Effects of choline on transition dairy cows

Effects of choline on transition dairy cows - Effects of...

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Effects of Choline on Transition Dairy Cows Katharine James 2/27/2008
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Effects of Choline on Transition Dairy Cows Choline is a quasi-vitamin and important nutrient for all animals. It is required for maintaining health and when methyl precursors are absent in the diet. Choline has several functions in a mammal. It is a component of the neurotransmitter acetylcholine, a direct precursor of betaine in methyl metabolism, and a component of prevailing phospholipids contained in membranes of cells in the body known as phosphatidylcholine. This paper will focus on the latter. Choline is being studied as an important factor for transition cows. The objective of this paper is to determine if phosphatidylcholine could prevent fatty liver and even increase milk production. Some species, including the dairy cow, are able to synthesize phosphatidylcholine (PC) through two different paths. One being the tri-methylation of phosphatidylethanolamine, which is originally synthesized from serine, with S- adenosylmethionine, and the other being the activation of cytadine diphosphate-choline and addition of a 1,2-diglyceride (Piepenbrink et al., 2003; Cooke et al., 2007). The synthesis of phosphatidylcholine stimulates the hepatic synthesis and secretion of very low density lipoproteins (VLDL). VLDL are protein transporters for triglycerides, including triacylglycerol (TAG), from the liver to the blood (Cooke et al., 2007). Dairy cows in the transition period have high requirements for energy, glucose, and amino acids (AA) to support lactation (Overton et al., 2004). Because of depressed feed intake and endocrine changes that occur during the periparturient period and early lactation, adipose tissue releases nonesterified fatty acids (NEFA) into the blood. The liver uptake of NEFA from the blood is proportional to its supply regardless of other tissues’ needs for energy or for milk fat. The hepatic capacity for fatty acid oxidation and
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VLDL export is not able to support the abundant supply of NEFA and can lead to lipidosis or fatty liver (Piepenbrink et al., 2003). Because PC stimulates the hepatic synthesis and secretion of VLDL, there is speculation that an increase in choline can increase the export of TAG decreasing the occurrence of fatty liver (Cooke et al., 2007). Triglyceride accretion in the liver can decrease the capacity for detoxification of ammonia to urea and therefore affect the capacity for gluconeogenesis from propionate (Piepenbrink et al., 2003). The depletion of glucose from the lack of gluconeogenesis will decrease lactose synthesis from
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This note was uploaded on 03/26/2008 for the course ANS ANS 483 taught by Professor Beede during the Spring '08 term at Michigan State University.

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Effects of choline on transition dairy cows - Effects of...

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