Can rye or rye bran in pig feed reduce salmonellosis pressure

A team of German scientists (Institute for Animal Nutrition of the University of Veterinary Medicine, Institute for Environmental Technology and Energy Economics of the Hamburg University of Technology, KWS Lochow GmbH) is studying rye in pig feed. The researchers described their recent findings in an article published in Animals 2023, on the MDPI portal: “In 2021, 60,050 cases of salmonellosis were reported in the EU . In Germany, according to the Robert Koch Institute, salmonellosis is the second most common bacterial gastrointestinal disease.

Because salmonellosis is a classic foodborne infection, several measures have been taken to combat it. For example, in Germany, pig farms are required to test their pig animals for salmonella at the slaughterhouse according to a sampling key.

Salmonella antibody results allow farms to be classified into three categories: I (≤20% positive samples), Category II (>20% and ≤40% positive samples) or Category III (>40% positive samples). 

In the case of category III, the farmer , together with the supervising veterinarian, must take measures to reduce the prevalence of Salmonella on the farm. 

Measures include key points (cleaning and disinfection, rodent control and reduction of possible entry points, vaccination ), as well as other approaches in addition to strengthening biosecurity measures. This is a coarser structure of the feed or a decrease in the pH in the feed, useful feed additives. 

Rye has many advantages when grown in dry and nutrient-poor soils. Breeders also made modern rye less susceptible to ergot alkaloids, allowing it to be used again in animal breeding.

Rye is a valuable cereal in terms of sustainability. Compound feeds high in rye combined with regional protein sources have been shown to result in a lower carbon footprint while maintaining the same performance.

Despite the similarity to feeding wheat, a diet rich in rye has a positive effect on the physicochemical properties of the digestive tract of pigs.

Rye leads to a longer feeling of satiety in animals due to increased viscosity and delayed gastric emptying. This is important when feeding, for example, pregnant sows.

Of particular interest is the high content of non-starch polysaccharides (NSP) in rye. These NSPs are not digested in the animal's small intestine and are therefore degraded by microorganisms in the large intestine. The process leads to an increased formation of SCFA (short chain fatty acids) - butyrate. Butyrate as a SALT or ester of butyric acid has various effects on the intestines. On the one hand, it serves as an energy supplier for colon cells and protects the intestinal epithelium, and on the other hand, it reduces inflammatory reactions and has bacteriostatic properties. Especially the last mentioned property can be used to combat Salmonella.

It should be noted that the food industry offers high quality components with high economic value. Since bran makes up about 10-15% of the weight of the grain, a lot of waste is generated during the grinding process. Rye bran is rich in dietary fiber, vitamins, minerals and other biologically active substances.

There is a study according to which feeding with rye leads to a significant reduction of salmonellosis pathogens in the faeces of young pigs. Accordingly, the purpose of this work was to test whether the positive aspects of rye or rye bran really work in real-life conditions in growing piglets and whether they lead to a reduction in salmonella excretion .

Latently infected animals are of great importance for the introduction and spread of Salmonella in swine herds. Thus, Salmonella control measures should not be limited to individual animals, but should cover the entire herd. Since Salmonella is present throughout the entire production chain, from piglets to fattening pigs, the reduction should start already with piglet producers. For example, the purchase of piglets in particular is a risk factor for salmonella entry into the farm, and there is great potential for improvement during quarantine or integration of piglets into the main herd. 

The study was conducted on three pig farms (A, B and C) in northern Germany from January 2021 to May 2023. Participation was voluntary due to recurrent salmonella infections. The farms had different numbers of livestock (A: 1000, B: 230, C: 1850).

The first part of the study was conducted between January 2021 and July 2022 and focused on the impact of rye on the prevalence of salmonella. The second part ran from March 2022 to May 2023 and was dedicated to rye bran as an ingredient in compound feed. Since different age groups of pigs have different nutritional requirements, a different diet has been developed for each age group. The form of the diet differed depending on the farm. Farms A and B feed as FLOUR, while farm C uses liquid feed. Depending on the age in the experimental group, 20 to 30% rye or 15 to 20% rye bran was used.

According to the results of this study, it is difficult to form an unambiguous opinion about the effect of rye bran on Salmonella, although in some groups with rye top dressing, antibody titers were significantly lower than in the control groups. However, the effect itself could not be clearly attributed to the effect of rye or rye bran, so further research and testing is required. 

However, rye supplements did not show any negative effects, which is also important. Rye, and rye bran in particular, provides an opportunity to replace other expensive coarse grains, which is an economic incentive in addition to the potential beneficial effects on animal HEALTH .”