ARTICLE 60 FEED & ADDITIVE MAGAZINE May 2025 Within the rumen, the digestion of proteins results in the production of peptides - peptides are further hydrolyzed to amino acids, some of which are deaminated, producing ammonia. Peptides, amino acids, and ammonia all individually serve as sources of N for various microbes. However, problems can occur when there is a high level of RDP present which can accumulate in the rumen. Energy is then needed to excrete excess nitrogen, rather than using energy for milk production. Feeding the cow a specific blend of essential oils— such as NOVATAN—increases protein use and reduces ammonia emissions. It improves protein efficiency and rebalances protein partitioning—with more bypass and less RDP. Therefore, the cow can utilise protein that would otherwise be wasted and which would be having a negative effect on the cow and on the environment. Fats and oils Fats and oils are concentrated sources of energy to the dairy cow where the majority of it is digested in the small intestine. The type and level of fat in the diet influences the milk fat content and fatty acid profile. Also feeding a lot of unsaturated fatty acids can be toxic to rumen bacteria, slow fiber digestion, and lower rumen pH which will negatively impact feed efficiency. RUMEN HEALTH Subacute Ruminal Acidosis (SARA) The rumen should ideally be at pH 6-7. Throughout the day there will be periods when the pH drops below pH 6, but it is for how long it stays below pH 6 that has a negative impact and this is when subacute ruminal acidosis (SARA) occurs. SARA in dairy cows is a common metabolic disease characterised by a prolonged, but not severe, decrease in rumen pH. The decrease in rumen pH can be caused by diets high in readily fermentable carbohydrates and low in fiber. SARA is associated with decreased fiber degradation, decreased acetate to propionate ratio, and decreased CH4 formation, which can reduce feed intake, milk yields and milk fat. Not only that but it can cause ‘leaky gut’ where the gut wall is compromised and will reduce the efficiency of nutrient absorption and increase the risk of unwanted bacteria and toxins getting into the blood. When bacteria or toxins are absorbed into the blood, this initiates an immune response, which is an energy cost to the animal. To assess the degree of safety regarding the risk of SARA, a rumen indicator was integrated into the data management tool EASY MAP, considering several parameters such as fat/protein ratio, fat equivalent lactation and fat drop.
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