Temporary nurse sows: How to increase the number of teats on batch farrowing systems

With the production of highly prolific female lines, one of the biggest challenges faced by a growing number of genetic companies these days is the difference between the average number of piglets born alive and the average number of productive teats in their sows. In order to to "come up" with more available teats in the farrowing rooms, this situation requires different management techniques. One of the most common strategies is the use of sows as nurse sows.

Basically, a nurse sow is a sow that will raise two different litters within the same lactation period, her own litter and another litter that she adopts after weaning her own. The use of nurse sows is easy on farms with weekly batches, since there are farrowings every week. As a result, there are sows in every stage of the lactation period at any given time. However, this procedure becomes more complicated in the case of farms that work on a three-week batch system, a management program that is very common in Spain. In addition, it is particularly complicated in the case of systems with a very strict batch farrowing management, i.e., systems without any insemination outside the insemination week. These farms only farrow every 3 weeks.

This article describes a nurse sow management technique that could be useful in batch farrowing systems. We call it “temporary nurse sows”. This concept has been developed during the last two years in the Swine Research Farm of Aguilafuente, Segovia, Spain, with excellent results. In this example, we will show the farrowing and weaning weeks of two consecutive batches from a farm with a strict three-week farrowing batch system.

Table 1-Farrowing and weaning weeks per batch

Week	1	2	3	4	5	6	7	8
Batch A	Farrowing				Weaning	Insemination
Batch B				Farrowing				Weaning

Let us start with farrowings in batch B, in week number 4. The steps will be as follows:

1. Take the leftover piglets from the principal day of farrowings and, after insuring good intake of colostrum, transfer them to the sows that have farrowed earlier in the same batch. (E.g., to sows that have been lactating for 2 or 3 days).
2. To accommodate the transferred piglets, the piglets from the early farrowed sows that are 2-3 days of age will be moved to sows that are in batch A that have been lactating for 21 days. The piglets from these sows will be weaned then, one week earlier than the rest of the piglets from the same batch. This sow is what we describe as the “temporary nurse sow”.
3. In week 5, one week later, the piglets from the temporary nurse sow, which are only 9-10 days old, will be moved to cull sows from batch A instead of weaned. Those sows, after weaning their own piglets, will adopt these piglets.
4. In week 8, the cull sows from batch A that have piglets from batch B will be weaned together with the sows from batch B. Their piglets will be 28-30 days, but their lactation length will be up to 7 weeks. These are the real nurse sows because they will have weaned two litters.

With this process, we will have some piglets weaned at 21 days and some sows weaned at 7 weeks of lactation. Because they will be culled after weaning, we are not concerned with any impact the long lactation could have on their productivity and we take full advantage of their valuable service prior their exit to the slaughter plant.

This management technique is very handy. Just a note of caution: For health reasons, we should always move sows and not piglets. As a result, both the temporary nurse sows and the regular nurse sows will be moved from batch A rooms to batch B rooms. The temporary nurse sows will not be considered real nurse sows because they do not wean two litters, only one, and the litter continues to lactate from the regular nurse sow. Next, we will show information of the different types of sows.

Table 2-Weaning age, lactation length, and number of litters per type of sow.

	Piglets age at weaning (days)	Sow lactation length (days)	No. litters weaned
Normal sow	28	28	1
Temporary nurse sow	21	28	1
Regular nurse sow	28	49	2

One question that could come up is why not use cull sows in step 2, so we can skip step 3 altogether? The two reasons to use these temporary nurse sows are:

• First and more importantly, for management reasons. While normal cull sows have a lower number of lactating piglets, temporary nurse sows should be sows with a higher number of piglets in their litters (e.g., 13-14). As a result, temporary nurse sows can have the same number of piglets as several cull sows.
• The second reason is due to piglet size. These temporary nurse sows will have smaller piglets than the normal cull sows (as long as they have the minimum size for being weaned). Because the difference in age between the piglets that will be weaned (21 days) and the ones that will be adopted (2-3 days) is high, we should try to minimize this difference as much as possible, in order to minimize its effect on the sow.

This management technique is probably the best available option for nursing piglets in farms using a strict three-week batch farrowing system. It is also an example of how changes in genetics towards more hyperprolific sows is driving us to address new management challenges.