Liver metabolism traits in two rabbit lines divergently selected for intramuscular fat

Abstract

[EN] Intramuscular fat (IMF) has a large effect in the sensory properties of meat because affects tenderness, juiciness and flavour. A divergent selection experiment for IMF in Longissimus dorsi (LD) muscle was performed in rabbits. As liver is the major site of lipogenesis in rabbits, the objective of this work is to study the liver metabolism in the two rabbit lines selected for high and low IMF. Intramuscular fat content, perirenal fat weight, liver weight, liver lipogenic activities and plasma parameters related to liver metabolism were measured in the eight generation of selection. Direct response on IMF was 0.34 g /100 g of LD, which represented 2.7 SD of the trait, and selection showed a positive correlated response in the perirenal fat weight. High-IMF line showed greater liver size and greater liver lipogenic activities of enzymes glucose-6-phosphate dehydrogenase and malic enzyme (EM), although the difference between lines for EM activity was not relevant, whereas we did not find differences between lines for fatty acid synthase lipogenic activity. With regard to plasma parameters, low-IMF line showed greater plasma concentration of triglycerides, cholesterol, bilirubin and alkaline phosphatase than high-IMF line, whereas high-IMF line showed greater albumin and alanine transaminase concentrations, and all the differences between lines were relevant except for cholesterol concentration. We did not observe differences between lines for glucose, total protein and plasma concentrations. Phenotypic correlations between fat (IMF and perirenal fat weight) and liver traits suggested that liver lipogenesis affects fat deposition in both, muscle and carcass. None of the plasma parameters measured was strongly correlated with IMF.