available when flocks show major delays in the onset of oestrus. Options that can be considered include: a. Draft off unmarked ewes immediately before AI and remove them from the program. This should be a standard routine but it becomes more importantwhen there is a serious delay in the onset of oestrus. These ewes can benaturally mated at a subsequent natural cycle (preferably using harnessed ramsso that onset of oestrus can be observed).
b. Delay the time of AI – this strategy might be useful with small shifts in the pattern of synchrony but would be of no value when the pattern is delayed byseveral days. Consultation with the veterinarian would be necessary in thissituation.
c. Use fresh semen (or low cost frozen semen) in unmarked ewes if they are to be inseminated. Again, this is unlikely to be of value if the pattern of oestrusis seriously delayed.
d. If possible, prepare more ewes for insemination to cover for ewes that are Time of insemination
1. Time of insemination (usual range 45 – 55h after pessary removal) is particularly important with frozen semen, especially if it is of poor quality (fertilising ability candecline within 4 - 6h of insemination). Timing is less critical with fresh semen.
2. Factors to consider when determining time of AI are: a. Ewes treated with CIDRs ovulate up to 6h earlier than ewes treated with sponges; in the Merino, ovulation generally starts at 45h after CIDR removaland 51h after sponge removal.
b. Maiden ewes usually ovulate up to 6h earlier than mature ewes.
c. Small differences in the dose of PMSG do not influence the time of ovulation.
3. It was once thought important to inseminate the flock before most ewes ovulated but it is now recognised that later insemination times (e.g. even after ovulation) canproduce good results. Later insemination (e.g. 55h after pessary removal) may beuseful when the quality of frozen semen is known to be poor.
4. Inseminating ewes as they are detected in oestrus, as compared with conventional fixed time insemination, is generally not recommended. It has been shown to be oflittle value – any potential benefit may be negated by stress associated withyarding/drafting.
Time of year
1. Sheep breeds cycle naturally as day length decreases (late summer – autumn) with associated increases in ovulation rate (subject to adequate nutrition).
2. However, in most Merino flocks in South Australia, a significant number of ewes cycle irrespective of time of year and those that aren’t cycling can be induced to cycleusing the teaser response.
3. Although Autumn is the height of the natural breeding season, both natural mating and AI can be successful in either Autumn or Spring.
4. Natural breeding patterns in other breeds (e.g. Suffolk and other terminal sire breeds) are more seasonal than in the Merino and insemination programs that areimplemented too early may experience problems. Little research has been done onthis issue but anecdotal evidence indicates that attempts to synchronise oestrus tooearly can result in poor synchrony and poor conception rates in ewes that do cycle.
Insemination and post-insemination care
1. Minimum stress is essential – factors to consider include frequency of drafting, presence of dogs, time ewes spend in the insemination cradle and availability of waterand shade. Whilst ewes need to be off food/water the night preceding AI, avoidshedding until necessary.
2. If possible, avoid exposing ewes to rain during the AI period (including the day after 3. Maintain ewe condition during the first week after AI (this helps embryo survival) followed by conventional management as pregnancy progresses.
4. Put back-up rams into flock about 12 days after AI. Additional rams are required to cover all ewes given that non-pregnant ewes will still show some synchrony atsubsequent cycles. This is particularly important at the first cycle after AI.
Curriculum vitae
Dr Simon Walker was Principal Scientist at Turretfield Research Centre, South AustralianResearch and Development Institute (SARDI) until 2006. His early research career focusedon controlled reproduction in sheep including developing improved protocols for AI andembryo collection programs. This work led eventually to the research into the basic andapplied aspects of sheep embryology and it was from this work that the laboratory receivedinternational recognition for its research. Achievements included the development of in vitrosystems for the culture of sheep and cattle embryos, the production of Australia’s firstgenetically engineered sheep, the production of Australia’s first cloned sheep, developmentof new perspectives on factors controlling embryo and fetal growth, the role of nutrition indetermining oocyte/embryo quality and development of the juvenile in vitro embryo transfer(JIVET) technology.
Dr Walker’s involvement in analysing data from the survey is a re-acquaintance withquestions that were raised from his own observations on synchrony of oestrus and ovulationduring the 1980s. The phenomenon of delayed ovulation was characterised but the existenceof this problem in industry has never been identified. It appears that the survey, among otherthings, has addressed this issue. Dr Walker is currently a SARDI affiliate and may becontacted on walkersa@adam.com.au

Source: http://www.merinosa.com.au/media/documents/Findings_laparoscopic_insemination_2013.pdf