ARTICLE FEED & ADDITIVE MAGAZINE September 2023 85 RESPONSES TO RPC EXTEND BEYOND THE PERIOD OF SUPPLEMENTATION Research conducted at the University of Florida, along with a recent study conducted by Barry Bradford at Michigan State University, has demonstrated that cows supplemented with RPC during the transition period exhibit heightened milk production during the supplementation phase, and this effect persists for several weeks after the supplementation period concludes10-12. In one experiment, cows were provided RPC from the close-up period until 21 days postpartum, resulting in a milk yield increase of 2,1 kg/day that continued for up to 40 weeks into lactation. In another separate experiment, an increase in milk yield of 2,0 kg/day was observed due to RPC supplementation, and this enhancement extended for 25 weeks into lactation. This phenomenon is consistent with observations from various dietary interventions introduced during the transition period, which tend to positively impact animal health and metabolism and subsequently extend their effects on production beyond the intervention period. However, the precise mechanism underlying this carry-over effect remains to be fully understood. Substantial progress has been made on our understanding of choline as a nutrient for dairy cows. The introduction of rumen-protected products containing choline chloride has facilitated research into various aspects of choline's mode of action within intermediary lipid metabolism in dairy cows. This advancement has also enabled the exploration of crucial questions regarding choline's role in maintaining hepatic health and enhancing productive performance during the critical transition period for cows. While the precise optimal dosage of choline to optimize both production and health in dairy cows is not yet definitively established, the existing data unequivocally demonstrate the positive impact of feeding choline ion through RPC, up to 25 g/day, during the transition period. This supplementation not only triggers lipotropic effects within the hepatic tissue but also exhibits tangible improvements in productive performance and health outcomes. These findings collectively provide compelling evidence that choline should be considered a required nutrient in the diet of transition dairy cows. References are available upon request. About José Eduardo P. Santos Dr. José E.P. Santos is a Professor in the Department of Animal Sciences at the University of Florida where he conducts research and extension in dairy cattle nutrition and reproduction. He earned his DVM degree from São Paulo State University in Brazil in 1992, completed the M.Sc. and Ph.D. degrees in 1995 and 1997 at the University of Arizona, and a clinical residency in Dairy Production Medicine in 2000 in the School of Veterinary Medicine at the University of California Davis. Before joining the University of Florida, José spent 8 years as a faculty member in the Department of Population Health and Reproduction in the School of Veterinary Medicine at the University of California Davis. About Usman Arshad Usman Arshad is from Pakistan and received his Doctor of Veterinary Medicine degree (2010-2015) from University of Veterinary and Animal Sciences (UVAS), Lahore. Usman completed his masters (M. Phil Theriogenology; 2015-2017) from UVAS and Ph.D. (Animal Molecular and Cell Biology; 2018-2023) from University of Florida with a major concentration in Dairy Cattle Nutrition and Reproduction. He has recently joined Dr. Heather White’s Lab at University of Wisconsin-Madison as a Post-Doctoral Research Associate. Usman is passionate about transition cow management and exploring molecular and cellular pathways related to hepatic tissue metabolism and feed efficiency in dairy cows. Usman has a longstanding interest in data analysis, especially conducting meta-analysis that benefits the dairy industry and facilitates dairy farmers in decision-making. During his post-doctoral training, Usman intends to gain additional experience in analysis of fatty acid composition, Western blots, flow cytometry, and use of cell culture models to elucidate intermediary metabolism in dairy cows.
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