The nutrition of young animals is essential. Why? At this stage of life, they are very susceptible. Their gut health, robustness, and resilience are still immature, going together with increased early mortality.

Just in this phase, young piglets face their biggest challenge: weaning. It is well-known that the period around weaning is marked by various stress factors from environmental, social, physiological, and nutritional changes, accompanied by marked changes in gastrointestinal physiology, microbiology, and immunology, often resulting in reduced feed intake and impaired growth performance (Hampson, 1986; Pluske et al., 1997; Brooks et al., 2001).

Why feed intake is crucial?

Reduced feed intake is a common challenge in piglets after weaning. The abrupt separation from their mother and the change from a liquid, animal-based diet (milk) to a solid, plant-origin feed during weaning results in a sudden drop of feed intake, ultimately influencing long-term performance.

Studies have shown that piglets maintaining or losing weight during the first weeks post-weaning will need 6-10 days more to reach their final slaughter maturity than piglets gained more than 227 g/d body weight during the same period (Tokach et al. (1992)).

As intestinal development depends on the stimulation of luminal nutrients, low feed intake can cause adverse changes in the gastrointestinal tract, such as reduced villi height and increased villus height:crypt depth ratio accompanied by intestinal atrophy, decreased nutrient absorption, and high status of inflammation (Pluske, 1997; McCracken et al., 1999). Pluske reported that the villus height, and thereby the surface for absorption of dietary nutrients, increases with increasing feed consumption of piglets five days after weaning, demonstrating the importance of early feed intake.

Post-weaning diarrhea – an everlasting challenge

As a thin layer of epithelial cells only forms the intestinal epithelium; it is incredibly vulnerable. Disruption of intestinal integrity leads to a 'leaky gut,' which is determined by an increased permeability for toxic substances and/or pathogens, thus burdening the immune system. Taken together with the poor gut morphology and increased inflammatory processes, these alterations in the gut explain the piglet's increased susceptibility to pathogens, e.g., enterotoxic E. Coli (ETEC) and, as a result to diarrhea and growth delays in the post-weaning period.

Even under current conditions in Europe, about 15-23% of all piglets are suffering from post-weaning diarrhea (PWD).

PWD is characterized by watery diarrhea, dehydration, loss of body weight, and high mortality. Failure in growth performance and requirement for (antibiotic) medication result in a loss of profit for the farmer.

Ban of AGP and ZnO

Seeking simple solutions to prevent PWD is not easy: Until the ban of antibiotic growth promotors in 2006 in Europe, colistin was used as a feed additive to improve growth and prevent intestinal disorders like PWD. But with the global efforts to reduce the usage of antibiotics, more countries are following, and China banned colistin in 2016.

In addition to colistin, the addition of zinc oxide (ZnO) to the diets used to be a common practice for counteracting PWD. Although ZnO has proven to reduce PWD incidence, there is evidence for a stimulation of antibiotic resistance and environmental issues; however, ZnO used at pharmacological levels will be banned in the EU by 2022.

Without the option of using neither AGP nor ZnO, there is a fear of increasing losses and rising medication costs. The time is now to look for alternative methods protecting young animals from post-weaning challenges.

While looking for solutions, a strong focus needs to be put on the animals' intestine. The intestinal tract is the most exposed surface within the body and sensitive to disruption during the initial post-weaning and other stress periods. As a selective barrier, the gut mucosa acts as the first line of defense against pathogenic agents responsible for PWD. Therefore, a healthy gut is an effective digestive and defensive organ, supplying the animal with nutrients and protection against enteric diseases. Solutions to enhance gut health and resilience are necessary to support piglets in their early life.

It makes sense using phytogenics

Besides management practices or feeding applications, various additives are commonly used to counteract weaning challenges. One of those is showing significant potential: phytogenic feed additives (PFA). This category of additives compromises plant-derived, natural active substances from different origins, like essential oils, bitter and pungent substances, mucilages, flavonoids, tannins, or saponins.

Feed preference tests in piglets have shown that phytogenic substances improve the palatability of feed and stimulate feed intake (Delacon, R&I). Besides sensorial stimulation and improving palatability, phytogenic actives provide a wide range of beneficial effects.

Natural protection on different levels

As weaning challenges are complex, strengthening only a single factor of the animals' resilience is not enough to support piglets during this critical period. The piglet needs protection from different angles: the sensitive intestinal wall must be protected from the adherence of pathogens and bacterial overgrowth, excessive oxidative and inflammatory processes must be prevented, and the animal defense should be strengthened from inside out. Simultaneously, the piglet should be encouraged and stimulated for an early and adequate feed intake.

Designing a specific phytogenic product for piglets, Delacon invested in fundamental research to develop Fresta^® F to support early feed intake, protect the intestinal mucosa and reduce oxidative and inflammatory processes in the intestine in post-weaning piglets. This process required a careful selection of several phytogenic compounds such as flavonoids, essential oils, and mucilages.

With Fresta^® F, the gut mucosa is protected by a fine film of phytogenic mucilages, preventing the adhesion of pathogens like E. coli. Besides, the active ingredients provide strong antioxidative and anti-inflammatory effects, mediated via upregulation of antioxidative and anti-inflammatory enzymes and direct scavenging of reactive oxygen species. Thus, the integrity of the intestinal mucosa is strengthened by reduced cell turnover. Simultaneously, an improved gut morphology can be observed in piglets supplemented with Fresta^® F compared to a negative and a positive control group receiving colistin (fig. 1).

Figure 1: Villi height and crypt depth in jejunum samples of piglets supplemented with PFA (abp<0.05)

Intestinal permeability of nutrients depends on the activity of specific transporters. Increasing the activity of those transporters enhances the capacity of the intestine to absorb nutrients. It was shown that intestinal epithelium from piglets fed with the phytogenic product had increased glucose transport capacity (+28%) via the SGLT1 (sodium-glucose linked transporter) transporter compared to a control diet, measured by Ussing chambers (fig. 2). Improved performance is supported from different angles, as a healthy intestinal wall increases nutrient uptake.

Figure 2: Transcellular transport of glucose via SGLT1

Optimal feeding and management strategies after weaning are the key to success and long-term profitability in pig production. Factors that support and improve gut health, such as feed digestion, nutrient absorption, the balance of the intestinal microbiota, and the immune system, may have a far-reaching influence on further performance in a piglet's early life. The broad-spectrum effects exerted by PFA's can influence these mechanisms resulting in improved animal performance and thus more efficient animal production.

With proven beneficial characteristics, PFAs are foreseen to have the potential to become a new generation of substances for innovative swine nutrition and welfare.

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Article made possible through the contribution of Delacon

Current challenges in young animal nutrition