Basic requirements
The groundwork for successful farrowing and reducing piglet mortality is not laid only when the sows are moved into the farrowing area and labour begins! It is a complex interplay of many factors. Some of these can be changed in the short term, whilst others can only be influenced over the long term.
2.1 Genetics of the sow
Even gilts require good management. Careful selection of genetics is essential here. This applies both to purchasing gilts and to rearing them on the farm. Genetics suitable for the farm must always be assessed in conjunction with management, feeding and housing conditions. The genetic component for reducing suckling piglet losses can only be influenced in the long term. Sow farmers benefit when breeding companies already take behavioural traits (e.g. maternal instinct) into account in breeding value estimation.
Functional traits in breeding sows have gained in importance in recent years. Studies have shown that, even where heritabilities are low, it is certainly possible to influence the reduction of suckling piglet losses through breeding. Scientific research suggests that calm behaviour combined with careful handling of piglets, improved suckling behaviour and higher colostrum quality should be taken into account during selection.12, 13
Many studies have shown that suckling piglet losses also increase with increasing litter size, regardless of whether sows are kept with or without piglet protection crates.8, 14, 15 This is primarily due to the lower birth weights of the piglets. Conversely, a smaller litter size, where each piglet has its own teat, or where surplus piglets can be reared by foster sows, can be advantageous as it leads to higher birth weights and, overall, more vigorous piglets. Assessing sows using a maternal index can also be helpful in improving rearing results, particularly for sows used for in-house replacement.16 Important criteria for in-house replacement include birthing behaviour, litter quality at birth and the sows’ docility during procedures involving the piglets.17, 18, 19 As free-range pens are currently found predominantly on organic farms, there is already a guidance sheet on in-house replacement in organic pig farming, which provides tips for selecting the desired maternal traits.20
Breeding organisations and breeding companies are increasingly taking further characteristics into account, such as the number and quality of teats.21, 22, 6, 23 These also contribute to improved rearing performance. ‘One teat per piglet’, i.e. 15 to 16 well-formed teats, should be the target when assessing breeding sows.
Another potential breeding approach is selection for good conformation, which has an indirect positive influence on crushing losses,24 as animals with conformation problems have difficulty standing up and lying down, which can pose a risk to the piglets.
When starting to use exercise or free-range pens, work is often carried out with an existing sow herd. As the transition can sometimes take several years, it is important to identify in advance which sows possess the necessary potential.
Several criteria relating to the sow’s behaviour should be assessed:
- Nest-building behaviour
- Cautious handling and good communication between the sow and the piglets whilst standing, moving and shortly before farrowing
- low activity in the first few hours after birth
Deal-breaker criteria:
- Aggression towards the animal caretaker
- Biting the piglets
2.2 Boar genetics
In addition to sow genetics, the choice of the right boar also has an impact on suckling piglet losses. However, this effect is more indirect, arising through litter size or the number of live-born piglets. The boar can have an influence, albeit a minor one, on litter size.25, 26 In studies, the influence of the sire on the genetic variances in litter size ranged between 2 and 5%.27, 28 Minor effects on piglet vitality were demonstrated by Pedersen et al.29 In this study, the Pietrain offspring showed higher mortality than the Duroc offspring. In general, there are genetic differences between breeds or lines that influence piglet vitality.
2.3 Health
The sow’s health has both a direct and an indirect impact on rearing performance. Mammary gland disorders lead to reduced milk production and, consequently, to increased crushing losses. Numerous conditions (e.g. lameness) have an indirect effect by impairing milk production and suckling behaviour.11 Malnourished piglets are at increased risk of being crushed. On the one hand, they tend to stay close to the sow whilst searching for her; on the other hand, physical weakness leads to slower reactions. It is not possible to list all potential health problems in this guide; therefore, a herd examination by the attending veterinary practice is always necessary.
Maternal vaccinations are also a key factor in ensuring healthy piglets. Unlike in humans, there is no transfer of antibodies to the foetuses in the uterus of pigs. Piglets are therefore born completely unprotected. They rely on antibodies from colostrum to provide them with early, passive protection against infections. By vaccinating sows a few weeks before birth, they produce increased levels of antibodies against the relevant pathogens. These can then be passed on to the piglets via the colostrum to protect them. Approved, commercial vaccines are available for most infectious diseases relevant to suckling piglets. These can be supplemented with herd-specific vaccines if necessary. As this always depends on the individual farm, please discuss this with your vet.
Overall, the following applies: good preventive healthcare and monitoring are important for both individual animals and the entire sow herd.
2.4 Foundations
Even when re-breeding gilts, attention must be paid to strong and weight-bearing limbs. Correct toe and leg alignment, with appropriate angulation in the hock and toe joints, is essential for good mobility, robust health and a long productive life for the sow. Hoof strength must also be taken into account.30
The interaction between hoof/foot health and the pen flooring is crucial: with around 14 lying down and standing up manoeuvres per day, controlled movement is essential to prevent crushing injuries.31 Lying down behaviour poses a significant risk of crushing. When lying down, the centre of gravity is momentarily under the hindquarters; it cannot be adequately supported by the sow’s hind legs and is therefore difficult for her to control.32 Sows with hoof and/or joint pain in particular will keep the lying-down process as brief as possible (Video 1) to avoid pain.
Regular assessment of hoof condition helps to prevent foot problems. This covers the entire hoof: the coronet band, the hoof wall, and the sole and pad areas are all assessed. Various assessment schemes are available for this purpose. The assessment scheme shown in Table 2 provides a starting point for gaining an overview of potential hoof problems within the herd. These should first be discussed with the farm vet in order to take further action. Help with the assessment is also provided, for example, by the illustrated guide to hoof health, which was produced as part of a project by the South Westphalia University of Applied Sciences on hoof problems in breeding sows and which also specifies threshold values for the respective hoof changes.
| Grade | Ball zone | Rear hooves | Main claws | Wall horn | Crown margin |
| 1 | No findings | No findings | No findings | No findings | No findings |
| 2 | Growths | slightly too long | slightly too long | small tears | minor injuries |
| 3 | tears | far too long | far too long | large tears | severe damage |
| 4 | Growths and tears | torn off | extremely long | extreme tears | severe inflammation |
<figcaption>Table 2: Hoof grading from 1 to 4 – assessment levels according to the assessment chart of the Dutch farmers’ network for group housing (‘Animal Sciences Group’)</figcaption>
2.5 Feeding
Feeding in general, and the feeding regime in particular, have a significant influence on the fertility of breeding sows, in addition to ensuring an adequate supply of energy and nutrients. The relevant nutritional requirements of the animals must be specifically met at every stage of their life. This guide briefly outlines the feeding recommendations for sows around the time of farrowing. Detailed information on nutritional recommendations and practical feeding guidelines can be found in the relevant feeding guidelines issued by the agricultural authorities of the various federal states, as summarised below (all subject to a fee).
Calculation Guide for Efficient Pig Feeding (LWK North Rhine-Westphalia, 2022)
2.5.1 Feeding pregnant sows
Objectives:
- Nutrition tailored to requirements during the early (NT) and late (HT) stages of pregnancy, with particular attention to fibre intake (ensure ‘free-choice feeding’)
- Maintaining gut health (fibre-rich feed, mycotoxin-free feed)
- Body condition: “fit rather than fat” through individual animal-specific conditioning feeding during gestation via targeted condition checks (Body Condition Score, fat cover, animal weights)
- Prevention of MMA and PHS (Mastitis-Metritis-Agalactia Syndrome, Periparturite Hypogalactia Syndrome)
- Preparation for optimal farrowing and lactation (taking into account the competing demands between energy and nutrient supply for sows and piglets and the goal of optimal farrowing and lactation)
- Consistent litter weights
Further, detailed information on the individual aspects:
- Nutrition of Farm Animals, Jeroch, Drochner, Rodehutscord, Simon A., Simon O., Zentek, 2020, ISBN 978-3-8252-8763-4
- Practical Handbook on Pig Feeding, Griep, Meyer, Stalljohann, Weber, 2022, ISBN 978-3-86263-162-9
- Feed for Farm Animals, Durst, Freitag, Bellof, 2021, ISBN 978-3-7690-0852-4
2.5.1.1 Assessment of physical condition
Good nutritional status is important for health. The best way to assess this is by examining the spinous processes of the thoracic spine. Visible spinous processes indicate that the feed is inadequate in terms of quantity or quality. Either the amount of feed per animal per day is incorrect, there are too few feeding stations, or there is a lack of energy and/or crude protein. Furthermore, emaciation may be an indication of a (chronic) illness or restricted access to feed, e.g. due to lameness. It is important to assess whether there is a varied or uniform state of development within the group of animals, or whether the pigs are ‘growing apart’.
During pregnancy, sows should build up sufficient body reserves to be able to compensate for a potential energy deficit during lactation by mobilising these reserves (primarily from backfat). However, they must not become obese. Body condition can be assessed subjectively using the Body Condition Score (Fig. 3).
The following guidelines should be followed:
| Condition score on transfer to the gestation pen** | Energy allowance for basic requirements of 35.5 MJ ME/day | Feed quantities at 12.2 MJ ME/kg feed |
| 4.0 | - | 2.9 |
| 3.5 | 1.0 | 3.0 |
| 3.0 | 4.0 | 3.2 |
| 2.5 | 8.0 | 3.6 |
| 2.0 | 12.0 | 3.9 |
<figcaption>Table 3: Guideline values for condition-based feeding of pregnant sows up to the 80th/85th day of gestation*34 </figcaption>
* From the 80th/85th day of gestation, the daily energy intake for all sows should generally not significantly exceed 43.5 MJ ME/day
** For body condition scores, see Figure 3
A high-fibre diet is intended to achieve both mechanical and chemical or hormonal satiety in gilts and pregnant sows. Mechanical satiety is achieved through the degree of stomach fullness. Energy-diluted feed leads to higher feed intake. Intensive digestion in the large intestine, combined with a more even release and supply of energy in fibre-rich feed, reduces the rapid drop in blood glucose levels. This results in chemical or hormonal satiety. The high-volume feed also lays the foundation for a high feed intake capacity during lactation.
Compliance with the legal requirements of the Animal Welfare and Livestock Management Ordinance can be ensured through the use of fibre mixes. Common ingredients in these high-fibre supplementary feeds include, for example:
- fruit pomace
- Soya bean hulls
- Dried pulp
- Green meal
- Lignocellulose
- Mill by-products
It should be noted that, depending on the fibre content, the mixing rates of the fibre mix into the feed for pregnant sows vary.
However, it is also possible to use appropriate complete feeds for pregnant breeding sows that already contain the fibre components mentioned above. When formulating complete feeds, in addition to the legally required declaration of crude fibre, the more meaningful fibre parameters aNDFom and ADFom should be taken into account. The recommendations from DLG Fact Sheet 463 serve as a basis here:
Crude fibre content: ≥ 70 g/kg, aNDFom ≥ 200 g/kg, ADFom ≤ 80 g/kg
‘Combined feeding’ offers an alternative for increasing the fibre content in the daily ration. This involves providing a complete feed for pregnant sows that meets all requirements for energy and nutrient supply. In addition, the sows are given ad libitum basic/roughage in separate troughs to meet the requirements for both satiety and activity. The quality requirements for on-farm feed, particularly with regard to hygienic quality (e.g. toxin levels, silage quality, etc.), require special attention.
Animal Welfare Ordinance
Section 30(6)
"Pregnant gilts and sows shall be fed, up to one week before the expected farrowing date, with complete feed containing a crude fibre content of at least 8 per cent in the dry matter, or in such a way as to ensure a daily intake of at least 200 grams of crude fibre per animal."
The aim of a pre-farrowing feed is to prepare the sow for farrowing in such a way that, from a physiological perspective, a favourable starting point is established for the care of both the sow and the piglets, whilst minimising any additional stress on the sow, such as that caused by the onset of MMA syndrome.
The following aspects must be taken into account in particular:
- A particular challenge is the abrupt transition from group housing to a phase of limited movement following placement in the farrowing pen approximately one week before the expected farrowing date.
- A prerequisite for high feed intake during lactation is undisturbed digestion in the period close to birth. The general decline in feed intake prior to birth must also be taken into account here.
- To prevent constipation or hard faeces, a sufficient supply of high-quality fibre components based on the DLG recommendations35 using aNDFom and NDFom is crucial. These should also contain swellable components to ensure the gut is sufficiently filled (this is not achieved, for example, by straw and hay). At the same time, a high intake of water of appropriate quality must be ensured.
- Faecal consistency must be checked regularly and, in the event of signs of constipation, practical experience suggests that a scoop of barley, wheat bran or dried pulp and brewers’ grains, each coarsely ground, may help. → Pre-calving feeds are specifically tailored to this phase and, like the farm’s own basic/roughage feeds, help to prevent intestinal sluggishness. 36, 35
- Promotion of calcium mobilisation through a shift in the electrolyte balance and a reduction in the pH value of the urine.36
2.5.2 Feeding lactating sows
During lactation, sows have high energy requirements, meaning that the recommended energy and nutrient intake can only be met if feed intake is sufficiently high. Consequently, particularly at the start of lactation, insufficient feed intake can lead to a significant mobilisation of the sow’s own reserves. However, this mobilisation should be kept to a minimum in order not to overburden the sow’s metabolism.
On the day of farrowing, the sow should consume 1.5 to 2 kg of feed; feed intake is then gradually increased (→ approx. 0.5–1 kg/day; the full feed allowance should be reached after about 10–12 days). Depending on the farm, it may also be appropriate to include breaks in the increase phase.
The following aspects should be noted:
- Provide a balanced, performance-oriented supply of energy and nutrients in small portions spread throughout the day (e.g. lactation feed via a feeding curve)
- Use palatable and digestible feed (e.g. brewers’ grains; limit the inclusion of, for example, lupins or rapeseed due to their content of anti-nutritional factors)35
- Ensure an adequate fibre supply to maintain gut health via non-starch polysaccharides (stimulation of gut microflora and gut activity) and fibre sources with high water-binding capacity (e.g. dried pulp)35
- Feed must be hygienically sound (free from spoilage bacteria, moulds, yeasts and mycotoxins)37
- Sufficient water (e.g. monitoring water intake via water meters) and cleanliness
Measures to maintain high feed intake in hot weather:
- feed early in the morning and late in the evening, or spread feed across additional meals
- palatable components and sufficient fibre supply
- it is also recommended to supplement the feed with 1–2% vegetable oil and/or a maximum of 3% crude glycerine (sweet; from 3–5% there is a risk of the feed clumping)