Lipoprotein metabolism in poultry

Abstract

Understanding the metabolism of lipoproteins in birds is important to enable nutritionists to design diets aimed at obtaining better meat characteristics and egg quality, and can furnish useful information for future studies. In comparison to mammals, there are a number of expressive differences in the metabolism of lipids in birds, such as the transport of dietary lipids to the liver, hepatic lipogenesis and the presence of unique lipoproteins in the blood (portomicrons). Greater differences are found in egg-laying hens during the production phase, in which lipoproteins produced in the liver, under the action of oestrogen, are used for the formation of the egg yolk. The regulation of the lipid metabolism by hormones and the participation of key enzymes associated to advances in molecular biology techniques could assist in the genetic selection of more productive birds and better quality products for consumers.

Atherosclerosis: Comparative Pathogenesis, Lipoprotein Metabolism, and Avian and Exotic Companion Mammal Models

“…Triglycerides are produced in the liver of birds, with lipogenesis being limited in the adipose tissue, unlike in mammals. 40 Similar enzymatic pathways, HMG-CoA reductase and synthase, are present in avian tissues. In addition, the large lipid deposits in the egg yolk have to be transported from the liver to the oocyte.…”

“…41,42 Lipoproteins have been primarily investigated in commercial domestic fowl and in avian models of atherosclerosis (e.g., pigeon and Japanese quail). 40,[42][43][44][45][46][47][48][49][50] The roles of the different classes of avian lipoprotein are similar to mammals, but a few differences exist. VLDLs serve to not only transport endogenous lipids but also exogenous lipids from the small intestines.…”

Fatty Liver Haemorrhagic Syndrome in Laying Hens: Field and Experimental Investigations

“…In chickens, lipids and especially triglycerides are stored in hepatocytes, adipocytes, and growing oocytes (Alvarenga et al, 2011). Triglyceride storage in these compartments depends on the availability of a plasma lipid substrate originating from either the diet or lipogenesis in the liver.…”

“…Lipid storage in the oocytes is associated with vitellogenesis (Walzem et al, 1994), while excessive fat accumulation in the liver causes hepatic steatosis and FLHS, which are of much concern. In broilers, excessive accumulation of lipids in the adipose tissue is also a major concern, because most fat depots are lost during meat processing incurring losses for meat producers (Alvarenga et al, 2011).…”

The contributions of hepatic de novo lipogenesis to the difference in body fat mass of genetically lean and fat duck breeds

“…Earlier studies have established that the in vitro incorporation of glucose into lipids was uniformly high in liver slices from ducks aged 2, 4 and 10 weeks but was very low in the adipose tissues of these animals (Evans 1972). Most of the endogenous body lipids are of hepatic origin, and the growth and subsequent fattening of adipose tissue depend more on the availability of plasma triglycerides (TG; O'Hea and Leveille 1969; Alvarenga et al 2011). Our initial data in ducks also demonstrated that DNL mainly occurred in the liver instead of in adipose tissue (Ding et al 2012).…”