The performance of sows in north-western Europe has increased dramatically over the past 10 years. The overall benchmark now is to produce 30 pigs/sow/year. To achieve this, the gastro-intestinal (GI) tract has to be supported and working well to optimally supply the uterus with nutrients and guarantee high performance.
By Ernst-Günther Hellwig and Dr. Heinrich Kleine Klausing*
The gastro-intestinal (GI) tract is one of the most sensitive systems in the pig. The intestine is in direct contact with the environment and has the task to enzymatically digest (small intestine) or bacterially digest (large intestine) feed that is processed and moved onward by peristaltic movement.
Through this process pathogenic bacteria can be ingested and/or a non-pathogenic load of bacteria are constantly present in the GI tract. As long as the system “GI tract” is working there will be no apparent clinical symptoms or disease.
If the system is disturbed – and sows often suffer from constipation during critical phases, for instance around birth or during lactation – pathogenic bacteria reproduce very quickly (clostridia) or ubiquitous gram negativeE. colidie in large amounts and their cell wall fractions flood the sows metabolism with endotoxins.
Today’s feeds are specifically formulated for this critical phase around birth, which amongst other tasks will keep the sows stool from firming. However, this does not mean that all feeding phases should not facilitate normal peristaltic movement.
Diarrhoea can occasionally be observed in sows. Often times bacteria likelawsoniaandbrachyspiruswill be the cause of this (less frequently, Salmonella). Of course, there are many other causes for diarrhoea which can be identified via dissection or individual analytical stool samples.
While we have been breeding for pig numbers over the years there is no positive correlation between uterus lengths, needed for pig numbers, and intestinal length. This means that the intestine has to work much more efficiently at 16-18 foetuses in late gestation, than if the sow were only to carry 7-9 foetuses. As a result we have to pay much more attention with modern sow lines, not only to the farrowing process and rearing but also to the way in which we manage the stool consistency around farrowing and during lactation. We could call this an optimisation of stool management.
Positively influencing gut micro flora
It is paramount to maintain intestinal peristaltic so that constipation does not occur and the health problems and performance reduction are not experienced. Especially around farrowing and during lactation but also during gestation it remains important to maintain good stool.
The most important influence on the gut peristaltic will be the ration and the correct fibrous structure of the feed (expandable, absorptive components with fermentable substances –Table 1). Mycotoxins need to be watched by using thorough quality control measures of raw materials. Equally as important, a clean water supply with low iron and manganese levels, a neutral pH without toxins (biofilm) and chlorinated.
Stabilising the gut microflora and a reduction of gut pathogens and their metabolic by-products and endotoxins can be achieved by using acids, prebiotics, probiotics and other additives. Antibacterial plant extracts and herbal oils are being used more and more.
The addition ofacids(formic-, lactic-, citric-, propionic and benzoeic acid) will strategically reduce the pH value in the stomach. This makes for a very pH consistent digesta entering the small intestine and alkalinity is avoided which is an important pre-requisite for the reduction of microbial colonisation of the gut. Acids will reduce orally ingested bacteria from multiplying in the stomach.Prebioticsare especially effective in the gut. They will be bacterially digested and produce short chain fatty acids that will affect the pH value and at the same time represent an energy source for enterocytes and the animal itself. Prebiotics are represented by fructooligosaccharides, mannanoligosaccharides, lactulose, xylooligosaccharides etc.Probioticshave the task of “occupying spaces” that would otherwise be taken up by pathogenic bacteria (e.g.E.coli). Probiotics will also induce the release of endogenous enzymes which will result in a better digestion and less food for pathogenic bacteria in small intestine. Probiotic bacteria stimulate the innate lactobacillus in the mucous membrane and immune competence of the protective barrier of the intestine. Ion exchangematerials such as aluminosilicates and bentonite are able to bind charged metabolic by-products like ammonia and detoxify the body.
Plant-derived materials as well as herbs and herbal oils will have an antibacterial and antioxidative effect on the gut microflora.
Increasedvitamindoses above nutritional requirements will also show positive results. Particularly vitamin E, vitamin C and vitamin B have proved to be very useful in practice.
Feed structure and crude fibre
Feed materials that are highly fermentable by bacteria (functional dietary components) are cereal roughage (like wheat bran), sugar beet pulp, maize and wheat feed as well as canola and sunflower extraction meals. Functional dietary components play an important role in the intestine. They improve gut motility and as a result passage rates which in turn results in a reduced incidence of constipation. They can, depending on the ingredient, take on more or less water which can also satisfy and improve gut-fill with identical intakes and energy contents. Unfortunately until now the measure for fibre fractions in feed for swine (or better, the structural carbohydrates) is still based on crude fibre. The fermentable carbohydrates in the caecum and the differences are not adequately graded. A measurable grading and a differential treatment of structural carbohydrates are offered by the analytical methods described by Soest (1991). Structural carbohydrates are listed and can be defined by the following fractions:
- NDF: (Neutral Detergent Fibre) - This fraction combines the hemicelluloses, pectin, cellulose and lignin in the feed. NDF can be simply described as the plant cell walls. Hemicelluloses, pectin and cellulose are the most important structural carbohydrates that are more (hemicelluloses, pectin) or less fermentable (cellulose).
- ADF: (Acid Detergent Fibre) - This fraction contains the fibres like cellulose and lignin in feed. The difference between the values derived for ADF and NDF is the amount of hemicelluloses. The contents of cellulose are calculated by taking the difference between ADF and ADL.
- ADL: (Acid Detergent Lignin) - The chemical analyses of this fraction describes lignin. The difference between ADF and ADL will give you a value for cellulose in feed. Lignin is almost completely indigestible for monogastric animals. Gidenne (2003) defined a category of “digestible fibre” that can be used to evaluate the fermentation capacity of feeds in the colon of pigs.
- DF: (Digestible Fibre) - The fraction of “digestible fibre”, are calculated from the sum of “hemicelluloses” (NDF – ADF) and water insoluble pectin (WIP). The majority of pectin is fermented and digested in the large intestine.
Table 1 gives an overview of the contents of structural carbohydrates in different components that can be used for the manufacture of sow and finishing feed.
...and in practice...
During practical routine diagnosis in farrowing operations the following symptoms may be seen:
- Units have problems with constipation starting in gestation;
- Hard stool starting before but also after birth continuing into the suckling period (2nd-3rd week) in a large portion of the sows;
- Reduced feed intake in lactating sows;
- Reduced milking in the important first days of lactation up to about 14 days post farrowing;
- Uneven development of the piglets in the affected litters, diarrhoea starting as early as the first few days, higher mortality (smothering, diarrhoea, starve-outs from insufficient milk).
Feed requirements around farrowing
What can be done from a feeding aspect and how can the sows be assisted? Extremely important: Check the water supply! Lactating sows have a daily requirement of up to 40 litres.
Are the sows being brought into the farrowing house early enough? It is required at least 7 days prior to farrowing. If the time is shorter and the feed is changed when moving the sow into the farrowing house (gestation feed to lactation feed) it can be useful to continue feeding the gestation diet up to two to three days after farrowing.
If feeding the lactation diet causes constipation, the nutritional state is always worse than if the sow continues to eat a gestation diet which is consumed and digested properly. The alternative is to use special products that will significantly reduce the risk of constipation.
If sows are kept on straw it makes sense to take them off the straw 14 days prior to farrowing. Sows will eat straw and straw can lead to constipation stressing the system; straw will not swell and absorb moisture. For this reason the sow’s intestinal tract should be free from straw around farrowing.
If an energy dense lactation diet is being fed (13.4 MJ ME/kg and higher) the use of fibrous materials will be limited. In such cases it is advisable to use a lower energy lactation diet (12.8-13.0 MJ ME per kg). Fibre content should be at least 5% and expandable fibre sources such as wheat bran and sugar beet pulp should be used. The energy source can be fat in such cases (min. 5% crude fat in the diet).
If hardened stool is already a fact in gestation then a feed review will be necessary.
Is there enough fibrous material and expandable material being offered? Are the gestating sows receiving enough good water? Could toxins be the cause of stool inconsistencies? Can the feed structure influence the stool consistency?
In critical situations mashed feed is the better choice. In problem cases a quick reaction is necessary, because high performing and susceptible animals will react very quickly with poor performance.
Even vaccinations that are given to animals during stress periods can lose some of their effectiveness (e.g. PRRS-vaccinations). Experience has shown that in such situations, it can be useful to support the animals’ metabolism and the immune systems. This can be done using vitamins especially high in B-complex as well as supplementing with Omega-3 fatty acids.
Especially during this critical phase around farrowing experience has taught us that special products based on heat treated linseed will alleviate constipation totally and improve the nutritional state of the sow. Linseed contains water soluble polysaccharides so-called mucilage. This substance will quell upon contact with water and form a linseed-mucous.
The heat treatment or cooking improves this process. The linseed mucous improves the digestion in the GI tract and aids fermentation in the lower intestine. This is evident through the improved consistency of the stool and the typical fermentation smell.
Healthy gut benefits performance
In summary, aiding a highly prolific sow is paramount. Gut peristaltic is to be maintained so that constipation or hardened stool is not observed.
The eubiotic state of the GI tract must be maintained and a proactive “stool management” should avoid the unbalanced state in the intestine. In general all the management issues should be discussed between the producer, the vet and the nutritionist. Only if all negative environmental factors, on the health status, can be removed then performance can be maintained or high performance achieved.
*Ernst Günther Hellwig is the founder and director of the AVA (Agricultural Veterinary Academy) based in Horstmar- Leer, Münsterland, Germany (www.ava1.de). Dr. Heinrich Kleine Klausing is the Technical Director with Deutsche Tiernahrung Cremer based in Düsseldorf, Germany. (www.deutsche-tiernahrung.de)