Changes in Adipose Tissue Physiology during the First Two Weeks Post‐hatch in Chicks from Lines Selected for Low or High Body Weight

Abstract

Chickens from lines selected for low or high body weight from a common foundation population differ in appetite and adiposity; however, mechanisms associated with the predisposition to becoming obese are unclear. The objective of this study was thus to evaluate developmental changes in depot‐specific adipose tissue during the first 14 days post‐hatch. The subcutaneous (SQ), clavicular (CL) and abdominal (AB) adipose depots were collected for histological and mRNA expression measurements from chicks of each line on day of hatch, day 4 and day 14 post‐hatch. Results showed that low line chicks had decreased SQ fat mass on a body weight basis with reduced adipocyte size from day of hatch to day 4 and increased body weight and fat mass with unchanged adipocyte size from day 4 to day 14 post‐hatch. High line chicks had increased body weight throughout the first 14 days post‐hatch, and increased fat mass in all three depots with significantly enlarged adipocytes in AB from day 4 to day 14 post‐hatch. Meanwhile, mRNA expression of CCAAT/enhancer‐binding protein alpha, neuropeptide Y and peroxisome proliferator‐activated receptor gamma, which are involved in adipogenesis, as well as acyl‐CoA dehydrogenase, long chain, which catalyzes fatty acid oxidation, had different expression patterns among depots between lines at different ages. From day of hatch to day 4 post‐hatch, low line chicks mobilized SQ fat and replenished the reservoir mainly through hyperplasia, whereas in the high line there was dependency on both hyperplasia and hypertrophy to maintain adipocyte size and depot mass. From day 4 to day 14, adipose tissue catabolism and adipogenesis slowed down in both lines. While the fat depot mass and adipocyte size were stable in the low line, there was rapid accumulation of fat in CL and AB regions of high line. Chicks predisposed to be anorexic or obese display different fat development patterns during the early post‐hatch period.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.