Guide to Pig Management: Weaning (Part 5):

Weaning is the culmination of all the previous stages in the production life cycle and determines the success of the business. A well-nourished piglet, protected by maternal antibodies, has a better chance of successfully overcoming this most critical time of its life.

However, the virtual cycle is not yet complete, and piglets are weaned much earlier than would occur in nature (21 to 28 days), which is a significant challenge for the piglet. The sudden separation from the mother is followed by mixing, transport, new housing and establishing hierarchies. But the most important issue is that the stomach of the piglet is not ready to process the sudden change in diet.

The diet changes from being based on milk proteins which needs a stomach pH of 4, to a vegetable/meat protein-based diet which needs a stomach pH of 3. However, the stomach does not yet produce hydrochloric acid effectively. A common solution is to provide in-feed organic acids. Organic acids have been shown to exert a bactericidal action mediated by non-dissociated organic acids, by:

• lowering the gastric pH
• increasing gut and pancreas enzyme secretion
• improving gut wall morphology

It has been postulated that organic acids may also enhance the non-specific immune response and improve disease resistance. In contrast, relatively little attention has been paid to the effect of organic acids on the stomach, but recent data show they can affect gastric histology, acid secretion and gastric emptying in different ways (Bosi et al., 1999; Lallès et al., 2009; Suiryanrayna and Ramana, 2015).

Management

A number of conditions are required to create a suitable environment for the newly weaned piglet. First, a nest with a comfortable temperature, especially for the piglet's ventral area until it starts to ingest enough to produce its own body heat, should be provided.

There must be an eating area next to the lying area, where the piglets can easily find the feed supply. If there is no nest and the pen floor is fully slatted, a plastic/rubber mat can be very useful to keep the piglet's belly warm when lying down. The piglet will only use the mat for a few days, after which it can be thoroughly washed and stored ready for the next batch.

Piglets start by investigating the pen floor, so scattering some loose pellets helps them find and possibly ingest the feed, leading to the discovery of the link between feed and satisfying their hunger. This also helps them to understand what the feeders are for.

All piglets would typically suckle the sow at the same time every 1.5 hours, a habit they will retain for some time after weaning. This means the stronger piglets will eat but if there is not enough space at the feeder, the weaker piglets will wait their turn, eat some pellets, and then run back to the group. When these weaker piglets lay back down in the nest, they always get the external, colder positions. These weaker piglets will easily get sick which compromises the health status of the whole group. This can be prevented by providing a minimum of 5 cm of feeder space per piglet.

Toys are a good way to enrich the environment to prevent boredom. Boredom can lead to pathological behaviors such as tail biting.

The starting temperature should be 29 °C, decreasing by 1 °C each week as the piglets start to eat. The pen should be free from drafts.

Water points should be near the feeders and to one side of the dunging area to develop the correct toilet habits. Water should be clean and fresh (pigs hate dirty, bitter water). There should be 1 nipple for every 15 heads, and the correct flow rate is 1 l/min. Adding a small amount of acid to the water can help water palatability and uptake.

There should be no more than 33 piglets/pen, as this is the maximum number of pen-mates that pigs can remember. The hierarchy in groups any larger than this is inevitably unstable, and there will be continuous fighting.

Litters from first-parity gilts naturally have less protection, and they are more susceptible to developing diseases compared to other piglets. Segregating these piglets reduces the risk and care can be provided to individual pens instead of the whole group.

Providing light 24 hours a day during the first and second days after weaning, even if it is not at full intensity, helps increase piglet feed intake.

Nutrition

It is difficult to meet the nutrient demand of the weaned piglets in the first few days post-weaning, so diets offered at this stage must include high-quality raw materials.From a nutritional point of view, there are two key drivers in this period: feed intake and digestibility. Gut health must be optimized, and post-weaning diarrhea prevented to reduce the negative energy balance and maximize growth potential.

Suckling piglets should have constant access to water from the first day of life. The theory that piglets do not need any water because they are drinking milk is incorrect. This is even more true in piglets with diarrhea which become dehydrated. In this case it is worth enriching the water with electrolytes.

Investing in specific watering systems for the piglets in the farrowing crate pays off in terms of weight gain and health status. Drinking water helps the piglets to eat solid feed, which they need to start from 5–10 days of age. Training the piglets to use the nipples in the farrowing room will improve water and feed intake after weaning.

Piglets face the most difficult period in their life at weaning as they deal with changes in their environment, they are separated from dams and littermates, and their feed changes from liquid to solid. Having access to and being able to drink fresh, clean water at this time will certainly reduce overall stress.

Antimicrobials

Implementing best practices during the stages before weaning often removes the need for antibiotics completely. It is common to medicate feed at weaning to overcome the challenges of this stage, but other factors should be considered first.

Modulating weaning age to obtain heavier, more mature piglets is better than gaining a few days in the sow's cycle. Every sow week is worth only about 0.5 piglets and, although a more digestible diet costs more, it prevents a great many problems.

The crude protein content in the first two weeks of the nursery phase must be highly digestible, but inclusion levels do not have to be that high to maximize growth. Crude protein that is less digestible can be very detrimental in terms of diarrhea and recovery time for gut morphology and the microbiome. Nothing can replace antibiotics; they are unique tools to cure disease. But they can be used more prudently as part of an integrated program that manages nutrition and incorporates feed additives.