The liver is a very sensitive organ and so many of the problems observed in animals (such as decreased production and poor feed conversion ratio) originate from the liver being damaged. The liver performs important functions, including the production of bile, protein synthesis, detoxification, and storage of carbohydrates, vitamins, and minerals.
Pathways to and from the liver
When feed is digested in the stomach and intestines, chemicals and nutrients move into the animal’s blood. This blood is transported to the liver via the hepatic portal vein. All the blood that leaves the stomach and intestines will pass through the liver. Up to 13% of total blood in the body is in the liver at any given time. The blood is detoxified, which will filter out all the poisons, chemicals, and recyclable haemoglobin. Haemoglobin is processed in order to reuse and store iron.
Some substances in the blood (such as medicines) have to be metabolised in the liver into active molecules that can affect the animal beneficially. The liver will excrete harmful substances either through the urine or the faeces.
Bile produced by the liver helps with the digestion of fats. Bile is a fluid, with a clear yellow or orange colour, which is transported from the liver to the gallbladder from where it will be released into the small intestine. Bile aids with fat digestion through the process of emulsification.
Emulsification is the process where large fat globules are reduced to smaller fat globules, therefore increasing surface area, making these globules easier for digestive enzymes to access. Bile also assists with the absorption of cholesterol, fat, and fat-soluble vitamins. In addition, it acts as an alkaline liquid in the small intestine, which helps to neutralise the acidic pH of the digesta that exits the stomach.
Based on various resources, between 80% and 94% of animal feed can be contaminated by mycotoxins, so it is important to support the pig’s liver in order for it to remain healthy. Some of the mycotoxins that enter the gut will be metabolised, but the majority will pass through the intestinal barrier and impair the pig’s performance by affecting the kidneys, liver, and gut. These mycotoxins have a negative effect on the animal, such as reducing growth rate and causing immune suppression. Mycotoxin residues in the liver and muscles that enter the food chain can be hazardous to human health. To avoid additional stressors from toxins, it is important to consider
providing additional support to the animal to enable it to cope with the onslaught that mycotoxin contamination makes on the liver. Many natural solutions have been provided by nature, of which some have only recently become available for use in animal nutrition. These products have been shown to strengthen the liver, by supporting the liver in metabolising more mycotoxins or by detoxifying mycotoxins by binding them.
Having a universal mycotoxin risk management strategy is key to running a pig operation. Most mycotoxins are non-polar, meaning that they can easily pass through the intestinal barrier as they cannot be bound by traditional mycotoxin-binding strategies. There are more than a thousand different mycotoxin molecules that can act synergistically and most of them are non-polar. Mycotoxin binding should not be the only approach. A holistic approach, lowering mycotoxin load combined with supporting the pig’s own detoxification process is a more sustainable solution.
Various products, such as phytogenic plant substances, can be used to support the liver and help to improve this detoxification process. If liver function is improved, the liver will be better equipped to perform its other important functions as well.
For centuries, a phytogenic extract called silymarin has been used to protect the liver. Silymarin is extracted from fruits and seeds of the herb called milk thistle. It acts as an antioxidant that helps to protect the liver. Antioxidants maintain the oxidative– antioxidative balance. A disruption in the balance will lead to oxidative stress, which is a negative process in the liver that causes liver disease. Silymarin helps with detoxification by maintaining high levels of glutathione. Glutathione is produced by the liver and is made up of the amino acids glycine, cysteine, and glutamic acid. It directly scavenges compounds (such as free radicles) that can be toxic. By maintaining high glutathione levels, vitamin C and E recycling will remain efficient. These vitamins also act as antioxidants, thus silymarin has a sparing effect on these vitamins. Silymarin also helps to restore damaged liver cells.
Another natural product that can be used is an extract from artichoke (Cynara scolymus). This herb is rich in minerals and has low levels of fats and a high proportion of essential plant extracts (phenolics). It also contains antioxidants like vitamin C and carotenoids. Artichoke can be used as an anti-fungal and liver-protection product. An extract from artichoke has the ability to improve fat digestion, taking pressure off the liver by increasing the activity of the enzyme lipase and lipoprotein lipase, which help with the digestion of fat. These extracts also have a choleretic action, promoting bile production in the liver. Additionally, artichoke extracts stimulate metabolism.