Protecting your pigs and your profits with liquid feed

27 November 2020

As mentioned in a previous blog post “Liquid Feed: the positives, the challenges and how we can help”, liquid feeding is an attractive and sustainable prospect for many pig producers as it makes full use of the feed-to-food chain, allows them flexibility over the content of their diets, and to take advantage of locally available and cost effective co-products. However, co-products are only truly cost effective if their nutrient content is maintained. Otherwise, an investment could end up costing more in terms of production losses than it saves.

Yeast is one of the main culprits for losses of the nutritional content in co-products, and can be a complex issue to solve. High yeast content in the initial co-product prevents proper colonisation by lactobacillus bacteria (bacteria shown to produce beneficial effects for the animal when they ferment the carbohydrates in the diet). This causes an overgrowth of harmful microbes which convert starches and sugars into carbon dioxide, leading to nutrient loss. Studies have shown that dry matter losses range between 2% and 40%, alongside losses in important amino acids such as lysine. Crystalline amino acids are routinely added to diets in order to lower crude protein and achieve their ideal ratios to lysine. These added amino acids are particularly suitable to degradation through fermentation. This can have serious consequences to growth and feed conversion. Fermentation can also result in palatability issues that can supress feed intake. Carbon dioxide gas produced by the yeast is present in pipelines, the wet feed itself and the stomach/intestinal tract of the animals. It can lead to intake problems due to taste and smell deviation and gas production in the intestines causing discomfort. All of this can lead to an increase in FCR and a decrease in overall animal health and wellbeing. In severe cases it can lead to additional health issues such as increased susceptibility to Clostridium infection, prolapses and intestinal torsion.

Acidification is a commonly used technique to control microbes, but how can you be sure you are using the most effective products?

 Figure 1. shows the pH at which different microorganisms are able to survive. It demonstrates that while pH reduction alone may prevent the growth of pathogenic bacteria such as E. Coli and Salmonella, it will not prevent the growth of yeast. The key is the type of product you use. Organic acids contain a carbon atom which is recognised as a potential energy source by yeast cells, and so are able to enter the cells and disrupt their functions, eventually causing death.

Inorganic acids which do not possess a carbon atom are unable to achieve this. Surfactants and cell wall destabilisers can enhance the ability of the organic acids to enter both bacterial and yeast cells.  Medium Chain Fatty Acids (MCFA) have a similar effect as well as providing a broader spectrum antimicrobial effect against gram positive bacteria. They can also be beneficial in helping to combat certain yeast species which are more difficult to control. The best way forward is to choose products that have been specifically formulated for use in the feedstuff or by-product concerned.

Selko has a range of different products, such as Revalet and BE+, designed to help maintain the nutritional quality of liquid feed, and the various by-products used to produce it. These products can also be used to maintain tank, silo and pipe hygiene to help keep the issue under control long term. Alongside this, Trouw Nutrition offers microbial testing to ensure that the correct product is used to ensure maximum effectiveness. Bespoke dosing solutions are also available to achieve the most effective and cost efficient dosing.


Dr. Sophie Prentice                                                                                                                                                                                                       Monogastric Feed Additive Product Manager