As sow performance continues to increase, pig producers are asking “how long can this go on?” If we use gilt litter size as a yard stick, the end is not in sight!
The best just
Analysis of data covering the last 12 months for over 22,300 sows from 45 herds in Northern Ireland shows that gilt performance has increased to an average of 12.4 pigs per litter. This figure has improved by 1.2 pigs over the last three years and is increasing at a faster rate than sow litter size over the same period. In fact, gilt litter size is now higher than sow litter size was only two years ago.
However, there is a wide range in gilt performance between herds. Although the best performing herd achieved a fantastic 15.3 pigs born alive per litter, with the top 25% of recording herds averaging 13.8 pigs, the bottom 25% produced 2.6 pigs less per litter.
Replacement rate on many pig units is approaching 50%. This means gilts contribute to approximately one fifth of all litters born and therefore have a major influence on unit performance and profitability. So what are the best performing units doing to get full potential from their gilts? There are a number of management factors which are common to many of the units achieving large gilt litters.
The use of high performance dam-line genetics has undoubtedly given a significant improvement in sow and gilt performance. However changing genetics is not a quick fix. Analysis of farm records clearly shows that gilts with identical genetics have very different levels of performance on different units. This highlights the importance of management on gilt output.
It was not that long ago that the target live weight for gilts at service was 120kg. But we are dealing with a very different animal now and the better herds are delaying service until gilts are at least 150kg. Some producers only serve gilts when they weigh at least 170kg. These gilts can easily be 40 weeks of age at service.
Serving gilts at heavier weights also improves lifetime performance as these gilts are in better body condition at weaning. This encourages quicker return to heat and reduces the incidence of second litter dip where numbers born in the second litter is less than the gilt litter.
However, the old rule of never serving gilts at first heat still applies. Effective stimulation by moving gilts to a different pen and giving full boar contact will help ensure regular heats.
Mixing gilts with a cull sow has also been very effective in inducing heat on many units. Gilt stimulation should be carried out even if the gilt will not be served during the heat period. As long as body condition is correct at second heat, there is little on-farm evidence to suggest that delaying to third heat will increase litter size further.
Although flushing gilts by feeding ad-lib before heat is still common, many producers also feed high levels between heats. In addition gilts are often fed approximately 1kg of glucose for two weeks before service and other energy supplements can also be offered over this period.
Many producers believe that these products stimulate the release of eggs and maximise litter size as well as producing more evenly sized pigs at birth. Modern gilts are therefore in much better body condition at farrowing that their predecessors and this is essential if they are to be well fleshed at weaning, after feeding a large litter.
Well there is no secret really, a lot comes down to managing the replacement gilt pool. To have a sufficient number of gilts, you must start with sow replacement rate.
Using this, you can calculate how many gilts should enter the sow herd each week. Allowing for the rejection of some maiden gilts, it is easy to set a target for the number of gilts selected each week. It is much more difficult to stick to this target and so a few extra gilts in the pool is a good safety net. If the gilt pool is correctly managed then sow culling can be planned. This will give a better parity distribution in the herd and gilts will have a better chance of a long and productive life.
Remember, as gilt performance improves, so must your management.