Transcriptional analysis of abdominal fat in chickens divergently selected on bodyweight at two ages reveals novel mechanisms controlling adiposity: validating visceral adipose tissue as a dynamic endocrine and metabolic organ

Decades of intensive genetic selection in the domestic chicken (Gallus gallus domesticus) have enabled the remarkable rapid growth of today’s broiler (meat-type) chickens. However, this enhanced growth rate was accompanied by several unfavorable traits (i.e., increased visceral fatness, leg weakness, and disorders of metabolism and reproduction). The present descriptive analysis of the abdominal fat transcriptome aimed to identify functional genes and biological pathways that likely contribute to an extreme difference in visceral fatness of divergently selected broiler chickens. We used the Del-Mar 14 K Chicken Integrated Systems microarray to take time-course snapshots of global gene transcription in abdominal fat of juvenile [1-11 weeks of age (wk)] chickens divergently selected on bodyweight at two ages (8 and 36 wk). Further, a RNA sequencing analysis was completed on the same abdominal fat samples taken from high-growth (HG) and low-growth (LG) cockerels at 7 wk, the age with the greatest divergence in body weight (3.2-fold) and visceral fatness (19.6-fold). Time-course microarray analysis revealed 312 differentially expressed genes (FDR ≤ 0.05) as the main effect of genotype (HG versus LG), 718 genes in the interaction of age and genotype, and 2918 genes as the main effect of age. The RNA sequencing analysis identified 2410 differentially expressed genes in abdominal fat of HG versus LG chickens at 7 wk. The HG chickens are fatter and over-express numerous genes that support higher rates of visceral adipogenesis and lipogenesis. In abdominal fat of LG chickens, we found higher expression of many genes involved in hemostasis, energy catabolism and endocrine signaling, which likely contribute to their leaner phenotype and slower growth. Many transcription factors and their direct target genes identified in HG and LG chickens could be involved in their divergence in adiposity and growth rate. The present analyses of the visceral fat transcriptome in chickens divergently selected for a large difference in growth rate and abdominal fatness clearly demonstrate that abdominal fat is a very dynamic metabolic and endocrine organ in the chicken. The HG chickens overexpress many transcription factors and their direct target genes, which should enhance in situ lipogenesis and ultimately adiposity. Our observation of enhanced expression of hemostasis and endocrine-signaling genes in diminished abdominal fat of LG cockerels provides insight into genetic mechanisms involved in divergence of abdominal fatness and somatic growth in avian and perhaps mammalian species, including humans.https://doi.org/10.1186/s12864-017-4035-

Meat quality and muscle fibre traits in rabbits of different genetic origin and sex

The results obtained in this study confirm that B and F crossbreds are less precocious than H rabbits. Furthermore, this study demonstrate that among B and F crossbreds, the B achieves earlier the fixed slaughter weight and produce leaner meat with a lower proportion of white muscle fibers but without change in the meat pHu and colour values. Compared to the H and F animals, the B ones evidenced a tendency towards higher CSA for all the fibre types in LL muscle. Further research need to be done in this area in order to clarify the relationship between the genetic origin and the fibre traits in rabbits slaughtered at advanced age for commercial purpose

Développement musculaire des poulets issus de lignées à croissance rapide ou lente

Cet article fait partie du dossier : Le déterminisme génétique du développement musculaireNational audienc

Effect of feed restriction during post-weaning growth on muscle energy metabolism and on fibre contractile and metabolic properties of biceps femoris muscle in the rabbit

none3Abstract in World Rabbit Science Journal (2004), 12,57-58.noneDALLE ZOTTE A.; REMIGNON H; OUHAYOUN JDALLE ZOTTE, Antonella; Remignon, H; Ouhayoun, J

Effect of feed restriction during post-weaning growth on fiber characteristics of Biceps femoris muscle in the rabbit

At weaning (five weeks of age), 50 hybrid rabbits were at random divided into five groups (labelled blocks). Block 1, which were fed ad libitum with a commercial diet during weaning period, were slaughtered. The remaining rabbits were placed in individual cages and fed the same amount of food until slaughter, but differently rationed. From 5 to 8 wk of age, the rabbits coming from blocks 2 and 4 received 70% of ad libitum, meanwhile those belonging to blocks 3 and 5 received 90% of ad libitum. Animals of blocks 2 and 3 were slaughtered at 8 wk of age, while those of blocks 4 and 5 received the reverse restriction level and were slaughtered at 11 wk of age. All the animals were weighed before slaughter and the Biceps femoris muscle was immediately dissected and thereafter its fibers were typed (\u3b2R, \u3b1R and \u3b1W) and mean cross-sectional area was determined for each muscle. As expected, at eight-weeks slaughter age, rabbits given for 3 weeks the strictest feed restriction (70% of the ad libitum) showed the lowest body weight but presented significantly higher (P<0.01) body weights after successive 3 weeks of rationing at 90% of the ad libitum, if compared with the rabbits that followed the inverse feeding treatment. The 70-90% rationing mode reduced the proportion of oxidative fibers. No relationship was found between the enlargement of muscle fibers and body weight. At the light of actual knowledge further investigations are needed to better understand the relationship between feed restriction and fiber characteristics