ISSUE FOCUS FEED & ADDITIVE MAGAZINE February 2024 45 valine) contained in high RDP feedstuffs, such as soybean, rapeseed, cottonseed or sunflower meals, are degraded in the rumen. The BCVFAs are then utilized by both amylolytic and fiber-digesting bacteria to produce microbial protein. BCVFAs act as carbon sources to be utilized with highly digestible protein (NPN) to produce the much-needed microbial protein and energy for production of milk by the mammary gland. When the cow produces higher levels of BCVFAs, both the fibrolytic and amylolytic bacteria respond by increasing digestion of both fibrous and non-fibrous carbohydrate feed components. This increases the microbial efficiency of producing energy and protein. This process is illustrated by the left-hand side of the rumen in Figure 1. Note, oftentimes this process will only partially meet the cow’s requirements for branched-chain volatile fatty acids. DIETARY CONDITIONS AFFECTING BCVFA PRODUCTION Under certain dietary conditions there may not be enough BCVFAs produced to meet the requirements of the rumen microbiome and specifically the fiber-digesting bacteria. These dietary conditions can include: • Lower protein diets, where RDP is limited and results in reduction of BCVFAs. • Short chop length, wet ingredients and/or insufficient starch and sugar. These can all limit proteolysis due to low rumen residence time or a smaller microbial pool. • Highly fermentable diets, which may create a large pool of starch and sugar digesters with the potential to outcompete fiber digesters for BCVFAs. An insufficient supply of BCVFAs is problematic as fiber-digesting bacteria not only use BCVFAs to synthesize microbial protein but they are also key to the formation of branched-chain long-chain fatty acids utilized in their cellular membranes. These fatty acids help give the bacteria cellular fluidity and are essential to their survival within the harsh rumen environment. A NEW LEVEL OF PERFORMANCE AND PRODUCTIVITY An alternative pathway to meet dairy cattle BCVFA* requirements Energy-corrected milk Dry matter intake Energy balance Feed e ciency Protect performance during heat stress Starch Digesters Sugar Digesters Fiber Digesters Zinpro IsoFerm is a fit when: POTENTIAL BENEFITS WHEN ZINPRO ISOFERM FULFILLS BCVFA REQUIREMENTS: 1True RDP = RDP minus ammonia N fraction. 2Short chop length, wet ingredients, insu cient starch and/or sugar limit proteolysis. 3Highly fermentable diets are defined as high corn silage, high grass silage and/or high starch or sugar. Microbial Protein & Energy Increased with Zinpro® IsoFerm® True RDP is Limited1 Fast Passage Rates2 Limit Proteolysis Feeding Highly Fermentable Diets3 *Branched-chain volatile fatty acids, also known as isoacids True Rumen Degradable Protein (RDP) BCVFAs Protein Breakdown (proteolysis) Directly and precisely feeding fiber-digesting bacteria, skipping steps and making the process more e cient, thereby increasing fiber digestibility Microbial Protein Formation (coupling of BCVFA + ammonia N + CO2) Individual Amino Acids Further Breakdown (removal of ammonia & CO2 from amino acids) PARTIALLY MEETS BCVFA REQUIREMENTS FULLY MEETS BCVFA REQUIREMENTS Also Proteolytic RDP Figure 1
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