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When comparing the efficiency between two farms, most of the time we look at production indexes of the sows that are present over a certain period, disregarding other parameters that directly or indirectly also have an influence on farm performance.
Here, we observe two farms that have similar efficiency in terms of pigs weaned/sow/year. Farm B has lower weaning results, which is compensated by a higher farrowing index than Farm A, mainly due to a shorter lactation period.
Table 1. Key production indices for farms A and B. Period: July 2018- June 2019.
| Farm A | Farm B | |
|---|---|---|
| Pigs weaned/sow/year | 31.0 | 30.9 |
| Average piglets weaned/sow | 13.7 | 12.6 |
| Farrowing rate (%) | 86.6 | 89.4 |
| Farrowing index | 2.42 | 2.53 |
| Lactation length (days) | 26.2 | 20.8 |
| Average age of females (parities) | 2.2 | 2.8 |
| Non-productive days/sow/year | 36.8 | 29.9 |
However, there are different complementary viewpoints when it comes to the productive efficiency of a farm. There are indices such as piglets weaned per sow lifetime (which we have discussed previously in the article "Piglets weaned per sow lifetime, the hidden index"). Another such index is related to the farm's ability to keep a group of gilts in production, farrowing after farrowing. This last concept brings us to an index that is becoming more and more important, the "retention rate".
The "retention rate" is the percentage of gilts, introduced in a period, who achieve various consecutive farrowings. A farm that shows a drop in the retention rate in the first parities would mean that it is losing sows at an early stage (losing a greater number of sows in the first parities); whereas a farm with a higher retention rate in the first cycles would mean that it keeps a greater number of sows until later parities; the impact of which would be greater payback as more sows reach later ages.
Having a high retention rate from cycle to cycle, is synonymous with a greater ability to keep sows on the farm, but it does not necessarily come hand in hand with a greater production efficiency in all cases; here different aspects would come into play, such as prolificacy, performance at weaning or our well-known index, non-productive days (NPDs).
The following tables show the retention rates recorded on both farms. Within each table you can see the retention rate individually recorded from 2013 to 2016, along with the average of these 4 years. Likewise, the tables show the average prolificacy by parity in each group of introduced gilts.
In the case of farm A, an average of 70.4% of the gilts introduced between 2013 and 2016 reached parity 4. The table clearly shows that the farm culls sows after parity 6; since the retention rate at parity 7 is already around 30%.
Table 2. Retention rate for Farm A. Period: January 2013 - December 2016.
| Gilt introductions | Parity 1 | Parity 2 | Parity 3 |
Parity 4 | Parity 5 |
Parity 6 | Parity 7 |
Parity 8 |
Parity 9 | Total born/sow/year | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 Jan - 31 Dec 2013 | 518 | 93.2 % | 83.2 % | 74.1 % | 66.2 % | 56.2 % | 44.2 % | 23.6 % | 7.3 % | 1.5 % | 39.3 |
| 14.2 | 13.9 | 14.9 | 15.5 | 15.3 | 15.9 | 15.1 | 15.4 | 14.6 | 14.8 | ||
| 1 Jan - 31 Dec 2014 | 338 | 95.3 % | 87.6 % | 82.0 % | 76.3 % | 70.4 % | 60.7 % | 48.2 % | 28.4 % | 2.4 % | 38.7 |
| 14.0 | 13.9 | 15.1 | 15.1 | 15.1 | 14.9 | 14.9 | 14.5 | 15.1 | 14.6 | ||
| 1 Jan - 31 Dec 2015 | 324 | 96.0 % | 87.7 % | 79.6 % | 71.9 % | 65.4 % | 55.2 % | 39.2 % | 6.2 % | 42.5 | |
| 15.0 | 15.5 | 16.3 | 16.6 | 16.6 | 17.2 | 17.1 | 16.9 | 16.2 | |||
| 1 Jan - 31 Dec 2016 | 500 | 91.8 % | 83.6 % | 76.4 % | 69.8 % | 63.8 % | 49.0 % | 25.0 % | 3.2 % | 42.4 | |
| 15.2 | 15.6 | 16.6 | 17.2 | 17.1 | 17.2 | 17.2 | 18.3 | 16.4 | |||
| Total | 1680 | 93.8 % | 85.1 % | 77.4 % | 70.4 % | 63.1 % | 51.1 % | 32.0 % | 10.1 % | 1.0 % | 40.7 |
| Average | 420.0 | 14.6 | 14.7 | 15.7 | 16.1 | 16.1 | 16.3 | 16.0 | 15.3 | 14.9 | 15.5 |
Table 3. Retention rate for Farm B. Period: January 2013 - December 2016.
| Gilt introductions | Parity 1 | Parity 2 | Parity 3 |
Parity 4 | Parity 5 | Parity 6 | Parity 7 | Parity 8 | Parity 9 | Total born/sow/year | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 Jan - 31 Dec 2013 | 958 | 90.2 % | 82.4 % | 76.7 % | 68.8 % | 60.8 % | 48.4 % | 32.7 % | 0.9 % | 35.7 | |
| 12.7 | 13.1 | 13.8 | 13.9 | 14.0 | 13.8 | 13.4 | 14.9 | 13.5 | |||
| 1 Jan - 31 Dec 2014 | 843 | 94.5 % | 89.3 % | 84.9 % | 76.6 % | 68.9 % | 60.3 % | 41.4 % | 7.8 % | 0.6 % | 37.3 |
| 12.6 | 13.4 | 14.4 | 14.8 | 14.7 | 14.5 | 14.4 | 14.0 | 12.6 | 14.0 | ||
| 1 Jan - 31 Dec 2015 | 887 | 95.4 % | 88.3 % | 84.0% | 78.5% | 74.0% | 66.5% | 52.2% | 9.6% | 0.6 % | 39.6 |
| 14.1 | 14.5 | 15.0 | 15.2 | 15.3 | 15.2 | 15.3 | 14.6 | 15.4 | 14.9 | ||
| 1 Jan - 31 Dec 2016 | 808 | 96.0 % | 91.5 % | 87.7% | 84.8% | 79.0% | 70.8% | 55.2% | 10.9% | 0.5 % | 39.4 |
| 13.6 | 14.1 | 15.2 | 15.5 | 15.7 | 15.9 | 15.8 | 15.7 | 15.8 | 15.0 | ||
| Total | 3496 | 93.9 % | 87.6 % | 83.1% | 76.8% | 70.3% | 61.0% | 44.9% | 7.1% | 0.4 % | 38.1 |
| Average | 874.0 | 13.2 | 13.8 | 14.6 | 14.9 | 14.9 | 14.9 | 14.9 | 14.8 | 14.5 | 14.4 |
Comparing the two farms, Farm B maintains a higher average multiparous retention rate (up to parity 7) than Farm A. The fact that farm B maintains a higher retention rate implies that a greater percentage of the gilts are reaching the most prolific parities, therefore, improving the payback of these animals.
We must understand the retention rate as a means and not as an end. Since having a very high retention rate does not necessarily mean it will be accompanied by better production levels. However, our objective must always be to have a high retention rate, combined with the best performance, cycle after cycle and minimizing NPDs as much as possible. In this way, we can make the most of our sows' potential, maximizing their payback based on productive days.
