Natural alternatives to antibiotics in cows: how garlic extracts keep the udder healthy

Garlic extracts as a natural alternative to antibiotics in cows?

Dairy cow's milk production is determined to a large extent by the healthiness of the udders. Therefore, dairy farmers must pay the necessary attention to keeping "the production facilities" healthy to prevent subclinical or clinical mastitis. It is generally accepted that subclinical mastitis occurs when the somatic cell count is over 200 000, even without symptoms [1].

The damage caused by mastitis is not small. The average cost of clinical mastitis varies between studies. In the USA the average cost of a case of clinical mastitis in the first 30 days in lactation is a whopping 444 euros [2]. In The Netherlands, the economic losses of a clinical case were calculated as 210 euros [3]. A Swedish study looked at both clinical and subclinical mastitis. The cost of clinical mastitis was 275 euros per case, while the cost of subclinical mastitis averaged on 60 euros per case [4]. Although the cost of a case of subclinical mastitis is lower, we should not forget that subclinical mastitis is much more common. Subclinical mastitis has a hidden cost.

The use of antibiotics in cows to prevent infectious diseases has led to a wide range of antibiotic-resistant bacteria. The call for natural alternatives to antibiotics is more present than ever. The evidence is growing that natural compounds with antibacterial properties could be considered an alternative to known antibiotics in cows [5]. Our boluses Mammitop and Mammitop Clinic are complementary feeds designed to keep the udder healthy. One of their most important active ingredients is garlic extracts. Garlic extracts have been found to be effective against antibiotic-resistant bacteria, but not all products are the same [6]. In this article, we focus on the impact of garlic extracts on udder health.

Udder health and somatic cell count

The somatic cell count (SCC) in the milk is an indicator of udder health. Somatic cells are white blood cells (leukocytes) that fight infection and repair tissue damage. When the udder is infected, these white blood cells move to the udder and into the milk to defend the cow against the invading bacteria [7] As we will see later, the SCC is decreased by garlic’s allicin, because it possesses antimicrobial activity.

An example of an udder infection can be seen in figure 1. The Staphylococcus aureus bacteria interact with the cow’s mammary gland cells. Toxins produced by the bacteria, lead to cell injury and eventually cell death. As a reaction Staphylococcal superantigens activate white blood cells resulting in inflammation [8].

Figure 1: Pathogenesis of Staphylococcus aureus of bovine origin [8].

Allicin: the hidden healer

Allicin is a compound found in garlic and is responsible for the poignant smell and taste of crushed garlic. Obviously, it is not this aromatic characteristic that is interesting to us. Garlic is known throughout human history as beneficial to our health and was used as a medicine for thousands of years by the Egyptians, Babylonians, Chinese, Vikings, Indians, and Romans [9]. Even the great Greek physician, Hippocrates, described the usage of garlic to treat pneumonia and heal wounds [10]. However, it was not until 1944 that the reason behind the benefits of garlic was discovered. Cavallito and Bailey [11] were the first to isolate and describe the properties of allicin. The reason behind this late discovery is simple: there is no allicin in garlic. Allicin is only produced when the garlic is under attack: it is the garlic’s defense mechanism. Allicin is the result of another garlic compound alliin reacting with the enzyme alliinase. Alliin and alliinase are stored separately in the garlic cloves. It’s only when the garlic is damaged (by cutting, crushing,…) that these two come in contact to create the defense mechanism allicin [12].

Figure 2: alliin reacting with the enzyme alliinase creating allicin [13]

Not all allicin is the same

The big problem however with allicin is its instability. The allicin that is created is gone in mere seconds. It remains active only for a short period before degrading. The reason for this is found in its purpose as a defense mechanism. Allicin is very effective in defending garlic against attackers such as fungi and other pathogens: a local outburst of allicin is enough to kill unwanted intruders. I bet you never thought of garlic as such a violent species. This very short active period is needed because the allicin would otherwise keep reacting with everything around it, which would eventually destruct the garlic itself [9].

So if allicin is this short-lived, how does it improve our health? Allicin is indeed unstable, but it transforms in lots of other components. After allicin has degraded, it creates about 200 other compounds. Of these 200 compounds, some have interesting qualities and other, rather useless. Moreover, only a few stay active long enough to be beneficial to our health. So, allicin can be seen as the mother molecule, producing a big range of other compounds [9]. This is the reason why we don’t use allicin in our products, and also the reason why you should be careful when evaluating products that use allicin. It is difficult to predict which compounds will be formed after the allicin degrades, and thus difficult to predict the effect of an “allicin supplement”. The question now is: which allicin-derived compound do we have to use?

Stable compounds

Studies have shown that the strength of allicin supplements varies greatly. Therefore, Mammitop and Mammitop Clinic don’t use allicin as an active ingredient but a number of organosulfur compounds that stand out because of their stability, even at higher temperatures. This makes them great to use in animal feed [5].

Moreover, products like Mammitop do not need to be stored at cold temperatures (2 to 8 °C) as is the case for many other ‘garlic’ or ‘allicin’ products. The antibiotic activity of these compounds was also demonstrated in vitro and in vivo against multidrug-resistant bacteria, both gram-positive and -negative, and in multiple animal species. They have strong antibacterial and antiseptic effects against a broad spectrum of bacteria. Including the most widespread causes of mastitis such as Staphylococcus aureus, Streptococcus uberis or Escherichia coli. While the precise mechanism of action is not yet known, the main antibacterial effect of thiosulfinates (as allicin) has been studied. In the next section, we discuss these mechanisms [14].

Working mechanism

So, how do these compounds keep the udders healthy? Their antimicrobial activity can be explained by two principal features. Firstly, they are able to reach the target, namely the inside of the bacteria that cause damage. They are able to get inside the microbial cell by diffusing across cell membranes. In other words: the organosulfur compounds are capable of getting through the ‘holes’ in the cell membrane, reaching the inside of the bacteria’s cells.

Secondly, they have a target that, if attacked, leads to cell inactivity or cell death. In this case, the thiosulfinate-group obstructs the enzymes of bacteria by reacting with the sulfhydryl-group of cysteine (figure 3) via a disulfide exchange-like reaction (figure 4) [15]. Enzymes are crucial to cell activity because they ultimately control which chemical reactions a cell can perform and at what rate. Enzymes are involved in the synthesis of nucleic acids and cell wall, which are necessary for the cell to function [16].

Our chosen compounds react with every cysteine residue as long as the –SH-group is freely available [15]. In short: the allicine-compounds in Mammitop (Clinic) are able to enter the bacteria’s cells, where they attack the important enzymes, eventually deactivating or ultimately killing the bacteria. Fewer bacteria lead to a healthier udder.

Figure 3: Cysteine

Figure 4: “The cysteine residue that is accessible for attack (indicated in red) reacts with the thiosulfinate-group of allicin via a disulfide exchange-reaction. The cysteine residue that is sterically blocked (indicated in blue) does not react with the thiosulfinate-group allicin.” [15]

Harmless for cattle

Mammals have far fewer proteins with SH groups than pathogens. Therefore, in cattle, glutathione protects thiol groups from damage. Microorganisms that are sensitive to allicin are unable to develop resistance to allicin due to allicin's deeply penetrating mechanism of action [17].

Boluses to improve udder health

Mammitop and Mammitop Clinic are two boluses with garlic extracts designed to improve the udder health in dairy cows. The results of the boluses are guaranteed as the product is stable and the quantities of active components are under control. To read more about these natural alternatives to antibiotics in cows, please visit the product pages.

Source list Natural alternatives to antibiotics in cows: how garlic extracts keep the udder healthy

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