Thermoneutral housing worsens MASLD and reveals defective brown adipose tissue response to β3-adrenergic stimulation.

Metabolic dysfunction-associated steatotic liver disease (MASLD), and its more advanced stage metabolic dysfunction-associated steatohepatitis, is the most common chronic liver disease, constituting a major public health issue. Relevant preclinical models are needed to define molecular mechanisms underlying MASLD pathogenesis and evaluate therapeutic approaches. The majority of the lipids accumulating in the liver upon MASLD originate from adipose tissue and appropriate models to study the liver-adipose tissue dialog are also needed.

Development of hepatic steatosis in male and female mule ducks after respective force-feeding programs.

Male and female mule ducks were subjected to a force-feeding diet to induce liver steatosis as it is generally done only with male ducks for the production of foie gras. The different biochemical measurements indicated that the course of hepatic steatosis development was present in both sexes and associated with a huge increase in liver weight mainly due to the synthesis and accumulation of lipids in hepatocytes. In livers of male and female ducks, this lipid accumulation was associated with oxidative stress and hypoxia.

Evolution of oxidative stress markers in livers of ducks during force-feeding.

Mule ducks have been force-fed to develop a hepatic steatosis, also called "foie gras", which is similar to the non-alcoholic fatty liver disease (NAFLD) described in humans and mammals. However, in hepatic steatosis resulting from force-feeding of ducks, very little is known about the fine biochemical events that occur due to the enormous and very rapid increase in total lipids that mainly accumulate in hepatocytes. To begin to reduce this lack of knowledge associated with the development of this specific hepatic steatosis, liver samples were taken at different times to follow the overall biochemical transformation of the liver as well as different markers of oxidative stress, hypoxia and apoptosis.

Slightly different metabolomic profiles are associated with high or low weight duck foie gras.

Understanding the evolution of fatty liver metabolism of ducks is a recurrent issue for researchers and industry. Indeed, the increase in weight during the overfeeding period leads to an important change in the liver metabolism. However, liver weight is highly variable at the end of overfeeding within a batch of animals reared, force-fed and slaughtered in the same way.

Roles of Estrogens in the Healthy and Diseased Oviparous Vertebrate Liver.

The liver is a vital organ that sustains multiple functions beneficial for the whole organism. It is sexually dimorphic, presenting sex-biased gene expression with implications for the phenotypic differences between males and females. Estrogens are involved in this sex dimorphism and their actions in the liver of several reptiles, fishes, amphibians, and birds are discussed.

Proteomic Analysis of Two Weight Classes of Mule Duck "" at the End of an Overfeeding Period.

The weight of the liver is one of the important selection criteria in the quality of "foie gras". This factor is highly variable despite the fact that individuals are reared, overfed and slaughtered in the same way. In this study, we performed an analysis of the proteome profile of two weight classes of light (between 550 and 599 g) and heavy (more than 700 g) livers.

Cellular markers of mule duck livers after force-feeding.

The "Foie gras" or fatty liver is the result of hepatic steatosis from nutritional origin and induced by the force-feeding of palmipeds. Despite identical rearing and force-feeding conditions of ducks from the same breed, different liver weights, within a range of 500 to more than 700 g, are generally observed at the time of evisceration. To better understand the determinism of this large variability in fatty liver weights, the activity of various metabolic pathways has been explored in 4 groups of steatotic livers differing by their weights.

Evolution of liver fattening and foie gras technological yield during the overfeeding period in mule duck.

In foie gras production the technological yield after the cooking process is one of the main issues of processors as it is closely linked to the cooking melting rate. This rate is subjected to strict laws and regulations since it directly affects the organoleptic and technological qualities of this gourmet product. The objective of the study was to better understand the liver fattening and the technological yield decrease during the overfeeding kinetics.

Two-Dimensional Zymography of Proteases from Steatotic Duck Liver.

Protease activity present in liver cells with steatosis can be electrophoretically characterized. Zymographic techniques allow semi-quantitative results, successfully detecting cathepsin and metalloprotease activity using polyacrylamide gels copolymerized with gelatin and quantified by densitometry. By using specific inhibitors, the identity of the proteases can be confirmed.

Relationship between Proteolytic Activities and Cooking Loss Variability in Liver Issued from Force-Fed Mule Ducks.

We investigated liver protease activities to better understand the mechanisms responsible for losses during the cooking of Mule ducks' fatty livers. Fatty livers of similar masses (520 g) were randomly selected among a large flock of overfed male Mule ducks and divided into two groups on the basis of their cooking loss rate, L+ (high cooking losses, 36%) and L- (low cooking losses, 21%). In addition to dry matter and total lipid contents, main hepatic protease (matrix metalloproteinase 2, cathepsins, and calpains) activities were measured by zymography.

Using 2-DE for the differentiation of local chicken breeds.

The aim of this study was to apply a proteomic approach for the characterisation of local chicken breeds. The experiment involved a total of 29 males of three local Italian chicken breeds: Pépoi, Padovana and Ermellinata di Rovigo. Sarcoplasmic protein fractions of breast muscle were analysed by 2-DE.

Effects of physical activities on biochemical and biomechanical properties of tendons in two commercial types of chickens.

The aim of our experiment was to study the effects of physical activities on the biochemical and biomechanical properties of tendons in 12 standard (S) broilers and 12 Label Rouge (LR) chickens. In the two types of birds no differences were found between control and active birds for body weights. Gastrocnemius (Gas) tendon and Pectoralis minor (Pm) tendons were harvested and processed for passive stretch tests prior to cooking or not.

Genetic parameters of meat technological quality traits in a grand-parental commercial line of turkey.

Genetic parameters for meat quality traits and their relationships with body weight and breast development were estimated for a total of 420 male turkeys using REML. The birds were slaughtered in a commercial plant and the traits measured included pH at 20 min (pH20) and 24 h post-mortem (pHu) and colour of the breast and thigh meat. The heritabilities of the rate and the extent of the pH fall in the breast muscle were estimated at h2=0.

The effects of overfeeding on myofibre characteristics and metabolical traits of the breast muscle in Muscovy ducks (Caïrina moschata).

The aim of this experiment was to study the consequences of precise feeding on the myofibre characteristics and metabolic traits of the breast muscle (Pectoralis major, Pm) of Muscovy ducks. Twenty-four samples of breast muscle, without skin or subcutaneous fat, from two groups of ducks, control and overfed respectively, were collected at 14 weeks of age. We assayed different chemical (water content, crude proteins, total lipid ashes, total and thermosoluble collagen), biochemical (activities of the CS, LDH and beta-HAD enzymes), histological (muscle fibre typing and intramuscular adipocyte measurements) and technological (drip and cooking losses, texture) determinations.