SPECIAL STORY FEED & ADDITIVE MAGAZINE September 2023 69 tive via nonlinear models (area under curve; AUC) (Graulet et al., 2005; Kihal et al., 2021), which is the accepted golden standard for nutritional models. The second study aimed to shed light on the current bioavailability of Kessent MF, sponsored by Kemin as a part of product innovation efforts. In dairy cattle, Lapierre et al. (2011) infused labeled HMBA [1-13C] and L[methyl-2H3] Met to the jugular vein (neck vein) to determine fate of HMBA via continuous samples from arterial portal, hepatic portal (central liver vein), and mammary veins. Evidence shows that the infused HMBA provided directly 15% of the Met required for milk protein secretion, with 0.2 mmol/h synthesized within the mammary gland. Among this 15%, about 33% originates from the metabolism that occurs in splanchnic tissues, 15% takes place in the mammary gland, and the remaining 52% comes from conversions happening in peripheral tissues. The remaining 85% of HMBA is indirectly metabolized, wherein Met synthesized from HMBA within tissues is utilized for intracellular protein synthesis. This process allows the Met released from protein breakdown to be exported and used by the mammary gland. In vitro, (McCollum et al., 2000) and ovine (Lobley et al., 2006) research showed that L-Met synthesis from HMBA occurs in many tissues of ruminants. It is similar to both D- and L- isomers of HMBA. L-HMBA oxidase exists predominantly in the liver and kidney; however, dehydrogenase of D-HMBA was available in most of the tissue (NRC, 2021). This data can be considered similar in terms of post-absorptive HMBi behaviours due to conversion to HMBA. The cow liver removed approximately 38% of the infused HMBA. However, this removed HMBA was not converted into Met in the liver, as there was a decrease in the net release of Met from the liver (Lapierre et al., 2011). The data mentioned above suggests that relying solely on plasma Met concenAmino acid nutrition is a game-changer for management of dairy sheep, lambs, and goats © Kemin Industries, Inc. and its group of companies 2023. All rights reserved. ® ™ Trademarks of Kemin Industries, Inc., U.S.A. Certain statements, product labeling and claims may differ by geography or as required by government requirements. Contact your local Kemin representative to find out more kemin.com/kessent
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