GROWTH in Performance Improvement:

Boars and gilts probed at Jakubec Farms in February give a new meaning to muscling at 100 kg for dam line pigs. Biggest loin for Landrace gilts is 72.1 mm; Landrace boars 69.0 mm; Yorkshire gilts 70.5 mm and for Yorkshire boars 69.2 mm.

Breed	No.	Average Backfat	Loin Depth	Age to 100 kg	Est. Lean Yield
Landrace gilts	21	8.7 mm	66.6mm	154	64.6%%
Landrace boars	5	10.2 mm	65.5 mm	139	63.9%
Yorkshire gilts	21	9.1 mm	67.3 mm	156	64.4%
Yorkshire boars	4	9.0 mm	67.0 mm	141	64.5%

We regret that several of our clients have decided to depopulate their herds during this time of financial distress but concur with their economic decision. We look forward to participating in their fills – either in new or renovated barns. The high health pigs will perform terrifically well!

We welcome the purchase of Lacombe, Landrace and Duroc boars by Pine Haven Colony to contribute to its specialized marketing plan.

We thank all of our continuing customers for their ongoing purchases of replacement boars and gilts!

(Reprinted from V5,No4 PEAK of Performance News! by the late Dr. Frank Aherne. This series will continue for nine episodes.)

Assuming that our herd is correctly sized to get maximum facility utilization (see Vol 11,No.3) we must next ensure that production efficiency is as good as it can be. We will start by assuming that you have excellent PEAK Swine Genetics so that the potential is there to achieve targets as good as those shown in Table 1 for the top 10% of producers.

Table 1. Breeding Herd Productivity in Canada

	Average	Top 10%
Repeat services, %	10.5	5.0
Multiple matings, %	80.1	99.0
Sows bred by 7 days, %	89.3	95.4
Farrowing rate, %	75.6	88.5
Wean-service, days	6.7	5.2
Average born live	10.6	11.3
Averaged weaned	9.3	10.1
Pigs weaned/sow/year	21.5	24.4
Non productive days	61.2	36.5
Culling rate, %	40.1	24.8
Sow death rate, %	4.4	1.7

All of the factors listed in Table 1 can and do influence the number of pigs weaned per year but the relative importance of some of these factors is shown in Table 2.

Table 2. Relative importance of factors influencing p/s/y

Number of sows served	60%
Farrowing rate	30%
Number born live/litter	5%
Pre-wean mortality	5%

As can be seen, meeting breeding targets and farrowing rates rank as the two most important factors affecting weaned pigs/sow/year. Mortality or low litter size may account for the loss of a pig or two, but not having bred the correct number of sows on a weekly basis will result in loss of whole litters. So the importance of meeting breeding targets is obvious.

So, how to meet breeding targets?
The number of females bred per week is dependent on three sub-populations: (1) number of weaned sows available, (2) number of gilts available and (3) number of opportunity sows still in the herd.
Opportunity sows are those that may be available for several reasons. Sows that return to heat on day 7 or later after weaning may be skipped to their next heat period. We will discuss the pros and cons of skip-a-heat breeding later in the series. If you can meet breeding targets from the gilt pool, then a skip-a-heat breeding system for late returning sows will increase the number of piglets weaned per sow because of improved farrowing rate and litter size.
Other sows in the opportunity group could be older sows, sows that have had poorer performance, sows due for lameness culling or sows that aborted. These are called active culls; sows available to be bred but otherwise would be culled.

Although the number of weaned sows returning to estrus within 6 days (or more) after weaning is by far the biggest contributor to number of sows served per week, this number will vary because of weekly farrowing rates and week-to-week variation in culling rates. A herd may have a farrowing rate between 75%-95% in any one week. Therefore, a major control in meeting breeding targets is provided by proper sizing and management of the gilt pool. If there aren’t enough service-ready gilts available, you can’t meet breeding targets. The quality of gilts and their subsequent nutrition and management will have a significant effect on culling rate and herd productivity.

In another article, we will discuss the role of the gilt in breeding herd efficiency. However, let’s close by explaining the difference between voluntary and involuntary culling: Voluntary culling is where the manager makes the decision to cull, and when. Involuntary culling is where the sow leaves you no choice except to cull her because of injury, lameness, disease or death. Unfortunately, in many herds most of the culling is involuntary and so parity distribution becomes far from ideal. Parity distribution will also be discussed in a future article.

Finally, one more suggestion regarding meeting breeding targets. Walk the gestation barn when bred sows are 12 weeks into gestation. Most people can tell if a sow is pregnant at 12 weeks. Then look at the sow, and her performance record, and decide if you want to cull her after weaning. You then have a good estimate of how many sows are available for breeding after weaning, about 7-8 weeks from that date. From this data, you know how many gilts need to be bred to meet breeding targets. You now have 7-8 weeks to get your gilt pool of cycling gilts for breeding when they are needed (that is, 4 weeks gestation plus 3 weeks lactation plus 5 days post-weaning). Start a puberty induction program or induce estrus using PG600 injections.

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