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Most normally, Thursday is the day of choice to wean sows to avoid having too many sows farrow at the weekend. But some units now choose Wednesday as weaning day and delay the first mating of sows that are quickly back into oestrus.
on July 1, 2009

Labour line-up on 3-week batches

Daily task distribution when the herd operates on a system of batches every 3 weeks provides the theme of this next instalment of our series explaining the choices for batch management

In looking at the choice of systems for batch management of a herd, a previous report has discussed some of the effects that each system would have on the workload for the unit. It gave a reminder that the main activities at the heart of the work schedule for any sow enterprise are weaning, mating and farrowing. This month, to illustrate how the daily distribution of these events and other tasks is affected, we take the example of a unit producing on the basis of batches every 3 weeks.

As we have seen before, in a system of batch management every 3 weeks the main activities are distributed weekly so that weaning in Week 1 is followed by matings in Week 2 and farrowings in Week 3. Weaning is the activity that dictates the actual timing of all the others. As an example, let us say the unit weans on a Thursday. We know that most of the sows will therefore be coming into oestrus on the following Monday and Tuesday.

With batches every 3 weeks, the sows generally are weaned after a lactation of 28 days. Usually that means they will come into heat better than sows on earlier weaning — sometimes, they are back in oestrus as much as one day sooner. Therefore a frequent finding is that a large percentage of 3-week-batch sows are mated on Monday if they have been weaned on the previous Thursday.

However, a majority of sows are mated 2-3 times in their oestrus period, so Tuesday still tends to be the day when most members of the 3-week batch receive at least one mating. They are either among the animals being mated for a second time after coming on heat on Monday, or the ones given a first mating because their heat has started on the Tuesday. Then the breeding work begins to decline on the Wednesday.

Just as the day of weaning helps to define when the sow will be mated, so the day of mating and gestation length combine to give the farrowing day. Gestation is typically 114-116 days long, so 16.5 weeks. Monday mating would then probably mean Thursday farrowing (see Table 1 ). But, to take other examples for the sow mated on a Monday, a gestation length of only 112 days or exactly 16 weeks will see her farrow on another Monday 16 weeks later whereas 114 days of gestation results in farrowing that took place on a Wednesday.

In practice on most farms with 3-week batch management, a usual gestation length of 115 days and the fact that matings tend to be done on Monday and Tuesday combine to give the main percentage of farrowings on a Thursday and Friday. A sow which is back in heat on a Tuesday and has a gestation of 115 days will farrow on a Friday. Unfortunately, however, if she is Tuesday-mated and her pregnancy lasts 116 days it means the farrowing will not be until Saturday, with all the weekend work issues this involves.

A schedule for the daily distribution of the 3 basic activities is starting to take shape. We can begin to plan the work tasks associated with them and with secondary events. The resulting daily timetable is summarised in Table 2 .

In the same way a simple 2-letter code for each task is used in Table 3, which sets out the daily scheduling of labour in Week 1 for a herd with batches every 3 weeks. We can look into the codes in a little more detail to explain what the chart shows.

Codes for labour charts

EW = Emptying weaning rooms: On Monday at the latest, the weaning rooms should be emptied to allow proper cleaning and disinfection of the facility before the next piglets are weaned on Thursday. This job could be done earlier, if more time is wanted to extend the period that the room stays empty as a sanitary precaution. The problem is that this would mean more work during the weekend or even doing it on the Friday of the previous week, which is already a high-labour day due to a large number of sows farrowing at that time.

CW = Cleaning weaning facilities: The same Monday, cleaning and disinfecting of the weaning facility needs to be started.

MS = Moving sows to gestation: This refers to the practice in most herds of holding mated sows in separate places until 35 days of gestation. At that point the sows are moved into the main gestation area. The places need to be emptied no later than the day before weaning, because they will be needed to receive the next batch of weaned sows on the following day.

SC = Switching on computers on weaning facilities: Computers that control the environment (including heaters) of the nursery should be switched on the day before weaning, so piglets will find a comfortable temperature when they arrive. That is very important in cold countries and during cool periods, although it can be delayed under warmer conditions.

WE = Weaning: Obviously, weaning will include not only moving the sows and piglets, but also arranging the different nursery pens so they contain piglets of a similar number and size and starting to feed them.

CF = Cleaning farrowing facilities: As soon as possible after it has been emptied, the farrowing room has to be cleaned and disinfected. This work should be started on Thursday and finished on Friday. Doing so, the facility can rest in its cleaned and disinfected state for almost one week.

HC = Heat check of weaned sows: Oestrus control is an activity that has to be done daily, but more time will be needed for it from the day after weaning because there will be more sows to come on heat. On Friday, Saturday and Sunday it is very important to stimulate sows properly using a good boar; give them enough time and close contact. When the job is done the right way the usual result is that sows come back into oestrus earlier and show clearer signs.

Codes for task charts

We can now consider the schedule of tasks in Week 2, again under a 3-week batch management system. Table 4  for this once more uses 2-letter codes.

MT = Mating of sows: The daily distribution of tasks that relate to mating of sows will vary according to the weaning day chosen and the number of days that the sows need to start to come into oestrus. It will also depend on the breeding guidelines that are used. For example, at some farms the time of first mating is delayed depending on the time from weaning until the first signs of heat. Sows that show signs quite soon after weaning (that is, on Saturday to Monday) can have a delayed mating, while sows that do not come into oestrus until after Wednesday need to be mated immediately. Their heat signs are evident so mating does not necessarily coincide with the day that the sow comes on heat.

MS = Moving sows to the farrowing facility: Working with batches every 3 weeks allows plenty of time for sows to enter the farrowing pen and become settled before they give birth. Their entry is shown in the chart as being on the Friday, so a sanitary break of one week has been allowed for the pen and the sows are entering it 5-6 days before their expected farrowing. Such a schedule adds to the confidence that sows will not farrow while still in the gestation area.

Table 5  shows the activities in Week 3, which is the week for farrowings in a 3-weeks batch system.

FA = Farrowing: Most farrowings will occur on Wednesday or Thursday if sows are mated early and have a short duration of gestation. This may slip back to Thursday or Friday if everything becomes a bit delayed. For labour reasons we do not want too many farrowings at the weekend, of course, which is why it is not a good idea to wean on Friday.

PP = Processing piglets: The processes indicated here are the routine ones of clipping or grinding teeth, giving an iron injection, perhaps administering an oral supplement and possibly (where permitted) clipping off the end of the tail. Piglets can be processed in this way the day after farrowing has occurred. But we can wait 2 days if the piglets were born on a Saturday, meaning that they are processed on the next Monday.

Finally, then, we see in Table 6  exactly how the different daily tasks come together into a daily and weekly schedule of labour at the herd with batch management every 3 weeks. At this point all the other activities that have to be done at the farm can be included on the chart, such as vaccinations, feeding changes for weaners or sows and ultrasound scanning. The smart manager tries to choose days with less other activity to fit in these tasks!  PIGI

Next month: An example of programming for all activities on a particular farm and how time can be distributed for the different workers.

When weaning on Thursday, most matings are focused on the first 3 days of the following week.
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