ARTICLE 82 FEED & ADDITIVE MAGAZINE September 2023 Indeed, models involving feed restriction have been utilized to replicate disturbances within the intestinal tract that mirror the naturally occurring decline in dry matter intake during the transitional phase. In a recent study conducted at the University of Florida, the impact of RPC supplementation on the digestibility of fat in dairy cows was investigated6. For this experiment, 33 prepartum Holstein cows were subjected to a feed restriction regimen aimed at disrupting intestinal integrity. These cows were divided into two groups, with one group receiving 0 g/day of choline ion and the other group receiving 25,8 g/day of choline ion supplementation for a duration of 9 days during the feed restriction period. On the ninth day, the cows were deprived of feed and were instead given a mixture of saturated fatty acids to assess the apparent digestibility of fat. Supra-mammary lymph samples were collected 6 hours after the cows consumed the fatty acids. The results indicated that providing RPC led to an increase in fat digestibility and the concentrations of triacylglycerol in both blood and lymph. This suggests that supplementing choline to cows experiencing a negative nutrient balance could potentially enhance the transport and absorption of fatty acids within the intestines. SUPPLEMENTING RPC BENEFITS PRODUCTIVE PERFORMANCE AND HEALTH While a wealth of literature exists detailing the various cellular mechanisms influenced by choline, a recurring question arises: Can its impact on phospholipid synthesis, liver function, or nutrient transport translate into improved health and productivity outcomes? However, experiments where interventions are applied to individual cows via diet and require careful feeding often face the challenge of limited sample sizes, which can restrict the ability to thoroughly investigate the effects of dietary changes on health and reproduction. To circumvent this limitation and ensure the broader applicability of interventions, researchers employ meta-analytical techniques that integrate findings from multiple published studies. In 2020, a systematic review of the available literature was conducted, followed by a comprehensive meta-analysis examining the effects of supplemental RPC during the transition period8. This analysis encompassed 20 publications, incorporating 21 experiments involving a total of 1.313 transition cows. These cows were randomly assigned to receive either 0 g/day of choline ion or varying amounts of choline ion via RPC starting before calving.
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