Phytogenic Compounds in Ruminant Nutrition
Phytogenic products are the result of distillation and concentration of compounds found in herbs and other plants that most people commonly know. As such, many discount the potential efficacy of products as being “voo-doo science”. The reality is that many medicinal compounds we are familiar with today came natural sources, perhaps the best known is penicillin. Additionally commercial products have concentrated the efficacious compounds that would be unavailable from the consumption of the raw foodstuffs.
In their concentrated forms, these active ingredients can have profound activities in a number of area including antimicrobial, anti-inflammatory, antioxidant, and other activities depending on compound. One of the difficulties with new technologies is the realization that not all phytogenic products are either formulated the same or the quality of the raw ingredients are the same. Distillation processes can have different efficiencies in concentrating key compounds and differing raw ingredients may have differing concentration of these same compounds. It is important that any product have a strong Quality Control (QC) program behind it to insure both consistency and efficacy.
Given the wide variety of actions from phytogenic compounds, it is important to know what effects are expected in helping to determine the best opportunities for improved animal performance. With ruminant nutrition, there are two major considerations: 1) how do products effect rumen fermentation through selection of bacterial species; perhaps stimulating some and decreasing others, 2) How do the products effect lower gut health in terms of both integrity and efficiency.
Cattle production has come under pressure due to concerns regarding the production of greenhouse gases. Much effort has gone into developing photogenic products that can reduce methane generation and increasing propionate to acetate ratios. Positive goals, but there can also be negative consequences. Sometimes there is a concomitant decrease in microbial protein that can result in both less and a poorer amino acid balance reaching the abomasum. To date there have been both success and failures, and more work needs to be done into fine-tuning products or identifying appropriate rumen conditions for use.
Having, or not having, a rumen effect does not preclude significant effects in the lower gut. There is published work showing phytogenic compounds having significant rumen bypass. In fact, many phytogenic compounds may have greater bypass value than “conventionally calculated”. Many phytogenic compounds exhibit their anti-microbial activity by entering the microbial cell wall and increasing permeability to hydrogen ions entering the cell. As these cells also pass down the GI tract, they are digested and the active phytogenic compounds may be rereleased where they can have an active effect in the lower gut.
Alternatives to antibiotics
Phytogenic products have been proposed as a potential replacement or supplement to antibiotics feed as growth promotants. Along these lines, it must be remembered that antibiotics effects on growth are as much or mostly due to their anti-inflammatory actions rather than their antimicrobial actions. As such, phytogenic products are well positioned to be effective feed additives. Thymol and eurgenol are well documented to exhibit anti-inflammatory effects in other species.
In addition to their potential to replace or supplement antibiotics, phytogenic compounds may actually potentiate or increase the effectiveness of antibiotics. In vitro studies have shown that both antibiotics and phytogenic compounds may have similar antimicrobial properties against specific compounds but combining the products has a much greater effect than either product separately. Could we reduce either or both the amount and the amount of time antibiotics are fed? Could this improve our ability to reduce specific pathogens known to cause specific problems such as F. necrophorum associated with liver abscesses common to both feedlot cattle and dairy cattle.
Perhaps the greatest effects of phytogenics are their anti-inflammatory and anti-oxidant properties. By reducing the inflammatory cost and oxidant cost typically associated with the digestive tract, even without clinical problems, phytogenic products can improve an animal’s ability to produce (milk or growth) by freeing up nutrients, in particular energy and amino acids. Dairy cattle receiving phytogenic products have had greater milk volume production and increased milk protein in earl lactation. Both these observations are consistent with improved energy balance. Decreased glucose needed for maintenance increases that available for the production of lactose, which is highly tied to milk volume. Increased milk protein may indicate that less protein was needed to produce lactose (via gluconeogenesis), freeing it for use in production of milk protein. Phytogenics used in dry cow rations have resulted in increased plasma amino acid content.
Gut integrity is an area of animal health that continues to receive additional interest and study. Gut integrity and the prevention of “leaky gut” can have a profound effect on animal performance. With leaky gut, you have the potential for proteins to enter the lumen of the intestine, resulting in a “bloom” of pathogenic bacteria such as clostridia, which can in turn produce toxins adding injury to the digestive tract. With leaky gut the cells in the villi must expend more energy to absorb nutrients resulting in reduced efficiency. Additionally leaky gut can allow greater absorption of pathogenic bacteria, lipopolysaccharides (LPS) and toxins including mycotoxins in the feed. Absorption of these compounds can also result in fevers and reduced feed intake both of which negatively affect production. Direct evidence in cattle is limited as such experiment can be difficult and expensive, however work in other species indicate the key phytogenics can assist in reducing or reducing the effect of leaky gut.
Leaky gut is also part of the problem cattle encounter with heat stress. Phytogenic products have the potential to assist in cattle undergoing heat stress. From a direct standpoint, capsicum has been used to help cattle keep cooler by increasing vasodilation. However, other phytogenic products may work through reducing heat stress by reducing the leaky gut issue. Through two completely different modes of action, phytogenic products have the potential to reduce heat stress in cattle.
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