Batch Farrowing Place
Gilt number
One major advantage of using batch farrowing place as a keystone to pig production is its ability to predict how many gilts are required for each batch.
Gilt requirements need to be well planned and not just on the day of weaning - or during the breeding week. You should never be short of gilts. There is no catch up in batch farrowing, you have to get the breeding target right first time.
When can gilts be added to the batch breeding pool?
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Sow culling option |
New Gilt weight kg |
Sow culling/Gilt introduction graphic assuming 4 week weaning |
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Weaning age |
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3w |
4w |
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Farrowing |
110 or |
25 |
18 |
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Weaning |
130 or |
40 |
35 |
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Breeding |
130 or |
45 |
40 |
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Pregnancy check (28 days) |
NA |
65 |
60 |
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Sow gestation check between 8 and 15 weeks |
Depends on biosecurity requirements |
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When should gilt numbers required for a specific batch be finalised?
Gilt numbers should be finally calculated when the batch is at 10/11 weeks of gestation. This allows for final adjustments to be made to the gilt pool which will be made available in 9 weeks time. Note as soon as a possible shortage of gilts can be identified adjustments should be made - for example 2 sows abort at 60 days of pregnancy.
Gilt development lifecycle
Calculation
There are some internal calculations that by default calculate your next batch time day (the day after your next weaning date).
From this batch start date, next start date is calculated from wean to service (4 days) plus gestation length (115 days) plus the lactation length.
The age of the gilt at any particular week is calculated from the formulae:
(ROUNDUP(-0.0744((((weight kg)/10)+1),2)+2.7618*(((weight kg)/10)+1)-0.2818,0))
The specific days in the gilt live cycle is important as they are relevant to selecting the gilt and can be coordinated in line with specific breeding events in the batch.
How many gilts do I need for this batch of pigs?
If the number of gilts are to be calculated when the batch is at 10/11 weeks, this calculator can be of help.
Can I calculate how many gilts I am going to need over the next couple of months?
Yes. Using batch farrowing you can approximate the number of gilts required. This should be carefully discussed with your genetic supplier.
Using a simple approach to above, a gilt requirement calculator can be written. The example shown is a 4 week weaning weekly batch system. Other models can be found in the gilt section.
The default is set up with an example pig pregnant per week of gestation for the selected batch size, but can be easily customised to actual events on the farm.
Playing with the gilt pool numbers can become quite additive. But:
Gilts are the fuel that run the farm
Batch farrowing is all about an efficient gilt pool whose purpose is to supply sufficient females to ensure that the real time batch breeding target is met and the farm can practice all-in/all-out.
