This article introduces the predisposing factors and the different control methods for Post-weaning Diarrhea, showing the effectivity of a natural product based on intestinal conditioner pronutrients to fight against the disease.

Weaning generally occurs during the first 3-4 weeks of age in the modern pig industry, much earlier than in the wild, where it is a progressive process that takes place around the next 17 weeks after calving.

Post-weaning diarrhea is one of the most common pathologies in pig farming. Animals develop intense to moderate watery diarrhea and show a decrease in the weight gain and a mortality rate of up to 25% of the piglets if not treated. Economic losses, without complicating factors, are of approximately 40 euros per sow per year (Sjölund et al., 2014).

Predisposing factors for post-weaning diarrhea

Weaning is a critical point in the productive life of piglets, since at that moment there are multiple stressors, including nutritional, social and environmental changes, which induce a transitory anorexia, intestinal inflammation and imbalance of the digestive flora.

Changes in immunity

Stressors trigger an adaptive reaction in the animal, which secretes hormones such as cortisol and corticotropin. They are beneficial at normal doses, but long-term or high concentrations can produce metabolic and immunosuppressive effects. In addition, by the same time, animals lose the benefits of passive immunity conferred by sows’ milk.

On the other hand, the presence of other infections can promote the appearance of post-weaning diarrhea. For instance, infection by Porcine Reproductive and Respiratory Syndrome virus (PRRSv) leads to immunosuppression, which makes the animal more susceptible to all types of infections.

Social and environmental changes

Social and environmental stress is caused by the separation of the mother and the age of the animal at weaning, the time and type of handling and transport, and the new facilities where animals of different origins come together.

Another fundamental factor is the environmental temperature in post-weaning facilities. A cold environment in this period slows down intestinal motility and facilitates the adhesion of pathogens to the intestine.

Nutritional changes

The new solid diet after weaning is less appetizing and different in composition, texture, temperature and taste compared to sow’s milk. At that moment, digestive system of piglets and digestion enzymes must adapt to digestion of different starches, proteins and fats.

This change in diet is associated with a transient anorexia of 24-48 hours and erratic consumption of food and water, which contribute to the reduction of gastric motility, intestinal inflammation, reduction of the height of the villi and atrophy of the intestinal mucosa, reduction in the absorption of nutrients and increase in the permeability of antigens and toxins. It should be noted that animals starting solid feed consumption before weaning showed a shorter period of fasting compared to those who have only taken milk.

Certain components of the diet, such as soy, favor the appearance of diarrhea, which could be caused by antinutritional factors and by certain antigenic capacity, which generates a hypersensitivity response in the first 3-10 days.

Changes in the gut microbiota

Gut microbiota has numerous beneficial functions for animals, such as fermentation of carbohydrates, production of vitamins, maintenance of the functions of intestinal villi, regulation of the immune response and protection of pathogenic bacteria. Numerous studies reported that dysbiosis of gut microbiota after weaning is one of the key factors in the appearance of enteric infections and diarrhea.

Loss of bacterial diversity, due to the decrease in population of Lactobacillus spp. and of obligate anaerobic bacteria, and the intestinal inflammation present in this period allow the relative growth of facultative anaerobic bacteria, such as coliforms. In addition, after the ingestion of enterotoxigenic E. coli (ETEC), the main pathogen involved in the appearance of post-weaning diarrhea, the disbalance in the normal microflora eases ETEC to colonize the intestine. Other agents may be the cause or play an enhancing role of enteritis, whether of bacterial origin, such as Salmonella spp. Or parasitic, such as Trichuris suis, coccidia or cryptosporidia.

Control of Post-weaning Diarrhea

The preventive approach to the disease is based on both management measures and the supplementation of products that maintain a good intestinal environment.

• Management measures include:
• Increase weaning age or weight.
• Encourage the early consumption of maternity feed.
• Maintain the temperature of the weaning pen at 28-32ᵒC and avoid drafts.
• Use of raw materials of high quality and digestibility, with a diet with low amount of soybean meal and, if possible, with proteins of dairy origin.
• Maintain good hygiene and daily eliminate feces.
• Carry out a good cleaning and disinfection of the pens during the sanitary vacuum.

Products used for the prevention of diarrhea include: chemical products, vaccines or products of natural origin.

Chemical products

Traditionally, we have worked with the inclusion of antibiotics or zinc oxide (ZnO) mixed in the food. The use of antibiotics in this period, either as growth promoters or as prophylactics, contributes to the emergence of bacterial resistance.

In relation to zinc oxide, the use of high levels has shown to have antimicrobial properties and, therefore, they are used in the fight against postweaning infections. However, its use is restricted to 15 days and different studies have shown that the product can have negative effects, such as the intestinal reduction of lactic acid bacteria, the accumulation of the compound in organs such as the liver, pancreas and kidneys, or the correlation between the increase of multiresistant strains of E. coli and resistance to metals. In addition, there is also the suspicion of environmental pollution that the product produces and, therefore, the prohibition of its use by the European Union is on the way.

Vaccines

There are oral vaccines against enterotoxigenic E. coli (ETEC) that only confer immunity in cases where the strain expresses F4 fimbria and reduce the incidence of diarrhea, bacterial colonization and fecal excretion.

Natural products

The excessive use of chemical substances, especially at this stage of swine production, is a problem both economic and public health. There are numerous studies that highlight the potential of different functional additives or supplementary foods to maintain intestinal health and productive parameters. In the search for non-chemical alternatives we can find different substances such as, for example, prebiotics or probiotics, organic acids or products based on pronutrients.

Pronutrients are active molecules of botanical origin capable of optimizing the physiology of animal organs by regulating the correct functioning of their genetic code. They are classified into 10 groups according to their target cell.

The most relevant pronutrients designed to the maintenance of the digestive functions are the intestinal conditioners, whose target cell are the enterocytes (cells of the intestinal mucosa). Its addition in the diet in small amounts promotes the correct regeneration and activity of the enterocytes: a better integrity of the intestinal mucosa allows a better absorption of nutrients and greater resistance to infections, which is finally reflected in an improvement of the productive parameters.

Being natural products, they have the advantages that do not create resistances, do not leave residues in animals or their products and do not have a negative impact on the environment.

Image on the left: microscopy of the intestinal mucosa without the use of an intestinal conditioner, showing loss of integrity and undigested feed. Image on the right: microscopy of the intestinal mucosa of an animal that has received an intestinal conditioner, showing adequate integrity and no feed traces attached

Use of intestinal conditioner pronutrients to control Post-weaning Diarrhea

The aim of this trial was to compare the effect of intestinal conditioner pronutrients and zinc oxide on productive parameters and control of Post-weaning Diarrhea in piglets.

Experimental design

66 piglets were separated in two batches with 3 repetitions per batch. Evaluation was performed from weaning, at 28 days of life, till 57^th days of life. One batch received the product rich in intestinal conditioner pronutrients at a dose of 0.5 kg/t, and the other batch received zinc oxide at 2 kg/t.

Results

The final weight and the gain during the trial period was greater in the batch that received the intestinal conditioner. In addition, the use of intestinal conditioner reduced the occurrence of diarrhea by 42% compared to the use of zinc oxide (4.18% vs. 7.21%), and the diarrhea that the animals showed in that batch were of a milder character (Chart 2).

Conclusions of the trial

The use of products rich in intestinal conditioner pronutrients allows to obtain better productive results in post-weaning piglets and a decrease in morbidity and mortality, making it a good alternative to zinc oxide.

General conclusions

A correct functioning of the digestive system and, especially, of the intestine is essential to assure a correct growth in animals of intensive breeding. The main objectives of the intestine are the efficient absorption of nutrients and the maintenance of a healthy intestinal environment.

Weaning is a critical period in which the normal functioning of the intestine is altered due to the stress that the piglets suffer.

The excessive use of chemical substances that is carried out during this stage supposes a problem as much economic as of public health and, for that reason, the search of natural alternatives is one of the main objectives of the porcine producers.

The use of products rich in intestinal conditioning pronutrients allows to replace the use of antibiotics growth promoters or zinc oxide, achieving even better productive results with a decrease in morbidity and mortality. In addition, since they are natural substances, they do not create resistances and do not leave residues in animals or their products.

This product rich in intestinal conditioner pronutrients is commercially available under the name of Alquernat Nebsui.

BIBLIOGRAPHY:

• Greese, R.; Chaucheyras-Durand, M. A. F.; Van de Wiele, T.; Forano, E. & Blanquet-Diot, S. (2017). Gut Microbiota Dysbiosis in Postweaning piglets: Understanding the Keys to Health. Trends in Microbiology – 2017.05.04.
• Pluske, J.R.; Hopwood, D.E. & Hampson, D.J. (2003). Relación entre la microbiótica intestinal, el pienso y la incidencia de diarreas, y su influencia sobre la salud del lechón tras el destete. XIX Curso de especialización FEDNA. 23 y 24 de octubre de 2003. Madrid.
• Rhouma, M.; Fairbrother, J. M.; Beaudry, F. & Letellier, A. (2017). Postweaning diarrhea in pigs: risk factors and non-colistin-based strategies. Acta Veterinaria Scandinavica – 2017; 59:31.
• Sjölund, M.; Zoric, M. & Wallgren, P. (2014). Financial impact of disease on pig production. Part III. Gastrointestinal disorders. 6^th European Symposium of Porcine Health Management (Italy).