Feeding gestating (dry) sows

Ensuring your sows are fed correctly throughout gestation will have a major impact on their future performance. Our information will help you to consider feeding requirements, body condition and more.

Gestation

This is a particularly important time for the sow and during this period, nutrition can have a considerable impact on her reproductive performance and longevity in the breeding herd. During gestation, the aim of nutrition is to rebuild and maintain body reserves, provide sufficient nutrients to the growing litter and ensure adequate mammary gland development in preparation for lactation.

If possible, nutrition during gestation should be tailored to the different parities because, largely to do with body size, sows can have different nutritional requirements. As the gilt is still growing, amino acid levels must be high enough to ensure both maternal and foetal growth, with an increased requirement for lysine of at least 1.5 g/day.

From parity 2 onwards, there is a reduced requirement for lysine and an increased requirement for energy. In older sows (parity 5 onwards), heavier weight means higher maintenance requirements, so it is important to consider whether they are getting sufficient vitamins and minerals. Insufficiency can result in decreased litter performance, including lower litter weights and piglet performance.

Phase feeding

This can be used to adjust feed as the gilts or sows’ requirements change. Research has demonstrated that, in the case of gilts, overfeeding post-service can negatively affect embryo survival. Therefore, during the first 14 days, it is recommended to avoid overfeeding gilts.

In contrast, it is beneficial for sows, particularly those that have lost body condition, to increase feed intake during early gestation. This has been linked to improvements in embryo and placental development.

In mid-gestation

The requirements for foetal and mammary development are still small, so the aim is to ensure maintenance of the sow’s body condition without over- or underfeeding.

In late gestation

The growing litter demands considerably more nutrients, so it is advisable to increase the daily feed allowance by approximately 1 kg, unless sows on the farm are susceptible to MMA (mastitis, metritis, agalactia), in which case high feed values can exacerbate the condition. However, during the last few days before farrowing, avoid overfeeding because this can affect feed intake during lactation.

Table 1 gives typical feed specifications for dry sows.

Table 1. Nutrient specifications for gestating sows

¹Amino acids are presented as ratios to standardised ileal digestible lysine

²Digestible phosphorus levels are based on diet formulation without the use of phytase. However, if phytase is being used, then phosphorus levels must be readjusted. Addition of phytase to the diet is recommended for improved digestibility

³The maximum permitted level of copper in feed for all pigs over eight weeks post-weaning is 25 mg/kg

In addition to the above nutrient recommendations, the following additives may also be considered for gestating sows:

• Phytase

The addition of phytase to gestating sow diets has been shown to increase the nutritional value of feed by increasing the release of phosphorus

• L-carnitine

Research has demonstrated that in some cases L-carnitine supplementation can improve piglet energy reserves at birth and increase birth weights, weaning weights and sow milk yield.

Gestating sows should be fed according to body condition. If feed intake is too high, sows will become fat and will subsequently reduce intake during lactation. If feed intake is too low, this can result in thin sows, which compromises the development of the litter and mammary glands.

In general, a daily feed allowance of 2.3–3.5 kg per sow is sufficient. Ultimately, the amount fed depends on the diet specification, sow’s size, body condition and parity, as well as other factors, including environment and health. Figure 1 shows an example guide to feeding gilts and sows during gestation, considering the specific phases and changes in requirements.

Ad-lib feeding during gestation is not recommended. It is difficult to prevent sows from overconsuming energy and would require a feed high in fibre. Variation with the sows can also become a major issue.

Recent studies generally agree that increased energy levels in gestation can result in low intakes in lactation, as well as reduced mammary gland development and subsequent lower milk yield. Additionally, return to oestrus and subsequent litters can be negatively affected.

Figure 1. Example feeding strategy for gestating sows and gilts

The energy requirements of gestating sows are temperature-sensitive and will increase with lower temperatures; for every degree below the lower critical temperature, an extra 2.5% of energy is required. As a guide, once the temperature falls below 20°C, additional energy is required to maintain the sow’s body temperature. Failure to provide this will result in loss of body condition.

Feed regimes on outdoor units should therefore consider seasonal changes in temperature and either increase feed levels during the colder months, or provide a diet of increased energy density. Providing insulated arks and dry bedding and other methods to reduce heat loss can offset some of the need for increased feed levels during colder months.

On indoor units, sows are mostly kept on straw yards in groups; however, in a particularly draughty environment, it may be necessary to increase the feed allowance for those sows to prevent them losing condition.

Feed is available in several different forms, including pellets, meal and rolls. There are benefits of each and, ultimately, the type of production system and feeding equipment available may dictate choice. Meal is cheaper to manufacture but wastage may be higher. Pelleting feed increases digestibility and can reduce wastage. Rolls (15-18 mm) are widely used for feeding outdoors but are difficult to manufacture and more expensive than nuts (5 mm), which are in turn more expensive than pellets (3-3.5 mm).

In outdoor systems, sow rolls and nuts may be used. These are beneficial because the sow will forage from the ground and, while on straw in the dry period, will help to increase intake and reduce wastage. 

In the UK, meal is generally a coarse grist product, which increases flowability and reduces blockages and dust. 

Managing the body condition of gestating sows is critical because overweight or underweight sows can have a considerable impact on the productivity of the breeding herd.

Body condition should be assessed regularly on an individual basis and feed intakes adjusted accordingly to help maintain a uniform breeding herd. Body condition is assessed using either a visual scorecard or backfat measurements.

A score of 1 indicates an emaciated sow with protruding bones, while a score of 5 indicates an overweight sow with excess fat cover (see Table 2 for descriptions). Ideally by week 4–5 of gestation, 85–90% of sows should score 3, which is average. 

Table 2. Body condition scoring of sows

This was written in conjunction with ABN, Primary Diets and Premier Nutrition.