title: The role of rumen-protected choline in hepatic function and performance of transition dairy cows.
abstract: High-producing dairy cows enter a period of negative energy balance during the first weeks of lactation. Energy intake is usually sufficient to cover the increase in energy requirements for fetal growth during the period before calving, but meeting the demand for energy is often difficult during the early stages of lactation. A catabolic state predominates during the transition period, leading to the mobilisation of energy reserves (NEFA and amino acids) that are utilised mainly by the liver and muscle. Increased uptake of mobilised NEFA by the liver, combined with the limited capacity of hepatocytes to either oxidise fatty acids for energy or to incorporate esterified fatty acids into VLDL results in fatty liver syndrome and ketosis. This metabolic disturbance can affect the general health, and it causes economic losses. Different nutritional strategies have been used to restrict negative effects associated with the energy challenge in transition cows. The provision of choline in the form of rumen-protected choline (RPC) can potentially improve liver function by increasing VLDL exportation from the liver. RPC increases gene expression of microsomal TAG transfer protein and APOB100 that are required for VLDL synthesis and secretion. Studies with RPC have looked at gene expression, metabolic hormones, metabolite profiles, milk production and postpartum reproduction. A reduction in liver fat and enhanced milk production has been observed with RPC supplementation. However, the effects of RPC on health and reproduction are equivocal, which could reflect the lack of sufficient dose-response studies.
authors.affiliation: 1School of Agriculture and Food Sciences,University of Queensland,Gatton campus,Gatton, QLD 4343,Australia.
authors.forename: Arash
authors.initials: A
authors.lastname: Shahsavari
authors.affiliation: 2School of Life and Environmental Sciences,Centre for Carbon, Water and Food, Faculty of Agriculture and Environment,The University of Sydney,380 Werombi Road,Camden,NSW 2570,Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: D'Occhio
authors.affiliation: 1School of Agriculture and Food Sciences,University of Queensland,Gatton campus,Gatton, QLD 4343,Australia.
authors.forename: Rafat
authors.initials: R
authors.lastname: Al Jassim
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D002794:Choline / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007774:Lactation / Q000502:physiology*; D008099:Liver / Q000187:drug effects*; D011247:Pregnancy; D012417:Rumen / Q000378:metabolism*
chemical_list: D002794:Choline
keywords: BCS body condition score; DMI DM intake; ER endoplasmic reticulum; FL fatty liver; Fatty liver syndrome; GH growth hormone; IGF-I insulin-like growth factor-I; Liver; MTTP microsomal TAG transfer protein; NEB negative energy balance; PC phosphatidylcholine; RPC rumen-protected choline; Rumen-protected choline; Transition dairy cows