This work aims at the identification of relevant intermediate metabolism enzymes contributing to improved meat production due to genetic selection. A wild rabbit (WR) breed and a highly meat selected breed (New Zealand (NZ) rabbit) were used. Food restriction was used as an experimental condition so as to enhance differences within the metabolic pathways under study. During a period of 30 days, NZ and WR experimental breeds were subjected to, respectively, 40% and 60% ad libitum food restriction leading to 17.7% and 21.1% initial weight. Hepatic glycolytic, lipidic and protein regulatory enzyme activity, transcriptional and metabolite levels were determined. Insulin-like growth factor (IGF-1), triiodothyronine, and cortisol were also evaluated. In the glycolytic pathways, the NZ control rabbits presented a higher phosphofructokinase and pyruvate kinase activity level when compared to the WR, while the latter group showed a higher expression of glycogen synthase, although with less glycogen content. In the nitrogen metabolism, our results showed a lower activity level of glutamate dehydrogenase in WR when subjected to food restriction. Within the lipid metabolism, results showed that although WR had a significantly higher mRNA hepatic lipase, non-esterified fatty acid levels were similar between the experimental groups. NZ rabbits presented a better glycemia control and greater energy substrate availability leading to enhanced productivities in which triiodothyronine and IGF-1 played a relevant role.Keywords: enzyme activity, intermediate metabolism, rabbits, regulatory enzymes, feed restriction
ImplicationsThe effects of feed restriction on the intermediate metabolism of breeds of rabbits selected for meat production induce an increase over non-selected rabbits on the efficiency of metabolic systems responsible for the homeostasis with reflection on the glycemia maintenance levels and on the excretion process of protein catabolism products. According to our results, seasonal draft periods inducing food restriction might not impair the use of highly productive breeds in upgrading animal production. Further studies are necessary regarding these metabolic pathways, including integrated genomic, transcriptomic and metabolomic approaches leading to results with practical consequences that are specifically required to upgrade livestock production in areas submitted to seasonal feedstuff shortage.