The effect of an alternative to synthetic choline on growth response, hepatic gene regulation and adiponectin expression in broilers

DIMA WHITE, STEVE LEESON and WOO KYUN KIM* report that a herbal feed supplement, consisting of natural and organic choline in conjugated form (phosphatidyl choline) along with certain phospholipids can successfully and economically replace choline chloride at lower inclusion levels and provide additional beneficial effects in poultry.

Choline, a water-soluble vitamin, is important for the metabolomic functions, physiological responses, optimum growth and modulation of the lipid metabolism in the liver and body of broiler chickens. Under choline deficiency conditions, lipogenesis increases in the body, resulting in increase in the liver fat and abdominal fat contents. This can cause fatty liver syndrome. Moreover, choline supports dietary energy digestion and utilization in the body and is a major component of membrane phospholipids, involved in lipid liver metabolism, prevention of liver fat accumulation and acetylcholine synthesis.
Synthetic choline is a beta-hydroxyethyltrimethylammonium hydroxide. Pure choline is a colorless, viscous, strongly alkaline liquid that is notably hygroscopic, corrosive, incompatible with vitamin premix and results in trimethylamine (TMA) formation. Choline is absorbed in the jejunum and ileum mainly by an energy and sodium dependent carrier mechanism. Only one-third of ingested choline in monogastric diets appears to be absorbed intact. Absorbed choline is transported into the lymphatic circulation primarily in the form of phosphatidyl choline bound to chylomicra; it is transported to the tissues predominantly as phospholipids associated with the plasma lipoproteins.

For prevention of fatty liver syndrome, choline chloride has to be transformed into phosphatidylcholine in the physiological system as phosphatidyl choline is required for the synthesis and secretion of lipoproteins such as very low-density lipoproteins (VLDL) which are the primary carriers of lipids in the blood. VLDL are important molecules necessary to avoid fat accumulation in the liver and thus prevent the severity and incidence of fatty liver.

BioCholine (M/S by Indian Herbs Specialties Ltd.) does not need intermediate steps and is readily available source of not only phosphatidylcholine but also certain other phospholipids, PUFA and phytoactive conjugates that bind with nuclear peroxisome proliferator-activated receptor (PPAR) receptors in the liver and activate them.  PPAR receptor is known as the master regulator of adipocyte differentiation, plays an important role in lipid metabolism and glucose homeostasis and adipogenesis in liver.  Upon activation, PPAR induces release of hormone adiponectin.  Adiponectin is an adipokine and protein hormone that influences several metabolic functions including glucose and lipid metabolism, glucose utilization and lipogenesis.  It is reported that adiponectin has a direct effect on regulating metabolic pathways in the liver thereby improving nutrient utilization and body weight gain.

A study was organized at Department of Poultry Science, University of Georgia, USA to establish mode of action of BioCholine by evaluating gene expression of key allosteric effectors of hepatic fat and glucose metabolism in cobb 500 broilers in a 6-week study period. A total of 240 day old Cobb 500 broiler chicks were randomly allocated into two treatment groups (2 treatments x 6 replicates x 20 birds/pen). The two treatments were T1= choline chloride 60%, and T2=BioCholine at 35% of synthetic choline chloride 60%.

Quantitative real time reverse transcription polymerase chain reaction (qRT-PCR) and Adiponectin ELISA were performed at five weeks of age for assessment of peroxisome proliferator-activated receptors (PPAR) gene expression and adiponectin protein expression in the liver, respectively. The data were subjected to a one-way ANOVA using the GLM procedure.

The study showed that no significant difference in feed intake and FCR was observed, whereas average body weight in BioCholine group (2.49kg) was significantly higher by 130 g than the choline chloride group (2.36kg) at 42^nd day of experiment.

qRT-PCR and ELSA results indicated that BioCholine supplementation had hepatic gene expression of PPAR receptors with a significant increase by 39.03% compared to the choline chloride group (Figure 1). The chicken adiponectin level in liver tissues with BioCholine supplementation was significantly higher by 14.61% compared to that of the choline chloride supplement group (Figure 2).

Bioactive components in BioCholine act as agonists of peroxisome proliferator-activated receptors (PPARs), which induce adiponectin, a downstream hormone regulated by PPARS. This initiate changes in lipid metabolism by limiting free fatty acid uptake in the liver and fat breakdown for better energy utilization in the body and potentially can reduce a risk for fatty liver syndrome in poultry.

The study demonstrates that BioCholine can successfully and economically replace choline chloride at a significantly lower inclusion rate and provide additional beneficial effects in poultry.