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Fine tuning insemination procedures

by 5m Editor
27 June 2005, at 12:00am

By Bernard Peet, Pig Production Training and thePigSite Consultant - Over the last few years I have carried out a number of audits of clients' insemination procedures, usually where farrowing rate or litter size have been below par. Insemination is a critical task, with many steps which contribute to the end result.

By Bernard Peet
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There are several reasons why the integrity of the procedure may deteriorate over time. First, operators may not have been well trained initially and not understand the importance of key parts of the procedure. Second, there is often a lack of knowledge regarding the physiology and behavioural aspects involved and third, some of the stages tend to get dropped or modified over time. When carrying out an audit, I observe the whole process while making notes and timing the various stages, then hold a review session with staff, explaining the reasons for improvement points I have identified.

I then assist with another AI session where we implement the revised procedure, demonstrating the crucial points. Where farrowing rate is poor it is likely that there will be one or two major errors or omissions and, in this case, it may be possible to improve farrowing rate by 10% or more. Even where the overall technique is good, it is often possible to realize a 5% improvement by fine tuning a number of areas. The following are some of the issues that have been identified on clients' farms.

First of these is quality control. Semen suppliers go to great lengths to ensure high quality semen leaves the stud and, when it reaches the farm, it is essential to continue the quality control process. Once the semen arrives, it should be unpacked and stored on its side, no more than three deep, to allow good air circulation. The storage temperature of 17oC should be checked twice daily using a maximum/minimum thermometer, even where there is a temperature readout on the fridge or storage box.

Semen needs to be re-suspended in the diluent by rocking the containers gently twice per day. If this is not done, the sperm settle out and their contact with the diluent is reduced, shortening semen life. I encourage producers to use a semen storage chart with a temperature graph so that operators can record that temperature has been checked and semen re-suspended. I've seen situations where flat-packs have been stored on their edges or semen tubes stored upright due to lack of storage space, which drastically reduces the surface area of sperm-to-diluent contact. In this case, a larger storage unit is the obvious answer. Hygiene in storage is another critical area and fridges or Koolatrons should be cleaned and wiped down with a mild disinfectant every few weeks. Similarly, the insulated container used to carry semen to the barn should be regularly cleaned.

The second area essential for successful AI is good heat detection. This requires a well-organized system in the breeding area. In larger units, I prefer to separate heat checking from AI because this allows a total focus on insemination once the time of first standing estrus is identified. In this case weaned sows should be checked twice daily and then moved to stalls in a breeding row in order of their time of estrus. The wean to estrus interval (WEI) varies from farm to farm so in order to develop a good service timing protocol it is necessary to know the typical starting time of estrus and its length.

A short WEI and long standing estrus makes it necessary to delay insemination by up to 24 hours because ovulation occurs two-thirds of the way through standing estrus. If the start of estrus is recorded on an individual sow card, the pre-determined service pattern can be written on the card (I like to use a thick felt-tip pen to make it stand out).

Controlled boar stimulation is another important aspect of AI. Boars should not be housed close to weaned sows or those prior to breeding otherwise their response to the boar during heat checking and insemination will be reduced. However, weaned sows need good boar exposure to stimulate the onset of estrus. I usually recommend that a boar is left in front of weaned sows for several hours on days 2, 3 and 4 after weaning, then removed several hours prior to a first heat check on the afternoon of day 4. Few sows will show full standing heat before this time. Use of a mature boar (more than 12 months old) that has a high libido and is very active is essential for both sow stimulation and heat checking. One final aspect of management prior to insemination is hygiene. Ideally stalls used for weaned sows and breeding should be washed down each week prior to sows being weaned. Sows with dirty backsides are a major reason for poor results.

Now on to the insemination technique itself. Assuming sows have been moved into the breeding row in order of estrus date, those that require insemination are easy to identify. This also makes it easier to work out the number of doses of semen required for the insemination session. Even on smaller units, I encourage producers to set up the breeding row with gates across the passage in front of the rows to control the boar. Ideally, for safety reasons, these should be capable of being operated from behind the sow and installed every 5-6 sows. The other thing I suggest is some means of holding the semen container, which may be as simple as a bulldog clip on a length of cord, fixed to a wire stretched above the stalls. This leaves the stockperson's hands free to do more important things than holding a semen container. It requires extension tubes to be fitted to the catheters.

Timing is one of the key aspects of a good insemination routine so all the required equipment needs to be readily to hand prior to starting. Once the boar is placed in front of the first group of sows, the clock really starts ticking. Sudden boar exposure will initiate the strong standing reflex in sows already in estrus. However, this strong response only lasts for 7-10 minutes, then sows enter a "quiet phase" when they are much less receptive. Therefore the AI routine needs to be slick so that the time between initial boar exposure and insertion of the catheter is very short. Minimizing the time spent cleaning vulvas by washing out stalls and having a well-organized AI cart help in this respect.

At least two people need to carry out insemination and the use of three is beneficial. It should take no more than 2 minutes to get a group of 5-6 sows "hooked up". Once the semen container is clipped in place, the operators can focus on intensive stimulation of the sows, another critical area in the AI process. Where a group of sows is inseminated together, I usually recommend the use of sand-filled saddlebags to mimic the weight of the boar. With the system suggested here, the majority of sows should draw in the semen within 3-4 minutes. The operators can focus attention on the sows that are slowest, by leaning on the sow's rump to add more weight, rubbing the udder and pulling on the loose fold of skin in front of the hind legs. I find that a good flank pulling technique is usually the best way to get the sow to draw in semen.

Getting the semen into the sow is not the end of the process; indeed it is only the start. It must be moved to the oviducts by uterine contractions stimulated by oxytocin release, requiring ongoing stimulation and boar contact. Assuming the first part of the insemination process takes 5-6 minutes, sows need a similar period for this to happen, bearing in mind the 7-10 minute window of opportunity. This means folding over the catheters and leaving them in, then moving a new boar in front of the sows, while the first boar is moved along to the next group of sows to be inseminated. The presence of the catheter in the cervix also helps to release oxytocin.

Finally a few smaller points that have cropped up during my audits:

  • Always ensure hands are washed before insemination, especially if the operator has smoked. Alternatively wear vinyl gloves.

  • Vulva cleaning should be done with a dry paper towel, never wet, to remove loose and wet manure. Never wipe inside the vulva unless there is contamination there.

  • Handle catheters and extension tubes in the centre section and do not touch the ends.

  • Be sparing with lubricant gel and ensure it does not cover the hole in the catheter tip. Try inseminating sows without using gel.

  • Ensure any semen that has reached barn temperature is used the same day, otherwise discard it.

This is not an exhaustive review but just some of the issues that have cropped up during my audits. Going through the whole insemination process in detail including facilities and organization of the barn is a worthwhile exercise on any production unit. There are very few occasions when it is not possible to identify areas for improvement, which, when implemented, will lead to an improvement in farrowing rate.

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By Bernard Peet, BSc - June 2005
Consultants to the International Pig Industry