ISSUE FOCUS 48 FEED & ADDITIVE MAGAZINE March 2022 Therefore, we can note that the level of LPS (endotoxins) present in the rumen is directly correlated with the pH of the rumen itself and with a symptomatologic picture dating back to SARA. This occurs when the mortality and lysis of Gram- bacteria (GNB) is high and through the consequent imbalance created with diets containing excess fermentable starches, compared to diets with higher fiber content. In fact, it was shown that the transition from a concentrated fodder ratio of 60:40 to a more stringent ratio of 40:60 caused the level of free LPS in the rumen to go from 410 to 4.310 EU / ml. ENDOTOXEMIA: PATHOLOGICAL CONSEQUENCES IN DAIRY COWS Once the LPS enter the bloodstream, they are transported to the liver (or other organs) for detoxification. However, sometimes this is not enough to neutralize all the endotoxins present in the blood. The remaining excess can cause issues such as the modification of the body's homeostasis or cause that cascade of inflammatory cytokines responsible for the most common pathologies typical in cows in the first phase of lactation. The most common symptoms are the increase of somatic cells in milk or claws inflammation. Pro-inflammatory cytokines as TNF, IL6, and IL8 induced by LPS-related inflammation are able to stimulate the production of ACTH (adrenocorticotropic hormone). Together with cortisol and the interleukins, ACTH inhibits the production of GnRH and LH, with severe effects on milk production. The productivity and the fertility of the animal are thus compromised. Moreover, prostaglandins are also stimulated by LPS and are linked with fever, anorexia, and ruminal stasis. This not only limits the amount of energy available for production and maintenance functions, but also induces a higher susceptibility to disease and adds up to the emergence of other metabolic conditions, such as laminitis and mastitis. PREVENTING RUMEN ACIDOSIS The solution to these massive risks is a prudent and proactive approach by the nutritionist towards all situations that can cause a rapid increase of Gram- in the rumen. Therefore, it is necessary to avoid cases of clinical and sub-clinical acidosis (SARA) to prevent the issues listed above. This would also help avoid stressful conditions for the animal that would lead to decreased performance and health. To maintain balance and a healthy status of the animal, the use of additives such as phytomolecules and binders is suggested in the first phase of lactation, starting from 15 days before giving birth. Activo Premium (a mix of phytogenic substances) has given excellent results in decreasing the acetic/ propionic acid ratio, while safeguarding the population of Gram+ bacteria. This is in contrast to treatments with ionophores, which, as is well known, interfere with the Gram+ population. CASE STUDY. ACETIC ACID: PROPIONIC ACID RATIO WITH ACTIVO PREMIUM In a study conducted at the University of Lavras and the Agricultural Research Comp. of Minas Gerais (both Brazil), 30 Holstein cows were allocated to two groups considering parity and milk production. One group was fed the standard feed (control), the other group received standard feed containing 150mg of Phytogenics/kg of dietary dry mass (DM). The following parameters were measured or calculated: intake of DM and milk production, milk ingredients such as fat, protein, lactose every week, body weight and body condition score every two weeks, and ruminal constituents (pH and SCFAs) through oesophageal samples at day 56. Phytogenics was able to decrease the ratio between acetic acid and propionic acid, and at the same time maintain the level of Gram+ bacteria in the rumen, thus reducing the risk of endotoxins. The same trial carried out at the University of Lavras demonstrated how the performance of the animals was superior in the group fed with Phytogenics compared to the control group (see next page).
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